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In The Queue 



Volume 6, Number 3 



March 1981 



Features 

20 Structured Programming and 

Structured Flowcharts by Gregg Williams 

A technique that makes programs easier to 
write, understand, fix, and change. 

36 Build the Disk-80: Memory 
Expansion and Floppy-Disk Control by 

Steve Garcia / Steve discusses how to use 
dynamic memory and floppy-disk-controller in- 
tegrated circuits and presents a design that in- 
corporates them. 

54 Three-Dimensional Computer 

Graphics, Part 1 by Franklin C Crow / Ways 
to display solid objects with the removal of hid- 
den lines and surfaces. 

132 What Is Good Documentation? 

by Jim Howard / How to write clear and effec- 
tive documentation. 

166 A Beginner's Guide to Spectral 

Analysis, Part 2 by Mark Zimmermann 

Images can be transformed into holograms via 
Fourier transforms. 

262 A Simple Approach to Data 

Smoothing by Fred Ruckdeschel and Janice 
A Krinsky / The techniques described here can 
aid in the interpretation of data taken from real- 
world situations. 

300 The New Literacy: Programming 

Languages as Languages by Jon Handel 

BASIC, ALGOL, and APL are compared to the 
English language. 



317 Computer Music: A Design 

Tutorial by Thomas P Orlofsky / A modest 
amount of theory provides the background for 
building a simple program-controlled digital tone 
generator. 

Reviews 

84 The Micro Matrix Photopoint Light 

Pen by Stephen B Gray 

90 What's Inside Radio Shack's Color 
Computer? by Tim Ahrens, Jack Browne, and 
Hunter Scales 

Nucleus 

6 Editorial: Is This Really Necessary? 
12 Letters 
152, 333 Programming Quickies: Computing the 

Determinant of a Matrix: Constellation I: An 

Astronomy Program 
155 Languages Forum: A Coding Sheet for FORTH 
164, 314, 316 BYTE's Bits 
216, 224, 234 Technical Forum: DATALINE; Addition 

and Subtraction: The 1802 Versus the Z80; Build 

a Simple Video Switch 
230 Desk-Top Wonders: Hunt the Wumpus with 

YourHP-41C 
236 System Notes: Software Addressing Modes for 

the 8080 
242 BYTELINES 
248 Software Received 
252 Books Received 
254 Ask BYTE 
308 Event Queue 
315 Clubs and Newsletters 
337 What's New? 

382 Unclassified Ads 

383 BOMB, BOMB Results 

384 Reader Service 



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Page 317 



March 1981 © BYTE Publications Inc 3 



m 



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In This Issue 

Do you have trouble making all the pieces fall in place when you are 
writing a new program? Robert Tinney's cover this month symbolizes the 
theme of programming methods. But the symbolism is only pictorial— the pro- 
cess of designing and putting a new program together is often much harder 
than assembling an intricate jigsaw puzzle. This issue includes several articles 
on different aspects of programming and design: "What Is Good Documenta- 
tion?" by Jim Howard; "Structured Programming and Structured Flowcharts" 
and the editorial, "Is This Really Necessary?", both by Editor Gregg Williams; 
"A Coding Sheet for FORTH," by John O Bumgarner; and "A Simple Ap- 
proach to Data Smoothing," by Fred Ruckdeschel and Janice A Krinsky. 



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Editorial 



Is This Really Necessary? 
A First Look at Design Techniques 

Gregg Williams, Editor 

Complete the following sentence: 

When I start programming, the first thing I 
do is . 

Some people draw flowcharts. A few adventuresome — usually foolhardy 
— souls type in lines of BASIC directly on their computers. Most of us start by 
scribbling and sketching on sheets of paper. However, is that enough? Perhaps 
so, if you're writing for yourself; but if anything important is at stake — time, 
money, or reputation — you probably need to spend more time designing. 

In this editorial, I'll show you what design is, why you need it, and how it 
works. I'll also present some new design tools (of which there are more and 
more every day), a design example, and a sampling of good books on design 
and programming. I promise to stay as far away from the concept of "struc- 
tured programming" as possible. Much has been written about it elsewhere. I 
want to concentrate on what happens before you start programming. 

What Is Design? 

Webster's New Collegiate Dictionary defines design, the verb, as "to con- 
ceive and plan." As a noun, a design is "a preliminary sketch showing the main 
features of something to be executed." In terms of programming, design 
becomes proportionately more important depending on the size of the prob- 
lem: We speak of program design when we write a game program for 
ourselves, project design when we design and write an accounting system on 
an existing computer at work, and system design when we draft a proposal for 
a hardware/software combination that will implement a given set of re- 
quirements for a data base system. (Actually, "system design" is used in the 
literature to describe the design of anything larger than one program; but I 
wanted to make a distinction between project design and system design 
because of the widely varying amounts of work they require.) 

In designing and writing programs, I've found that the point dividing system 
design from program design is the point at which I have specified the function 
of the program and its use of computer resources (eg: are records stored on 
disk in a random-access file and called as needed, or are they read into 
memory before any processing is done?). After this point, I am designing the 
program (usually a fairly straightforward — though nontrivial — process). 
Before this point, I'm making certain critical decisions that strongly influence 
the requirements and performance of the proposed implementation of the pro- 
gram. In this sense, such decisions will often need to be made even when I'm 
designing and writing a single program. I can then see that both system design 
and program design have enough in common so I can eliminate the modifier 
and speak simply of design. I can safely say then that design is concerned with 
making a set of performance-related decisions and specifying the program(s) 
that implement them. 

(An integral part of design, of course, is documentation. Documentation of 
the overall design should be followed by documentation of the program design 
and its implementation. The finished documentation package, which should 
clarify both the organization of the system/project/program and the details of 



March 1981 © BYTE Publications Inc 



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Editorial 

the program(s) involved, will be of immense help to you, 
or anyone else, during debugging, testing, and 
maintenance.) 

To put the role of design in perspective let's look at the 
lifespan of a medium-sized system: 

• (System) Design: This is the step I talk about in most of 
this article. It includes finding out what the problem is, 
devising alternative schemes to solve it, deciding on the 
one that (you think) will result in the "best" implementa- 
tion, and filling in the design details with regard to the 
items that go into the system (input), the manipulations 
made on these items (process), and the results that are 
generated by the system (output). By the end of this pro- 
cess, you will have divided the entire system into pro- 
grams and specified the input, process (what, not how), 
and output of each one. 

• Program Design: This is where structured program- 
ming is used. You know what the program is supposed to 
do and what computer resources are to be used; now you 
must fill in the details of how its objectives are to be ac- 
complished. It is commonly accepted that the best way to 
design a program is to repeatedly break the task to be ac- 
complished into subtasks, until each subtask is simple 
enough to be programmed in the language you are using. 
Note that the design process ends without your having 
written any lines of computer code. In this step, you are 
simply filling in the details of what the program is to do 
without worrying about the particular syntax of the com- 
puter language you will use. (There are numerous design 
notations to help in this process. The two I like most are 
structured pseudocode, described below, and structured 
flowcharts, which is described in my article, "Structured 
Programming and Structured Flowcharts," on page 20 of 
this issue.) 

• Coding: This is what most people call "programming," 
even though they are referring to the entire design/ coding 
process. Coding is the specific act of translating a pro- 
gram design into the particular syntax of the computer 
language you are using (often called the target language). 
The more detailed the design is, the more coding becomes 
a rote task. The completeness of the design is determined 
by several factors. These are: how well you think you 
know the application being programmed and the com- 
puter language used, how important it is to get the pro- 
gram right the first time, and how many surprises (mostly 
of the "oops, I forgot to..." kind) you can tolerate during 



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8 March 1981 © BYTE Publications Inc 



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now, they're something to think 
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at one of our three mainframes, at 
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(Series II boards are compatible 
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as other manufacturers get around 
to building them.) 

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and beyond. Full compatibility 
with 8- and 16-bit CPUs, pe- 
ripherals and other devices. Eight 
levels of prioritized interrupts. Up 
to 16 individually-addressable 
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overlapped operation. User-selec- 
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switch or jumpers, eliminating sol- 
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The best part is that all this 
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our advanced processor — a full 
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Whatever your needs, why 
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Ithaca Intersystems Inc., 

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607-257-0190/TWX: 510 255 4346 




Micros for bigger ideas. 




/ 



BYTE March 1981 



Editorial. 



coding. In most informal situations (ie: when you're not 
programming for hire), a sketchy design provides an ac- 
ceptable compromise between no design and a rigorous 
design. 




Figure 1: A pie chart giving average percentages for activities 
within the process of designing, writing, and testing a program. 
The chart does not include maintenance of the program, which 
is estimated to take twice as much time as design, writing, and 
testing. 




(Let your computer play psychiatrist!) 

ANALIZA is a program which simulates a 
conversation with a psychiatrist. You are the 
patient, the computer becomes the doctor. 

ANALIZA is based on the famous "Eliza" 
program from MIT some years back, but has 
been greatly enhanced. It provides both enter- 
tainment as well as an interesting example of 
Artificial Intelligence. Below is a sample: 

Patient: I have feelings of paranoia 

Computer: Does it please you to have 
feelings of paranoia? 

Patient: No it bothers me 

Computer: Then why have feelings of 
paranoia? 

ANALIZA is a match for anyone. 

Requires: 48K CP/M, CBASIC2 
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• Testing and Debugging: This section is actually two in- 
tertwined processes — testing, the search for errors (both 
syntactic and logical), and debugging, the elimination of 
those errors. Most programmers estimate that this pro- 
cess can take as much time as both designing and coding. 
The results in figure 1 (by M V Zelkowitz in " Perspec- 
tives on Software Engineering," ACM Computing Sur- 
veys, June 1978, page 198) support this conclusion. The 
amount of needed debugging and testing greatly increases 
depending on the program's size and importance. It de- 
creases with the amount of design and structured pro- 
gramming carried out before the coding. In a multi- 
program system, programs are first tested and debugged 
(labeled "module test" in figure 1), then the entire system 
is tested and debugged (labeled "integration test" in figure 
1). 

• Maintenance: This section applies mostly to large pro- 
grams for personal use and systems that are used in a 
work environment. Maintenance runs the gamut from 
fixing the occasional (or not-so-occasional) bug, to add- 
ing new features, or to moving a system of programs to 
an entirely new computer system. It's been estimated that 
maintenance occupies up to 90 percent of a (professional) 
programmer's time. Fortunately, most personal computer 
users don't have to carry this burden. 

Why Designing Is Necessary 

Whether we like it or not adventures begin only when 
something unexpected happens. In fantasy, adventures 
are always positive and exciting; in real life and in pro- 
gramming, they are usually unwanted, inconvenient, and 
sometimes costly or dangerous. Only short personal pro- 
grams can squeeze by without some basic design work 
behind them. If the program gets longer, or if you are 
writing for somebody else (either friends or employers), 
you probably can't afford a programming "adventure." 
Remember that the design process includes finding and 
making decisions that influence the quality of a program 
or system. In other words, the more important it is to 
write the best program, the more design you need to do. 

Here are some reasons that argue strongly in favor of 
well-thought-out design: 

• Limited resources (eg: not enough computer memory or 
disk space, or a slow system response time) 

• Time/money constraints (ie: the need to complete a 
program or system within deadline and under budget) 

• The need for increased reliability 

• The need for program stability and flexibility in the face 
of long-term maintenance 

In addition to contributing to the quality and reliability 
of a program, design also contributes to your mental 
health as a programmer — you usually save time when 
you design; you eliminate all-night emergency program- 
ming marathons; the process of testing and debugging is 
shorter and less nerve-racking; and you're less likely to 
have your program "crash" at an embarrassing or crucial 
moment. 

Some Popular Excuses, and Rebuttals 

"I don't know where to start": Read some of the books 

Text continued on page 200 



10 March 1981 © BYTE Publications Inc 



Circle 7 on inquiry card. 



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IEEE -488 Controller in a snap. 



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Our board converts the Apple II into a truly sophisticated controller that 
programs and controls up to 15 different instruments connected together 
on the 488 bus. 

We make programming easy. The 68488 chip, designed by Motorola, forms the 
heart of our A488. We back this chip with powerful on-board firmware to 
give you system control via simple string commands. The only software 
you need is easy-to-program Applesoft* Basic. To develop special purpose 
firmware, simply replace our PROM with a RAM. With the A488, bus com- 
munications operate at top speed — without depending on software loops for 
timing. And like the more expensive IEEE-488 controllers, this system interfaces 
with more than 1200 instruments and peripherals. 

Suitable for OEMs as well as end users. Whether you make test/measurement systems for 
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Letters 



On Technical Writing 

I enjoyed Chris Morgan's editorial on 
technical writing ("What's Wrong with 
Technical Writing Today?" December 
1980 BYTE, page 6), but there is a sad 
exception to his first law: Academics can 
benefit from not writing clearly. I sug- 
gest a paper by J S Armstrong in the 
April 1980 Interfaces, published by The 
Institute of Management Sciences. 

Armstrong, from the Wharton School, 
found that material more difficult to 
read was rated higher in research com- 
petence. "Management scientists gain 
prestige by unintelligible writing." My 
wife, an academic biologist, and I have 
seen similar hypotheses about academic 
publishing in computer science. {Com- 
munications of the ACM may be a 
perfect example.) 

Since such "news" would only under- 
mine the effort you folks are making at 
BYTE, you must keep all this a secret. 

Gerald Ruderman 
Management Decision Systems Inc 
300 Third Ave 
Waltham MA 02154 



In the December 1980 editorial, Chris 
Morgan says that "Jargon isn't intrin- 
sically bad...." 

Ha! I caught you. Jargon is intrinsical- 
ly bad; it may be necessary sometimes — 
an evil necessity — but it's always bad. 
I've often wondered if those who edited 
BYTE were in favor of jargon. Now I 
know. 

Like many aspects of our society, 
jargon has two purposes: an obvious 
one, and a hidden, unadmitted one. The 
obvious purpose is to save space, as Mr 
Morgan pointed out. The hidden one is 
to exclude outsiders from the circle of 
the insiders. 

To use jargon in explaining the work- 
ings of a particular product would be 
justifiable in a manual directed toward 
sophisticated, knowledgeable profes- 
sionals, if the product were released in a 
specific, well-known context. An exam- 
ple is all the funny words people 
familiar with IBM equipment always 
use. Such an approach in a journal like 
BYTE is entirely inappropriate. 

The distinctive difference between 
BYTE and some of its less successful 



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competitors is that many BYTE articles, 
even though written in jargon, try to ex- 
plain something, while too many articles 
in other magazines use jargon purely for 
the purpose of mystifying. 

Jargon may have many purposes, but 
the rapid, effective spread of informa- 
tion is not one of them. If you really 
wish to communicate ideas, write in 
English — or some common human lan- 
guage. 

The balance of Mr Morgan's editorial 
was actually quite to the point. I'd like 
to add, "DON'T use big concepts when 
small ones will do." 

James Gregor Owen 
14 Ocean Dr 
Freeville NY 13068 

The December editorial apparently 
struck a nerve among readers, judging 
from the comments we received. Mr 
Owen raises a point I did not cover: the 
"high priesthood" syndrome that arises 
when a writer sets out to impress and 
mystify through jargon. At BYTE, we 
wage a (not always successful) battle 
against this philosophy, and hope that 
our readers will continue to tell us when 
we go astray. I'd also like to thank the 
editors at General DataComm Industries 
Inc, Danbury, Connecticut, and several 
other readers who caught some minor 
gaucheries in my editorial. Oh, the irony 
of it.... CM 



Intel's Educational Products 

As the manager of Intel Corporation's 
Educational Products Group I would like 
to thank BYTE for suggesting our com- 
pany as a source for blemished com- 
ponents. Steve Ciarcia's reply to an 
"Ask BYTE" letter has generated a large 
response from students and educators. 
(See "Quick and Cheap," December 1980 
BYTE, page 320.) In order to help 
BYTE's readers to more fully benefit 
from our program, I would like to bring 
some additional information to their at- 
tention. 

The Educational Products Group has 
the responsibility for the administration 
of the component kit program. To avoid 
delays of up to 4 weeks, all inquiries 
should be directed to us, not the product 
manager. 

We no longer offer an 8080-based kit; 



12 



March 1981 © BYTE Publications Inc 



Circle 8 on inquiry card. 



Circle 9 on inquiry card. 







Edison had over 
1,800 patents in 
his name, but 
you can be just as inventive 

with an Apple. 






Apple is the company with the brightest ideas in 
hardware and software and the best support — so you can 
be as creative with a personal computer system as Edison 
was with the incandescent bulb. 

How Apple grows with you. 

With Apple's reliable product family, the possibilities of 
creating your own system are endless. Have expansion capa- 
bilities of 4 or 8 accessory slots with your choice of system. 

Expand memory to 64K bytes or 128K bytes. Add an 
A to D conversion board. Plug into time sharing, news and 
electronic mail services. Use an IEEE 488 bus to monitor 
lab instruments. Add 4 or 6 disk drives — the 5 l A" 143K 
bytes, high-speed, low-cost drive that's the most popular 
on the market. 

Apple speaks many languages. 

Since more than 100 companies create software for 
Apple, you'll have the most extensive library in the personal 



computer world. Want to write your own programs? 
Apple is fluent in BASIC, Pascal, FORTRAN, PILOT and 
6502 assembly language. 

There's even a series of utility programs called the 
DOS Tool Kit that not only lets you design high-resolution 
graphic displays, but lets you work wonders with 
creative animation. 

More illuminating experiences in store. 

You won't want to miss all the Apple products being 
introduced at your computer store all the time. Don't let 

A history pass you by. Visit your nearest 
.^fejEfe. Apple dealer or call 800-538-9696. 
In California, 800-662-9238. Or write: 
^ Apple Computer, 10260 Bandley Drive, 
^ Cupertino, CA 95014. 

cippkz computer inc. 




Letters ..1.—.— —————— 

instead we offer a broad line of kits 
based upon the 8085, 8048, 8086, and 
8088 microprocessors. The 8086 and 
8088 kits include a serial monitor. Kit 
prices range from $35 up to $90, and 
each contains enough components to 
construct a minimum system. 

Intel is in the process of expanding the 
program, and we publish a quarterly 
magazine to let prospective members of 
the academic community know of these 
developments. 

Please contact us if you would like 
more information on how we can help 
you. Our telephone number is (408) 
987-5020. 

Steven A Lapham 

Manager, Educational Products 

Intel Corporation 

3065 Bowers Ave 

Santa Clara CA 95051 



Intertec Responds to Criticism 

In response to Mr Phillip Lemmons's 
letter (see "Superb Brain," October 1980 
BYTE, page 22), I would like to make 
the following observation. We at Inter- 
tec disagree with his analysis of the situ- 
ation and feel that clearing up the facts 



would be a benefit to Intertec and our 
users alike. 

Everyone must realize that nothing re- 
mains static in the computer industry. 
New ideas constantly emerge, resulting 
in a stream of new developments. The 
continual upgrading of technology, and 
the subsequent evolution of computer 
software and hardware, is the basis of 
high technology as all of us know it to- 
day. As responsible manufacturers, we 
feel obliged to pass on these techno- 
logical advancements to our users. 

As improvements are added to our 
products, we offer our previous 
customers, whenever feasible, an 
upgrade option at nominal cost. If the 
modification cannot be accomplished 
with a simple EPROM change, for in- 
stance, we still feel a responsibility to 
offer some kind of solution to our 
customers. 

Such is the case with Mr Lemmons's 
"$1500 enhancement." The modifications 
to which he refers involved changing the 
whole unit: processor module, power 
supply assembly, disk drives, etc. In 
January 1980, the SuperBrain was 
modified to offer even more capabilities 
than our advertisements claim. There- 
fore, had Mr Lemmons purchased this 
enhancement, he would, in effect, have 



MARK GORDON 

COMPUTERS 

DIVISION OF MARK GORDON ASSOCIATES. INC 

P.O. Box 77, Charleston MA 02129 1617)4917505 



COMPUTERS 

Atari 800 W I 6K 799.00 

4K Model III 599.00 

Model-It C.4K System 1499.00 

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80 Tradi 5 >/t 544.00 

4DiskDriveCable 39.00 

PRINTERS 

Centronics 730 599.00 

Epson MX80B Call for price 

Centronics 737 849.00 

Okidata Mictoline 83 1044.00 

Integral Data 440G 999.00 

NEC 5 510 wrractot 2679.00 

Olddata Microline 80 599.00 

Diablo 630 2495.00 

MISC HARDWARE 

Expansion in TRS80(Olt) 249.00 

Novation D-Cat Modern 166.00 

I t>l< Memory Kit 41.99 

Leedex Monitof 1 09.00 

Printer Cable for above . ... 49.00 

ISO 2 Isolator 54.00 

ACLINEFILTER 24.00 

STORAGE MEDIA 

Scotch-box 1 0-5 14 27.00 

Memorex-box 105'. 22.00 

Plastic Siorage Box 5.00 



OPERATING SYSTEMS 

NEWDOS by APPARAT INC 49.00 

NEWDOS+ by APPARAT INC 99.00 

MMS FORTH DISKETTE PRIMER 79.95 

NEWDOS 80 1 49.00 

DISKETTE TRS-80* 
BUSINESS SOFTWARE BY SBSG 

Free enhancements and upgrades to registered owners lor 
the cost ol media and mailing 30 day Iree telephone sup- 
port User reference on request 
Fully Interactive Accounting Package. General Ledger, 

Accounts Payable. Accounts Receivable and Payroll 

Report Generating 

Complete Package (requires 3 or 4 drives) 5475.00 

Individual Moduleslrequires 1 or 3 drives) 51 25.00 

Inventory II (requires 2 or 3 drives) $ 99.00 

Mailing List Name 6. Address II 

(requires 2 drives) $129.00 

Intelligent Terminal System ST 80 III 5 1 50.00 

TheEleclnc Pencil f torn Michael Shrayer 5150.00 

file Management System $ 49.00 



FINE PRINT 
TRS-ao is a Tandy Corporation trademark use ot above operating sys 

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ORDERING INFORMATION 

We accept Visa and Masteicharge We will ship COO certiliedcheck 

oi money o'dcs only Massachusetts residents add 5 percent sales lax 

To order call toll Iree 1 600 343-5206 

For mlormalion call 617-4917505 

Tha Company cannot be liable tor pictorial or typographical inaccuracies. 



received a completely new unit for 
$1500 — half the end-user cost for the 
same unit. 

As for the software problem Mr 
Lemmons referred to, we are confident 
that an EPROM update costing $100 
would have taken care of his problems. 
Mr Klein of Information Engineering 
sold it to him for $150. Admittedly, Mr 
Lemmons may have received this update 
a little sooner than he would have had 
he purchased directly from the factory; 
nevertheless, the EPROM is available 
from us. 

For an end-user price of $2995 for our 
basic SuperBrain model, we think (and 
we have thousands of testimonials from 
happy SuperBrain users to support this) 
that Intertec offers the best price/perfor- 
mance ratio in the industry. 

If any other BYTE readers have prob- 
lems similar to Mr Lemmons's, please 
call our Product Services department at 
(803) 798-9100. Our staff of application 
engineers will be glad to assist you in 
any way possible. 

At Intertec, the customer has always 
been (and still is) our main concern. Our 
phenomenal growth in recent years 
would not have been possible if we did 
not hold steadfastly to this simple 
management principle. We hope Mr 
Lemmons (and any others who may be 
dissatisfied with us) will understand our 
point of view and give us a chance to 
demonstrate the sincerity of all of our 
customer-support programs. 

Denise Stevens 

Marketing Communications Manager 

Intertec Data Systems 

2300 Broad River Rd 

Columbia SC 29210 



Hurray for muSIMP 

I recently purchased muSIMP/ 
muMATH for my Radio Shack TRS-80 
Model I, so I was interested in Gregg 
Williams's review in the November 1980 
BYTE. (See 'The muSIMP/ 
muMATH-79 Symbolic Math System," 
page 324.) The version I purchased is the 
small, inexpensive TRS-80 version, 
which does not include the trace, array, 
and matrix packages. 

While the discussion of muMATH was 
complete, I was disappointed that Mr 
Williams only touched briefly on the ca- 
pabilities of the underlying muSIMP lan- 
guage used to implement muMATH. 
The introduction of a low-cost version 
(or any version) of LISP for the TRS-80 
should be marked as a major develop- 
ment. muSIMP is a close cousin of LISP, 
and, in this light, muMATH is seen as a 
powerful illustration of its capabilities. 
The impressive achievements of muMath 



14 



March 1981 © BYTE Publications Inc 



Circle 10 on inquiry card. 



Introducing the COLOR CONNECTION 

Plug A TRS-80 * Color 
Computer into the World of 
System-50" Computing. 

Now you can expand Tandy's exciting new TRS- 
80* Color Computer using proven System-50 
products. Expansion possibilities are limitless. 
And expansion is easy. Plug one end of the 
COLOR CONNECTION into the Program 
Pak* connector of the Color Computer. 
Plug the other end into a System-50 bus 
motherboard. Now add the functions you 
want, selecting from an inventory of 
standard modules manufactured by 
competent, long-established firms 
— from the inventory of solid per- 
formers, like Percom Data 
Company. 

Mini-disk storage — today! 

Available off-the-shelf for your ex- 
tended system is Percom's field- 
proven LFD mini-disk system. The 
first choice of knowledgeable 680X 
computerists since 1977, Percom 
LFD mini-disk systems come com- 
plete, ready to plug in and run. File 
storage capacities range from 102 
Kbytes for a one-drive LFD-400™ 
system to almost 0.6 
Mbyte for a three-drive 
LFD- 800™ system. 






Get serious! 

For serious computing like 
word processing add the Per- 
com ELECTRIC WINDOW™. 
This memory-mapped video 
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formed upper and lower case 
characters, and more. The 
ELECTRIC WINDOW pro- 
vides either composite or sepa- 
rate sync-video output, and 
interfaces a standard black-&- 
white video display monitor. 



System Requirements 



The COLOR CONNEC- 
TION interfaces a TRS-80* 
Color Computer to a System- 
50 bus motherboard. Power for 
the COLOR CONNECTION is 
obtained from the computer. Power 
for the extended bus cards must be pro- 
vided by an external source, such as Percom's System-50 
Power Supply. The COLOR CONNECTION provides for 
disabling the computer internal memory at 8-Kbyte 
boundaries to prevent contention with external memory. 

The COLOR CONNECTION $99.95 



Beyond 16K 

Another option is incremental 
memory expansion. Add 8-, 16- or 
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dynamic RAM with our M48DSS card. 
The COLOR CONNECTION prevents 
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The right motherboard 

Fast mini-disk storage, full-format alphanumerics and 
memory add-on are obvious expansion possibilities. The 
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with our 30-pin I/O motherboard. The richness of readily 
available peripheral interface cards provides an uncom- 
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The System-50 (SS-50) bus community. With a TRS-80* 
Color Computer and the COLOR CONNECTION, it's 
your world. Enjoy! 



Quality Percom products are available at Percom dealers nation- 
wide. Call toll-free, 1-800-527 1592. for the address of your 
nearest dealer, or to order direct from Percom. 



PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE. 
PRICES DO NOT INCLUDE SHIPPING AND HANDLING. 

™ trademark of Percom Data Company. Inc. 

* trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company. 




PERCOM DATA COMPANY, INC. 

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Circle 11 on inquiry card. 



Letters _^^— __ 

have overwhelmed the fact that muSIMP 
is a general language suitable for more 
than symbolic mathematics applications. 
The differences between muSIMP and 
LISP are mostly at the user interface. 
The input syntax and the output format 
have been altered to provide a congenial 
environment for symbolic mathematics, 
but internally muSIMP is LISP with only 
a few minor alterations (which could 
well be regarded as improvements over 
the original). These alterations are sum- 
marized in "LISP-Based Symbolic Math 
Systems" by David R Stoutemyer, which 
appeared in the BYTE LISP issue of 
August 1979, page 176. 

At $75 (plus another $20 for the com- 
plete reference manual) muSIMP for the 
TRS-80 is a great bargain. Yet 
Microsoft's ads have pushed muMATH 
with only a passing reference to 
muSIMP's close relationship to LISP. 

The documentation that comes with 
the TRS-80 version of muSIMP/ 
muMATH does not include a number of 
important muSIMP functions. For exam- 
ple, the functions related to property 
lists are not even mentioned. Property- 
driven functions are a major component 
of muMATH's power and extensibility. 
The TRS-80 owner who wants to ex- 
plore the power of muSIMP definitely 



needs to purchase the full reference 
manual to supplement the material that 
accompanies the package. 

The full reference manual is im- 
pressive. It includes listings of on-line 
tutorials apparently available with the 
larger CP/M version. Unfortunately, it 
does not specifically address the system 
environment of the reduced TRS-80 
package. A number of system functions 
are not included (SAVE, LOAD, 
OBLIST). While the manual is extremely 
useful to the TRS-80 owner, it would be 
even more useful if it included a sum- 
mary of the differences between the full 
CP/M version and the reduced TRS-80 
version. 

In short, for the TRS-80 owner who is 
interested in experimenting with artificial 
intelligence projects, muSIMP alone is 
worth the price of the muSIMP/ 
muMATH package. 

John R Goldin 
66 Brownell St 
New Haven CT 06511 



BYTE Saluted 

I am a career Army officer. After five 
years of assignments outside of the data- 



processing field, I have returned to that 
arena; however, the landscape has 
changed. It is covered with new tech- 
nology, methods, technical terms, and 
jargon. 

I want the world to know how useful 
BYTE is in overcoming the insecure feel- 
ing of operating in this new landscape. 
Particularly noteworthy and helpful is 
BYTE's editorial policy of parenthetically 
explaining all jargon and technical terms. 
While other trade journals seem to take 
delight in obscurity, BYTE consistently 
targets on clarity. I hope other publica- 
tions will follow BYTE's lead. It's 
needed. 

Keep up the good work, BYTE! 

James H Powers 

Lieutenant Colonel, US Army 

Director, ADP (Automatic Data Processing) 

Support Division 
US Army War College 
Carlisle Barracks PA 17013 



Self-Replicating Code 

I would like to point out the shortest 
self -replicating program I know of. It is 
written in Microsoft BASIC, as found in 
the Commodore PET (also known as the 



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16 



March 1981 © BYTE Publications Inc 



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Letters, 



CBM 2001). It relies on the fact that 
PET BASIC sees all commands the same 
way. In many BASICs, you can write a 
1-line instruction without a line number 
and it will be executed when entered. 
But PET BASIC also allows commands 
like RUN or LOAD to be inserted into a 
program with a line number, like any in- 
struction. The program is: 

1LIST 

Because of the compact storing of code 
in the PET's memory, the program takes 
up only 2 bytes, one for the line num- 
ber, and one for the PET's internal 
representation of LIST (the space be- 
tween is provided by the subroutine that 
controls the printout of integers). 

I'm currently in the 9th grade, and am 
fluent in BASIC. I intend to learn 
Pascal when the school library gets the 
book it just ordered. 

William Sommerfeld 
3 Mary Ln 
Greenvale NY 11548 



Printers Challenged 

For some months now, I have been 
searching for a printer that meets all of 
my needs, and have met with little suc- 
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want by looking at magazine advertise- 
ments, visiting computer stores, and 
circling numbers on reader-service cards. 
I would like to issue this challenge: 

If any printer manufactuer or distributor 
has a machine that fits all (and I mean 
all) of the requirements listed below, I 
will buy it, pure and simple. 

• It must have some form of letter- 
quality printing. A fast, low-quality 
mode and a slow, high-quality mode 
would be fine. ("Letter-quality," as far 
as I am concerned, means lowercase let- 
ters with descenders.) 

• It must be able to handle both single- 
sheet and fanfold paper (with either pin 
or tractor feed). 

• It must have graphics capability. I can 
write the graphics software if I must, but 
the graphics must be real, not block 
graphics or plotting of Xs. 

• It must have at least some minor forms 
control. Even a simple top-of-page for 
11-inch paper would be sufficient. 

• I must have some convenient way to 
get the printer fixed when it breaks. I 
live in Brooklyn; a service center any- 



where in the New York City metropoli- 
tan area would be fine. 

• The printer should cost $1000 or less. 
The highest I am willing to go, including 
tax, shipping, and all the options I need, 
is $1200. 

Are all these requirements unreason- 
able? I don't think so. There are a num- 
ber of printers advertised in BYTE that 
miss by only one or two points. For ex- 
ample, MPI's 88G printer does not have 
lowercase descenders and the closest 
place 1 could have it repaired is in 
Ridgewood, New Jersey; otherwise, I 
would have purchased it right away. 
The Centronics 737 has no graphics (no 
Centronics I know of does). Okidata's 
Slimline cannot handle single sheets, 
while their Microline has no descenders 
and only block graphics. The Base2 
prints in dark-blue ink and can't handle 
single sheets either, neither can the 
Anadex GraphicsPLUS... and so on. 

I suppose printer manufacturers have 
their own reasons for not including this 
capability or that feature in their 
printers, but I have a pretty good reason 
for wanting the features I want. I don't 
do just one thing with my computer, I 
do a whole range of things, from busi- 
ness writing to hobbies to simulations to 
music synthesis. I refuse to invest in 
another printer that does not help me 
use my computer to its greatest poten- 
tial. 

Bill Seligman 
667 Rugby Rd 
Brooklyn NY 11230 



Run Down 

Being a Hewlett-Packard fan and own- 
ing an HP-41C, I was anxious to read 
Bruce D Carbrey's review of the cal- 
culator in the December 1980 BYTE. 
(See "A Pocket Computer? Sizing up the 
HP-41C," page 244.) I feel that the 
review was quite good and that all of 
Mr Carbrey's judgments were fair and 
realistic, especially when comparing it 
with Texas Instruments' TI-59. 

However, I must disagree with one of 
Mr Carbrey's observations. He said that 
the typical life-span of the nonrecharge- 
able size-N batteries is 1 to 2 months. I 
have had my calculator for 13 months, 
and I have used it a good deal during 
that time. Only a week ago did it 
become necessary to replace the original 
set of batteries. 

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108 Shelly Ln 
Delran NJ 08075 ■ 



18 March 1981 © BYTE Publications Inc 



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Structured Programming 
and Structured Flowcharts 



Gregg Williams, Editor 

BYTE 

POB 372 

Hancock NH 03449 



Structured programming — that 
phrase, unfamiliar to me and, I 
assume, to most people several years 
ago — is now endowed with such 
magical powers that most books on 
programming include it somewhere in 
their titles. 

But what is structured program- 
ming? Most of us feel that it is prob- 
ably good for us, like getting regular 
exercise or brushing our teeth after 
each meal. You may also think it's 
too complicated (not true), that it 
slows down programming (wrong, it 
usually speeds it up), or that it cannot 
be done unless your computer runs a 
language like Pascal or ALGOL 
(wrong again). 

Simply put, structured program- 
ming is a set of techniques that makes 
programs easier to write, easier to 
understand, easier to fix, and easier 
to change. These techniques are sim- 
ple and general and can be adapted to 
any computer language that has a 
goto statement — that includes 
BASIC, assembly language, FOR- 
TRAN, and COBOL. The purpose of 
this article is to show you a new form 
of notation that will help you write 
structured programs. But first, let's 
review structured programming. 

The Elements of Structured Pro- 
gramming 

A structured program is like a set 
of notes written in outline form. The 
headings accompanied by Roman nu- 
merals — I, II, III, and so on — provide 
the overall organization. Each Roman 
numeral topic is broken into several 
component topics (A, B, and C, for 
example) and each of these is sub- 
divided further (1, 2, 3, ...) and fur- 
ther (a, b, c, ...) as needed. Table 1 



shows a problem and its solution 
written in this outline form. 

The above example demonstrates a 
process known as decomposition: 
breaking a task (problem) into its 
subtasks. This process represents the 
most important concept in structured 
programming, ie: that a problem can 
be solved by repeatedly breaking it 
into subproblems, until every sub- 
problem can be solved. If you plan 
this decomposition before you try to 
write it out in the narrow, precise, 
and time-consuming syntax of the 
target language (ie: the programming 
language you use to solve the prob- 
lem), you will have a better chance of 
getting your program right the first 
time. 



It has been 

mathematically proven 

that any program can 

be written using three 

basic constructs. 



But how do you decide which way 
to break the problem into sub- 
problems? Common sense helps. Ask 
yourself, "What sequence of actions 
and decisions would I have to make if 
I were doing this without a 
computer?" 

The rest of the answer comes from 
the literature of structured program- 
ming. It has been mathematically 
proven that any program can be writ- 
ten using three basic patterns, called 
programming constructs (or simply 
constructs): sequence, if. ..then. ..else, 
and while. ..do. The first construct, 
sequence, gives you the basic capa- 



bility of breaking a task into a set of 
subtasks that accomplish the main 
task when executed sequentially. 

The second construct, if... then... 
else, performs one of two subtasks, 
depending on the truth or falsity of a 
stated condition. An everyday exam- 
ple of this construct is given in the 
following sentence: "If it is raining 
outside, I will take my umbrella with 
me; if it is not, I will leave the um- 
brella at home." 

The third and least familiar con- 
struct, while. ..do, is actually a 
generalized do-loop that repeats a set 
of actions (called the body of the 
loop) while a stated condition is true. 
You use this construct when making 
iced tea from a mix: "As long as 
(while) the mix is not completely 
dissolved, I will continue to stir it." 

If you combine lines of code in the 
three ways described above, the re- 
sulting program is said to be struc- 
tured. In most languages (BASIC, for 
example) you will still use goto 
statements, but they will be restricted 
to carrying your program to specific 
points, ie: the beginnings and ends of 
tasks or subtasks. Each module (sub- 
task) in a structured program has a 
property known as "one-in, one-out"; 
that is, there is only one entrance and 
one exit from these modules, and no 
module will ever jump into the mid- 
dle of another one. Instead of being 
like a plate of spaghetti, a program is 
more like a string of pearls (with each 
pearl containing another, smaller 
string of pearls, and so on); each 
module has a definite and unchanging 
position on the string. When such 
regularity can be counted on, existing 
modules can be changed or deleted, 
and entirely new modules can be add- 



20 March 1981 © BYTE Publications lnc 




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Structured Programming: A 
Qualification 

About a year ago, I thought that 
structured programming was the 
ultimate tool in the analysis, 
design, and implementation of a 
computer program. I had read sev- 
eral books on the subject, browsed 
through a great many more, and 
successfully applied the techniques 
to real-world problems. Many 
books spoke of structured design, 
but I saw the concept as simply the 
same structured programming 
tools applied to the earlier process 
of program design — that is, of 
transforming a situation to be 
solved into a set of programs that 
will accomplish the task. I was 
more wrong than right. 

Through my experience with a 
particular programming project, I 
suddenly recognized a major point 
that I had formerly not compre- 
hended: that structured program- 
ming does not encompass the en- 
tire process of programming. The 



process of programming begins 
with some sort of description or 
specification of the program to be 
w ritten. With small programs (the 
kind we spend most of our lives 
writing), this is usually enough. 
But as the problem gets bigger (and 
perhaps more ill-defined), more 
and more crucial design decisions 
must be made before you divide 
the problem into programs. 

I also learned that certain design 
decisions within a given program 
are overlooked by the main ideas 
of structured programming. Struc- 
tured programming is a literal- 
minded discipline that deals ex- 
clusively with the orderly dis- 
assembly of a problem into the 
series of program statements that 
solves it., It does this while assum- 
ing several givens: the overall 
algorithm to be used (eg: bubble 
sort or heapsort), the data struc- 
tures used (eg: linked lists, arrays, 
or binary trees), and implementa- 
tion details (eg: sequential or ran- 



dom-access files, the packing of 
one or two characters per byte). 
These details, which may have a 
tremendous effect on the quality of 
the program (in such aspects as 
size, speed, readability, and main- 
tainability), are factors that are 
evaluated and weighed in the de- 
sign process. 

The purpose of these paragraphs 
is two-fold: first, to affirm that the 
techniques described in this article 
can make a significant improve- 
ment in your skills as a program- 
mer and that they are sufficient for 
many programs; and, second, to 
emphasize that the quality of a 
program can often be greatly im- 
proved by attention to the design 
decisions that are made in the early 
stages of analyzing the program 
design. I am including a list of par- 
ticularly helpful books and articles 
in the references at the end of this 
article. 



ed without problems caused by unex- 
pected module interaction. 

That is the theory of structured 
programming — now for putting it in- 
to practice. Figures 1 thru 3 show the 
three constructs (sequence, if... 
then. ..else, and while. ..do) in stan- 
dard flowchart form and as BASIC 
code. (For a more detailed look at 
writing structured programs in 
BASIC, see 'Applied Structured Pro- 
gramming," listed in the references. 
This article appears in an anthology 
that contains several other good ar- 
ticles on program decomposition — 



sometimes called top-down design or 
programming by stepwise refine- 
ment — and structured programming.) 

The Origins of a New Notation 

When I got my first job as a com- 
mercial programmer, I realized that I 
was going to have to write longer 
programs than I had previously writ- 
ten. This prompted me to adapt struc- 
tured programming techniques to my 
work in BASIC, COBOL, and RPG 
II. (As it turned out, my longest pro- 
gram was a 35-page COBOL program 
that grew to 75 pages without going 



Problem: Given a numeric array V with N 
elements, find the largest element, MAXV, 
and its index, MAXINDEX. These variables 
are related as follows: 

• 1 < MAXINDEX < N 

• MAXV = V (MAXINDEX) 

• MAXV is the largest value in V(1), 
V(2),...V(N). 

Table 1: A problem and its solution in 
outline form. The common outline 
form used for summarizing a body of 
material can also be used to give struc- 
ture to the emerging design of a pro- 
gram. Table la gives a statement of the 
problem and table lb gives its solution 
in outline form. 



Solution: 

I. Set problem up: 

A. Set MAXVAL = -9x 10 2 ° 

B. Set MAXINDEX = 

C. Set INDEX = 1 

II. Find largest element: 

A. Set up a loop that increments the 
variable INDEX from the beginning to the 
end of the array V. 
For each valueof INDEX: 

1. Compare the current array value ( V 

(INDEX)) to MAXVAL: 

a. if MAXVAL is equal or larger, do 
nothing; 

b. if MAXVAL is smaller, replace MAX- 
VAL with the current array value and 
MAXINDEX with the current index 
(the value of INDEX). 

III. Print the largest element(MAXVAL)and its 
index (MAXINDEX). 



out of control. I could not have done 
this without the rigorous use of struc- 
tured programming techniques.) 

As my programs grew larger, I be- 
came dissatisfied with the methods I 
used to plan my programs. Conven- 
tional flowcharts obscured the struc- 
ture of my programs. Nassi-Schnei- 
derman charts and Warnier-Orr dia- 
grams were unsatisfactory for other 
reasons. 

The best solution offered in struc- 
tured programming texts was struc- 
tured pseudocode, an informally 
written Pascal-like "program" that 
uses terse English phrases to describe 
the program. Listing 1 shows the 
structured pseudocode for the pro- 
gram outlined in table lb. I used 
structured pseudocode extensively to 
outline programs but found that the 
details of the resulting pseudocode 
often obscured the overall design of 
the program. 

In retrospect, I can see that I 
wanted a design notation that could 
do the following: 

• Completely describe the algorithm 
to be programmed 

• Provide overview and detailed 
documentation that was easy to read 

• Not need to be redrawn every time 

Text continued on page 26 



22 March 1981 © BYTE Publications Inc 



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Listing 1: A structured pseudocode solution of the FINDMAX problem given in the text 
and in table 1, Structured pseudocode is a terse, informal, Pascal-like program that 
helps the user design a program before writing it in a formal programming language. 

Program FINDMAX: 

Initialize system variables (MAXV = -9 x 10 2 °, MAXINDEX = 0, INDEX = 1) 

While INDEX < N 

find value of current array element ( CURRV = V (INDEX) ); 

if current array element (CURRV) > maximum element so far (MAXV) 
new maximum element = current element 
new maximum index = current index ( MAXINDEX = INDEX ) 

endif 

increment INDEX by 1 
endwhile 

print MAXV, MAXINDEX 
(end of program) 

Listing 2: A BASIC implementation of the FINDMAX problem from table 1 . In this pro- 
gram, the variable MAXINDEX has been shortened to MINDEX to distinguish it from 
the variable MAXV. This program is written in TRS-80 Model I Level II BASIC, and it 
will run on other computers that use Microsoft BASIC. 



lOO 
110 
120 
130 
140 
150 
160 
170 
180 
1 90 
200 
210 
220 
230 
240 
250 
260 
270 
280 
290 
300 
310 
320 
330 
340 
350 
360 
370 
380 
390 
400 
410 
420 
430 
440 
450 
460 
470 
480 
490 
500 
510 
520 
530 
5 40 
550 
560 
570 
760 
770 
780 
790 
800 
810 
B20 
830 
B40 



REM 

REM 
REM 
REM 
REM 

REM 
REM 



PROCSRAI'I FINDMAX 

THIS PROGRAM TAKES AN ARRAY OF NUMBERS, V, AND 
FINDS THE LARGEST ELEMENT, MAXV, AND ITS INDEX,, 
MAXINDEX, SUCH THAT: 

MAXV = V (MAXINDEX) 

(FOR THE PURPOSES OF ILLUSTRATION, WE WILL ASSUME 
THAT THE DATA IS ALREADY IN THE ARRAY V.) 



REM =========== 

DIM V ( 1 2 > 
GOSUB 800: REM 
REM 



MAIN PROGRAM 



-NOT PART OF ALGORITHM IN FIGURE 6; THIS 
SUBROUTINE ENTERS DATA INTO ARRAY V 



REM 



BOX 1: INITIALIZATION ROUTINE 



MAXV = -9 * 10 [20 
MINDEX = 
INDEX = 1 



REM 



BOX 2: FIND LARGEST VALUE 



REM — (BEGINNING OF WHILE... DO LOOP) 
IF INDEX > N THEN 520 
CURRV = V (INDEX) 

IF CURRV < MAXV THEN 440 

MAXV = CURRV: REM (THIS PART EXECUTED IF FALSE) 

MINDEX = INDEX 

INDEX = INDEX + 1 

REM — (JUMP TO BEGINNING OF WHILE... DO LOOP) 
GOTO 370 



REM 



BOX 



PRINT FINAL VALUES 



PRINT: 

PRINT 

PRINT 



PRINT "THE LARGEST VALUE IN THE V ARRAY IS: 
V<"; MINDEX ; ") = " ; MAXV 



END 

REM ============== END OF MAIN PROGRAM 



REM SUBROUTINE TO FILL V ARRAY 



DATA 12: REM — (NUMBER OF ITEMS TO BE READ IN) 

DATA 1, 15, -28, 3.24, -17.92, 0, 5, 1, 0, 21.4, 

RE«D N 

FOR 1=1 TO N: READ V(I): NEXT I 

RETURN 



-205, 17 



24 



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March 1981 © BYTE Publications Inc 



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Text continued from page 22: 

a change was made in the flowchart 

• Use a minimum of unfamiliar nota- 
tion 

• Be visually pleasing 

This structured flowchart notation, 
which I developed over a period of 
several years, meets these criteria. 

Basic Constructs in Structured 
Flowcharting 

According to the tenets of struc- 



(a) 



SUBTASK 1 



tured programming, any program 
can be expressed as a combination of 
four basic building blocks. These are 
sequence, if... then... else, while... do, 
and decomposition. (The first three 
constructs, described in '""'ventional 
flowcharts in figures la thru 3a, are 
given in structured flowcharts in 
figures 4a, 4b, and 4c, respectively.) 
The sequence construct (figure 4a) 
is identical for both conventional and 
structured flowcharts; however, a 
later construct, decomposition, will 
distinguish the structured flowchart 
sequence construct from its conven- 
tional counterpart. 



SUBTASK 2 



(b) 



SUBTASK 3 



100 (BASIC statement for subtask 1) 
110 (BASIC statement lor subtask 2) 
120 (BASIC statement for subtask 3) 



Figure 1: Sequence as a control structure. Figure la shows how a linear sequence of sub- 
tasks is drawn using conventional flowchart notation. Figure lb shows the equivalent 
sequence as a series of BASIC lines. 



(a) 



^condition) .> 

Tf 








SUBTASK DONE IF 
CONDITION IS FALSE 




SUBTASK DONE IF 
CONDITION IS TRUE 


' 


\ 








' 











(b) 



(a) CONVENTIONAL 



100 IF (condition) THEN 200 
120 (BASIC statements for subtask 
done if condition is false) 



190 GOTO 300 

200 (BASIC statements for subtask done if 
condition is true) 



299 (last statement of "true" subtask) 

300 (first statement of next construct) 



Figure 2: The if. ..then. ..else construct as a control structure. Figure 2a shows the con- 
ventional notation for this construct, while figure 2b shows the BASIC equivalent. 



26 March 1981 © BYTE Publications lnc 




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INCORPORATED 



(a) CONVENTIONAL 




(b) 

100 IF (opposite of condition) THEN 300 
110 (BASIC statements for body of loop, 
done if condition is true) 



299 GOTO 100 

300 (first statement of next construct) 

Figure 3: The while... do loop as a control 
structure. Figure 3a shows the while... do 
loop in conventional flowchart notation. 
Figure 3b shows the equivalent loop in 
BASIC code. 



SUBTASK 1 



SUBTASK 2 



SUBTASK 3 



to 




SUBTASK DONE IF 
CONDITION IS TRUE 



SUBTASK DONE IF 
CONDITION IS FALSE 



(b) 



WHILE 
(CONDITION) 



(c) 




BODY OF LOOP 



Figure 4: The basic structured flowchart notations. Figure 4a shows the structured flow- 
chart notation for a sequence of tasks; it is equivalent to the flowchart of figure la. 
Figure 4b shows the structured flowchart notation for the if... then... else construct 
(equivalent to figure 2a); note that it is the placement of the letters T and F (for true and 
false) that determines the conditions under which a given subtask is performed. Figure 
4c shows the structured flowchart notation for the while... do construct (equivalent to 
figure 3a); the diagonal line leading down indicates that the condition (in the hexagon) is 
performed before the body of the loop. 



The if, . . then . . . else construct is fair- 
ly straightforward in the conven- 
tional flowchart (figure 2a). In the 
structured flowchart version (figure 
4b), the boxes to be performed are to 
the right of the decision diamond, 
with the understanding that only one 
of the two boxes will be performed 
based on the value of the condition in 
the diamond. If the "else" side of the 



construct is not needed, the box 
labeled F is eliminated. In this case, if 
the condition does not evaluate to 
true, no action is performed, and con- 
trol continues with the next construct 
following the decision diamond. 

The notation for the while... do 
construct is not as easily derived. The 
conventional flowchart cannot direct- 
ly express this kind of loop; it must 



use a decision diamond and an exter- 
na] loop (figure 3a). The structured 
flowchart version (figure 4c) intro- 
duces a new symbol, a hexagon. (Ac- 
tually, the hexagon is used to denote 
one of several kinds of loop struc- 
tures; the word while makes this a 
while... do loop.) The box connected 
below and to the right of the hexagon 
is performed as long as the condition 



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TASK X 




























SUBTASK 


1 
















SUBTASK 


2 








\T 
















jT IF 




SUBTASK 3a 




'F 
























SUBTASK 3b 


/ WHILE 
\ B>Y 


X 














* 














SUBTASK 4 




SUBTASK 


5 









Figure 5: Example of the subdivision of a task. A central rule of structured flowcharts is 
that any box can be broken into multiple boxes that represent the necessary subtasks. 
Here, task X is broken into five subtasks executed in top-to-bottom order. Subtasks 1, 
2, and 5 are simple subtasks. Subtask 3 is an if. ..then. ..else construct. Subtask 4 is a 
while... do loop. 



listed in the hexagon is true. The con- 
dition is performed first (denoted by 
the position of the hexagon being 
spatially above the box being per- 
formed); this allows the possibility of 
the body of the loop being performed 
zero times if the condition is initially 
false. 

The fourth and pivotal construct of 
this programming notation, decom- 
position, can best be stated as a rule: 
any box representing a task can be 
broken into multiple boxes that repre- 
sent the necessary subtasks. The sub- 
tasks may be rectangular boxes that 
represent simple tasks, or they may 
be any other valid structured flow- 
chart construct (if ...then. ..else, 
while... do, etc). They are written top 
to bottom in the order of perfor- 
mance, with the line denoting pro- 
gram flow entering each subtask box 
from its top and exiting from the bot- 
tom. 

Figure 5 illustrates the above con- 
struct. Task X is composed of five 
subtasks performed in numeric se- 
quence. Tasks 1, 2, and 5 are simple 
subtasks. Subtask 3 is an if... then... 
else construct that allows either sub- 
task 3a or subtask 3b to be per- 



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formed. Subtask 4 is performed as 
long as the condition within the hexa- 
gon (B>Y) is true. Of course, any 
subtask box may be further divided 
into its component subtasks. 

Since any box can be broken into 
component subtasks, you can now 
see how this notation is used to design 
a program. The boxes in the leftmost 
column give the overall design of the 
program; boxes are then expanded to 
the right as each box (task) is divided 
into boxes representing the appropri- 
ate combination of subtasks. As a 
result, you can scan any one of 
several of the leftmost column of 
boxes for an overview of varying 
depths of the program design, or you 
can study the implementation of any 
major or minor subtask by concen- 
trating on only the boxes and control 
structures growing to the right of the 
given subtask. 



An Example 

The following 



example will il- 



( FINDMAXj 



lustrate the process of developing a 
program using structured flowcharts. 
Using the example of table la, sup- 
pose you are given an array of N 
numbers, V(l), V(2),...V(N), and 
have to find the index value MAX- 
INDEX such that the largest value in 
the V array is MAXV = V(M AX- 
INDEX). The entire structured flow- 
chart for this problem is given in 
figure 6. 

Cover the right three-fourths of the 
flowchart so that only the subtasks 
numbered 1, 2, and 3 are visible. This 
is what the "first pass" of the flow- 
charting effort should look like. Sub- 
task 1 is the initialization of the prob- 
lem. Subtask 2 is the determination of 
MAXINDEX and MAXV. Subtask 3 
is the printing of these two values. 
Since the task in subtask 3 is simple 
enough to be directly accomplished in 
the target language (for example, 
BASIC), it need not be subdivided. 

Subtasks 1 and 2 are developed 
concurrently. Subtask 2 is basically a 
loop that examines V(l), V(2),...V(N) 
in turn, keeping the appropriate 
values for MAXV and MAXINDEX 
for the I elements encountered thus 



INITIALIZATION 



1.1 



MAXV--S1Q' 



1.2 



MAXINDEX = 



1.3 



INDEX = 1 



FIND LARGEST VALUE MAXV 
AND ITS INDEX MAXINDEX 



2.1 



WHILE 
INDEX <N 



2.1.1 



far. The values of MAXV, MAX- 
INDEX, and INDEX must be set (as is 
done in subtasks 1.1, 1.2, and 1.3). 
Note that this loop could have been 
done more easily using a do-loop; 
other optimizations could also have 
been made, but this example is given 
for the purposes of illustration only. 

The main work for each element is 
done as subtask 2.1.2: if the current V 
element being examined (ie:CURRV) 
is greater than the maximum V ele- 
ment so far, MAXV and MAXINDEX 
are set to the current array and index 
values, respectively. These subtasks, 
numbered 2.1.2.1 and 2.1.2.2, are 
performed only when the relationship 
given in the diamond of 2.1.2 is true. 

Once the structured flowchart has 
reached the level of detail shown in 
figure 6, most of the design considera- 
tions have been conceived and per- 
fected; it is then a simple task to 
translate the program into BASIC 
(see listing 2) or any other general- 
purpose computer language. The 
benefits are more pronounced when 
used with a larger program. If a struc- 
tured flowchart is subdivided to the 
right until each box represents a task 
that can be directly coded in the tar- 
get language, you will catch most of 
the "oops, I forgot to..." insertions 
and changes that programmers 
generally think of after they have 
started coding the program. 

Other Control Structures 

Although the three constructs 
discussed so far are sufficient for 
writing any program, it is not always 
convenient to use only these con- 
structs. Other control structures can 
be devised for the convenience of the 
programmer. For example, boxes 1.3, 



CDRRV- V( INDEX) 



2.1.2 




PRINT MAXV, MAXINDEX 



2.1.3 



f END J 



2.1.2.1 



MAXV-- CURRY 



2.1.2.2 



INDEX = INDEX + 1 



MAXINDEX --INDEX 



Figure 6: Structured flowchart for program F1NDMAX. Given an array V with N elements, the problem is to find the largest element, 
MAXV, and its index within the V array, MAXINDEX. The numbers above each box give the sequence and level of that box in rela- 
tion to the entire problem. For example, box 1 can be broken into three subtask boxes: 1.1, 1.2, and 1,3. 



32 



March 1981 © BYTE Publications lnc 



Circle 23 on Inquiry card. 



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with high performance through distributed 
processing.) 

Look for a single user CP/M® system that ex- 
pands to multiuser configurations economically. 

Look for independent 6 MHz Z80B-based User 
Modules with 64Rof RAM memory, each module 
with a port to the user term inal capable of handl ing 
baud rates of up to 38K under program selection. 
Look for high-speed block data transfers from user 
modules to the Global Processor for disk storage. 
That way, CP/M programs run independently for 
each user. Fast. And each users's station acts just 
like the fastest standalone system — no delays, no 
waiting for other users. 

Look for a Z80-based Global Processor for disk 
and tape I/O that transfers data from disk to user 
modules at the data transfer rate of the peripheral 
device. And a controller that handles as many as 8 



SMD disk drives for up to 528 megabytes of hard 
disk storage, plus up to four 8" floppies, plus op- 
tional streaming tape backup. 

And look for a Z80-based General I/O Processor 
that supports up to eight printers — with 64K bytes 
of independent buffer memory. 

That's part of how you tell if it's a White Com- 
puter. There's a lot more. Here's a number and 
address for more information. 

CP/M is a registered trademark of Digital Reseach. 

Z80, Z80A, Z80B are registered trademarks of Zilog Corporation. 




White Computer Company A 1876 Industrial Way 
Redwood City, California 94063 A 415 364 7570 



2.1, and 2.1.3 in figure 6 can be re- 
placed by a control structure that is 
available in most programming lan- 
guages — a do-loop that varies INDEX 
from 1 to N. An example of the nota- 
tion I have devised for this is given in 
figure 7a; the body of the loop is per- 
formed according to the parameters 
given in the hexagon. 

Another well-known control struc- 
ture is the repeat... until loop, shown 
in figure 7b. The position of the body 



of the loop, above and to the right of 
its associated hexagon, is meant to 
signify that the body of the loop is 
performed before the condition is 
tested. Although the meaning of this 
notation does not implicitly follow 
from its form, it was chosen for its 
simplicity and consistency with the 
notation already developed. 

Other constructs come to mind: a 
case structure, an unconditional goto, 
and two controlled gotos — the restart 



FOR I = 
1 TO 10 



BODY OF LOOP 



BODY OF DO-LOOP 



I UNTIL 
V(CONDITION) 



(a I 



lb) 




Figure 7: Structured flowchart notation for a do-loop and a repeat. ..until loop. In the 
do-loop, figure 7a, the hexagon contains all pertinent information defining the loop, 
and in the form most comfortable to the user. In the repeat... until loop, figure 7b, the 
notation is interpreted as showing the body of the loop being executed before the condi- 
tion is tested. In both cases, the box representing the body of the loop can be expanded 
to the right, into its component subtasks. 



If You Own a 56K CP/M Machine, 
Then You Should Have Leverage 



Leverage is an innovative new informa- 
tion management system recently intro- 
duced by Urban Software Corporation. It 
combines a number of powerful tools, 
including full screen data entry, report 
generation, word processing, and subset 
extraction, into an integrated, easy-to-use 
package. The Leverage system provides 
many capabilities previously available only 
through costly custom programming, yet it 
is designed for use by non-programmers. 

Leverage Highlights 

• Data bases are easily configured to 

your particular applications; prototypes for 

mailing lists, personnel files, appointment 

calendars and inventory systems are pro- 



vided. 

• Flexible report generator lets you 
define report formats such as alphabetized 
lists, tables, directories and schedules. 

• A "Help Key" allows instant, in-con- 
text access to an on-line manual over 
80,000 characters long. 

• Graphic menu selection provides opti- 
mal responsiveness and ease of use. 

• Written in "C," a powerful systems pro- 
gramming language developed by Bell Labs 
in conjunction with its UNIX operating 
system (most of UNIX is written in "C"). 

• Sophisticated programming techniques 
like hash table coding, dynamic overlays, 
shell sort and heap sort guarantee maxi- 
mum efficiency. 



Leverage Program $185 

Manual alone $ 15 (Applicable to subsequent purchase of program) 

Educational rates available. UNIX is a trademark of Bell Labs, CP/M of Digital Research. 

If your local dealer does not yet have Leverage, use the reader service card or call 
Urban Software for a brochure. 

Urban Software Corporation 

19 West 34th Street • New York, NY 10001 • (212) 947-3811 



(restart the innermost containing 
loop) and the exit (go to the first task 
after the innermost containing loop). 
Although I have used some of these 
constructs for quite some time, they 
are not presented here because I am 
not yet satisfied with the notations I 
have developed for them. In any case, 
structured flowcharts are meant to be 
a personal notation — you should add 
to and modify these constructs to fit 
your needs. 

Conclusions 

I have found structured flowcharts 
helpful in designing programs. The 
notation is obviously intended for 
weakly structured languages (like 
BASIC), as its utility decreases when 
the structure of the target language 
increases. 

The notation is, at the moment, in- 
formal, and it should stay that way. 
It should be extended and modified in 
whatever way seems useful to you. In 
particular, you should use additional 
notation for special features of the 
target language (eg: global and local 
variables, use of a stack of inter- 
mediate computation) when appli- 
cable. If the structured flowchart is to 
be read by another person, however, 
you should define all the structures 
used in terms of their equivalent 
unstructured (conventional) flow- 
charts. 

If the final structured flowchart is 
to be redrawn, you should do so with 
clarity in mind. Place only those 
boxes that help explain the overall 
design with the main flowchart; leave 
the implementation details to subor- 
dinate flowcharts. 

I hope you will find this notation 
useful. I would appreciate your sug- 
gestions, criticism, and comments. ■ 



References 

1 . Page-Jones, Meillir. The Practical Guide to 
Structured Systems Design. New York: Your- 
don Press, 1980. 

2. Ross, D T, J B Goodenough, C A Irvine. 
"Software Engineering: Process, Principles, 
and Goals." Computer. Institute of Electrical 
and Electronics Engineers (IEEE), May 1975. 
Also Tutorial on Software Design Techniques, 
Third Edition, P Freeman and A I Wasserman, 
editors. Long Beach CA: IEEE Computer 
Society, 1980. 

3. Williams, G. "Applied Structured Program- 
ming." Program Design, Blaise Liffick, editor. 
Peterborough NH: BYTE Books, 1978. 

4. Classics in Software Engineering, E N 
Yourdon, editor. New York: Yourdon Press, 
1979. 



34 



March 1981 © BYTE Publications Inc 



Circle 24 on inquiry card. 



TRS-80* Model I Computer Owners . 




Double-density storage, 
It's really here! 



Here at Percom. And your authorized Percom dealers. 

And double-density storage is here in a big way. Because now 
you can choose from three different levels of mini-disk systems — 
all double-density rated. 

And get the storage that precisely meets your application 
needs. 

Not to mention the service and quality that's made Percom the 
industry leader. 



1 



ISK) 



Although rated for double-density operation, all 
levels of Percom drives work equally well in single- 
density applications. 

You can operate these drives in ordinary single- 
density format using TRSDOS*, Percom OS-80™ 
or any other single-density operating system. 

Or, you can add a Percom DOUBLER™ to your 
Tandy Expansion Interface and store data and 
programs in either single- or double-density 
format. 



Under double-density operation, you can store 
as much as 350 Kbytes of formatted data — de- 
pending on the drive model — on one side of a 
five-inch minidiskette. That's four times the 
capacity of standard 35-track Model I mini- 
disks, almost 100 Kbytes more than the capacity 
of the eight-inch IBM 3740 format! 

Available in 1-, 2- and 3-drive configurations in 
all three model lines, Percom burned-in, fully- 
tested drives start at only $399. 






TFD-40™ Drives 

TFD-40 Drives store 180 Kbytes (double-density) or 
102 Kbytes (single-density) of formatted data on one 
side of a 40-track minidiskette. Although economical- 
ly priced, TFD-40 drives receive the same full Percom 
quality control measures as TFD-100 and TFD-200 
drives. 



TFD-100™ Drives 

TFD-100 drives are "flippy" drives. You store twice 
the data per minidiskette by using both sides of the 
disk. TFD-100 drives store 180 Kbytes (double- 
density) or 102 Kbytes (single-density) per side. 
Under double-density operation, you can store a 70- 
page document on one minidiskette. 



TFD-200™ Drives 

TFD-200 drives store 350 Kbytes (double-density) or 
197 Kbytes (single-density) on one side of a minidis- 
kette. By comparison, 3740-formatted eight-inch 
disks store only 256 Kbytes. Enormous on-line stor- 
age capacity in a 5" drive, plus proven Percom 
reliability. That's what you get in a TFD-200. 




The DOUBLER™ — This proprietary 
adapter for the TRS-80* Model I com- 
puter packs approximately twice the 
data on a disk track. 

Depending on the type of drive, you 
can store up to four times as much 
data — 350 Kbytes — on one side of a 
^felt"* ™W"* minidiskette as you can store using a 
Tandy standard Model I computer drive. 

Easy to install, the DOUBLER merely plugs into the disk 
controller chip socket of your Expansion Interface. No rewir- 
ing. No trace cutting. 

And because the DOUBLER reads, writes and formats 
either single- or double-density disks, you can continue to 
run all of your single-density software, then switch to dou- 
ble-density operation at any convenient time. 

Included with the PC card adapter is a TRSDOS*- 
compatible double-density disk operating system, called 
DBLDOS™, plus a CONVERT utility that converts files and 
programs from single- to double-density or double- to sing- 
le-density format. 

Each DOUBLER also includes an on-card high- 
performance data separator circuit which ensures reliable 
disk read operation. 

The DOUBLER works with standard 35-, 40-, 77- and 
80-track drives rated for double-density operation. 

Note. Opening the Expansion Interface to install the 
DOUBLER may void Tandy's limited 90-day warranty. 

Free software patch with drive purchase. This software 
patch, called PATCH PAK, ,M upgrades TRSDOS* for single- 
density operation with improved 40- and 77-track drives. 



Quality Percom products are available at authorized dealers. Call toll free 
1-800-527-1592 for the address of your nearest dealer or to order directly from 
Percom. In Canada call 519-824-7041. 

tm , Ir . r^ A i Prices and specifications subject to change without notice, 

trademark of Percom Data Company, Inc. 



PEACOM 



trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company 



PERCOM DATA COMPANY, INC. 

211 N KIRBY ■ GARLAND TX ■ 75042 
1214)272-3431 



Circle 25 on inquiry card. 



Ciarcia's Circuit Cellar 



Build the Disk-80 

Memory Expansion and Floppy-Disk Control 



Steve Ciarcia 

POB 582 

Glastonbury CT 06033 



The term "memory expansion" no 
longer causes the same pained expres- 
sion among computer owners as it did 
a few years ago. Back in the "Model 
T" days of personal computing, it 
was a major undertaking, often the 
largest expense of setting up a per- 
sonal computer system. At that time, 
volatile memory integrated circuits 
contained only a fraction of the 
capacity of those available today, 
and mass storage often consisted of 
slow audio cassettes. 

Back in 1975, if you were adding 
32 K bytes of memory to your com- 
puter you would probably have used 
256 type-2102A 1 K by 1-bit static 
memory chips. These cost between $2 
and $5 each, and you probably would 
have needed a power supply larger 
and heavier than the computer. 
Believe it or not, the 2102A was a ma- 
jor improvement over the previous 
type-1101 memories (256 by 1-bit 
static devices). It would have taken 
1024 (1 K) of the type-1101 com- 
ponents to make 32 K bytes. 

Since that time, memory tech- 
nology has progressed by leaps and 
bounds, and the cost per bit has 
dropped considerably. Many com- 
puter manufacturers now use dynamic 



rather than static memory. The result 
is much higher density, lower system 
cost, and easier after-market memory 
expansion on most computers. 

The 64 K-byte personal computer 
system is more common than you 
would imagine. Adding another 16 or 
32 K bytes of memory these days 
simply means plugging a few (8 or 16) 
integrated circuits into a memory- 
expansion unit or motherboard. 
Usually the standard power supply 
suffices. 

Even with these advantages, using 




Photo 1: The Disk-80 mounted in its 
enclosure and attached to the TRS-80 
Model 1 computer. The Disk-80 is about 
half the size of the Radio Shack TRS-80 
Expansion Interface. 



dynamic memory is not quite as sim- 
ple as it sounds. There are con- 
siderable differences between static 
and dynamic memory. Most people 
know relatively little about designing 
a dynamic-memory system, and even 
professional designers are intimidated 
by having to deal with multiplexing 
addresses, selecting bus drivers, se- 
quencing activation of power sup- 
plies, and decoupling and noise. I 
don't expect that reading this article 
will make you into an authority on 
dynamic memory, but perhaps you 
will at least have a better under- 
standing of it. 

Mass-storage technology has also 
progressed during this same period. 
Displacing the audio cassette as the 
exclusive medium, the floppy disk 
and Winchester-technology hard disk 
have become the de facto storage 
standards. 

For some time I have wanted to 
present articles on dynamic-memory 
and disk-controller integrated cir- 
cuits. I have delayed chiefly because I 
generally prefer to present my articles 
as usable applications. 

The three largest-selling personal 
computers, the Radio Shack TRS-80, 
the Apple II, and the Commodore 



36 



March 1981 © BYTE Publications Inc 




Photo 2: The Disk-80 
printed-circuit board (cir- 
cuit of figure 2). The red 
cable connects to the ex- 
pansion connector on the 
TRS-80 keyboard/pro- 
cessor module. The 34-pin 
edge connector above the 
red cable is a 5-inch 
floppy-disk drive interface 
connector. The sixteen in- 
tegrated circuits lined 
against the left side of the 
board are 32 K bytes' 
worth of type-4116 
16 K-bit dynamic memory 
devices. 



PET, use 16 K-bit dynamic-memory 
chips. Only the TRS-80 Model I re- 
quires the user to add extra memory 
via an external module, the TRS-80 
Expansion Interface. (The TRS-80 
Model 111 does not.) 

This month's hardware project, the 
Disk-80, is an expansion interface for 
use with the TRS-80 Model I that ex- 
pands the user memory and provides 
for the attachment and control of 
floppy-disk drives. Dynamic memory 
and a specialized floppy-disk-drive 
controller are used. Although this 
project was designed for use with the 
TRS-80 Model I, the elements of the 
systems and the principles involved 
are applicable to any personal com- 
puter. 

What's Inside the Disk-80? 

The Disk-80, shown in photo 1, is 
completely hardware- and software- 
compatible with the TRS-80 Model I 
and includes hardware enhancements 
for increased reliability. Readers 
familiar with the TRS-80 Expansion 
Interface will note that the Disk-80 is 



Copyright © 1 98 1 by Steven A Garcia. 
All rights reserved. 



considerably smaller. 

The keyboard/processor module of 
the TRS-80 Model I system is a single- 
board computer with memory- 
mapped video display and keyboard. 
The only provision for I/O (in- 
put/output) in the basic configura- 
tion is an I/O port for an audio- 
cassette recorder and a single-bit 
relay line for control of the recorder 
motor. Any user-memory expansion 
beyond 16 K bytes and any printer or 
disk I/O must be handled externally. 
The unit sold by Tandy /Radio Shack 
to perform these functions is called 
the TRS-80 Expansion Interface. 

Figure 1 is a block diagram of the 
Disk-80. It attaches to the key- 
board/processor unit through the 
40-pin TRS-BUS connector and pro- 
vides the following functions: 
32 K-byte user-memory expansion, 
Centronics-compatible parallel 
printer port (full 8 bits), real-time 
clock, four-drive 5-inch floppy-disk 
controller, external data separator 
(used in reading floppy disks), buf- 
fered TRS-BUS connection to other 
peripheral devices, and power sup- 
ply. 

The three major functional sections 
are as follows: 



• Memory-expansion section, which 
accommodates up to 32 K bytes of 
dynamic memory; 

• Four-drive 5-inch floppy-disk con- 
troller; and 

• Parallel printer port. 

The activities of these sections are 
coordinated through a common ad- 
dress decoder. 

The Disk-80 system is divided into 
two circuit boards. The main board, 
shown in photo 2 and outlined 
schematically in figures 2a, 2b, and 
2c, contains everything except the 
power supply and the printer port. 
The other board, referred to as the 
power-supply/printer-interface 
board, is shown in photo 3 on page 
45. 

Disk-80 Addressing 

The disk controller, printer, and 
real-time clock are addressed as 
memory-mapped parallel I/O ports 
through IC28, a 74LS155 decoder. 
Eight strobe signals are produced to 
decode memory addresses within the 
range of hexadecimal 37E0 to 37EC 
(only six of these are used in the 
Disk-80) to coordinate these pe- 
ripherals. Their functions are shown 



March 1981 © BYTE Publications Inc 



37 



POWER-SUPPLY /PRINTER- INTERFACE BOARD 



POWER SUPPLY 

(TO ALL SECTIONS) 



B-BIT LATCH 

AND 

B-BIT INPUT BUFFER 



~N 



36-PIN 
PRINTER-PORT 
EDGE CONNECTOR 



DISK-BO BOARD 



ADDRESS 

BUS 

BUFFERS 



ADDRESS 
DECODER 
(TO ALL SECTIONS) 



DATA BUS 
BUFFERS 



FLOPPY- DISK 
CONTROLLER 
CHIP 



REAL-TIME 
CLOCK 



32 K-BYTE 
EXPANSION 
MEMORY 



CLOCK 
GENERATOR 



HARDWARE 

DATA 

SEPARATOR 



LINE 
DRIVERS 



LINE 
RECEIVERS 



J" 



•\ 



34-PIN 

FLOPPY-DISK DRIVE 
EDGE CONNECTOR 



Figure 1: Block diagram of the Disk-80 expansion interface for the Radio Shack TRS-80 Model I. 



Elements of the 

systems presented and 

the principles involved 

are applicable to any 

personal computer. 



in table 1 on page 44. 

IC26, an eight-input NAND gate, 
and IC27, a 74LS139 decoder, func- 
tion as memory-bank decoders. They 
produce tw o str obe signals. One, 
designated 32 K (or informally, 
32 K enable), is the active-low enable 
strobe for expansion memory be- 
tween hexadecimal addresses 8000 
and BFFF. The second strobe, 48 K 
(or 48 K enable), controls the bank of 
memory between C000 and FFFF. 

Operation of Dynamic Memory 

When designing memory systems, 



it is necessary to understand both the 
components and the computer sys- 
tem. In the past, the most popular 
dynamic memory components were 
MK4096- and MK4027-type 4 K by 
1-bit devices. Today the standard 
memory component in personal com- 
puters is the MK4116. (More recent- 
ly, maximum density has increased to 
64 K bits per chip. Unfortunately, 
these parts are expensive, about $70 
each, and are not yet generally used 
in personal computers.) 

The 4116 is a 16 K-bit dynamic 
memory device. The 14 address bits 
required to specify one of the 16,384 
cell locations that each store a single 
bit of data are multiplexed into seven 
shared pins. The timing of the signals 
presented to these pins is shown in 
figure 3 on page 45. 

During execution of a Z80 
memory-read or memory-write in- 
struction, a 16-bit address is present 
on the processor's address bus. If the 
memory address is between hexa- 



decimal 8000 and FFFF, the processor 
will try to find the addressed memory 
devices in the Disk-80's memory- 
expansion section. Decoding address 
lines A14 and A15 determines 
whether the location is in the 32 K or 
the 48 K memory range and enables 
the appropriate bank. The remaining 
14 bits are multiplexed directly into 
the eight 4116s (one 4116 is used for 
each bit of the addressed byte loca- 
tion). 

IC20 and IC21, 74LS157 quad 2-to- 
1-line multiplexers, apply the first 7 
row-address bits to each 4116 
when the MUX (multiplex) and RAS 
(row-address strobe) signals are low. 
This latches the row address into the 
4116. Next, the MUX signal goes 
high, applying the 7 colum n-address 
bits to the 4116, and CAS (column- 
address strobe) goes low. At the con- 
clusion of this sequence, data is either 
written into or read from the 4116 

Text continued on page 44 



38 



March 1981 © BYTE Publications Inc 



RIBBON-CABLE 40-PIN 

CONNECTOR 

TO J2 +5V 



HZ> 32K 




Figure 2a: Schematic diagram of the address-decoding and buffering section of the Disk-80. Figure notes are found in the text box on 
page 44. 



March 1981 © BYTE Publications Inc 



39 



AO'O- 
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A2'C>- 
A3'C^ 

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11 



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Figure 2b: The memory -expansion section of the Disk-80 module. See notes on page 44. 

40 March 19S1 © BYTE Publications Ihc 



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14 



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14 



March 1981 © BYTE Publications Inc 41 






RIBBON-CABLE PC CONNECTOR 



40 PINS 
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ft 



£ 



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I 74LS367 1 

1 s * 1 r 



► 5V 



IR27 
J4.7K 



IC39 * 

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N/C = NO CONNECTION 



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DISK -CONTROLLER, CLOCK -GENERATOR, 
AND COMPUTER-INTERFACE SECTION 



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Figure 2c: Schematic diagram of the disk-controller, clock-generator, keyboard/processor-module-interface, external-data-separator, 
and disk-drive-interface sections of the Disk-80 expansion module. See figure notes on page 44. 



42 March 1981 © BYTE Publications Inc 



►5V 



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IC330 
74LS123 



13 



1C69 
• 10 M F 



D30^ 

02[> 
DlC^ 
DOO 



13 



37E0WR^>- 



IC31 
74LS20 



32 



<Li 



15 



I 1 



fr* 



IC29 
7416 



34-PIN 

DISK DRIVE BUS 

CONNECTOR 



CLR 
4D 

3D 

2D 

ID 

CLOCK 

IC32 * 
74LS175 



40 
30 
2Q 

10 
40 
3Q 
2Q 
1Q 



15 



$£> MOTOR ON 



14 



L 



■[32> DS3 
■|14> DS2 
M> DS1 
■(10> DSO 



30 



IC30 ! 

7416 ! 



"N> 



26 



IC36 
4 ^d3_ 



IC36 
74LS04 



^<F 



IC35 
74LS00 



<Dn 



C 7 ri ? 

\°°' F 6 2K 



10 12 



IC37a 
74LS74 



CLOCK 
C 



IC380 * 
74LS74 

CLOCK Q 

C 



11 



10 



IC38b 
74LS74 



CLOCK 



13 



IC36 
74LS04 



Wfe 



18 



22 



-i-M^-— ^ 



lR22 
>4.7K 



f5V 



DATA-SEPARATOR AND 
DISK-INTERFACE SECTION 




IC50 
74LS14 



March 1981 © BYTE Publications Inc 43 



Text continued from page 38: 

dep ending upon the polarity of 
the Write Enable input. In turn, 
the Read Enable line controls the 
direction of data flow through the 
memory data buffers, IC17 and IC18, 
74LS244 non- inver ting o ctal b uffers. 

The MUX, CAS, and RAS signals 
are generated within the TRS-80 
keyboard /processor module in a 3-bit 
shift register. Figure 4 on page 46 il- 
lustrates, in simplified logic, the 
derivation of these signals. 

At the beginning of each read or 
write cy cle, the Z80 microprocessor's 
MREQ (mem ory req uest) line is 
pulled low. The MREQ signal i s also 
used by the TRS-8 as the RAS 
signal. The RD and WR (negative- 
logic read-enable and write-enable) 
lines are logically ORed to feed the 
CLR (clear) inputs and the D input of 
FF1, the first flip-flop in the 3-bit shift 
register. When either RD or WR 
goes low, a logic 1 is loaded into FFl 
at the occurrence of the rising edge of 
the 10.6445 MHz master clock pulse. 
On the next clock pulse, the logic 1 is 
shifted into FF2, the second flip-flop, 
of which the Q output controls the 
MUX signal. The next clock pulse 
shifts the logic 1 into flip-flop FF3. 
The inve rted Q output of FF3 is 
the CA S signa l to memory. When 
theRD or WR line goes high again, 
the three flip-flops are cleared and the 



Notes 

1. On IC1 thru IC16 (the 4116 
components) the +5 V lead on 
each IC should have one de- 
coupling capacitor. One decou- 
pling capacitor should be on every 
other chip for the +12 V and 
—5 V leads, for a total of thirty- 
two decoupling capacitors. Careful 
placement of decoupling capac- 
itors is absolutely critical to proper 
operation. 

2. All other places where de- 
coupling capacitors are required 
are denoted by an asterisk (*) on 
the diagram. 

3. All capacitors are 12 V ceramic 
disk type unless otherwise noted. 

4. All resistors are 1/4 W 5% 
tolerance carbon-film type unless 
otherwise noted. 



address multiplexers are reset. 

It is easy to see that multiplexing 
the addreses is fairly simple, especial- 
ly when the signals needed are 
available on the 40-pin TRS-BUS con- 
nector. 

Interestingly enough, Radio Shack 
did not use these signals in late- 



production TRS-80 Expansion Inter- 
faces. Because some of the signal 
pulses are very short in duration 
(about 200 ns) and susceptible to 
noise, the early-production Expan- 
sion Interfaces had to have a buffered 
cable to eliminate memory errors. 
Eventually, this arrangement was 



Write Strobes 

37E0 — disk-drive select (1 ot 4) 

37E4 — not used 

37E8 — printer data out 

37EC — set disk-controller registers 

Read Strobes 
37E0 — read real-time clock/reset interrupt 
37E4 — not used 
37E8 — read printer status 
37EC — read disk-controller registers 



Table 1: Hexadecimal memory-mapped addresses of registers used by the Disk-80 to 
coordinate the disk-drive controller, the printer interface, and the real-time clock. 



IC N 


umber 


Type 


+ 5V 


GND +12V -5V 


1 thru 16 


4116 (200 ns) 


9 


16 


8 1 


17 




74LS244 


20 


10 




18 




74LS244 


20 


10 




19 




74LS32 


14 


7 




20 




74LS157 


16 


8 




21 




74LS157 


16 


8 




22 




74LS00 • 


14 


7 




23 




74LS14 


14 


7 




24 




74LS244 


20 


10 




25 




74LS244 


20 


10 




26 




74LS30 


14 


7 




27 




74LS139 


16 


8 




28 




74LS155 


16 


8 




29 




7416 


14 


7 




30 




7416 


14 


7 




31 




74LS20 


14 


7 




32 




74LS175 


16 


8 




33 




74LS123 


16 


8 




34 




74LS123 


16 


8 




35 




74LS00 


14 


7 




36 




74LS04 


14 


7 




37 




74LS74 


14 


7 




38 




74LS74 


14 


7 




39 




74LS240 


20 


10 




40 




74LS240 


20 


10 




41 




74LS367 


16 


8 




42 




INS1771D-1 


21 


20 


40 1 


43 




CD4049 


1 


8 




44 




74LS90 


5 


10 




45 




CD4518 


16 


8 




46 




CD4518 


16 


8 




47 




74LS74 


14 


7 




48 




74LS74 


14 


7 




49 




74LS00 


14 


7 




50 




74LS14 


14 


7 




51 












Table 2: List of integrated circuits and power-win 


ng requirements for the Disk-80, 


excluding those integrated circuits found on the 


optional 


power-supply / print er- 


interface circuit board. 


The entity marked IC51 on 


the schematic diagram is really a 


connector for 


the 14-conductor ribbon 


cable running between the power-supply/ 


printer-interface board and the disk-cor 


troller board. 





44 



March 1981 © BYTE Publications Inc 



replaced with a circuit in the Expan- 
sion Inter face that derives the MUX 
and CAS signals by sending RAS 
through a delay line. Of the three 
original signals, only the RAS 
signal, which has the longest pulse 
duration, is used. 

If cable lengths are kept to a 
minimum and proper signal termina- 
tion is employed, there is no good 
reason why any signal available from 
the keyboard/processor module 
should not be used. The Disk-80 uses 
a combination of active termination 
and Schmitt-trigger inputs to 
guarantee reception of all available 
signals. 

Memory Refreshing 

So far you have heard only the 
good things about dynamic memory. 
One of the less desirable character- 
istics is called memory refreshing. 
Unlike static memory, which stores 
data in active bistable circuits com- 
posed of three transistors, the 
dynamic 4116 stores its Is and Os in 
single-transistor cells that simulate 
capacitors. As from a capacitor, the 
electrical charge that represents a bit 
slowly drains off unless it is "re- 
freshed." Refreshing is accomplished 
by addressing ail memory cells (or a 
required minimum of them) on a 
regular basis. 

The 4116 is a RAS-only-refresh 
device. Instead of addressing all 
16,384 bit-cell locations, only the 128 

rows are cycled. This type of 

refreshing uses only the RAS signal 
and is achieved in less time than 
methods that use both row and col- 
umn addr essing. Because the MUX 
and CAS pulses are not used, the 
memory is not enabled, and the 
refreshing does not interfere with 
other system operations. However, 
all 128 rows must be addressed at 
least every 2 ms to avoid loss of data. 

Refresh circuits are generally 
binary counters that generate sequen- 
tial addresses which are applied to the 
memory chips. The Z80 pr ocesso r in- 
cludes a built-in 8-bit RAS-only 
refresh register. During the decoding 
and execution of an instruction op 
code, the 7 bits of the refresh register 
contents are placed on the low-order 
line s of the address bus, and 
the MREQ line is strobed. In effect, 
the Z80 accomplishes "hidden 
refresh" as it executes its normal pro- 
gram. For more information on this 
capability, I refer you to the Zilog 



Z80-CPU Technical Manual. 

Sequencing the Power Supply and 
Decoupling 

Unfortunately, in addition to 
refreshing dynamic memory, a 
designer has to be concerned about 
sequencing the turning on of the 



ov 

+ 5V 



OV 
+ 5V 



OV 
+ 5V 







































































































Dqut 





Figure 3: RAS, CAS, and MUX timing 
diagram for 4116-type 16-pin dynamic- 
memory integrated circuit. A 14-bit 
address (16,384 by 1) is multiplexed into 
seven address pins. When MUX and RAS 
are low, the row-address bits are read into 
the 4 116. Later, when MUX is high and 
CAS goes low, the column bits are read 
into the 4116, activating the data output 
for that memory cell. 



power supplies. While some brands 
of type-4116 memory devices are 
more tolerant than others, the follow- 
ing rule must be applied: the —5 V 
supply (V B b) must be applied to the 
4116 before the +12 V supply (V DD ), 
and the —5 V supply must remain on 
until the +12 V supply has been 
removed. The +5 V (V C c) supply is 
less critical, but it is best to turn it on 
and off synchronously with the 
+ 12 V supply. Many dynamic- 
memory components have been de- 
stroyed by designers not adhering to 
these rules. 

Supplying Power 

Power-supply sequencing is impor- 
tant because many power supplies 
overshoot their rated voltages when 
they are turned on. If V BB ( — 5 V) is 
not turned on and V DD ( + 12 V) over- 
shoots to more than +15 V, the chip 
will blow. Applying V BB first pro- 
vides an extra margin to prevent 
device destruction. Also, V BB must 
never go positive with respect to any 
other input. 

The Disk-80 power supply, shown 
in photo 3 with the optional printer 
interface, meets these requirements. It 
is designed such that the time con- 
stants of the various sections produce 
a phased start-up and shutdown. This 
sequential operation is primarily 
achieved by use of filter components 




Photo 3: The Disk-80 power supply with the parallel printer interface. The power sup- 
ply provides 1 A at +5 V , 400 mA at +12 V, and 50 mA at — 5 V, and is designed for 
use with dynamic memories such as the 4116 that require sequenced application of 
power. 



March 1981 © BYTE Publications Inc 45 



TRS-80 KEYBOARD/PROCESSOR 
UNIT 







AO 

A} 

A2 

A3 

A7 

A8 

A9 

A10 

Z80 
PROCESSOR 

A4 

A5 

A6 

All 
A12 
A13 



EQUIVALENT 
OF "OR" GATE 



10.6445[3>— < 

MHz 

CLOCK 



3-BIT 

SHIFT REGISTER 



D 

FF1 
74LS74 

CLOCK 

CLR 



D 

FF2 
74LS74 

CLOCK 

CLR 



FF3 
74LS74 



CLOCK Q 
CLR 



EXPANSION INTERFACE UNIT 



1Y 



2Y 



74LS157 



1A 

2A 

3A 

4A 

IB 

2B 

3B 4Y 

4B S 



3Y 



ADDRESS 
MULTIPLEXER 



1A 
2A 
3A 

IB 
2B 
3B 



1Y 

74LS157 
2Y 

3Y 



MK4116 
A0/A7 

A1/A8 

A2/A9 

A3/A10 

A4/A11 

A5/A12 D 0UT 

A6/A13 

WR 

RAS CAS 



J 



1 

-5V 



(16K BY 3 
BIT) 



.DATA 
OUT 



Figure 4: Simplified schematic diagram of the internal circuitry of the TRS-80 Model I showing the derivation of the memory-refresh 
logic. 



that are matched to the transformer 
impedance. Also, because I have 
designed it around a transformer with 
specific secondary voltages, the 
Disk-80 power supply is very efficient 
and produces relatively little heat. It 
is designed as a separate circuit 
board, allowing it to be used with any 
project requiring power for dynamic 
memory. It easily powers the full 
fifty-four-chip Disk-80, including 
32 K bytes of memory. 

A Centronics-compatible parallel 
printer port can be optionally built on 
the power-supply board. A schematic 
diagram of this port was printed in 
my previous article, "I/O Expansion 
for the TRS-80, Part 2: Serial Ports," 
BYTE, June 1980, page 42. 

Finally, techniques of properly 
distributing power and decoupling 
transient noise voltages must be ad- 



dressed. Correct layout of the com- 
ponents in the Disk-80 is critical. The 
4116s can generate high-current tran- 
sients when in operation. Resulting 
voltage spikes can cause data loss 
unless the voltage transients are 
minimized by properly placed 
decoupling capacitors (a capacitor, 
usually a ceramic disk type with a 
value of 0.01 *iF to 0.1 /i¥ attached 
between power and ground). 

Some suggestions that are of par- 
ticular concern in the memory area of 
the circuit board: 

• Decouple the V BB and V DD supply 
lines on every other chip. 

• Distribute larger capacitors around 
the board to reduce supply-voltage 
droop. 

• Decouple V cc every few chips. 
•Keep signal lines short. 



Real-Time Clock 

To be compatible with TRS-80 
hardware, the Disk-80 contains a 
real-time clock. It provides an inter- 
rupt to the Z80 at a rate of 40 times a 
second (every 25 ms). When the NMI 
(nonmaskable interrupt) is enabled, 
the clock-produced interrupts cause 
the Z80 to transfer control to a 
specific ROM (read-only memory) 
address (the interrupt vector). Unless 
there is a user-supplied routine to be 
executed, the Z80 simply returns 
from the interrupt sequence and con- 
tinues where it left off. Various disk 
operating systems for the TRS-80 use 
an interrupt-servicing routine called 
in this manner to increment a time-of- 
day clock or event timer. 

Five-Inch Floppy-Disk Controller 

The Disk-80 uses an LSI (large- 



46 March 1981 © BYTE Publications Inc 



TO DISK- 
CONTROLLER 
CHIP SEPARATED 



XLOCK 



74LS04 



EXTERNAL DATA SEPARATOR 



74LS00 



I-5V 



EXTERNAL^— I 
CLOCK ^ — r 



-< 



DATA 



<^-<3- 



SEPARATED 
DATA 



+ 5V 



\ 



^y^y 1 



FALSE CLOCK 
WINDOW GENERATOR 



^h 



5.4/iS 
74LS123 



■>■ 



-)h 



H5V 



400ns 



74LS123 



-<& 



FLOPPY-DISK 
DRIVE 



-<CDread DATA 



74LS14 



~2 



► 5V 
J 



+ 5V 

L 



DATA-WINDOW GENERATOR 



-vyt- 



74LS74 



74LS00 



->T>, 



CLOCK 
C 



CLOCK Q 
C 



74LS74 

CLOCK 
C 




3-BIT COUNTER 



Figure 5: Simplified schematic diagram of a 5-inch floppy-disk external data separator. The internal data separator of the FD1771 is 
not recommended for use in such applications. This circuit can be added to any existing TRS-80 Expansion Interface (which does not 
have an external data separator) to improve performance. 



scale integration) floppy-disk- 
controller integrated circuit. This one 
component performs the following 
functions: encoding, decoding, pat- 
tern recognition, serial-to-parallel 
and parallel-to-serial conversion, 
CRC- (cyclic redundancy check) 
character generation, and control of 
the disk-drive mechanism. 

Floppy-disk controllers are 
available from a number of manufac- 
turers in both single- and double- 
density versions. Since practically all 
TRS-80 Model I disk software is 
stored in single density, the Disk-80 
uses a Western Digital FD1771-B01 
single-density disk-controller in- 
tegrated circuit. This component is 
second-sourced by National Semicon- 
ductor as the INS1771D-1. 

The standard single-density 5-inch 
floppy-disk drive stores 110 K unfor- 
matted bytes per disk distributed on 
thirty-five tracks (some drives can use 



forty or more tracks). Using a soft- 
sectored format like that used in the 
IBM 3740 Data-Entry System, each 
track is divided into 16 sectors storing 
128 bytes each. The total amount of 
data that can be stored on a disk is a 
function of the disk operating system 
and the number of tracks per disk 
supported by the drive itself. 

The 5-inch floppy disk is rotated by 
a DC motor at a speed of 300 rpm. 
An 8-inch floppy-disk drive contains 
an AC synchronous motor, which 
spins the disk at 360 rpm. The bit 
density of the data is the same, but, 
due to the differences in rotational 
speed and disk diameter, the 5-inch 
drive transfers data at 125 kbps 
(thousand bits per second) as com- 
pared to the 8-inch drive's rate of 
250 kbps. The 5-inch drive's lower 
data rate makes programmed I/O a 
practical transfer method. Pro- 
grammed data transfer through 



specific registers requires less complex 
hardware than DMA (direct memory 
access) transfer. 

Drive selection is handled by IC32, 
a 74LS175 4-bit register, and IC33a, a 
74LS123 one-shot (monostable 
multivibrator). Only one drive is 
selected at a time, and the drive 
motors are turned off between disk 
accesses. To address a particular 
drive, a one-of-four drive code is 
loaded into IC32 through the 
memory-mapped register at hexa- 
decimal address 37E0. This action 
starts a 5-second "motor-on" timer, 
which is activated whenever a drive is 
selected. It also activates the Head 
Load Time (HLT) control line on the 
FD1771. The software takes into ac- 
count the 1 second required for the 
motor to come up to speed and the 
80 ms required for head loading. 
Unless another access is made to this 
same drive, the motor will shut off 



March 1981 © BYTE Publications Inc 47 




The following items are available postpaid in the US from: 


The MicroMint Inc 
917 Midway 
Woodmere NY 11598 
(516) 374-6793 




Item 


Ordering Description 


Price 


Disk-80 blank circuit board 
(containing no components) 


Disk-80 PCB 


$48 


Power-supply/ printer- 
interface blank board 


PWR/P1 PCB 


$16 


Power-supply only 
blank board 


PWR PCB 


$12 


INS1771D-1 disk controller 
chip with manual 


INS1771D-1 


$24 


16 K bytes (8 chips) of 
memory: 4116s, 200 ns 


16 K MEM 


$40 


prime units 






Power supply complete kit: 
PC board and parts (add $15 
for printer port and parts) 


PWR Kit 


$38 


Disk-80 complete kit: case, 
power supply, printer port, 
cable and 16 K memory 


Disk-80 Kit 


$275 


Disk-80 expansion interface: 
completely assembled and 
tested with 16 K bytes of 
memory and printer port 


Disk-80 Assembled 


$379.95 


All printed-circuit boards are solder-masked and silkscreened and come 
with assembly instructions. Various other components and kits are also 
available. Call or write for a complete price list. 


New York residents please add 7% sales tax. 





Photo 4: External-data-separator section 
of the Disk-80 board. An external data 
separator is recommended when using the 
FD1771 disk controller with the 5-inch 
floppy disks. This circuit (shown in figure 
5) can also be added to the Radio Shack 
TRS-80 Expansion Interface to improve 
performance. After setting the adjustment 
potentiometers, use nail polish as shown 
to lock their positions. 



after 5 seconds. 

The Z80 bus structure makes it 
relatively easy to use a floppy-disk 
system. All data, commands, and 
control for the FD1771 are handled 
through conventional memory- 
reference instructions. Eight memory- 
mapped ports (four in and four out) 
handle all the communication be- 
tween the Z80 and the FD1771. The 
range of addresses is hexadecimal 
37EC to 37EF. 

The Z80 controls the FD1771 
through eleven commands, which are 
divided into four groups: 

Type I — Commands that move 
the read/write head: 
Restore, Seek, Step, 
Step-in, Step-out. 

Type II — Commands that read 
and write data: Read 
sector, Write sector. 

Type III — Commands that per- 
form status checking 
and formatting: Read 
address, Read track, 
Write track. 

Type IV — Force-interrupt com- 
mand. 

An address map of Type I, II, and 
III FD1771 register-access functions is 
shown in table 3 on page 50. The 
commands and data are com- 
municated to the FD1771 by setting 
the appropriate logic levels on ad- 
dress lines A0 and Al (pins 5 and 6 on 
the _FD1771) and str obing either 
the RE (read-enable) or WE (write- 
enable) inputs (pins 4 and 2). 

Many disk-control commands re- 
quire a parameter such as a track or 
sector address. This data must first be 
loaded into the appropriate register in 
the FD1771. To send a track address, 
for example, the 8-bit track address is 
loaded into the Z80's accumulator, 
and a store-accumulator [LD (HL), A] 
instruction to the track-register port 
at address 37ED is executed. 

Of the FDl771's sixteen control 



48 



March 1981 © BYTE Publications Inc 



Circle 26 on inquiry card. 



baZic is written entirely in Z80® code — baZic runs as much 
as 30% faster than North Star 8 BASIC. The greater execu- 
tion speed is significantly advantageous forhea\y number 
crunching, multiuser and multitasking operations. 

baZic has all the features of North Star BASIC — and 
then some. baZic, with minor exceptions, is 100% compatible 
with existing North Star BASIC programs. Our new baZic 
runs under all Micro Mike's timesharing and hard disk 
operating so tware, including JOEDOS/JOESHARE/ 
HDSHARE and 5SHARE. 

CHECK THESE FEATURES AT YOUR 
COMPUTER DEALER: 

■ Takes full advantage of the Z80 instruction set 

■ Can be used on any Z80-based microcomputer operating 
under North StarTJQS or CP/M® (CP/M versions available 
early '81) 

■ Supports North Star floating point board for even faster 
execution of compute intensive programs 



■ Makes Multiuser systems with floppy disks more practical 

■ Improves performance of Multiuser Hard Disk systems 

■ baZic adds functions to assist in screen formatting, as well as 
features to simplify programming, e.g. APPEND command/ 
statement, ON GOSUB, cursor-addressable PRINT, etc. 

■ baZic, as shipped, includes 8, 10, 12 and 14 digit precisions, 
including both software and hardware floating point versions 

■ baZic is now included with Micro Mike's operating system 
software and applications programs 

Dealers and OEM's: Special Discounts Available 

For complete information, contact your North Star dealer or 
send $1 to Micro Mike's for complete technical presentation. 



g North Star Computers. Inc. 

"ZiloH, Inc. 

^Digital Research, Inc. 



JMAfee a 

Micro Mike's Inc. 

905 S. Buchanan, Amarillo, Texas 79101 

806-372-3633 



[ardfact: 

>150 package makes your Horizon 
execute programs up to 30% faster! 







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lines, seven interface directly to the 
disk drive through drivers and 
receivers (type-7 416 and 74LS14 com- 
ponents). The Write Data line 
transmits the digitized serial com- 
posite data to be written on the flop- 
py disk. The Write Gate line enables 
the actual writing process. The 
Index input transmits the pulse 
from the index-hole photodetector 
that indicates t he beginning of a 
track, and the Write Protect line 
tells the controller when a write- 
protected disk has been i nserted into 
the drive. The Track 00 line is ac- 
tivated when the read/write head is 
positioned over track 00 (the outer- 
most track) of th e disk's surface. The 
Direction Select line defines the 
direction i n whi ch the head will move 
when the Step line is pulsed. Each 
pulse moves the head one track. 

An External Data Separator Is the 
Best Insurance 

As previously mentioned, the 
5-inch floppy-disk drive transfers 
data at 125 kbps, while an 8-inch 
drive transfers at 250 kbps. The dif- 
ference in data rates affects the data 
separator's timing values as well as 
the clock rate used by the controller 
chip. The 5-inch drive requires a 
1 MHz clock, while a standard 8-inch 
drive uses a 2 MHz clock. 

Data received from the drive's elec- 
tronic circuitry is a multiplexed com- 
bination of data and clock pulses. 
The FDl771's internal data separator 
can separate the data and clock bits, 
but use of the FDl771's internal data 
separator is not recommended where 
high reliability is required. An exter- 
nal data separator must be added to 
maintain a soft-error rate better than 
1 in 10 s . 

The internal separator operates 
from the 1 MHz system clock, which 
is not synchronous with the clock 
pulses of the disk data. Due to 
mechanical variations and other fac- 
tors, sometimes a bit of data can ar- 
rive at the FD1771 at a point in time 
"outside the data window," that is, 
when the controller is not expecting 
it. 

[Editor's Note: For a more detailed 
explanation of the importance of the 
data window, see "Interface a Floppy- 
Disk Drive to an 8080A-Based Com- 
puter" by John Hoeppner in the May 
1980 issue of BYTE, page 72. ...RSS] 
The nonsynchronous data window's 
1 ins (microsecond) resolution can 



Hexadecimal 
Memory-Mapped 

37EC 
37ED 
37EF 
37EF 



A1 



1 
1 



A0 


1 


1 



37EC 
Read Enable 

Status Register 
Track Register 
Sector Register 
Data Register 



37EC 



Write Enable 

Command Register 
Track Register 
Sector Register 
Data Register 



Table 3: Memory-mapped addresses used by the Disk-80 to communicate with the 
FD1771 or INS1771 floppy-disk-controller integrated circuit. The FD1771 interacts 
with the Z80 processor by memory-reference instructions, not by DMA. The 
FD1771 can execute eleven high-level function commands. 



MISSING CLOCK PULSES 




SERIAL DATA 



DATA WINDOW 
(6 M s ONE-SHOT) 



FALSE CLOCK 
PULSE GENERATOR 
<5.4,is ONE-SHOT) 



SEPARATED DATA 





i n p 


n^ rn L^ n L^ 






L 




n 




U L 




1_ 




i 


1 



"1" 



Figure 6: Timing diagram illustrating the operation of the external data separator shown 
in figure 5 on page 47. Clock pulses are denoted by the letter C, data pulses by the letter 
D. 



move with respect to a data bit's ar- 
rival by enough that the data bit can 
actually fall outside the data window. 
This would be interpreted as an error. 

To help eliminate what has been a 
major problem for TRS-80 Model I 
disk users, the Disk-80 includes an ex- 
ternal data separator. Neither the 
Radio Shack TRS-80 Expansion Inter- 
face nor the LNW Research System 
Expansion Board has an external data 
separator. Figures 5 and 6 illustrate 
the circuitry and function of the 
Disk-80's external data separator. 

The external data separator places 
a 4 00 ns (nano second) one-shot on 
the Read Data line from the drive . 
This a rrangement reduces the Read 
Data input pulse width from 1.2 (is 
to 400 ns. When configured for ex- 
ternal clock and data separation, the 
FD1771 requires pulse widths be- 
tween 300 and 700 ns. The narrower 
the pulse width, the better the data 
separator's resolution. 

To produce the separator's data 
window, a 6 fts one-shot is triggered 
by the leading edge of the clock pulse. 
Since the time between clock pulses is 



8 (is, a data bit is expected within 4 fis 
after the clock pulse's leading edge. 
The extra 2 (is allow for shifts in the 
phase of the data or clock bits. This is 
all that is required to satisfy any 
potential timing problems. However, 
since we also have to be IBM 3740 
compatible, more is required. 

The IBM 3740 format creates a 
unique addressing mark by dropping 
three clock pulses during the address- 
mark clock pattern. To produce data 
windows during missing clock-pulse 
intervals, a false clock pulse is 
generated with a 5.4 (is one-shot. If 
the 5.4 (is one-shot times out past the 
expected instant of the next clock 
pulse, its own pulse's trailing edge 
triggers the other (6 /is) one-shot, 
generating a data window. 

A 3-bit counter distinguishes be- 
tween missing clock pulses and ad- 
dress marks. If the data separator is 
already in phase, it is constantly reset 
by the separated clock output. When 
the separator encounters the address 
mark, the counter is incremented by a 
pulse on the separated data line. On 
the occurrence of the fourth missing 



50 



March 1981 © BYTE Publications Inc 



The 

Brains of Men 

and Machines 



by Ernest W. Kent 

When the "Brains of Men and 
Machines" series of articles originally 
appeared in BYTE magazine, the re- 
sponse was immediate and enthusiastic. 
Now Ernest W. Kent has expanded his 
ideas about the brain into a full-length 
book. 

As researchers begin to unravel the 
mysteries of the brain's chemical, elec- 
trical, and synaptic circuitry, their find- 
ings are becoming immediately ap- 
plicable to advances in robotic behavior 
and computer design. The Brains of 
Men and Machines "dissects" the 
brain to provide new insights into com- 
puter design and artificial intelligence. 

It is one of the rare books that tran- 
scends disciplinary boundaries. In it the 
ever increasing relationship between 
man and machine is freshly examined — 
a relationship, Professor Kent con- 
cludes, that is today being reexamined 
in the light of man's own neurological 
self-image. 

T T , no . Call TOLL FREE: 800-258-5420 

Hardcover 304 pages or Mail To: 



ktitiIj! 70 Main SL 

BLIIirya Peterborough, NH 03458 



ISBN #0-07.034123-0 

Price 115.95 

Please remit in U.S. funds or draw on a U.S. Bank 



Please send □ 



. copies of 



The Brains of Men and Machines 



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□ Check enclosed in the amount of $ 

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Add 75* per book to cover 
postage and handling. 



m 




clock pulse, the data window is reset. 
The separator becomes in-phase 
again on the next true clock pulse. 

Photo 4 shows the location of the 
false-clock and data-window adjust- 
ment potentiometers, R20 and R21, 
on the Disk-80 circuit board. These 
are the only user adjustments in the 
unit. The best method for setting 
them is to use an oscilloscope and a 
pulse source. With only IC34 inserted 
in the board and the +5 V supply on, 
apply a 50 to 100 kHz clock pulse 
first to IC34's pin 1. With a scope 
probe on pin 4, adjust R20 until the 
one-shot period is 5.4 /is. A similar 
clock signal is applied to pin 9 of 



IC34: that section should be set for a 
period of 6.0 /ts by turning R21. 

In Conclusion 

The TRS-80 Model I may no longer 
be on the minds of the marketing 
moguls at Tandy Corporation, but 
the hundreds of thousands of Model I 
owners will want to keep using it. 
Now that you know what is inside an 
expansion interface, you could build 
one, if necessary. 

Correctly assembling an expansion 
interface from the circuit diagrams of 
figure 2 is more than just making all 
the right connections, however. 
Layout, decoupling, and power 



You can extend the useful- 
ness and data entry speed 
of your TRS-80 by giving it 
the graphics and menu ca- 
pabilities of the Bit Pad One 
digitizer. 

With the Bit Pad and 
proper software, you can 
generate schematic dia- 
grams; describe sales 
curves to your computer; enter alphanu- 
meric information by merely touching 
printed letters on a menu, orenterorderor 




inventory information by 
merely checking boxes on 
printed forms, 

Bit Pad One, complete 
with stylus, specially de- 
signed plug-in TRS-80 in- 
terface and power supply 
cost just slightly over 
$1,000. 

If you don't have a digi- 
tizer, you are restricting your TRS-80's 
abilities. We'll gladly send you a list of dis- 
tributors who have the Bit Pad One. 

^^ mr "cotporalKHi 

tt tftfrtHi 35 Brentwood Avenue, Fairfield, 
CT 06430, (203) 384-1344 



Now, Bit Pad One ™ 
digitizer makes it easy to add 
graphics capability 
to your TRS-80! 




H 2 


3 


4 


3 


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G 


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P JQ 


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distribution are probably the most 
critical factors to be considered. 

I had to be aware of these same 
considerations while I was designing 
the Disk-80, and I had a dilemma 
when it came time to build the pro- 
totype I do for every Circuit Cellar 
article. The Disk-80 uses fifty-four in- 
tegrated circuits and 120 resistors and 
capacitors. The placement of these 
components is as important, in many 
cases, as the inclusion of the compo- 
nent. 

To eliminate major trouble- 
shooting headaches and make it 
easier for others to construct this in- 
terface, I went straight from my 
schematic diagram to a printed- 
circuit board, without breadboarding 
or wire-wrapping. Besides making it 
easier for me, the result is an elimina- 
tion of the concern that experimenters 
would have about the placement of 
components and decoupling capac- 
itors and the routing of signal lines. 
The printed-circuit boards are 
available from The MicroMint, at the 
address given in the text box on page 
48. The schematic diagram of the 
power supply is not provided here 
because the correct sequential ap- 
plication of the voltages depends on 
the use of the exact transformer and 
components I specified; the circuit 
may not work with substitute com- 
ponents. If you really want a 
schematic diagram and a parts list for 
the power supply, send a stamped, 
self-addressed envelope to The 
MicroMint. 

I hope that many of you will take 
this opportunity to build your own 
expansion interfaces. ■ 

Next Month: 

Build a low-cost logic analyzer. 



References 

1. Z80CPU Technical Manual. Zilog Inc, 
10460 Bubb Rd, Cupertino CA 95014, 
1977. 

2. Hoeppner, John. "Interface a Floppy- 
Disk Drive to an 8080A-Based Com- 
puter." BYTE, May 1980, page 72. 



Editor's Note: Steve often refers to previous 
Circuit Cellar articles as reference material for 
the articles he presents each month. These 
articles are available in reprint books from 
BYTE Books, 70 Main St, Peterborough NH 
03458. Ciarcia's Circuit Cellar covers articles 
appearing in BYTE from September 1977 thru 
November 1978. Ciarcia's Circuit Cellar, 
Volume 11 presents articles from December 
1978 thru June 1980. 



52 



March 1981 © BYTE Publications Inc 



Circle 28 on inquiry card. 



New iSBX Multimodule boards 

Intel introduces a whole new dimension 
in configuring single board computer systems. 



Intel pioneered the concept of 
flexible microcomputer system design 
in 1976, with our family of iSBC™ 
single-board computers interfaced via 
the Multibus™ system bus — presently 
accepted as the industry standard. 

Now we've extended this well- 
accepted concept to board-level 
design: A new generation of Multi- 
module boards interface to iSBCs via 
the new iSBX bus. So now you have 
a second design option. You can 
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with Multibus boards. Or in smaller, 
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Multimodules. 

The key to configuration 
flexibility 

The iSBX bus — the first physical/ 
electrical interface for direct on- 
board expansion of iSBC systems — 
assures compatibility between these 
systems and the emerging Multi- 
module product line. 

Present on all future Intel 
single-board computers, the 
iSBX bus saves design time and 
space, and facilitates fast, easy 
upgrading. System performance is 



New Multimodules and iSBX Bus-compatible iSBCs 



I DJOOOOOQOM J 

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ISBC 80/10B Single Board Computer 
8080A-based microcomputer with one 
iSBX bus connector; 48 programmable 
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for1K-4KbytesRAM;upto16K 
EPROM 



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iSBC 80/24 Single Board Computer 

8085A-2 based microcomputer oper- 
ating at 4.8 MHz (2.4 MHz optional); 
two iSBX bus connectors; 48 program- 
mable I/O lines; one USART; three 
programmable timers; programmable 
interrupt Controller; capacity for 4K-8K 
bytes RAM; up to 16K EPROM 



D Dnona 



ISBX 311 Analog Input Multimodule 

8 or 16 input channels, voltage pro- 
tected; 12-bit resolution; ±20 mV to 
5V lull scale; 20 kHz samples/sec: 
compatible with iCS 910 Signal Condi- 
tioning Termination Panel 



■u)'l 



ISBX 328 Analog Output Multimodule 
8 channels of analog output; voltage or 
4-20 ma current loop; 12-bit resolu- 
tion; compatible with iCS 910 Screw 
Termination Panel 



HI eF 



ISBX 331 Fixed/Floating Point Math 
Multimodule 

Fixed point single- (16-bit) and double- 
(32-bit) precision arithmetic; floating 
point single- (32-bit) precision func- 
tions; floating-to-fixed and fixed-to- 
floating point conversions: transcen- 
dental functions 



111 eH 



ISBX 332 Floating Point Math 

Multimodule 

Single- (32-bit) and double- (64-bit) 

precision arithmetic; compatible with 

proposed IEEE format and existing 

Intel floating point standard 



also improved because Multimodules 
tie directly to the iSBC internal bus. 
Connection to the iSBX bus is made 
with a set of rugged connectors — 
one on the iSBC board, the other 
on the Multimodule itself. 

The new Multimodule family 

Multimodules represent a whole 
new family of plug-in expansion 
boards. They allow you to add a 
variety of special performance 
features to your existing iSBC system. 
Currently available add-ons are 
shown below. Soon you'll also be 
able to add other Multimodules for 
IEEE 488 GPIB control, com- 
munications, peripheral interfaces 
— and more. 

With those modules 
you can now 
respond 



quickly 

to new applications opportunities. 
Examples? For data acquisition 
from thermocouples and strain 
gauges, simply plug in the iSBX 311. 
For 4-20 ma current loop control, 
use the iSBX 328. In laboratory 
control applications, instead of an 
independent math processor, 
now you can choose the more 

Circle 29 on inquiry card. 





economical iSBX 331 or 332 math 
modules. 

Three Multimodule-compatible 
iSBC boards 

Intel's 8-bit 
iSBC 80/10B, 
80/24 and 88/40 
single-board com- 
puters are the first 
of many iSBCs to 
offer iSBX Multi- 
module expansion 
iSBX 960-5 connector capabilities. The 

first two are improved versions of 
widely used iSBC boards. (See table). 

Custom tailoring, too 

For users who want to design their 
own Multimodule boards, Intel offers 
iSBX 960-5 connectors. When used 
in conjunction with the iSBX specifi- 
cations, this set of connectors lets 
you create modular boards that meet 
your own unique requirements. 

Available from Intel today are 
the first six iSBX Multimodules and 
three iSBX-compatible iSBCs. For 
further information, or to order, 
return this coupon or call your local 

ntel sales office or distributor. Or 

contact Intel at the address below. 

int^T delivers 
solutions. 

Europe: Intel International, Brussels, Belgium. 
Japan: Intel Japan, Tokyo. United States and 
Canadian distributors: Alliance, Almac/ 
Stroum, Arrow Electronics, Avnet Electronics, 
Component Specialties, Hamilton/Avnet, 
Hamilton/Electro Sales, Harvey, Industrial 
Components. Pioneer, LA.Varah, 
Wyle Distribution Group, Zentronics. 



Please send information on: 

□ iSBX Multimodules D iSBC 80/10B 
D iSBC 80/24 □ Configuration Guide 

□ Other 

D Please have a Sales Representative call. 

Name 

Title/Organization . 

Add ress 



City/State/Zip_ 
Phone 



Intel Corporation, 3065 Bovvers Avenue, Santa 
Clara, CA 95051. Telephone (408) 987-8080. 



Three-Dimensional Computer 

Graphics, Part 1 



Franklin C Crow 

Department of Computer and Information Science 

Ohio State University 

2036 Neil Ave Mall 

Columbus OH 43210 

The process of generating computer representations of 
three-dimensional structures has been pretty thoroughly 
worked out over the past fifteen years. Several books on 
computer graphics describe the necessary steps and com- 
mercial graphic software has been available for some 
time. Recently, three-dimensional graphic software has 
been made available even to those using microcomputers 
for personal or recreational purposes. 

The software necessary for producing representations 
of simple shapes is not terribly complicated. In this arti- 
cle, I will try to lay out a few fundamental algorithms 
that can form the core of a three-dimensional graphics 
package. However, in order to make sense of these 
algorithms, considerable explanation will be necessary. 

To generate an image of a three-dimensional shape, we 
have to have a computer-readable representation of the 
shape. (I will describe a couple of ways to represent 
shapes.) Then the data for the shape must be transformed 
to conform to the view of the shape that would be seen 
from a given point. The data must then be further 
transformed to fit the shape to the limits of a display sur- 
face (video display or plotter). Finally, those parts of the 
shape that are hidden from view, either because they ex- 
ceed the limits of the display or because they are hidden 
by other parts of the shape, must be eliminated. 



Getting the Data 

The first decision to be made when generating three- 
dimensional data for input to a graphics system is which 
coordinate system to use. A right-handed Cartesian 
system is most often used. Standing at the origin of such a 



system, the x axis would go to the right, the y axis 
straight ahead, and the z axis straight up. If we think in 
terms of a small area of the earth, x would measure 
longitude (east positive, west negative), y latitude, and z 
altitude. 

Points in this space can be defined as a trio of numbers 
giving x, y, and z coordinates. A three-dimensional 
drawing of an object can then be considered a set of lines 
connecting points in space. An object can be described by 
listing all its points in the order in which we would draw 
them. We can then draw the object by "following the 
dots." 

However, we rarely see drawings that are made 
without ever lifting pencil from paper, so we should add 
an indicator wherever we move to a point without draw- 
ing a line. Thus one format for describing objects consists 
of a list of sets of numbers. Each set contains three 
numbers describing a position in space and a command to 
draw a line to that position or just move to that position 
without drawing a line, a total of three numbers and a 
character. An example of this format can be seen in figure 
la, with the associated data given in table la. The Pascal 
procedures given in listing 1 (on page 70) read and dis- 
play objects defined in this format. 

This format is fine if we just want to make drawings of 
objects that appear to be constructed of straight pieces of 
wire. To represent a solid object, we have to define a sur- 
face enclosing the object and therefore need another for- 
mat. Surfaces are most easily represented if we define 
them as sets of faces, or polygons. 

To define objects made of polygons, we must list the 
polygons individually. This can be done by listing the 
coordinates of each vertex (point) of the polygon in 
clockwise order (as seen from outside the object) around 
the periphery of the polygon. It is important that all 
polygons be described consistently since the clockwise 
order is useful for calculations determining which side of 
a polygon is facing the viewer. 




Photo 1: High-resolution display of solid three-dimensional ob- Photo 2: Low-resolution display of the same objects as in photo 
jects defined as sets of polygons. 1. 



54 March 1981 © BYTE Publications lnc 



Circle 30 on inquiry card. 






Multi-User 



UniFLEX is the first full capability multi-user 
operating system available for microprocessors. 
Designed for the 6809 and 68000, it offers its 
users a very friendly computing environment. 
After a user 'logs-in' with his user name and 
password, any of the system programs may be 
run at will. One user may run the text editor 
while another runs BASIC and still another runs 
the C compiler. Each user operates in his own 
system environment, unaware of other user 
activity. The total number of users is only 
restricted by the resources and efficiency of the 
hardware in use. 




Suppor 



The design of UniFLEX, with its hierarchical file 
system and device independent I/O, allows the 
creation of a variety of complex support 
programs. There is currently a wide variety of 
software available and under development. 
Included in this list is a Text Processing System 
for word processing functions, BASIC interpreter 
and precompiler for general programming and 
educational use, native C and Pascal 
compilers for more advanced programming, 
sort/merge for business applications, and a 
variety ordebug packages. The standard 
system includes a text editor, assembler, and 
about forty utility programs. UniFLEX for 6809 is 
sold with a single CPU license and one years 
maintenance for $450.00. Additional yearly 
maintenance is available for $100.00. OEM 
licenses are also available. 



FLEX 



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UniFLEX is a true multi-tasking operating system. 
Not only may several users run different 
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using the text editor. New tasks are generated 
in the system by the 'fork operation. Tasks may 
be run in the background or 'locked' in main 
memory to assist critical response times. Inter- 
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UniFLEX is offered for the advanced 
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A solid object is customarily defined as a group of ad- 
joining polygons. Since neighboring polygons share ver- 
tices along common borders, objects can be more com- 
pactly defined by first listing all the vertices belonging to 
the object and then listing polygons by the numbers of 
the vertices they use. An example of this sort of format is 
seen in figure lb, with data in table lb. The procedures in 
listing 2 read and display objects as a set of polygons. 

Now that we know how to read and display objects, 
where do we get the data describing the objects? The 
simplest way is to dream it up. After all, much of the joy 
of computer graphics lies in creating imaginary worlds. 
Take a piece of graph paper and draw front and side 
views of an object you'd like to represent. Then measure 
the vertices of the object by counting squares from some 
point of origin on the paper. The front view will give you 
the x and z coordinates, and the side view will give you 
the y coordinate (see figure 2). 

People who are involved in creating three-dimensional 
graphics generally build software to aid in designing ob- 
jects. For example, a program to generate surfaces of 
revolution is relatively easy to write. Then shapes such as 
wine glasses and vases are easy to make. A surface of 
revolution can be defined by a sequence of points follow- 




Photo 3: Removal of hidden surfaces can be clearly observed in 
this display generated on a custom graphics display unit con- 
nected to a Digital Equipment VAX 11/780. 




Photo 4: Transformation of a scene due to a change in the loca- 
tion of the eyepoint as well as transformation of the objects 
within the scene. Compare with photo 3. 



ing a path up one side of the surface. The points then 
sweep out a surface by rotating about a central axis. Sur- 
faces of revolution are widely used in computer imagery. 
More advanced techniques make use of high-speed in- 
teractive graphics terminals (costing $20,000 to $150,000) 
in conjunction with elaborate software to define and 
modify shapes. See the papers by Crow and Parent (listed 
among the suggested readings at the end of this article) 
for examples of this approach to data gathering. 

Defining a View of Some Objects 

Once data describing an object is available, it is time to 
figure out how to look at it. In the real world, when we 
look at an object, what we see is determined by our view- 
point and the position of the object. How can we emulate 
this in an imaginary world? 

We want the choice of viewing an object from any 
viewpoint. Therefore we must have an algorithm that 
will move the vertices of the object to the proper posi- 
tion, given a particular viewpoint. The input to this 
algorithm consists of two points in space: the position 
from which we are looking and the position at which we 
are looking. I will refer to these as the eyepoint and the 
center of interest, respectively. 

In order to understand how such an algorithm works, 
we need to know more about how to move objects about 
in an imaginary world. So far I have defined an object 
within its own space or frame of reference. Now we 
would like to arrange a number of objects in a scene, each 
in a different position and orientation. 

Changing the position of an object is relatively simple. 
Using the longitude, latitude, altitude model of space, we 
can move an object east by simply adding some positive 
number to the x coordinates of all its vertices. To move 
an object north, we add some positive number to all its y 
coordinates. To move an object up or down, we change 
all its z coordinates. This process is called translation. 

Similarly, to change the size of an object we multiply 
all its coordinates by the same number. This is called scal- 
ing. To make an object twice as large in every dimension, 
we multiply all coordinates of every vertex by two. Thus, 
changing the position or size of an object is relatively 
straightforward. Rotating an object or combining suc- 
cessive operations, however, requires more sophisticated 
techniques. 

Objects can be moved about quite elegantly using 
techniques provided by matrix algebra. We devise a sort 
of template that is filled in to provide the operation 
desired. Filled templates, called transformation matrices, 
can then be combined to provide complicated operations. 

A template, or matrix, consists of sixteen positions 
(four rows by four columns). Numbers loaded into a 
matrix are combined with vertex coordinates to yield up- 
dated coordinates by matrix multiplication. The first col- 
umn of the matrix affects only the x coordinate and 
therefore contains all the numbers that define the updated 
x coordinate. The second column treats the y coordinate 
similarly, and the third column handles the z coordinate. 
The fourth column is for completeness, to make things 
more elegant. It also allows us to pull some fancy tricks 
such as finding the inverse of a transformation. I won't 
use the fourth column in this article, however. 

A vertex is "transformed" by the matrix as follows: To 
get the new x coordinate, the old x coordinate is 



56 March 1981 © BYTE Publications Inc 



Don't play games 
with your company's money. 




Our entry level computer system is the first step in 
a full range of computer products. Not the last step in 
a full range of computer games. 

We call it VIP. The Vector Intelligent Partner. And 
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VIP has all the assets and none of the liabilities of 
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You'll beabletodo low cost word processing, 
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Economy Sized Computers 



Circle 31 on inquiry card. 



BYTE March 1981 



57 



la 



lb 



M 


1.0 


-1.0 


-1.0 


d 


-1.0 


-1 .0 


-1.0 


d 


-1.0 


-1 .0 


.00 


d 


-.00 


-1.0 


1 .0 


d 


1.0 


-1 .0 


1 .u 


d 


1.0 


1 .0 


1 . 


d 


1 .0 


1 .0 


-1.0 


d 


1 .0 


-1.0 


-1.0 


d 


1.0 


-1.0 


1 .0 


M 


-t.o 


-1.0 


.00 


d 


-1 .0 


-.00 


1 .0 


d 


-1 .0 


1 .0 


1 .0 


d 


-1.0 


1.0 


-1.0 


j 

u 


A 

- 1 . V 


-1.0 


-1 .0 


M 


-1.0 


-.00 


1.0 


d 


-.00 


-'1.0 


1.0 


M 


-1.0 


1 .0 


-1.0 


d 


1.0 


1 .0 


-1.0 


H 


1.0 


1 .0 


1.0 


d 


-1.0 


1.0 


1 .0 



10 



7 

1 .0 

-1 .0 

-1 .0 

-.00 

1.0 

-1 .0 

-1.0 

1 . 

1.0 

-1.0 



(NufiF'ts NuriFuivs .) 
-1.0 -1.0 
1.0 
.00 
1 .0 
1 .0 



-1.0 
-1.0 
-1.0 
-1.0 
-.00 
1.0 

i .0 

1.0 
1 .0 
3 



1 .0 
-1.0 
-1.0 



i 



4 
9 

10 

6 
i 

10 



Table 1: Data for an object defined as a set of lines (table la) 
and for an object defined as a set of polygons (table lb). In 
table la, the "m" and "d" in the first column mean "move to" 
or "draw to" the point with x, y, and z coordinates as given 
in the next three columns, respectively. In table lb, the first 
line gives the number of points (10) and polygons (7) in the 
shape. The next 10 lines give the point number (1 thru 10) 
and the x, y, and z coordinates of the point. The last seven 
rows describe the seven polygons: the first number gives the 
number of points making up that polygon, and the rest of the 
numbers on that line give the point numbers (as described by 
the point description lines) that make up the polygon. Both 
tables la and lb describe the shape shown in figure lb. 



(1,1,1) 





Figure 1: Three-dimensional object displayed as a set of straight 
lines defined by 10 points (figure la) and a set of polygons de- 
fined by using the same points (figure lb). See table 1 for 
associated data. 

multiplied by the top number in the first column, then 
added to the product of the old y coordinate and the se- 
cond number in the first column. The sum is then added 
to the product of the old z coordinate and the third 
number in the first column. Finally, the whole thing is 
added to the bottom number in the first column. The new 
y coordinate can be obtained by combining the second 
column and the old vertex coordinates in the same way. 
Similarly, the new z coordinate is produced using the 
third column. The Pascal procedure in listing 3 (on page 
70) transforms a vertex. 

Under the rules stated above, the bottom row of the 
matrix holds numbers that translate the object. A number 
at the bottom of the first column is added to all x coor- 
dinates to move an object east or west. Similarly, 
numbers at the bottom of the second and third columns 
affect the y and z coordinates. To scale objects, we enter 
the scaling factor along the top-left-to-bottom-right 
diagonal of the matrix. The top-left number in the matrix 
is multiplied by the old x coordinate to yield the new x 
coordinate. Similarly, the second number in the second 
column multiplies the y coordinate and the third number 
in the third column multiplies the z coordinate. 

Rather than trying to explain rotations in the limited 
space here, I will simply illustrate how to fill in the 
matrix. Trying a few examples by hand should convince 
you that rotations work. Simple rotations are those that 
rotate an object about one of the axes of our space. For 
instance, to rotate an object about the z axis by an angle 
A, use the following matrix: 



cos(A) 


sin(A) 








sin(A) 


cos(A) 














1 














1 



Note that this matrix leaves the z coordinate unchanged, 
which is what we would expect from a rotation about the 
z axis. Furthermore, a rotation through a zero angle 
leaves everything unchanged since the cosine of zero is 1 
and the sine of zero is 0. 

I always use the convention that a positive rotation oc- 
curs in a counterclockwise direction looking in the 
negative direction along the axis about which you are 
rotating. This means that if the thumb of your right hand 
is pointed in the same direction as that axis, your fingers 
will curl in the direction of positive rotation. Keeping 



58 March 1981 © BYTE Publications Inc 



TH 7TT 



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'Apple II is a trade name o\ 
Apple Computer. Inc 











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Figure 2: Vertices for objects to be displayed in three dimen- 
sions may be measured from front and side views laid out on or- 
dinary graph paper. 

track of such things requires a strong sense for visualizing 
space. When in doubt, I sketch things with pencil and 
paper. 

To rotate about the x axis, use the following matrix: 



1 







cos(A) 
— sin(A) 






sin(A) 
cos(A) 









1 



To rotate about the y axis, use the following matrix: 



cos(A) 


sin(A) 






1 





— sin(A) 


cos(A) 

o- 







1 



Combining these fundamental rotations results in even 
more interesting rotations. 

Note that all transformations occur relative to the 
origin of the given space. Thus, to rotate or scale an ob- 
ject without changing its position, we must first be sure 
that it is centered on the origin. Therefore, a rotation or 
scaling "in place" (ie: without changing position) requires 
a translation to center on the origin, followed by rotation 
or scaling, then a second translation back to the original 
position. 

Once all the objects in a scene have been transformed 
to the desired positions and orientations, a view from a 
given eyepoint in the direction of the object of interest is 
simulated by an additional transformation that places the 
object in the desired position and orientation. This 
simulation can be achieved by combining a few rotation 
matrices. 

In the first step, we move everything so that the eye- 
point lies at the origin of the space and the center of in- 
terest lies on the y axis, or due north. To do this, we 
translate the eyepoint to the origin and apply the same 
matrix to all the other data. The translation matrix is as 
follows: 



1 














1 














1 





ye.X 


-Eye.Y 


— Eye.Z 


1 



where Eye.X, Eye.Y, and Eye.Z are the x, y, and z coor- 
dinates of the eyepoint. 



60 March 1981 © BYTE Publications Inc 



Circle 33 on inquiry card. 



The Perfect Fit 



The Micromodem II data communications system 
and the Apple II* computer. What better combination to 
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This popular direct connect modem can transmit 
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*" Micromodem II is a trademark of Hayes Microcomputer Products, Inc. 

* Apple II is a registered trademark of Apple Computer Inc. 

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A rotation about the z axis can now be used to move 
the center of interest in a northerly direction. In par- 
ticular, we move the center of interest into the plane 
defined by the y and z axes. The angle of rotation is 
found by passing the center of interest through the eye- 
point translation matrix defined above and then applying 
the following formulas: 



cos(A) = Cl.Y/ V(Cl.X) 2 + (Cl.Y) 2 
sin(A) = Cl.X/V(Cl.X) 2 + (Cl.Y) 2 

where A is the angle of rotation and Cl.X and Cl.Y are 
the x and y coordinates of the translated center of in- 
terest, respectively (see figure 3). 

The process of moving the center of interest onto the y 
axis is completed by rotating the object about the x axis, 
using the following formulas: 



cos(A) = C2.Y/V( C2D 2 + (C2.Z) 2 
sin(A) i C2.ZA/(C2.Y) 2 + (C2.Z) 2 

where C2.Y and C2.Z are, respectively, the y and z coor- 
dinates of the translated and rotated center of interest (see 
figure 4). 

Because all this is done with the intention of displaying 
the resulting coordinates on a flat surface, one more 
transformation is called for. It is useful to think about the 
display surface (video display, plotter, etc) as a space in 
which the x axis measures width, the y axis height, and 
the z axis depth. We can place our transformed coor- 
dinates into this space by interchanging the y and z axes, 
using the following matrix: 



1 

















1 








1 

















1 



Given coordinates for an eyepoint and a center of in- 
terest, we can use the matrix multiply procedure to com- 
bine the above operations into a single orientation for 
displaying a view of the scene. The procedure in listing 4 
(on pages 70 and 72) builds such a matrix. We refer to the 
resulting arrangement of a scene as the eyespace. 

Clipping 

Once all the data in the scene is transformed to the 
eyespace, we must decide how much of the scene fits on 
the display. The display can be thought of as a window 
into an imaginary world. Things such as the size of the 
window and our distance from it determine what can and 
cannot be seen: We can use the edges of the window and 
the origin of the space (ie: the eyepoint) to define planes 
that clip parts of polygons not visible through the win- 
dow (see figure 5). 

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the habit of looking at a 12-inch video display from a 
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located 16 inches from the eyepoint. 



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Figure 3: Graphical representation of calculating the rotational 
angle about the z axis in computing the eyespace matrix. 




C2.Z 



Figure 4: Graphical representation of calculating a rotation 
about the x axis. 




The first step of the clipping process is to define the 
planes to be clipped against. Planes can be defined by 
four numbers, the coefficients of an equation of the 
following form: 

AXx + BXy + CXz + D = 

We can simplify this equation somewhat since all the 
planes we are interested in pass through the origin. For all 
planes passing through the origin, the fourth coefficient, 
D, equals zero. 

Our window can then be characterized by a sequence 
of sets of three numbers, each set describing one plane. 
Listing 5 produces the coefficients of the plane equations 
needed for clipping. Input is assumed to be a polygon. 
Each clipping plane is determined by three points: the 
eyepoint and the two endpoints of an edge from the input 
polygon. This assumes that polygon vertices are taken 
clockwise as seen from the eyepoint and that a "left- 
handed" (width, height, depth) eyespace is used. 

Once we have the clipping-plane coefficients, they can 
be applied to all the vertices of a polygon to find out 
which lie inside and which lie outside the field of view. 
The clipping coefficients are applied to a vertex using the 
following formula in Pascal style: 



Distance : = 



Vtx.X 
Vtx.Z 



Clp.X 
Clp.Z 



+ Vtx.Y * Clp.Y + 



Figure 5: Representation of how a viewing window "clips" por- 
tions of polygons lying outside the pyramid defined by the win- 
dow and the eyepoint. 



This operation (known as a vector dot product) yields a 
distance measure that tells us how far inside or outside 
the viewable area the vertices lie. Negative numbers in- 
dicate that a vertex lies outside, positive numbers that a 
vertex lies inside. If distances for all clipping planes ap- 
plied to all vertices of a polygon are positive, it is com- 
pletely visible. If distances for all vertices and any of the 
clipping planes arenegative, the polygon is entirely out- 
side the window and thus not visible (assuming the clip- 
ping window is convex). If some distances are positive 
and some are negative, we may have to cut the polygon 
into inside and outside portions. 

The procedure in listing 6 takes a polygon and clips it 
by a set of plane coefficients stored in a second polygon 
array. Each plane is tested in turn against each polygon 
vertex. Vertices lying inside (on the positive side of) a 
plane are copied to a temporary polygon array. Where 
two adjacent vertices are found to lie on opposite sides of 
a plane (ie: D1XD2<0.0, meaning the signs of the 
distances are different), the intersection point of the clip- 
ping plane and the edge connecting the two vertices is 
copied to the temporary array. When all the vertices of 
the polygon have been clipped against one plane, the 
temporary array is copied back into the input array and 
clipped against the next plane. This process eliminates 
parts of polygons lying outside an unbounded pyramid 
emanating from the eyepoint and delimited by the win- 
dow polygon. 

Displaying 

Any polygon found to lie within the field of vision 
must be displayed. An additional transform is necessary 
to take the coordinates of the eyespace to the coordinates 
used by the display device, the "screen space." Further- 
more, a division is necessary to achieve the appearance of 



64 March 1981 © BITE Publications lnc 



It's all 

relative, 

especially 

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An Equal Opportunity • Affirmative Action Employer. 



BYTE March 1981 



65 






perspective (ie: objects in the distance should be smaller). 
This transform can take the form of a scaling matrix as 
follows: 

Scale. X : = DotsAcross * WinDist/WinWidth 
Scale.Y : = DotsDown * (V 3 ) * WinDist/WinWidth 

The matrix is then: 



Scale. X 














Scale.Y 














1 





Middl.X 


Middl.Y 





1 



In the above transform, DotsAcross is the number of 
dots across the display, DotsDown the number of lines 
on the display from top to bottom, WinDist the distance 
to the window in eyespace, Win Width the width of the 
window, and Middl.X and Middl.Y are the x and y coor- 
dinates of the middle of the display (in screen space, 
usually DotsAcross/2 and DotsDown/2). The factor (V 3 ) 
takes into account that the standard video display is V 3 
as wide as it is high (the aspect ratio). It is assumed that 
the window has the same proportions as the display. 

Nonrectangular windows require a more careful 
calculation. If the maximum width of the window is less 
than V 3 times the maximum height, another number 
must be substituted for the window width in the above 
calculations. That number should be the maximum of the 
window width and V 3 times the window height. Of 
course, if we use a display with a different aspect ratio, 
the width of the display divided by its height should 
replace the V 3 . 

The procedure in listing 7 divides the x and y coor- 
dinates of each vertex by its z coordinate to achieve the 
perspective effect, then applies the transformation to 
display coordinates directly, rather than using a matrix 
transformation. 

This completes the process of computing an image of 
objects with all data shown, as though the objects were 
made of pieces of straight wire. Next, we look at how to 
achieve the appearance of solid objects capable of hiding 
each other. 

Hidden Faces 

There are two methods that allow solid objects to hide 
parts of themselves or other objects. The first uses the 
plane equation of each polygon to determine whether or 
not it lies on the far side of its object. If it does, the 
polygon is clearly hidden by closer parts of the object. 
The second uses a clipping procedure similar to the one 
described earlier to remove parts of faces that are hidden 
by closer faces. 

In everything that follows, polygons are assumed to be 
convex. Restricting things in this way simplifies the task 
considerably at a very small increase in the cost of 
preparing object descriptions. 

Earlier in the article, I stressed the importance of taking 
the vertices of all polygons in a consistent order, usually 
clockwise as seen from outside the object. Many objects 
are closed surfaces, meaning that the inside of the object 
can be seen only by passing through the surface. In fact, 
if we choose to do so, we can construct all objects as 
closed surfaces for display purposes. 



In any event, if a polygon appears on the screen with 
its vertices in counterclockwise order, we must be seeing 
it from the inside. If we are looking at a closed surface 
from the inside, some other part of the surface must lie 
between us and the polygon in question. Therefore, when 
making pictures of solid objects made of closed surfaces, 
we can immediately reject any polygons appearing in 
counterclockwise order. 

Earlier we used planes for clipping by evaluating the 
positive or negative distance from a point to the plane. 
Similarly, when the eyepoint lies on the positive side of 
the plane of a polygon, the vertices of that polygon ap- 
pear in clockwise order. When on the negative side, they 
appear in counterclockwise order. Some of the pro- 
cedures developed earlier can be used to determine 
whether or not a polygon "faces the eyepoint." 

Three of the vertices of the polygon define a plane. 
Here we can use the procedure developed earlier for find- 
ing a plane defined by two window vertices and the eye- 
point. Use the three points to define two lines. If the two 
lines are treated as direction vectors (subtract one end- 
point from the other), the two vectors can be passed to 
the procedure, which then returns coefficients for a plane 
parallel to the polygon and passing through the origin. 
These coefficients, when used in a dot product with one 
vertex of the polygon, yield a number that tells us on 
which side of the polygon the eye lies. The function in 
listing 8 does the job. 

If a closed convex surface is being displayed by itself, 
the above process is adequate to produce the image with 
only visible faces shown. However, if the surface is not 
convex, or there is more than one object involved, fur- 
ther procedures are necessary. 

Those polygons surviving the clipping procedure and 
the "eye-facing" test can be sorted by their distance from 
the eyepoint. We base the sort on the average of the z 
coordinates of each polygon in turn. If all polygons are 
roughly the same size, no two polygons intersect each 
other, and no two polygons lie close to each other in 
nearly parallel planes, the sort order will allow us to 
eliminate hidden parts of polygons. Most scenes involv- 
ing separated, reasonably simple objects will conform to 
the above conditions. 

Since the polygons must be transformed, clipped, and 
tested for "eye-facing" one by one, it makes sense to use 
an insertion sort to order the polygons displayed. A list 
of polygons to be displayed is built by inserting each new 
polygon description (number of vertices and position in 
vertex array) in the already sorted list of previous 
polygons. A binary search can be used to reduce the 
search time for finding the insertion point. The procedure 
in listing 9 implements a binary insertion sort. Note that 
polygon vertices are stored in an array in contiguous 
groups. The z coordinate of the first element of the group 
is used to hold the average z coordinate of the polygon 
for subsequent tests. 

Sorting is a major part of nearly all hidden-line and 
hidden-surface algorithms. For a thorough discussion of 
sorting and other aspects of hidden-surface algorithms, 
see the paper by Sutherland and others listed in the sug- 
gested readings. Also see the third volume of Donald E 
Knuth's The Art of Computer Programming for a 
thorough treatment of sorting in general. 

Text continued on page 82 



66 March 1981 © BYTE Publications Inc 




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BYTE March 1981 



67 



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70 



March 1981 © BYTE Publications Inc 



ook what's happened to 



HIPL0T 



TM 



$1,385* 




$1,850" 



(T: I 

I 


1-1 1 


• 



It's grown into a complete 
family of quality low cost digital plotters 



In just two short years, The 
HIPL0T has become the most 
popular digital plotter among 
small systems users. With a 
record like that, what can we do 
for an encore? WE'VE IN- 
TRODUCED A COMPLETE LINE 
OF HIPL0TS...with a model 
suited for just about every plot- 
ting application. 

The HIPL0T DMP Series is a 
new family of digital plotters 
with both "standard" and "in- 
telligent" models available with 
surface areas of 8 1 / 2 " x 1 1 " (DIN 
A4)and 11" x 17" (DIN A3). For 
the user needing a basic reliable 
plotter, we have the "old stan- 
dard" DMP-2 (8 1 / 2 " x 1 1 ") and the 
"new standard" DMP-5 (11" x 
17"). For those needing a lit- 
tle more capability, there are 
the DMP-3 (8 1 / 2 " x 11") and 
the DMP-6 (11" x 17")-both 



TM HIPLOT and DM/PL are Trademarks 
of Houston Instrument 



Yes, they are UL listed!** 

microprocessor controlled and 
providing easy remote position- 
ing of the X and Y axes (perfect 
for the OEM). For those who 
want this intelligence plus the 
convenience of front panel elec- 
tronic controls, we've provided 
the DMP-4 (8 1 / 2 " x 11") and the 
DMP-7(11" x 17"). 

The "standard" plotters come 
complete with an RS-232-C and 
a parallel interface. The "intel- 
ligent" DMP plotters accept data 
from either an RS-232-C or Centronics 
data source. For the "standard" plot- 
ters, software is available from 
our ever expanding "Micrographic 
Users Group." The "intelligent" 
HIPLOTs use our exclusive 
DM/PL™ language which min- 
inimizes plot software to a 
fraction of that normally as- 

houston instrument 

GRAPHICS DIVISION OF 

BAUSCH&LOMB 



Circle 40 for literature 

Circle 41 to have representative call 

sociated wth digital plotting. 

With the new DMP Series, 
high quality digital plotting can 
now be a part of your system. It 
just doesn't make sense to be 
without this valuable tool when 
there is a DMP plotter with the 
plot size, speed and capabilities 
that are exactly tailored to your 
specific needs. ..and your 
budget. 

Prices for the DMP series 
range from $1,085* to $1,985*. 

For complete information con- 
tact Houston Instrument. One 
Houston Square, Austin, Texas 
78753. (512) 837-2820. For rush 
literature requests, outside Texas 
call toll free 1-800-531-5205. For 
technical information ask for 
operator #5. In Europe contact 
Houston Instrument, Rochester- 
laan 6, 8240 Gistel, Belgium. 
Telephone 059/27-74-45. 



'U.S. suggested retail prices only. 
■•□MP 2,3 and 4 UL listed 
DMP 5, 6 and 7 UL listing pending 



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72 March 1981 © BYTE Publications Inc 



Circle 42 on inquiry card. 



STOP PLAYING GAMES 



nan 




IlllUlKilW 



Corvus Transforms the Personal Computer 
into a Powerful Business Tool. 

In business, professional offices, and schools through- 
out the world, thousands of Corvus intelligent peripherals 
bring mass storage, increased speed, and multi-user 
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ance, mathematics and science, and other large and 
complex files. 

Corvus proven Winchester disk technology provides 
10 to 80 million bytes of capacity, fully compatible with 
your current operating system. This is up to 500 times the 
capacity of a floppy disk. 

The Corvus CONSTELLATION links up to 64 com- 
puters in a state-of-the-art multi-processor network. It 
provides shared mass storage, pipes for inter-computer 
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that of larger and more expensive networks. 

Backup data protection and archival storage are pro- 
vided by the Corvus MIRROR (Patent Pending), a low- 
cost backup using standard video cassette recorders. 

Contact your local Corvus dealer for the full story 
about these innovative new products. . 

r CORVUS SYSTEMS 

* 2029 OToole Avenue 

'f San Jose, California 95131 
(408) 946-7700/TWX 910-338-0226 



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74 March 1981 © BYTE Publications lnc 




SYNCHRO-SOUND ENTERPRISES 
ANNOUNCES OUR 



NEW MICRO-COMPUTER 
SYSTEMS CENTER 

We are one of the oldest, most experienced, highly dedicated 

micro-computer systems houses in the metropolitan New York area... 

the ORIGINAL Computer People who KNOW computers and offer 

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Call, write or stop in 
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see why you don't 
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anyplace else! 



AAA SYNCHRO-SOUND 

\u/ ENTERPRISES, INC. THE COMPUTER 

r V 125 MINEOLA AVENUE, PEOPLE 
ROSLYN HEIGHTS, N.Y. 11577 

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Bill Budges Space Game Album 39 

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TO ORDER: Phone orders invited using Visa, Mastercard, or hank wire transfers. Visa & MC credit card service charge ol 2%. Mail orders 
may send charge card number (include expiralion date), cashiers check, money order, or personal check (allow 10 business days forchecks 
to clear). Please include phone number. Inc'ide 3% ($5.00 minimum) shipping, handling, and insurance in USA. Shipments within Calif, 
add 6% sales Tax, Foreign orders include 1% handling — shipped freight collect. Foreign orders over S 1000 allow 3 weeks extra and include 
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(714) 579-0330 • MAIL TO: 1251 broadway, el cajon, ca. 92021 



Circle 43 on inquiry card. 



fHoTTiWT?^ 



AUTHORIZED 
APPLE 
SALES & » r , , , „ , „ - ■■ , 

SERVICE V K. ^ II II I -^V ./X. A. II 







ITIOM 



▼ 



■Kl/ERS 











The Byte Covers shown at left are available as 
Collector Edition Prints. Each full color print is: 

• 1 1 " X 1 4" including a 1 W border. 

• Part of an edition strictly limited to only 100 
prints. 

• Personally inspected, signed and numbered 
by the artist, Robert Tinney. 

• Accompanied by a Certificate of Authenticity. 

• Carefully packed and shipped first class. 

• Priced at $20, plus $3 ($6 overseas) for post- 
age and handling. If Set 1-4 or Set 5-8 is 
ordered, the price for all 4 prints is only $70. 

To order, use the coupon below. Visa or Master- 
Charge orders may call Toll Free. 



i i Pli 
I tio 



Please send me the following Collector Edi- 
tion Byte Covers and Certificates of Authen- 
ticity. 

Qty. Cover Amount 

#1-7 Bridges ol Konigsberg $20 

#2-Fun and Games S20 

#3-Homebrew $20 

#4-Software Mirage $20 

#5-Computer Engineering $20 

#6-Total Eclipse $20 

#7-Computer Hardware $20 

#8-Perspectives $20 

No/s 1-4 $70 

No.'s 5-8 $70 

Post. & hand. ($3 in US , $6 overseas) $ 

Total 



D I have enclosed check or money order 

□ Visa D MasterCharge 

Card # 



Expiration Date 

Send my print(s) to: 
Name 



Address. 

City 

State 



-Hip- 



-800 



TOLL 



854-, 



B*S*" 



24 



<°°°li 2/Ext 9lO 



Ho "»s*ZTy* 



DAYi 



■ 910 



days 



Mail this coupon to: 

robert tinney graphics 

1864 N. Pamela Dr. 
Baton Rouge, LA 

FOR W^rrT — -^ 7 ° 815 



week. 




Let Crystal Be Your Guide on the Road to Adventure 



I APPLE J 






those systems with sound capability, our games have Crystalsonics — a new 
some truely superlative hires graphics. In fact. Sands of Mars offers 3-D grapr 
maps of Martian terrain. 



cept in tone generation. For Apple and Atari there are 



Wi" now serve over 30 countries around the world. Dealership and distributor inquiries are welcome. Special rates are available on larger orders. We 
have 48 hours delivery to anywhere in the continental United States. We are also looking for experienced programmers and new game software. Our 
royalty terms are extremely generous. If you have what you consider to be a quality product that you would like to have marketed please give us a call. 
If you would like to be a member of the Crystal User's Club and be eligible to receive free user contributed software, please submit a program of any 
type and a $10.00 membership fee. In return you will receive a Crystal Membership Card, a copy of The House of Usher, and a year's subscription to 
Crystal Vision. 



HOUSE OF USHER — Wander through a haunted house. Rooms and LASAR WARS — Crystalsonics - hires graphics - protect the planet 

scenery in 15 color lo-res graphics. We offer a $100.00 prize to the first earth from a full scale alien invasion. Over three types of invading craft 

person to solve the mystery. Over 200 monsters, objects and perils. and hundreds of approach simulations. The games speaks for itself. 

$24.95 $29.95 

GALACTIC QUEST — Crystalsonics - hires graphics -the ultimate WORLD WAR III — Crystalsonics- hires graphics -for you war game 

space adventure. Vegan warships attack and fire in real time Simula- freaks, this is it! Iran and Irag - nuclear missiles - hires 3 scene bat- 

tion. Land on and trade with over 64 star systems in 3 galaxies. Allow tlefield - demolition squads - tanks - strategy. Custom designed for two 

6-12 hours for play. $29.95 arm chair generals. Save-the world from nuclear holocaust! $29.95 

SUMER — Travel back through time to ancient Sumeria in the middle BENEATH THE PYRAMID — Crystalsonics - hires graphics - brand 

east. You are given 10 years as king to restore this kingdom to prosper- new! Explore the pyramids and miles of winding secret tunnels beneath 

ity. Plant, war, consult the astrologers - very hard to beat! $19.95 them. Enter at the Sphinx and find the hidden treasure chamber. All in 

hires with very aggressive monsters and many many perils. To win you 
must find the golden cat and your way out!!! $29.95 

LITTLE CRYSTAL — Especially designed anthology for children from ages 5 to 80. Includes Mr. Music which turns your Apple into an organ of 
sorts, gunk where two weird monsters shoot it out and many other educational as well as entertaining programs for children. True unique addition for 
kids who always feel left out of Dad or Mom's computerizing. $39.95 

SANDS OF MARS — What we at Crystal believe to be the finest adventure game available to date. In addition to hires graphics and super tone 
routines where the user's system will support it, this game provides landing simulation, animation, and revolutionary 3-D graphics, it is the ultimate 
in space adventure and may take several weeks or months to play. It is the Oydessy of the Starship Herman on its maiden flight to Mars. The initial lift- 
off is animated and paddle controlled. The flight through space is in Hires 3-D Graphics with many animated scenarias. You must land your starship 
on Mars. It will lack enough fuel and supplies for a return voyage. You must lead your party through hundreds of Hires maps of Martian terrain and 
subterrainian passages. You then will secure adequate resources for take off, navigate your ship back to earth and attempt a successful touchdown. 
There is a mystery buried in the ancient city of Lemuria beneath the sands of Mars. We offer a $100.00 prize to the first space gamer to discover it. 
Good luck! $39.95 



For more information you may write or call: 
Crystal Computer, 12215 Murphy Avenue, San Martin, California 95046 

Circle 44 on Inquiry card. 



(408)683-0696 



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80 



March 1981 © BYTE Publications Inc 



Circle 45 on Inquiry card. 



Suddenly Radio Shack's New 
TRS-80 Color Computer is 

Even Better! 



New Extended Color BASIC. Here's an advanced TRS-80 
Color Computer that includes a 16K ROM Extended BASIC 
with advanced graphics, eight brilliant colors, and sound, for 
an unprecedented low price! You can draw ine lines, circles, 
rectangles, boxes and more with easy-to-use one-line com- 
mands. Four graphic modes with two color sets allow up to 
49,152 programmable screen points (pixels). There are 255 
separate tones for music or sound effects. All this on a 16K 
RAM machine (including video memory) loaded with the 
dynamic features a serious programmer demands. You get 
a 32x16 screen, multi-character variable names (two signifi- 
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string arrays, floating point 9-digit accuracy, and even 
machine language routines. 

Priced at Only $599, the TRS-80 Extended Color BASIC 
Computer is useful, entertaining and educational. Yet using 
it can be as simple as plugging in one of Radio Shack's 
instant-loading Program Paks. Come in and see what's 
already available. The computer attaches to your TV, or our 
own $399 TRS-80 Color Video Receiver. For just $24.95, 
you can add a pair of joysticks which add flexibility to games 
and video displays. A built-in serial interface lets you attach 
a printer or a modem. A tutorial Color BASIC instruction 
manual is included, of course. 

More Good News. Extended Color BASIC is also available as 
an upgrade kit ($99) for the 4K Color Computer (16K RAM 
required — $119). There's a modest installation charge fa 
each kit. 



New TRS-80 VIDEOTEX Software (with the modem shown 
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491. 






Text continued from page 66: 

Once the polygons are sorted, we can apply a clipping 
algorithm in a reversed sense. We will remove any parts 
of polygons lying inside a closer polygon as seen on the 
display. Starting with the closest polygon and working 
outward, each polygon will be clipped by all its 
predecessors. Remember, keeping things simple will re- 
quire that polygons be convex. (Nonconvex polygons can 
always be broken into a set of convex ones.) 

In order to use a polygon for clipping, its edges must be 
converted to clipping planes. Therefore, once any part of 
a polygon is determined to be visible, the entire polygon 
is subsequently converted to plane coefficients using the 
same procedure used earlier to convert the window 
description for clipping. 

Since each polygon edge, once clipped, can be 
displayed without further treatment, it is easiest to clip 
each edge individually. This process is not as straightfor- 
ward as it may seem. A polygon may clip an edge into 
two parts, each of which must then be subsequently clip- 
ped by the remaining polygons. Of course, any of the 
later polygons may further divide one of the edge 
fragments. This sort of situation is best handled using 
recursion. Therefore, the procedure given in listing 10 
recursively clips a polygon by all closer polygons and 
flags visible polygons for use in subsequent clipping. Hid- 
den polygons obviously need not be used to clip more 
distant polygons. 

Conclusion 

The preceding procedures provide essentially 



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everything needed to display three-dimensional line 
drawings representing solid objects modeled by 
polygons. An effort has been made to make the pro- 
cedures concise. This has been done at the expense of effi- 
ciency and sometimes, perhaps, even at the expense of 
clarity. I have assumed the availability of a display of 
some kind that can be used to draw lines. Most systems 
capable of full graphics provide software for generating 
lines. 

In the interests of completeness, Part 2 will present a 
complete program incorporating the procedures de- 
scribed above. I have been able to use it, somewhat 
crudely, with a semigraphic terminal (Zenith H-19) and 
the UCSD Pascal system (see photo 2) and, more satisfy- 
ingly, with a 500-line raster display and a Pascal inter- 
preter running under the UNIX operating system (see 
photos 1, 3, and 4; photos are on pages 54 and 56). 

If you have a serious interest in three-dimensional 
graphics, a full understanding of what has been presented 
here is heartily recommended. In addition, you should 
consult the suggested readings listed below for more 
material. Many people have spent time on the problems 
discussed in this article and have published useful articles 
describing other ways to produce computer-generated 
three-dimensional images. 

In addition to line drawing images, much computer 
graphics is now displayed using the features offered by 
raster displays. Quite realistic imagery is possible, offer- 
ing a vast array of possibilities well beyond those de- 
scribed here. There is much work to be done in this area 
yet, so if you are interested, go to it!B 

Acknowledgments 

Mary Lieb handled text-editing and formatting chores. Some of the 
software development and all the higher-resolution computer-generated 
images were done on equipment supplied in part by the National 
Science Foundation (equipment grant § MCS 80-06322) and in part by 
the Ohio State University. 



Suggested Reading 

Newman, W and R Sproull, Principles of Interactive Computer 
Graphics, 2nd edition, McGraw-Hill, 1978. The classic text on com- 
puter graphics — some consider it difficult, but you must read it if you 
are serious about the subject. 

Rogers, D F and J A Adams, An Introduction to Computer 
Graphics, McGraw-Hill, 1977. A cookbook approach to the subject 
with many useful algorithms listed in BASIC. 

Giloi, W K, Interactive Computer Graphics, Prentice-Hall, 1978. An 
introductory textbook with a somewhat different approach than that 
of the two books above. 

Knuth, D E, The Art of Computer Programming: Volume 3, Sorting 
and Searching, Addison Wesley, 1973. A treasure trove of algorithms 
and analyses of algorithms — a very important book. 

Sutherland, I E, et al, "A Characterization of Ten Hidden-Surface 
Algorithms," ACM Computing Surveys, March 1974. A very infor- 
mative explanation of the extant hidden-surface algorithms of the 
time. Computing Surveys is available in most technical libraries. 

Crow, F C, "A System for the Design of Three-Dimensional Ob- 
jects," Proceedings of the ACM National Conference, 7977. A 
system for designing three-dimensional shapes involving simple 
curved surfaces, available from the Association for Computing 
Machinery, 1133 Avenue of the Americas, New York NY 10036. 

Parent, R, "Three-Dimensional Object Synthesis," Proceedings of 
SIGGRAPH '76, 1976. A more comprehensive system for building 
three-dimensional objects. See also the proceedings of the annual 
SIGGRAPH conferences for the last five years or so, which contain 
papers describing most of the interesting work done in recent 
years — the best way to keep up with what's going on. Available from 
the Association for Computing Machinery, listed above. 



82 



March 1981 © BYTE Publications Inc 



Circle 52 on Inquiry card. 



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Product Review 



The Micro Matrix 
Photopoint Light Pen 

Stephen B Gray, 219 W 81 St, Apt 7C, New York NY 10024 



Because it's called a light pen, and because of the way it 
seems to be used, many people have the incorrect impres- 
sion that a light pen does something directly to the image 
on the video screen. In actuality, it's the other way 
around. A light pen contains a photodiode that detects 
the movement of a point of light on the video screen, 
determines the coordinates of that point, and branches to 
a specified action for that point. 



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For example, if you're playing tic-tac-toe, you only 
have to point the light pen at the square in which you 
want to place your X. With a scan limited to nine areas 
on the video screen, the photodiode detects which area 
you're pointing to and puts an X in that square. 

Applications 

As hinted above, one of the most popular applications 
for the light pen is games. Instead of pressing a key, you 
need only point the pen. This eliminates having to 
memorize which key does what. 

Another popular application is the fast selection of 
items in a screen menu. Some advanced graphics pro- 
grams use light pens and menus. A screen may present a 
selection of shapes along one side, for example. You 
touch one, then touch the point on the screen where you 
want the computer to place the shape. Using small menus 
along the bottom of the screen, you control the size and 
rotation of the shapes to create complex subjects. 

Micro Matrix Photopoint 

One of the several light pens on the market for the 
Radio Shack TRS-80 is the $19.95 Photopoint from 
Micro Matrix, POB 938, Pacifica CA 94044. (The Photo- 
point is also available from Quality Software, 6660 
Reseda Blvd, Suite 105, Reseda CA 91335.) The 
documentation notes that "The light pen allows the user 
to use their CRT as a programmable keyboard where 
your own BASIC program (or a prepackaged one) can be 
written to ask questions and the operator just points at 
the appropriate answer. No more fumbling with 
keyboards! The Photopoint can be used with any DOS 
and with any size memory (must be a Level II TRS-80)." 
Fortunately, the rest of the documentation is not as con- 
fusing as that first sentence. 

For your $19.95 you receive a light pen that looks like a 
slender felt-tip pen, with a two-part cable which connects 
to a 9 V battery and to your recorder. You also receive a 
cassette with backgammon, tic-tac-toe, Word Sampler, 
and a light-pen subroutine; documentation containing 
another game and a listing of the subroutine is also in- 
cluded. 



84 



March 1981 © BYTE Publications Inc 



Circle 46 on inquiry card. 




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410 Recorder $ 55 

830 Modern $140 

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BYTE March 1981 85 



(la) 




Photo 1: Three of six demonstration programs included with 
the Micro Matrix Photopoint light pen: x, y plotting (la), 
backgammon (lb), and tic-tac-toe (1c). The light pen requires a 
TRS-80 Level 11 with 16 K bytes of programmable memory. 



Using the Photopoint 

The pen's miniature plug is connected either to your 
cassette recorder's auxiliary or microphone jack. When 
plugged into the auxiliary jack, the pen responds to 
graphics but not to normal text. When plugged into the 
microphone jack, the pen is sensitive to both text and 
graphics (the suggested mode for most uses). 

One of the main reasons for Photopoint's comparative- 
ly low price is that it uses the amplifier in your tape 
recorder. To turn on the amplifier, remove any cassette 
from the recorder; then, while holding in the record in- 
terlock pin (at the rear of the cassette compartment), 
press the RECORD and PLAY buttons simultaneously. 
The only thing left to do is connect a 9 V battery to the 
battery- clip, and you're set to go. 

After loading the light-pen subroutine, you will see a 
menu from which you can choose any of six demonstra- 
tion programs. 

The light pen doesn't read instantly; you have to wait 
for the scan to pass the square you're aiming at, and then 
a bit longer for the software to react. One good way to 
get a feel for what is going on is to place a broadcast-band 
AM radio near the TRS-80 keyboard. You'll hear 
something like a "dit-dit-dit-un-pah" as the computer 
recognizes a flashing square. Since it can't "read" a static 
square, the program flashes the squares in sequence to 
give the photodiode a target to pick out. 

The first two demonstration programs are similar, with 
a series of eight squares arranged horizontally (in pro- 
gram 1) and vertically (in program 2). When any square 
is touched by the light pen, the number of the square (1 
thru 8) is printed on the screen. The third demonstration 
program uses the same principle — this time with a series 
of fifty blocks; the fourth scans eight randomly placed 
squares; and the fifth (see photo la) plots lines and curves 
by lighting an asterisk when a pair of squares along the 
x and y axes are touched. 

The backgammon program (see photo lb) allows you 
to use the light pen to roll the dice, redraw the board, or 
play a new game. Or, you can move by aiming the light 
pen at FROM and TO selection squares. 

Tic-tac-toe (see photo lc) is played with a large field 
and double-size characters. You play against the com- 
puter, and indicate a square by pointing the pen to the 
right of the number in that square. 

The computer puts an X in the square you select, then 
an O in the square it selects. The process continues until 
the computer detects that the game has been won or 
drawn. 

The fourth program on the cassette is Word Sampler. 
You or the computer enters a sentence. Then you point 
the light pen at any word, and the computer displays that 
word above the sentence, starting at the left margin and 
continuing with further words you select. Thus you can 
construct a new sentence by rearranging the words of the 
old one. 

The fifth program is called Cube Chase. After you key 
in eight lines, you point the light pen at a white square on 
the screen, and the square quickly moves elsewhere. 

If you plug the light pen into the auxiliary jack, remove 
the black plastic plug from the microphone jack, and then 
whistle or snap your fingers, the cube will change its posi- 
tion on the screen. (This works on my CTR-41, although 
perhaps not on some other cassette recorders.) 



86 March 1981 © BYTE Publications Inc 



The first personal computer 
forunder$200i ^^> 



The Sinclair ZX80. 
A complete computer- 
only $199.95 plus $5.00 shipping. 

Now, for just $199.95, you can get a 
complete, powerful, full-function computer, 
matching or surpassing other personal 
computers costing several times more. 

It's the Sinclair ZX80. The computer that 
"Personal Computer World" gave 5 stars 
for 'excellent value.' 

The ZX80 cuts away computer jargon 
and mystique. It takes you straight into 
BASIC, the most common, easy-to-use 
computer language. 

You simply take it out of the box, con- 
nect it to your TV, and turn it on. And if 
you want, you can use an ordinary cassette 
recorder to store programs. With the man- 
ual in your hand, you'll be running programs 
in an hour. Within a week, you'll be writing 
complex programs with confidence. 

All for under $200. 

Sophisticated design makes the 
ZX80 easy to learn, easy to use. 

We've packed the conventional computer 
onto fewer, more powerful LSI chips- 
including the Z80A microprocessor, the 
faster version of the famous Z80. This 
makes the ZX80 the world's first truly port- 
able computer (6W x 8W x Vk" and a mere 
12 oz.). The ZX80 also features a touch 
sensitive, wipe-clean keyboard and a 
32-character by 24-line display. 

Yet, with all this power, the ZX80 is easy 
to use, even for beginners. 




Your course in computing. 

The ZX80 comes complete with its own 
128-page guide to computing. The manual 
is perfect for both novice and expert. For 
every chapter of theory, there's a chapter 
of practice. So you learn by doing— not just 
by reading. It makes learning easy, exciting 
and enjoyable. 

You'll also receive a catalog packed with 
items that can make your ZX80 even more 
useful. Including 27 program cassettes, from 
games and home budgeting for just $6. 95, 
to Sinclair's unique Computer Learning Lab 
(a workbook, six cassettes with 100 lessons, 
and two cassettes for storing programs ) . 

ZX80's advanced design features. 

Sinclair's 4K integer BASIC has perfor- 
mance features you'd expect only on much 
larger and more expensive computers. 
■ Unique 'one touch' entry. Key words 

(RUN, PRINT, LIST, etc.) have their 

own single-key entry to reduce typing 

and save memory space. 




■ Automatic 
error detection 
A cursor identifies errors 
immediately to prevent entering 
programs with faults. 

■ Powerful text editing facilities. 

■ Also programmable in machine code. 

■ Excellent string handling capability— up 
to 26 string variables of any length. 

■ Graphics, with 22 standard symbols. 

■ Built-in random number generator for 
games and simulations. 

Sinclair's BASIC places no arbitrary re- 
strictions on you— with many other flexible 
features, such as variable names of any 
length. 

And the computer that can do so much 
for you now will do even more in the fu- 
ture. Options will include expansion of IK 
user memory to 16K, a plug-in 8K floating- 
point BASIC chip, applications software, 
and other peripherals. 

Order your ZX80 now! 

The ZX80 is available only by mail from 
Sinclair, a leading manufacturer of con- 
sumer electronics worldwide. 

To order by mail, use the coupon below. 
But for fastest delivery, order by phone 
and charge to your Master Charge or VISA. 
The ZX80 is backed by a 10-day money- 
back guarantee, and a 90-day limited warranty 



Price includes TV and cassette connectors, 
AC adaptor, and 128-page manual. 

All you need to use your ZX80 is a standard TV 
(color or black and white). The ZX80 comes complete 
with connectors that easily hook up to the antenna 
terminals of your TV. Also included is a connector for 
a portable cassette recorder, if you choose to store 
programs. (You use an ordinary blank cassette.) 




The ZX80 is a family learning aid. Children lOand 
above will quickly understand the principles of 
computing— and have fun learning. 



To order call toll free: 800-543-3000. 

In Ohio call: 800-582-1364. 

Ask for operator #508. 

which can be extended by 12 months under Sin- Phones open 24 hours a day, 7 days a week, 
clair's extended service program for $25.00. 




Sinclair Research Ltd., 475 Main St., 
P.O. Box 3027, Wallingford, CT 06492. 

I 

• To: Sinclair Research Ltd., 475 Main St., P.O. Box3027, Wallingford, CT 06492. 

| Please send me ZX80 personal computer(s) at $199.95 each (US dollars), plus $5 

I shipping. (Your ZX80 may be tax deductible.) For Conn, deliveries, add sales tax. 
Send me Computer Learning Lab(s) at $49.95 each. 

I Register me for extended service program(s) at $25.00 each. 
I enclose a check/money orderpayable to Sinclair Research Ltd. for$ 

I Name 



Address. 



■ City 

| Occupation. 



. State . 



. Zip _ 



-Age. 



I 



Intended use of ZX80 

Have you ever used a computer? D Yes D No Do you own another personal computer? □ Yes D No 



tJ 



The explanation is simple: The TRS-80 receives its in- 
formation from the Photopoint light pen through tape 
port 255. The program makes the recorder think the light 
pen is a microphone. A sudden change of impedance oc- 
curs when a scanning blip of light is detected by the pen's 
photodiode. 




Photo 2: Quick Draw enables use of the light pen to draw or 
erase figures in a 48 by 64 graphic field. More complex drawing 
programs may be written but the manual gives no information 
on how to do this. 



MICROSTAT 
NOW AVAILABLE FOR CP/M* 

MICROSTAT, the most powerful statistics package available 
for microcomputers, is completely file-oriented with a power- 
ful Data Management Subsystem (QMS) that allows you to 
edit, delete, augment, sort, rank-order, lag and transform (1 1 
transformations, including linear, exponential and log) existing 
data into new data. After a file is created with DMS, Microstat 
provides statistical analysis in the following general areas: 
Descriptive Statistics (mean, sample, and population S.D., 
variance, etc.). Frequency Distributions (grouped or individ- 
ual). Hypothesis Testing (mean or proportion). Correlation and 
Regression Analysis (with support statistics). Non-parametric 
Tests (Kolmogorov-Smirnov, Wilcoxon, etc.). Probability Dis- 
tributions (8 of them), Crosstabs and Chi-square, AN OVA (one 
andtwo way). Factorials, Combinations and Permutations, plus 
other unique and useful features. 

MICROSTAT requires 48K, Microsoft Basic 80 with CP/M 
and is sent on a single-density 8" Disk. It is also available on 
5" diskettes for North Star DOS and Basic (32K and two 
drives recommended), specify which when ordering. The 
price for Microstat is $250.00. The user's manual is $15.00 
and includes sample data and printouts. We have other 
business and educational software, call or write: 



«H ECOSOFT 

P.O. Box 68602 

Indianapolis, IN 46268 

(317)283-8883 

* CP/M is a registered trade mark of Digital Research. 



[master charge] 



Micro Matrix is also reportedly planning an interface 
for Sargon II so you can play chess using a light pen. Also 
planned are a number of chase games. 

PENBASIC 

For $14.95, Micro Matrix is offering Steve Bjork's 
PENBASIC, which adds ten new commands to Level II 
BASIC. Among the most interesting are: 

• P = &NOTE(exp) produces a tone on the cassette out- 
put with (exp) ranging from (highest pitch) to 255 
(lowest pitch). 

• P = &PEN PEEK tests to determine if the light pen is 
pointed at a lighted part of the display. 

• P = &PEN performs a full screen search for the pen 
position. If the pen is not found, a — 1 is returned; if it is 
found, PRINT @ (position) is returned. 

• P = &PEN USING searches for the pen only at the 
points specified in the expression. 

• P = &PEN FOR searches for the pen at the points 
defined in a one-dimensional integer array. 

Using PENBASIC, any of the 1024 locations on the 
TRS-80 video display can be detected. The four-page 
PENBASIC manual explains eight of the ten commands 
and includes brief examples of using them within pro- 
grams. The manual appears to be written for those with a 
good knowledge of BASIC. In fact, two of the functions 
aren't explained at all. 

Along with PENBASIC, the demonstration tape con- 
tains two programs: Quick Draw and Line of Five. 

Quick Draw (see photo 2) enables you to use the light 
pen to draw and erase figures in a 64 by 48 graphic field. 
You use related key commands to draw, erase, position 
the cursor, load and save to and from tape, and end the 
program. Turning on a square can take several seconds 
(sometimes longer). Quick Draw is described as a "simple 
drawing program," which hints that more complex (and, 
perhaps, faster) programs can be written. The manual 
gives no clues how to do this. 

Line of Five is described as "the first in a series of ap- 
plication programs for PENBASIC." It's a simple game of 
capturing five squares in a row before the computer does. 
The computer plays a fairly aggressive game but can be 
beaten. , 

The Micro Matrix Photopoint light pen and PEN- 
BASIC make a useful package for examining light-pen 
applications. What makes it even more attractive is that 
the price is the lowest on the market. ■ 



Why Can't a Light Pen Use the Raster Scan? 

The Exidy Sorcerer is probably the only home com- 
puter that can use the raster scan, according to Mike 
Banks, president of Micro Matrix. The Sorcerer uses 
the microprocessor to control the video and sets up a 
counter to keep track of the vertical scan. The TRS-80 
has no such counter, and thus cannot ask, as the 
Sorcerer can, "What was the count at the moment I 
saw the light?" In PENBASIC, when the PEN PEEK 
command detects a lighted part of the display, it is 
merely looking to see if the tape-recorder output, at 
port 255, is high or low. 



88 



March 1981 © BYTE Publications Inc 



Circle 47 on inquiry card. 



Circle 48 on inquiry card. 



SayAhh... 




Our New grafixPLUS™ 80-column printer 
opens wide for easy servicing. 



Introducing the newest members of our 
grafixPLUS ,M family— the DP-9000 Series 80/132 
column printers— built on the same tradition of 
quality printout, solid design and low cost of 
ownership established by our 132/220 column 
DP-9500 Series. 

A Case for Serviceability 

Not that is comes up often, but want to get inside? 
Simple. Just remove a few screws and the clam- 
shell case swings open exposing all major compo- 
nents. This easy access plus built-in self-test and 
minimum component count yields an MTTR of one- 
half hour. The 9-wire print head replacement's even 
simpler . . . two screws and it's out. Without 
opening the case. And without a service call. 

Performance Plus 

The DP-9000 Series prints the full ASCII 96 charac- 
ter set, including descenders and underlining, bi- 
directionally, at up to 200 CPS. Number of columns, 
can go up to 80 or 132, depending on character 
density— switch or data source selectable from 10 
to 16.7 characters per inch. And all characters can 
be printed double width. The print head produces 
razor-sharp characters and high-density graphics 
with dot resolutions of 72X75 dots/inch under 
direct data source control. <• 

Interface Flexibility 

The three ASCII compatible interfaces (parallel, 
RS-232-C and current loop) are standard, so con- 
necting your computer is usually a matter of plug- 



it-in and print. Also standard are: a sophisticated 
communications interface for printer control and 
full point-to-point communications, DEC PROTO- 
COL, and a 700 character FIFO buffer. An addi- 
tional 2K buffer is optional. 
When you're ready for a printer (or several 
thousand), look into the grafixPLUS DP-9000 Series 
from Anadex— you'll find an open and shut case 
for quality. Contact us today for details, discounts 
and demonstrations. 



...the plus in printers 



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SALES OFFICES: San Jose, CA (408) 247-3933 

Fullerton. CA (714) 8710501 • Wakefield, MA (617) 245-9160 • Austin, TX (512) 327-5250 

ANADEX, INC. • 9825 DeSoto Avenue • Chatsworth. California 91311. U.S.A. • Telephone: (213) 998-8010 • TW 
ANADEX, LTD. t Dorna House. Guildford Road • West End. Woking. Surrey GU24 9PW. England • Tel: Chobham (09905) 6333 • Telex: 858762 AN*" 



What's Inside Radio Shack's 
Color Computer? 



Tim Ahrens, Jack Browne, Hunter Scales 

3501 Ed Bluestein Blvd 

Austin TX 78721 



The only similarity between Tandy Corporation's new 
Color Computer and its older brother — the original TRS- 
80 — is the name. Even the microprocessor has been 
changed. In an apparent breakaway from the Z80, the 
Color Computer uses the Motorola MC6809E 
microprocessor as the workhorse of the new silver box. 
In fact, when we opened the enclosure, we didn't see any 
semiconductors that weren't made by Motorola. 

The Color Computer is totally self-contained— no 
bulky separate power transformers — and the only cord, 
the one to the wall socket, has a standard three-prong 
connector. It can work with any color or black-and- 
white television set and has provisions for joysticks, a 
1500 bps (bits per second) cassette interface, and an 





Number 




Device 




Part 


of Pins 


Quantity Number Description 


MC6809E 


40 


1 


1 


Microprocessor 


MC6821 


40 


2 


2, 3 


Parallel Interface 
Adapter 


MC6883 


40 


1 


4 


Synchronous Address 
Multiplexer 


MC6847 


40 


1 


5 


Video Display 
Generator 


MCM68A364 


24 


2 


6, 7 


8 K-byte Read-Only 
Memory 


MCM4027 


16 


8 


8 thru 


15 4 K-bit Program- 
mable Memory 


MC74LS138 


16 


1 


16 


3-bit Decoder 


MC74LS02 


14 


1 


17 


Quad 2-lnput NOR 
Gate 


MC74LS244 


20 


1 


18 


Octal Buffer/Line Driver 


MC74LS273 


20 


1 


19 


8-bit Latch 


MC14050B 


14 


1 


20 


Hex Noninverting 
CMOS Buffer 


MC14529B 


16 


1 


21 


Dual 4-Channel Analog 


MC1372 


14 


1 


22 


Color-Subcarrier 
Modulator 


MLM339 


14 


1 


23 


Quad Voltage Com- 
parator 


MC723C 


14 


1 


24 


Voltage Regulator 


MC78M12 


3 


1 


25 


Voltage Regulator 


MC79M12 


3 


1 


26 


Voltage Regulator 


MC79M05 


3 


1 


27 


Voltage Regulator 


UM 1285-8 


NA 


1 


28 


ASTEC Video 
Modulator 


Table 1: List of integrated 


circuits used in the TRS-80 Color 


Computer. 


Large-scale integration 


reduces the number of 


devices necessary to 


build 


in sophisticated capabilities, and 


improves ri 


liability. 


All circuits used are manufactured by 


Motorola. 











expansion connector for preprogrammed game car- 
tridges. 

Our aim in this article is to expose the insides of the 
computer and show what makes it run. Using this infor- 
mation, you should be able to expand the Color Com- 
puter in a number of ways, with a minimum of expertise. 
We will also describe the graphics interface so that do-it- 
yourself graphics routines should be a piece of cake. 

System Hardware 

Taking the cover off is simply a matter of removing 
seven screws and lifting the lid. Be warned, however, that 
Tandy takes a dim view of owners fooling around with 
their hardware. Opening the case voids the warranty on 
the machine (one of the screws lies under a paper label 
that gives this warning). 

The first surprise is that the entire computer is built on 
a single printed-circuit board — including the power 
supply. Most of the digital circuitry lies inside an RFI 
(radio-frequency interference) shield — this was probably 
necessary to get FCC (Federal Communications Commis- 
sion) Type Approval, but it also helps to give a clean 
display. To get a look at the parts, simply pry off the top 
of the shield. 

There are only twenty-four DIPs (dual in-line 
packages) in the system and they are all made by 
Motorola. (The parts list is shown in table 1.) The 
machine comes stuffed with 4 K-byte memory circuits; 
but there is a simple way to change these to 16 K-byte 
devices and a tricky way to get 32 K bytes of on-board 
memory — more on this later. 

While we do not yet have a schematic diagram, the 
block diagram in figure 1 should be sufficiently detailed 
to allow a thorough understanding of the system. There 
are four basic sections: 

•the microprocessor 

•the video-display circuitry 

•the memory 

•the other I/O (input/output) devices (keyboard, 

cassette, serial port, and joysticks) 

The microprocessor is Motorola's advanced 8-bit 
machine, the MC6809E. It was designed to support 
today's high-level languages, including the Extended 

Text continued on page 96 



90 March 1981 © BYTE Publications Inc 



IF YOU CAN 

miT A MINUTE, 

WE CAN S/y E 



YOU %i 



iii 



With the Starwriter™ Daisy 
Wheel 25 cps printer from C. Itoh. 

A business letter, written on a 45 cps 
word-processing printer, might take 
about two minutes to print. 

With the Starwriter, it might take 
closer to three. 

The typical 45 cps printer retails for 
about $3, 000. 

But the Starwriter 25 retails for about 
$1,895— thus saving you about $1,000. 

And therein lies the biggest difference 
between the Starwriter 25 and the more 
expensive, daisy wheel printers. 

The Starwriter 25 comes complete 
and ready-to-use, requiring no changes 
in hardware or software. It uses indus- 
try-standard ribbon cartridges, and it's 
"plug-in" compatible to interface with a 



wide variety of systems, to help lower 
system-integration costs. 

Using a 96-character wheel, it 
produces excellent letter-quality print- 
ing on three sharp copies with up to 163 
columns, and offers the most precise 
character-placement available, for out- 
standing print performance. 

C. Itoh's warranty; 

3 months on parts and labor, sup- 
ported by one of the best service organi- 
zations in the industry. 




'iOOOOFF 

Leading Edge Products, Inc., 
225 Turnpike Street, 
Canton, Massachusetts 02021 

Dear Leading Edge: 

I'd like to know more about the Starwriter, and 
how spendinga minute can save me a grand. 
Please send me the name of my nearest dealer. 



Name_ 
Title_ 



Company. 

Street . 

State 



_Zip_ 



Phone: Area Code. 
Number 



LEADING 
EDGE. 



Leading Edge Products, Inc., 225 Turnpike Street, Canton, Massachusetts 02021 

Dealer inquiries invited. For immediate delivery from the Leading Edge Inventory Bank™ call toll free 1-800-343-6833 

In Massachusetts, call collect (617)828-8150. Telex 951-624 



BYTE March 1981 



91 



SuperSoft's 

Gallery off CP/M Masierwbrks 




£- 




DIAGNOSTICS I: A system diagnostic package. 
Tests: 

• Memory • CPU (8080/8085/Z80) • Terminal • Disk • Printer 
To our knowledge the CPU test is the first ot its kind anywhere. Diagnostics 
I can help you find problems before they become serious. A good set of 
diagnostic routines are a must in any program library. Minimal re- 
quirements: 32K CP/M. Supplied with complete user manual: S75.00 Manual 
alone: $15.00 

DIAGNOSTICS II: The most comprehensive set of CP/M compatible 
system check-out programs ever assembled. Includes all of 
Diagnostics I, plus: 

• Every test is "submlt"-able 

• A complete Splnwrlter/Diablo/Qume test has been added 
(Serial Interlace only) 

• Output may be logged to disk 

• Expanded memory test 

• Expanded terminal test 

• Expanded disk test 

Diagnostics II provides the next level In system maintenance. 
Requires: 32K CP/M 
Price: $100.00 Manual only: $15.00 



t Price: $ 

KS3E 



SYSTEM MAINTENANCE 



SUPER-M-LIST: A complete, easy to use mailing list program 
package. Allows for two names, two addresses, city, state, zip and 
a three digit code field for added flexibility. Super-M-List can sort 
on any field and produce mailing labels direct to printer or disk file 
for later printing or use by other programs. Super-M-List is the 
perfect companion toTFS. Handles 1981 Zip Codes! 
Requires: 48K CP/M 
Supplied with complete user manual: $75.00 manual alone: $10.00 

TFS-Ttxl Formatting Syttam: An extremely powerful formatter. 
More than 50 commands. Supports all major features Including; 

• left & right margin justification • user defined macros 

• dynamic Insertion from disk file • underlining and backspace 
TFS lets you make multiple copies of any text. For example: Per- 
sonalized form letters complete with name, address & other Inser- 
tions from a disk file. Text Is not limited to the size of RAM making 
TFS perfect for reports or any big Job. Text Is entered using CP/M 
standard editor or most any CP/M compatible editor. 
Requires: 24K CP/M 

Supplied with extensive user manual: $85.00 manual alone: $20.00 
Source to TFS In 8080 assembler (can be assembled using stan- 
dard CP/M assembler) plus user manual: $250.00. 




4 



TEXT PROCESSING 



I 




UTILITIES I: A collection of programs that you will find useful and 

maybe even necessary In your dally work (we did!). 

Includes: 

GREP: Searches files for a specilied string 

SORT: In core sort of variable length records 

CMP: Compare two flies for equality 

PRINT: Formatted listings to printer 

PG: Lists files to CRT a page at a time 

. . . plus more . . , 
Requires: 24K CP/M 
Supplied with manual on discette: $60.00 

UTILITIES II: Many new programs not available elsewhere. Includes these 
"file" utilities: 

DIFF: Source comparltor 

Powerful multlcolumn output formatter 
Desk calculator 
Substitute strings in files 

. . . plus more . . . 
Requires: 24K CP/M $60.00 
Supplied with manual on discette 




UTILITIES 



j353& 



ANALIZA: An amazingly accurate 
simulation of a session with a 
psychiatrist. Better than the famous 
"ELIZA" program. Enlightening as 
well as fun. An excellent example of 
Artificial Intelligence. 
Requires: 48K CP/M, CBASIC2 
Cost: $35.00 



ENTERTAINMENT 



m 



Z8000CROSSASSEMBLER:Supports 
full ZB000 syntax, segmented and 
unsegmented mode, full 32-bit 
arithmetic, hex output, listing output, 
"downloader". 
Requires: 56K CP/M $50000 
1 year maintenance $300.00 
manual alone 5 5000 



m\m 



zeooo toot I 



^J 



On line "Help" system provided with every program package. 



SuperSoft 

First in Software Technology 



CPIM REGISTERED TRADEMARK DIGITAL RESEARCH 



ft * * * * * 4 * * x x x * * x x x ^ST-JT 



SSS FORTRAN: The SSS FORTRAN compiler is fast, efficient, and complete 
(full 1966 ANSI standard with extensions). The RATFOR compiler compiles into 
FORTRAN allowing the user to write structured code while retaining the 
benefits of FORTRAN. The FORTRAN supports many advanced features not 
found in less complete implementations, including: complex arithmetic, 
character variables, and functions Complete sequencial and random disk I/O 
are supported. SSS FORTRAN will compile up to 600 lines per minute! Recur- 
sive subroutines with sialic variables are supported. ROMable "COM" files 
may be generated. SSS RATFOR allows the use of contemporary loop control 
and structured programming techniques. SSS RATFOR is similar to FORTRAN 
77 in that it supports such things as: 

• REPEAT.. .UNTIL • WHILE • IF...THEN...ELSE 
SSS RATFOR is supplied with source code in FORTRAN and RATFOR. 
System Requirements & Prices: 

SSS FORTRAN requires a 32K CP/M system. 

SSS FORTRAN with RATFOR: $325.00 

SS FORTRAN alone: $250.00 

RATFOR alone: $100.00 

(RATFOR sold only with valid SSS FORTRAN license) 

STACKWORK'S FORTH: A lull, extended Forth interpreter/compiler produces 
COMPACT, ROMABLE code. As fast as compiled FORTRAN, as easy to use as in- 
teractive BASIC. 
SELF COMPILING; Includes every line of source code necessary to recompile 

itself. 
EXTENSIBLE: Add functions at will. 
Z80 or 8080 ASSEMBLER Included. 
Single license, OEM licensing available. 
Please specify CPU type: Z60 or 8080 
Supplied with extensive user manual and tutorial: $175.00 
Documentation alone: $25.00 

'TINY' PASCAL II: We still call it 'Tiny' but it's bigger and better than ever! This is 
the famousChung-Yuen 'Tiny' Pascal with more features added. Features include: 

• recursive procedures/functions • integer arithmetic • CASE 

• FOR (loop) " sequential disk I/O " 1 dimensional arrays 

• IF.. THEN. ..ELSE • WHILE • PEAK & POKE 

• READS, WRITE • REPEAT...UNTIL • more 

'Tiny' Pascal is fast. Programs execute up to ten times faster than similar BASIC 
programs. SOURCE TOO! We still distribute source, In 'Tiny' Pascal, on each 
discette sold. You can even recompile the compiler, add features or Just gain in- 
sight Into compiler construction. 

Requires; 36K CP/M. Supplied with complete user manual and source on discette: 
$85.00. Manual alone: $10.00 



ag '♦"♦"♦"»"< 



PROGRAMMING LANGUAGES 



Bggggg B 



TERM: A complete intercommunications package for linking your com- 
puter to other computers. Link either to other CP/M computers or to large 
timesharing systems. TERM is comparable to other systems but costs 
less, delivers more and source is provided on discette! With TERM you 
can send and receive ASCII and Hex files (COM too, with included conver- 
tion program) with any other real time communication between users on 
separate systems as well as acting as timesharing terminal. 

• Engage/disengage printer • errorcheckingandauto retry 

• terminal mode for timesharing between systems 

• conversational mode • send files ■ receive files 
Requires; 32K CP/M 

Supplied with user manual and 8080 source code: $150.00 
Manual alone: $15.00 



^INTERCOMPUTER COMMUNICATIONS* 



ENCODE/DECODE: A complete software security system for CP/M. 
Encode/Decode Is a sophisticated coding program package which trans- 
forms data stored on disk into coded text which is completely unrecog- 
nizable. Encode/Decode supports multiple security levels and passwords. 
A user defined combination (One billion possible) is used to code and 
decode a file. Uses are unlimited. Below are a few examples: 

• data bases • payroll files ■ programs ■ tax records 

Encode/Decode is available in two versions: 

Encode/Decode I provides a level of security suitable for normal use 
Encode/Decode II provides enhanced security for the most demanding 
needs. 
Encode/Decode I: $50.00 Encode/Decode II: $100.00 manual alone: $15.00 



SOFTWARE SECURITY 



F= 



CP/M Formats: 8" soft sectored, 5" Northstar, 5" Micropo- 
lis Mod II, Vector MZ, Superbrain DD/QD 
All Orders and General Information: 
SUPERSOFT ASSOCIATES 
P.O. BOX 1628 
CHAMPAIGN, IL 61820 
(217) 359-2112 

Technical Hot Line: (217) 359-2691 
(answered only when technician Is available) 

Far East Distribution: 

ASR International 

3-15-8. Nl SHI-SHIM BASHI. MINATO-KU, TOKYO j 105 JAPAN 

(031437-5471 



SwperSofft's Masterpiece 
of the Month 




,0 to 






SSS ANSI *ee STANDARD 

rCCTCAN IV 

WITH 

EArrcc 



o,~- 



P€R CP/M 



TOGETHER AT LAST 



SSS FORTRAN & RATFOR are the critic's choice! 

The SSS FORTRAN compiler is fast, efficient, and complete (full 1966 ANSI 
standard with extensions). The RATFOR compiler compiles into FORTRAN allowing 
the user to write structured code while retaining the benefits of FORTRAN, 
Together they form an incredible team! 

SSS FORTRAN Specifics 
SSS FORTRAN makes full FORTRAN IV available to microcomputers. SSS 
FORTRAN meets and exceeds the ANS1 1966 FORTRAN standard. The compiler 
supports many advanced features not found in less complete implementations, 
including: complex arithmetic, character variables, and functions. SSS FORTRAN 
will compile up to 600 lines per minute! Recursive subroutines with static 
variables are supported. ROMable ".COM" files may be generated. 



FEATURES 

Code generation: ROMable ".COM" files or intermediate code files (saves disk 
space). External routines may be called. 

Data types: Byte, integer, real, double precision, complex, logical, charac- 

ter and varying length strings. 

Operations: All standard operations plus string comparisons, assignments, 

and .XOR. 

Constants: Hexadecimal, decimal, and character literals with features to 

imbed control characters. 

Statements: ANSI 1966 standard with multiple statement lines, state- 

ments may end with a ' :'. 

Controls: Map. List, and Symbol table output options. 

I/O: Read, Write, Append, Rewind, Close, Delete. Rename, Search, 

sequencial and Random I/O on disk files. Supports all CP/M 
devices. The User can add device handlers to use custom I/O 
devices. 

Errors: Over 200 distinct compiler error messages, precision and 

illegal instruction warnings during execution. 

Interrupts: FORTRAN programs may be interrupted at any time; the stack 

pointer is always preserved. 



• • PE AXUCING m • 



SSS RATFOR 
RATFOR is a preprocessor that compiles to SSS FORTRAN. SSS 
RATFOR allows the use of contemporary loop control and struc- 
tured programing techinques. SSS RATFOR is similar to FORTRAN 
77 in that it supports such things as: 
REPEAT ... UNTIL WHILE IF .. .THEN ... ELSE 

Begin End Brackets Macro Defines 

SSS RATFOR is supplied with source code. The source code 
is distributed in both RATFOR and SSS FORTRAN. Not only does 
this prevent obsolescence, but allows the user to add enhance- 
ments as desired. 



• ••••••••••• 

System Requirements & Prices 

SSS FORTRAN requires a 32k CP/M system. Z80 only. 
SSS FORTRAN with RATFOR: $325.00 
SSS FORTRAN alone: $250.00 

RATFOR alone: $100.00 

(Sold only with valid SSS FORTRAN license) 

CP/M Formats: 8" soft sectored, 5" Morthstar. 5" Micropolis Mod II. 
Vector MZ. Superbrain DD/OD 

All Orders and General Information: 

SUPERSOFT ASSOCIATES 

P.O. BOX 1628 

CHAMPAIGN, IL 61820 

(217)359-2112 

Technical Hot Line: (217) 359-2691 

(answered only when technician is available) 

•CP/M REGISTERED TRADEMARK DIGITAL RESEARCH 

SSS FORTRAN is the copyright ot 
Small Systems Services. Urbana. Illinois 



SuperSoft 

First in Software Technology 



BYTE March 1981 



93 







Figure 1: Block diagram of the Radio Shack Color Computer. Although a detailed schematic diagram is not available, the connec- 
tion of the main components can be readily determined. Note that the use of large-scale integrated circuits (the microprocessor, 
SAM dynamic-memory handler, video-display generator, and parallel port interfaces) means that a minimum number of com- 
ponents is necessary to build this flexible computer. 



94 March 1981 © BYTE Publications Inc 



Circle 50 on Inquiry card. 



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v ssC 


1 


40 


] HALT 


NMI [ 


2 


39 


]TSC 


Frq [ 


3 


38 


] LIC 


fTrq Q" 


4 


37 


J RESET 


BS [ 


5 


36 


] AVMA 


BA [ 


6 


35 


]Q 


v ccC 


7 


34 


]E 


AO [ 


8 


33 


]BUSY 


Al[ 


9 


32 


]r/w 


A2[ 


10 


31 


]oo 


A3[ 


11 


30 


]D1 


A 4 [ 


12 


29 


]02 


»U 


13 


28 


]D3 


A6 [ 


14 


27 


]D4 


A7[ 


15 


26 


]05 


A8[ 


16 


25 


]06 


A9 [ 


17 


24 


]07 


AlO [ 


18 


23 


]A15 


All [ 


19 


22 


1A14 


A12 [ 


20 


21 


]A13 



Figure 2: Pin description of Motorola's MC6809E 
microprocessor. The device has several 16-bit instructions that, 
coupled with ease of programming and speed, make for a very 
powerful 8-bit processor. 



15 







X-INDEX REGISTER 


Y-INDEX REGISTER 


U-USER STACK POINTER 


S- HARDWARE STACK POINTER 


PC 


A 


B 


V 


' 



POINTER REGISTERS 



PROGRAM COUNTER 
ACCUMULATORS 



Text continued from page 90: 

BASICs now available. It has two 16-bit index registers 
and two 16-bit stack pointers, as well as two 8-bit 
accumulators that can be used as a double-precision 
16-bit accumulator. It supports both position- 
independent code (code that can be executed anywhere in 
memory without reassembly) and reentrant (interrupti- 
ble) code. 

The video display is generated by the Motorola 
MC6847 VDG (video display generator). This is a 40-pin 
LSI (large-scale integration) part that reads from Vi K 
bytes to 6 K bytes of memory, depending on mode, to 
produce an analog video signal. This signal is fed to the 
MC1372 color-subcarrier modulator to get composite 
video, which is then modulated by the ASTEC video 
modulator to channel 3 or 4. 

The Color BASIC interpreter is stored in an 8 K by 8 
bit ROM (read-only memory). Its companion, Extended 
BASIC, comes in another ROM of the same type. The 
basic machine comes with only the first ROM; the ex- 
tended ROM costs $99 plus installation. 

As mentioned, the computer comes with eight 
MCM4027 4 K-bit dynamic memory circuits. Tandy will 
upgrade your system to 16 K bytes by replacing these 
with MCM4116s (16 K-bit devices) for $119. Or you can 
buy the system with 16 K bytes and the Extended BASIC 
ROM for $599. 

These memory circuits are controlled and refreshed by 
a special part, the MC6883 SAM (synchronous address 
multiplexer). It provides all the signals for the memory 
and the VDG and also provides the timing signals for the 
microprocessor. 

The other I/O functions are all handled by parallel 
ports in the form of MC6821 PIAs (peripheral interface 
adapters). The keyboard is connected to these and is 
scanned and decoded in software. The serial port and 
cassette port are both derived from a single parallel line 
and are selected by software. The optional joysticks are 
encoded with an A/D (analog-to-digital) converter com- 
posed of a resistive-summing network hooked to a 6-bit 
parallel port and an LM339 comparator. 



DP 



DIRECT PAGE 
REGISTER 



CC-CONDITION CODE 
REGISTER 

CARRY 

OVERFLOW 

ZERO 

NEGATIVE 

IRQ MASK 

HALF CARRY 

FIRQ MASK 

ENTIRE FLAG 



Figure 3: Registers available in the 6809. Similar in architecture 
to the 6800, the 6809 has three extra registers to facilitate mem- 
ory acesses: a direct page register, a user stack register, and a 
second index register. The instruction set is also more robust, 
with the addition of 16-bit add, subtract, and multiply opera- 
tions. 



The MC6809E Microprocessor 

The third-generation MC6809E 8-bit microprocessor 
features several 16-bit operations. This puts it functional- 
ly between the 8- and the 16-bit processors. A description 
of the MC6809E signals appears in figure 2. 

The programming model of the MC6809E is shown in 
figure 3. Three registers were added to the register set of 
the original MC6800: 

•a direct page register 
•a user stack pointer 
•a second index register 

There are two 8-bit accumulator registers, the A register 
and the B register, that are used for data manipulation 
and serve as holding registers for arithmetic calculations. 
The MC6809E has many 16-bit arithmetic operations, in- 
cluding additions, subtractions, loads, stores, and an 8 
bit by 8 bit multiplication. The 16-bit arithmetic opera- 
tions use both accumulators — with the A register treated 



96 March 1981 © BYTE Publications Inc 



Circle 51 on Inquiry card. 



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Efficient position-independent code 

can be written using the 

capabilities of the MC6809E. 

as the most significant byte. When the A and B registers 
are concatenated, they are referred to as the D register. 

The DP (direct page) register is one of the new 
registers. Its contents form the high-order byte of the 
address bus during instructions utilizing the direct 
addressing mode. This register may be changed to allow 
direct addressing anywhere in the 64 K-byte memory 
map, as compared to the MC6800, which allowed direct 
addressing only in the first 256 bytes of the memory map. 
Direct addressing uses the immediate byte of the instruc- 
tion as a 1-byte pointer into a single 256-byte "page" of 
memory. This shortens instruction execution time 
because the high-order byte is furnished by the direct 
page register. MC6800 source code compatibility is en- 
sured because actuation of the RESET line clears the 
direct page register. 

The MC6809E has four 16-bit pointer registers 
available to the user. The U and S registers support stack- 
oriented instructions such as PSH and PUL. The S 
register is used as the hardware stack pointer to support 
interrupts and subroutine calls. The U register gives the 
designer the capability of maintaining an independent 
stack. 

The other two registers, X and Y, are intended primari- 
ly for use as index registers, although special indexing 



modes allow them to be used to maintain additional stack 
areas. All four pointer registers can be used as index 
registers, allowing indexed addressing, indirect address- 
ing, or indexed indirect addressing. These pointer register 
capabilities permit the MC6809E to function efficiently as 
a stack processor, allowing the microprocessor to sup- 
port graphics, high-level languages, and modular pro- 
gramming techniques. 

The microprocessor's program counter, while primari- 
ly used by the processor to address the next instruction, 
may be referenced as an index register, thus allowing 
addressing relative to the program counter. 

The condition code register defines the state of the 
microprocessor such that conditional branch instructions 
may be used. The condition code register also allows 
masking of some of the interrupts. 

The register set is manipulated with the 59 instructions 
shown in table 2. Over 1460 different op codes are 
available to the programmer if all modes of the instruc- 
tions are considered. However, only the 59 mnemonics 
must be remembered when using an assembler. 

Efficient PIC (position-independent code) can be 
written using the capabilities of the MC6809E. The pro- 
gram counter can be used as a pointer to provide offsets 
within the program. For example, when a portion of PIC 
is executed, the stack addresses, peripheral addresses, 
and other addresses may be specified as offsets from the 
current program counter address. 

Other key factors in effective position-independent 
code writing are the use of long and short relative-branch 

Text continued on page 102 



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98 March 1961 © BYTE Publications Inc 



C ^Pascal 

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Idris is a trademark of Whitesmiths, Lid I Unix is a trademark of Bell Laboratories I CP/M is a trad cm ark of Digital Research Company ■ VMS, 
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Circle 75 on inquiry card. 



BYTE March 1981 99 



Circle 53 on inquiry card. 
/ 

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8-BIT OPERATIONS 


Mnemonic 


Description 


ABX 


Add B register to X register unsigned. 


ADCA, ADCB 


Add memory to accumulator with carry. 


ADDA, ADDB 


Add memory to accumulator. 


ANDA, ANDB 


AND memory with accumulator. 


ANDCC 


AND immediate with condition code register. 


ASLA, ASLB, ASL 


Arithmetic shift left accumulator or memory. 


ASRA, ASRB, ARS 


Arithmetic shift right accumulator or memory. 


BITA, BITB 


Bit test memory with accumulator. 


CLRA, CLRB, clr 


Clear accumulator or memory. 


CMPA, CMPB 


Compare memory with accumulator. 


COMA, COMB, COM 


Complement accumulator or memory. 


DAA 


Decimal Adjust A accumulator. 


DECA, DECB, DEC 


Decrement accumulator or memory. 


EORA, EORB 


Exclusive OR memory with accumulator. 


EXG R1, R2 


Exchange R1 and R2. 


INCA, INCB, INC 


Increment accumulator or memory. 


LDA, LDB 


Load accumulator from memory. 


LSLA, LSLB, lsl 


Logical shift left accumulator or memory. 


LSRA, LSRB, LSR 


Logical shift right accumulator or memory. 


MUL 


Unsigned multiply (8 bit by 8 bit = 16 bit). 


NEGA, NEGB, NEG 


Negate accumulator or memory. 


ORA, ORB 


OR memory with accumulator. 


ORCC 


OR immediate with condition code register. 


PSHS (register list) 


Push register(s) on hardware stack. 


PSHU (register list) 


Push register(s) on user stack. 


PULS (register list) 


Pull register(s) from hardware stack. 


PULU (register list) 


Pull register(s) from user stack. 


ROLA, ROLB, ROL 


Rotate accumulator or memory left. 


RORA, RORB, ROR 


Rotate accumulator or memory right. 


SBCA, SBCB 


Subtract memory from accumulator with borrow. 


STA, STB 


Store accumulator to memory. 


SUBA, SUBB 


Subtract memory from accumulator. 


TSTA, TSTB, TST 


Test accumulator or memory. 


TFR R1, R2 


Transfer register R1 to register R2. 




16-BIT OPERATIONS 


Mnemonic 


Description 


ADDD 


Add to D accumulator. 


SUBD 


Subtract from D accumulator. 


LDD 


Load D accumulator. 


STD 


Store D accumulator. 


CMPD 


Compare D accumulator. 


LDX, LDY, LDX, LDU 


Load pointer register. 


STX, STY, STS, STU 


Store printer register. 


CMPX, CMPY, CMPU, 




CM PS 


Compare pointer register. 


LEAX, LEAY, LEAS, 




LEAU 


Load effective address into pointer register. 


SEX 


Sign extend 


TFR register, register 


Transfer register to register. 


EXG register, register 


Exchange register to register. 


PSHS (register list) 


Push register(s) onto hardware stack. 


PSHU (register list) 


Push register(s) onto user stack. 


PULS (register list) 


Pull register(s) from hardware stack. 


PULU (register list) 


Pull register(s) from user stack. 


Table 2: The 6809 instruction set. 



100 



March 1981 © BYTE Publications Inc 



Circle 54 on inquiry card. 





INDEXED ADDRESSING MODES 


Mnemonic 


Description 


0, R 


Indexed with zero offset. 


[0, R] 


Indexed with zero offset indirect. 


,R + 


Autoincrement by 1 . 


,R+ + 


Autoincrement by 2. 


l,R++] 


Autoincrement by 2 indirect. 


,-R 


Autodecrement by 1. 


, R 


Aufodecrement by 2. 


[,--R] 


Autodecrement by 2 indirect. 


n, P 


Indexed with signed n as offset (n = 5, 8, or 16 bits). 


[n. P] 


Indexed with signed n as offset indirect. 


A, R 


Indexed with accumulator A as offset. 


[A, R] 


Indexed with accumulator A as offset indirect. 


B, R 


Indexed with accumulator B as offset. 


[B, R] 


Indexed with accumulator B as offset indirect. 


D, R 


Indexed with accumulator D as offset. 


[D, R] 


Indexed with accumulator D as offset indirect. 


NOTE: Ft = 


X, Y, U, or S; P = PC, X, Y, U, or S. Brackets indicate indirection. D 


means use AB accumulator pair. 




6809 RELATIVE SHORT AND LONG BRANCHES 


Mnemonic 


Description 


BCC, LBCC 


Branch if carry clear. 


BCS, LBCS 


Branch if carry set. 


BEQ, LBEQ 


Branch if equal. 


BGE, LBGE 


Branch if greater than or equal (signed). 


BGT, LBGT 


Branch if greater (signed). 


BHI, LBHI 


Branch if higher (unsigned). 


BHS, LBHS 


Branch if higher or same (unsigned). 


BLE, LBLE 


Branch if less than or equal (signed). 


BLO, LBLO 


Branch if lower (unsigned). 


BLS, LBLS 


Branch if lower or same (unsigned). 


BLT, LBLT 


Branch if less than (signed). 


BMI, LBMI 


Branch if minus. 


BNE, LBNE 


Branch if not equal. 


BPL, LBPL 


Branch if plus. 


BRA, LBRA 


Branch always. 


BRN, LBRN 


Branch never. 


BSR, LBSR 


Branch to subroutine. 


BVC, LBVC 


Branch if overflow clear. 


BVS, LBVS 


Branch if overflow set. 




6809 MISCELLANEOUS INSTRUCTIONS 


Mnemonic 


Description 


CWAI 


Clear condition code register bits and wait for interrupt. 


NOP 


No operation. 


JMP 


Jump. 


JSR 


Jump to subroutine. 


RTI 


Return from interrupt. 


RTS 


Return from subroutine. 


SEX 


Sign extend B register into A register. 


SWI, SWI2, 


SWI3 Software interrupts. 


SYNC 


Synchronize with interrupt line. 



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First in Software Technology 

"CP/M registered trademark Digital Research 



Text continued from page 98: 

instructions and LEA (load effective address) instruc- 
tions. The relative-branch instructions allow PCR (pro- 
gram counter relative) branching. When an 8-bit offset 
is used, control may be transferred anywhere within a 
256-byte area. A 16-bit offset allows transfer of control 
anywhere in the entire 64 K-byte address space. The 
following are examples of the relative-branch instruc- 
tions: 

DECA Decrement A Accumulator 

BEQ CAT If A = then go to CAT 

(CAT is within ± 128 bytes) 

INCA Increment A Accumulator 

LBEQ DOG If A = then go to DOG 

(DOG is within ± 32,768 bytes) 

The LEA instructions work by calculating the effective 
address of an indexed instruction and storing it in the 
specified pointer register. This allows the programmer to 
use all the internal addressing hardware of the 
microprocessor. Below are some examples of the LEA 
instructions. 



Instruction 
LEAX 10,X 
LEAY A,Y 
LEAX D,Y 
LEAU -10,U 
LEAX TABLE,PCR 



Operation 
X + 10 - X 

Y + A - Y 

Y + D - X 
U - 10 - U 
(see text below) 



102 March 1981 © BYTE Publications Inc 



Note how the registers may be incremented or 
decremented using the LEA instructions. In addition, 
registers may be used as offsets, as explained above. The 
program counter may be used as a pointer register with 
8- or 16-bit signed offsets. As in relative addressing, the 
offset is added to the current contents of the program 
counter register to create the effective address. 

The last example calculates the offset of TABLE and 
adds it to the current value of the program counter 
register. This value is then placed in the X register. Tables 
related to a particular routine will maintain the same rela- 
tionship after the routine is moved, since addresses are 
calculated when the code is executed. 

Position-independent code is not without disadvan- 
tages, the major being that it generally takes 5 to 10 per- 
cent more space than nonrelocatable code. In addition, 
PIC usually takes 5 to 10 percent more time to execute. 
Typically, PIC would be used for utility programs where 
the run-time addresses are dynamically determined. This 
eliminates the need for a linking loader to perform a 
relocation operation. Common examples of this type of 
code would be machine-language utilities such as graphic 
routines and subroutines called by BASIC programs. 

The MC6809E has several very interesting hardware 
features also. Referring to the signal descriptions of figure 
2, note that not only does the microprocessor have 16 
address lines, 8 data lines, and an R/W (read/write) line, 
but there are several other control lines. The MC6809E is 
synchronized to the video-display circuit by the two 
clock inputs, E and Q. These two clocks control internal 
operation of the microprocessor. Figure 4 shows typical 
timing diagrams for bus operations. 

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Pearl Level III (best prog, tool available) $645 

CBASIC-2 $110 

TRS-80® MODIICP/M® 2.2 (Pickles & Trout) $1 85 
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CP/M® is a registered trademark ot Digital Research. 
TRS-80® is a registered trademark ol Radio Shack, Inc. 



Three interrupt control lines, NMI, FIRQ, and IRQ, 
allow peripherals to request (demand!) support. Each in- 
terrupt causes the microprocessor to retrieve a vector 
from a specific address and use it to begin executing 
instructions. 

The Color Computer uses IRQ (interrupt request) and 
FIRQ (fast interrupt request) to support real-time clock 
input (driven by the horizontal and vertical sync signal 
from the VDG) and to auto-start read-only memory car- 
tridges. The NMI (nonmaskable interrupt) input is 
reserved for use by the expansion port. 

These interrupts function in different manners. The 
NMI cannot be disabled or postponed under software 
control and is useful in real-time interrupt-servicing disk 
transfers. The other two interrupts are maskable under 
software control. One is "faster" than the other in that a 
response to an FIRQ saves only the condition code 
register and the program counter on the stack. The other, 
IRQ, "stacks" all the registers, as does NMI. Separate in- 
terrupts were used for the PIAs (parallel interface 
adapters) to provide independent vector addresses for the 
service routines, thereby minimizing the software 
overhead. 

The interrupt vectors in the Color Computer are map- 
ped to the top of the BASIC ROM by the SAM chip. 
These vectors point to locations in programmable 
memory starting at address hexadecimal 100. On reset, 
the BASIC program stores jump instructions in these 
locations which point to the interrupt-service routines. 
Each jump call consists of 3 bytes: the jump extended op 
code (hexadecimal 7E) and the address of the routine. If a 
particular interrupt is not being used, all 3 bytes of its 
jump call would contain 00. See table 3 for a map of the 
interrupt-service addresses. 

To define a jump call, program the 3 bytes with the re- 
quired jump instruction. For example, if the SWI (soft- 
ware interrupt) service routine is located at hexadecimal 
8000, the SWI jump call should be loaded with 7E 80 00. 
The following BASIC program would load the SWI jump 
call with this vector: 

POKE 264,0 
POKE 263,128 
POKE 262,126 

This example program defines the last byte of the jump 
call first, then the middle byte, then the first byte. This 
approach is required to prevent interrupt service until the 
jump call is completely defined. If the jump call was 
defined by starting with the first byte, an interrupt could 
be vectored to the wrong address. All interrupt-service 
routines should end with a hexadecimal 3B (Return from 
Interrupt op code) to restore the Color Computer to the 
proper state. 

Two other MC6809E input-control signals used by the 
Color Computer are HALT and RESET. RESET is con- 
trolled by the pushbutton switch on the rear right-hand 
portion of the Color Computer. When the switch is 
pressed, RESET goes low to initiate a restart routine. The 
HALT input is connected to the expansion port. When 
HALT goes low, the MC6809E completes the current in- 
struction, then releases the address, data, and R/W lines 
to the high-impedance state. This allows another device, 

Text continued on page 110 



104 March 1981 © BYTE Publications Inc 



Circle 87 on inquiry card. 



Circle 57 on inquiry card. 



Whatever 
happened to 
eenie, meenie, 
mi new mo? 



.a perfect 
gift for that 
urban cowgirl! 



X 



I could be 
another 
Solomon . 



#", 



This may put 
the Godfather 
^out of business . 

Ufonly 
my heart \ 
would stopl 

^racing. .. A 



It must use 

Bayesian, 

weighted factor 

.analysis, and.. . 



Brilliant! 
Like a window 
into the future. 




Maybe this'll 


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help me choose 








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a career. . . ^ 


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in this economy'. 




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5? 






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ADDR 
BA, BS* 



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Figure 4: Timing diagrams for 6809 bus operations. As with the 6800, both memory and peripherals are accessed in the same way 
and share the same address space. The complete instruction cycle.for reads (figure 4a) and writes (figure 4b) is the same: approx- 
imately 1.1 us. 



106 March 1981 © BYTE Publications Inc 



Circle 27 on inquiry card. 




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For sophisticated editing or simple 
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CP/M" and MP/M ,m are trademarks of Digital Research 



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Circle 59 on inquiry card. 









Contents of 






Address of 


Indirect 


Indirect 






Interrupt 


Routine 


Routine 




Interrupt 


Vector Call Address 


Call 




Source 


(hexadecimal) (hexadecimal) (hexadecimal) 


Reset 


FFFE 


A027 


none 


direct 
call to 
restart 


NMI 


FFFC 


0109 


undefined 


not used 


SWI 


FFFA 


0106 


undefined 


not used 


IRQ 


FFF8 


010C 


A9B3 


Extended 

BASIC 

uses 

894C to 

update 

real-time 

clock. 


FIRQ 


FFF6 


010F 


A0F6 




SWI2 


FFF4 


0103 


undefined 


not used 


SWI3 


FFF2 


0100 


undefined 


not used 


Table 3: 


Interrupt vectors for Color 


Computer BASIC. At 


the reception of an interrupt, control 


is transferred to a ser- 


vice routine via a call to an address stored near the 


top of the 


64 K address space (occupied by th 


e BASIC ROM). The 


address points to a 3-byte 


jump instruction (loaded into pro- 


grammable memory when BASIC is initialized); that, in 


turn, po 


nts to an interrupt-handling 


routine. 





Bus Available 
Signal 


Bus Status 
Signal 


Machine State 


low 
low 
high 
high 


low 
high 
low 
high 




Normal (running) 
Synchronize Acknowledge 
Interrupt Acknowledge 
Halt/Bus-Grant Acknowledge 


Table 4: The four possible machine states. The Bus 
Available and Bus Status signals can be decoded to detect 
when the bus is not being used by the processor. 



Text continued from page 104: 

such as a DMA (direct-memory access) controller, to 
control the bus. 

Since the microprocessor is not halted until completion 
of the current instruction, the external bus controller has 
to wait 20 bus cycles before driving the bus. This delay is 
required because the longest execution time for an 
MC6809E instruction is 20 cycles for a CWAI instruction 
(see table 2). 

This delay could have been minimized if the BA and BS 
lines were brought out to the expansion port. BA and BS 
(Bus Available and Bus Status) indicate one of four 
machine states. These four states and the BA and BS 
signal combinations are shown in table 4. 

Of the four states, the Halt/ Bus-Grant Acknowledge is 
the only one pertinent to the design of the Color Com- 
puter. The Normal state indicates that the 
microprocessor is executing code. The Synchronize 
Acknowledge state, which allows the processor to be syn- 
chronized to an external event, is not required in the 
Color Computer. Nor is the Interrupt Acknowledge 
state, which indicates that vector fetches are occurring. 

Four other MC6809E signals were ignored by the Color 
Computer's designers: TSC, AVMA, BUSY, and LIC. 
TSC (Three State Control) is used to put the buses into 
the high-impedance state for cycle-stealing operations. 



1 


[ 


v S s 


007 ] 40 


2 


c 


DD6 


CSS 


]39 


3 


c 


DD0 


HS 


] 38 


4 


c 


DD1 


FS ] 37 


5 


c 


0D2 


RP 


] 36 


6 


c 


DD3 


A/G 


] 35 


7 


[ 


DD4 


A/S 


5 34 


8 


c 


DD5 


CLK 


] 33 


9 


r 


CHB 


INV 


]32 


10 


[ 


c>B 


iTTf/EXT 


]31 


u 


c 


cfcA 


GM0 


] 30 


12 


c 


MS 


SMI 


] 29 


13 


c 


DA5 


Y 


] 28 


14 


[ DA6 


GM2 


]27 


15 


[ DA7 


DA4 


]26 


16 


[ DA8 


DA3 


]25 


17 


C v cc 


DA 2 


]24 


18 


[ DA9 


DAI 


]23 


19 


[ DA10 


DA0 


] 22 


20 


c 


0A11 


DA12 


]21 



Figure 5: Pin description of Motorola's MC6847 Video Display 
Generator. In concert with the Synchronous Address Multi- 
plexer (see figure 6), this device interprets the contents of a block 
of memory to create a color display (using either an internal 
character generator or an external one). The output signal is 
converted to composite video by an MC1372, while a device 
built of discrete components modulates the signal to radio fre- 
quencies for reception on a standard television. 



This type of operation is typically used for DMA or 
dynamic-memory refresh and is not needed in the Color 
Computer. 

AVMA, BUSY, and LIC are intended primarily for use 
in multiprocessor systems (which the Color Computer is 
not). AVMA (Advanced Valid Memory Access) is the 
signal indication that the processor will use the bus 
during the next cycle. The BUSY output provides the "in- 
divisible" memory indication required for a "test and set" 
operation (operations of this type are required for effi- 
cient multiprocessor support on a common bus). LIC 
(Last Instruction Cycle) indicates that the first byte of an 
op code will be latched at the end of the present bus cycle. 

The MC6809E was the best choice of the 
microprocessors available for use when the Color Com- 
puter was designed. The external clock inputs allow the 
microprocessor to be synchronized to the video display 
to allow interleaved memory accesses. In addition, the 
power of the MC6809E instruction set allows the efficient 
graphics drivers supported by the Extended BASIC. 

The Video Display and the Memory Controller 

The "Color" in Color Computer comes from the 
MC6847 Video Display Generator. This device can 
display information stored in memory using a variety of 
alphanumeric, semigraphic, and graphic modes. To 
understand how it works, refer to the signal description 
shown in figure 5. Normally the address lines DA0 thru 
DA12 would be connected to a block of programmable 
memory (usually static devices such as MCM2114s) 
shared with the microprocessor. Depending on the mode 
selected, the VDG would read the memory and, taking 



110 March 1981 © BYTE Publications Inc 




CM -600 
Circuit 
Mount 




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NEW CM-600 SOLDERLESS PROTOTYPE BOARD 

CM- 600 is a unique system for solderless construction of circuit prototypes, useful to 
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including DIP's are mounted by simply inserting leads into the holes in the long life 
neoprene material. Interconnections are easily made using 20 or 22 AWG(0,8 or 
0,65mm) wire jumpers. Positive contact is assured by the elasticity of the hole, which 
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circuits. CM-600 also features numbered rows and columns for easy reference. 
Accessory Kit RW-50 contains 50 pes of AWG 20 (0,8mm) insulated jumper wires of 
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Tel. (212) 994-6600 Telex 125091 

S. *Minimum billings $25.00, add shipping charge $8.00 

\. New York State residents add applicable tax 



Circle 60 on inquiry card. 



BYTE March 1981 



&n[ 


1 


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OSC OUT [ 


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DAqC 


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3Z5 


HS[ 


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32 


PZ4 


WE[ 


10 


31 


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CAS [ 


11 


30 


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RASoC 


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29 


3Z1 


QC 


13 


28 


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EC 


14 


27 


Iso 


R/W £ 


15 


26 


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AOQ 


16 


25 


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Alt 


17 


24 


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A2[ 


18 


23 


]A6 


A3 rj 


19 


22 


]A5 


GND[ 


20 


21 


]A4 



Figure 6: Pin description of Motorola's MC6883 Synchronous 
Address Multiplexer. This device provides the complex timing 
signals required by the microprocessor and for refresh of 
dynamic memories, as well as multiplexing addresses going into 
the memories. The various programmable modes of the video- 
display generator are provided for so that the SAM can help to 
refresh the video display. (This occurs during the portions of 
instruction cycles that the processor does not access memory.) 



INTRODUCING 



WllWl 



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MP/M USERS GROUP 

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the information off its data lines (DD0 thru DD7), it 
would format and shift out video information to its com- 
panion part (the MC1372 Color Television Modulator) to 
be transmitted to a TV receiver. 

This method of using the part is fine, but it has a few 
drawbacks. First, there needs to be a way to allow the 
microprocessor to write its output data to memory. This 
means that there must be three-state buffers between the 
microprocessor bus and the VDG bus (and logic to con- 
trol them). A control pin on the VDG, Memory Select 
(MS), must be used to put the VDG's address lines in the 
high-impedance state when the processor accesses the 
memory. 

One side effect of this is that the VDG shift registers 
will be filled with the data from its data bus as usual, ex- 
cept that the address lines are under the control of the 
microprocessor, and so the data that gets sent out on the 
video lines is incorrect. This results in "sparkles" of ran- 
dom color on the TV screen and can be annoying when 
you are trying to move your TIE fighter out of enemy 
gunsights! 

Second, there is only one block of memory for the 
VDG to "look" at. In trying to implement computer 
animation, it would be nice to allow the microprocessor 
to draw one picture while another is being displayed. 
Then you would simply swap memory pages and, voila, 
the horse moves! You can't do this with the system out- 
lined above unless you resort to fancy hardware. 

Of course, both of these problems can be overcome. 
We have seen it done with an entire board full of TTL 
(transistor-transistor logic) packages but this is expen- 
sive and not for the faint of heart. Fortunately, these 
problems have a solution in the form of another LSI 
device from — you guessed it — Motorola. The MC6883 
SAM (Synchronous Address Multiplexer) is a 40-pin TTL 
part that marries the MC6809E and the MC6847 to some 
dynamic programmable memory. 

SAM, the Synchronous Address Multiplexer 

The little jewel called the SAM should really interest 
computer experimenters. In the first place, it provides the 
clock signals needed by the microprocessor. The E and Q 
clocks are derived from the 14.31818 MHz crystal — they 
are normally 895 kHz — but this can be changed, as we 
will see. Secondly, the SAM also provides RAS (row- 
address strobe) and CAS (column-address strobe) 
signals for dynamic-memory refresh. As anyone who has 
tried to design a dynamic-memory board can tell you, it 
isn't easy; and one of the hardest things is deriving RAS 
and CAS and hiding the refresh cycle from the processor. 
The SAM does it all and could do it even without a VDG. 
A complete memory board could be designed around this 
device even if you didn't want a video display. A signal 
description of the MC6883 is given in figure 6. 

To conserve the number of pins on a dynamic-memory 
circuit the address is multiplexed in 6-bit pieces (7 bits for 
16 K-bit devices). The SAM takes all the microprocessor 
address lines, multiplexes them to the memory, and con- 
trols RAS, CAS, and WE (Write Enable). A typical read 
cycle is shown in figure 7. 

The microprocessor puts out an address to read a loca- 
tion in the dynamic memory. The SAM splits this address 
into the row address and the column address. First the 
row address is presented to the memory on the output 



112 March 1981 © BYTE Publications lnc 



Circle 61 on inquiry card. 



Circle 62 on inquiry card. 



First compare quality. 
Then compare cost. 

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hard disk system: $3,695. 



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about half the cost of com- 
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COMPLETE SUBSYSTEMS. 

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That's single unit. Quantity prices are 
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BUILDTO FOUR DRIVES. 

104 Megabytes with the M26. 40+ 
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M10: $3,195. Quantity discounts 
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AND NORTH STAR* 

The M26 and M10 are sealed-media 
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. . . materially increasing system through- 
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Call Micro Mike's, 
Amarillo, TX, 
(806) 372-3633 
for the software 
package that allows 
the M26and M10to run 
on North Star DOS. MICAH of 



■■: ■■ - . 




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Three serial and two parallel output 
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Price: $299 (kit), $349 assembled 
and tested. 

MAKE HARD COMPARISONS. 

You'll find that Morrow Designs' hard 
disk systems offer the best price/ 
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subsystems at your computer dealer. 
Or, write Morrow Designs. Need infor- 
mation fast? Call us at (415) 524-2101. 

Look to Morrow 
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MORROW OESIGN5 



•CP/M is a trademark of Digital Research Corp. 
'Cromemco is a trademark of Cromemco. Inc. 
"North Star is a trademark of North Star Computers. Inc. 



5221 Central Avenue 
Richmond, CA 94804 



\ 



/ 



\ 



/ 



\ 



D0-D7 



I 



VALID DATA 



I 



MEMORY 
A0-A7 



V INVALID Y 



ROW ADDRESS 



X 



COLUMN ADDRESS 



CAS 



V 



J 



RAS 



V 



/ 



WE 



/ 



Figure 7: Typical read cycle of 4116-type dynamic memory circuits. To reduce the number of pins required, the memory device in- 
terprets the address being accessed as two sets of 7 bits that come at different times over the same set of pins. The memory cells of 
each device are arranged in an array, and the two sets of bits define a row address and a column address. When a set of address bits 
is valid, either the CAS (column-address strobe) or the RAS (row-address strobe) signal is sent to latch in the respective portion of 
the address. 



lines ZO thru Z5, and the falling edge of RAS causes the 
memory to latch this part of the address into internal 
decoders. The SAM then puts out the column address 
and drops CAS. This causes the memory device to latch 
the column address and decodes the location in the inter- 
nal memory array. The memory's stored data is then put 
on the data-output lines and through a buffer to the 
microprocessor. 

Now, what about refreshing? Dynamic-memory cir- 
cuits are made of small capacitor cells and, unless they 
are refreshed, the charge that represents the stored infor- 
mation will bleed off in a very short time. The memories 
are constructed such that merely accessing all the row 
addresses every 2 ms will keep the data alive. Usually this 
is done with counters that need only count from to 63 (0 
to 127 for 16 K-bit devices). The trick is to hide this from 
the microprocessor. 

In the MC6809E, this is possible because the 
microprocessor needs to access memory only during the 
time that the E clock is high, so all that must be done is to 
refresh the memories when E is low. The SAM also does 
this little chore. 

There are two differences between a system that uses 4 
K-bit circuits and one that uses 16 K-bit devices. First, the 
MCM4116 integrated circuits have an extra address line 
which must be connected to the Z6 output of the SAM. 
Second, the refresh counters in the SAM must be pro- 
grammed to put out 128 refresh addresses for the 
MCM4116s instead of the 64 needed for the MCM4027s. 



The SAM has to be programmed to do this. How this is 
done will be detailed later. 

In the Color Computer, the change is simple. There are 
only two jumpers that need to be switched to select either 
4 K-bit or 16 K-bit memory devices. One of these con- 
nects the seventh address line, and one is connected to a 
PIA input line. Upon reset, the BASIC interpreter reads 
this bit and sets up the SAM for the type of memory in- 
dicated. That's all there is to it. 

So what does all this have to do with the VDG? Since 
the VDG needs to be able to read memory to refresh the 
video screen, the SAM takes care of this, also. The 
address lines of the VDG are not connected at all in this 
system. Rather, the SAM is programmed into the same 
mode as the VDG and duplicates the timing of the VDG's 
address bus, except that it accesses memory to refresh the 
VDG during the E low time (so that the VDG accesses are 
transparent to the microprocessor). Since there is no 
possibility of a bus fight between the processor and the 
VDG, there is no need to deny the VDG access to the 
memory and the screen remains glitchless. 

The full timing is shown in figure 8. The SAM usually 
provides memories with the address needed to access the 
data for the VDG to output as video. During the active 
display time (one frame of video) these addresses 
automatically refresh the memory devices. During the 
vertical retrace time, the SAM puts out refresh addresses. 
The microprocessor can access the memory at any time E 
is high and is therefore not affected. 



114 March 1981 © BYTE Publications lnc 



T 



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BYTE March 1981 



A 



/ 



V 



/ 



A 



D0-D7 



Y VDG DATA Y 



X PROCESSOR Y 
DATfl A / 



OUTPUTS 
Z0-Z7 



W VDG/REF Vf/\/ \l\l\l VALID VOG/REF V V VpROCESSOR V V V pb 

Aa^dVss ft7wW°A columnTddress A A A"°" *™«^\h\ 



OCESSOR COLUMN ADDRESS 



I 



f 



A 



/ 



\ 



V 



J 



V 



[ 



Figure 8: Diagram of a typical dynamic-memory refresh cycle. The SAM provides every dynamic memory with a signal on each row 
address, as required, to refresh the data contained within. 



The VDG supports one 

alphanumeric mode, two 

semigraphic modes, and eight full 

graphic modes. 

Programming the VDG 

The VDG has 5 mode-control pins that determine how 
the address lines behave and how the data that is obtain- 
ed from the memory is to be interpreted. In this system, 
these lines are connected to lines PB3 thru PB7 of PIA2. 
The data-output register for this device is located at 
address hexadecimal FF22. The microprocessor can write 
directly to this port to select the VDG mode. In fact, 
Extended Color BASIC has a statement, PMODE, to do 
just this. 

The VDG has one alphanumeric mode (using its inter- 
nal character generator or an external one), two 
semigraphic modes, and eight full-graphic modes. The 
modes and the way the mode-control pins must be pro- 
grammed are shown in table 5. 

The alphanumeric mode is the one used by BASIC to 
print on the screen. The VDG sequentially reads 512 
bytes from memory for each TV frame. The data is inter- 
preted as character codes, with the first byte correspond- 
ing to the top left corner ("home" position). There are 16 
rows of 32 characters for a total of 512 characters on the 
screen. The character code is given in table 6. 

Lowercase characters are displayed as inverted (light 
characters on a dark background). This is done by tying 
bit 6 (DD6) of the VDG to the INVERT pin. Because this 
bit is set in all lowercase numbers, they are inverted. 

To support the SET and RESET commands in Radio 
Shack's Level I BASIC, data line DD7 onjhe VDG is con- 
nected to the alpha/semigraphic pin (A/S). Whenever 



this bit is set, the VDG will interpret the data in the 
manner shown in table 5, under the semigraphic-4 mode. 
Instead of displaying a character, a colored block that is 
divided into four smaller blocks is displayed. The code in 
the byte read from memory determines which pattern of 
blocks is shown and what color it is. Using the smaller 
element within the block as a pixel, this gives a grid of 64 
by 32 blocks, which are the dimensions of the SET and 
RESET commands. The other semigraphic mode is 
similar to this, but each large block is divided into six 
blocks (instead of four) and has a choice of two sets of 
four colors, controlled by the CSS (Color Set Select) pin. 
(Refer to the semigraphic-6 mode in table 5.) 

The remaining eight modes are of the bit-mapped 
graphic type. They require 1, 1.5, 2, 3, or 6 K bytes of 
memory, depending on the mode. Basically, the data in 
memory is interpreted as pixels. In the four-color modes 
(1-C, 2-C, 3-C, and 6-C), each pixel is represented by 2 
bits, selecting one of four colors. The set of colors is 
selectable by the CSS pin. In the two-color modes (1-R, 
2-R, 3-R, and 6-R), each bit is mapped one-to-one on the 
screen. If the bit is set, the pixel is colored, and if it is not 
set, the pixel is black. The color set can be changed so the 
pixel can be either buff or green; color sets are controlled 
by the CSS pin. The resolution of these modes varies 
from 64 by 64 to 256 by 192 pixels horizontal and vertical 
respectively. 

To use these graphic modes, you simply program the 
VDG by writing the mode code into the PIA output 
register, and write to the "screen memory" addresses. The 
only problem is that the VDG's address lines are not con- 
nected to any memory. As mentioned before, the SAM 
provides the addresses and the VDG interprets the data 
from the memory, so the SAM must be programmed to 
be in the same mode as the VDG in order to get a mean- 

Text continued on page 120 



116 



March 1981 © BYTE Publications Inc 




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Circle 63 on inquiry card. 



BYTE March 1981 



117 



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118 March 1981 © BYTE Publications Inc 



Circle 64 on inquiry card. 



Low cost, high quality 

An exceptional 16Kmemory 

at an exceptional price 




Our 16K Memory Merchant is 
the first in a series of low 
cost, remarkably engineered 
memory boards. . 

It's a low power 16K Static 
RAM (2114) with bank select 
logic and extended 24 bit 
adaress. Memory Merchant is 
compatible with 2 Mhz 8080, 
4MhzZ80and5Mhz8085.0ne 



of its four independent 4K 
blocks has "windowing 
capability" — any or all four 
of the 1 K sub-blocks may be 
removed from the memory 
block. Design features include 
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High-Order 

Hexadecimal 

Digit 



Low-Order Hexadecimal Digit 
0123456789ABCDEF 

©ABCDEFGHUJKLMNO 
PQRSTUVWXYZ[\]t~ 

0123456789: ;<=>? 



@ A B C 


D E F G H 


U 


J K L M N 


P Q R S 


T U V W X 


Y 


Z [ \ ] I - 


! " # 


$ % & ' ( 


) 


* + ,-■/ 


12 3 


4 5 6 7 8 


9 


: ; < = > ? 



Table 6: Codes for the characters stored in the VDG's internal character generator. The lower section contains inverse-video char- 
acters, dark characters on a light background. 



Text continued from page 116: 

ingful display. 

Programming the SAM 

With a SAM in the system, the memory map is pretty 
much fixed. The SAM directly decodes the addresses 
from the processor to access memory, and provides 
device selects for the rest of the sytem on the SO thru S2 
pins. These pins are decoded by a 3-to-8 decoder 
(74LS138) to get the active-low select signals for the rest 
of the system. Refer to the memory map shown in figure 
9. 

The reset vector and interrupt vectors at the top of the 
map are mapped from hexadecimal FFF2 thru FFFF to 
BFF2 thru BFFF. This allows these vectors to be stored in 
the 8 K-byte BASIC ROM beginning at address hexa- 




decimal A000. The addresses of the two PIAs, the second 
ROM, and the off-board ROM cartridges are also shown 
in figure 9. 

The block of addresses from hexadecimal FFCO to 
FFDF are the locations of the SAM registers. The SAM is 
programmed and its various options selected by writing 
to these locations. The data is immaterial since the data 
bus is not connected to the SAM. Each register bit has 
two unique locations, an even location and an odd one. 
Writing to the even location will clear the register bit. 
Writing to the odd location will set the bit. By encoding 
the bits, and accessing the appropriate locations, the 
SAM can be programmed. 

The memory map in figure 9 shows the modes and the 
locations associated with each. S stands for set and C for 
clear in the diagram. The programmable attributes in- 
clude: 

•VDG mode — mode of address lines during VDG refresh 

time. 

•Display offset — the base address of the memory used by 

the VDG is specified here. This is the address of the pixel 

in the upper left-hand corner of the screen in graphic 

mode. Programmable in Vi K pages. 

•Memory size — 4 K-bit, 16 K-bit or 64 K-bit dynamic 

memories or a full map of static memory and I/O. 

•Microprocessor clock rate —can be set for 0.8, 1.8 MHz 

or address-dependent rate. 

•Page — allows two 32 K-byte memory pages between 

hexadecimal 0000 and 7FFF. 

The VDG mode bits in the SAM must be programmed 
to match the mode selected for the VDG on its mode pins. 
Table 7 shows the correspondence between the SAM and 
the VDG modes. If the two modes do not agree, 
interesting results can be obtained. Some of these "mixed" 
modes include graphics mixed with alphanumerics. 

The VDG address offset specifies where the SAM 
should start the address counters. Figure 10 shows the 
address sent by the SAM as a function of this offset. This 
allows the VDG display to be "paged" through memory in 
512-byte pages, allowing fast page swapping for anima- 
tion, etc. On reset, BASIC will set the offset to hexa- 
decimal 400 so all the screen output of the BASIC inter- 
preter is at locations hexadecimal 400 thru 5FF. Try 
POKEing to these locations to use the alphanumeric and 
semigraphic modes. 

The Extended BASIC supports the higher-resolution 

Text continued on page 124 



120 March 1981 © BYTE Publications In 



Circle 65 on inquiry card. 



Introducing 

quality print at matrix speed. 

rot only $1295! 



Until now, word processing output 
was a slow, expensive proposition. Vbu 
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quality character printer. Or give up 
print quality for matrix speed and price. 

Butthat was before Paper Tiger'" 460 
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The new Paper Tiger 460 is the first 
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The secret? A unique nine-wire, stag- 
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What's more, Paper Tiger 460 
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nostics and self-test. Proportional spacing. 
Automatic text justification. DotPlot'" high 



Integral Data Systems stands re.- 
performance printers ideally so 
printer, the IDS 460, offers feat 

Automatic proportional spacing, 
processing systems, plus the cap 
resolution of 84 by 84 dots per 



Paper Tiger 460 Print Sample 

resolution graphics option. RS232 and paral- 
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But its most important feature is high relia- 
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tough and dependable. It has rugged, 
stepper-motor head and paper drives. 
A new rugged ballistic-type print head. 



Circle 66 on inquiry card. 




And its simple, chassis-mounted 
cartridge ribbon lasts up to four times 
longer than cassette or spool ribbons. 

Paper Tiger 460 is the one printer 
that gives your Apple/ TRS-80,*or 
other small business computer both 
data processing and word process- 
ing output. At a price you can afford. 
Get your paws on Paper 
Tiger 460, and join the tens of 
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■w) ) Integral Data Systems, Inc. 



*Suggested single-unit U.S. retail price. 

t Apple is a trademark of Apple Computer Inc. 

tTRS-80 is a trademark of Radio Shack, a division of Tandy Corp. 





HE 

8 
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KADECIMAL 

6809 6809 
\DDRESS ADDRESS 

S2,S| , So 
VALUE LABEL DEFINITION 


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■< A000 
-<8000 

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MEMORY 

(USUALLY 

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(S=3) 




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RESET 




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FFFE 


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FFFD 


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SWI2 






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FFF3 


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SWI 3 






FFF2 


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FFF1 


RESERVED 

(FOR FUTURE 
MPU 
ENHANCEMENTS) 

DO NOT USE! 






(S=2) / / 


FFFO 






FFEF 








/ / ' 

1 


FFEE 






FFED 






FFEC 






MEMORY 

(USUALLY 

ROMj) 

(S=2) 


FFEB 






FFEA 






FFE9 






FFE8 






FFE7 






FFE6 






FFE5 






64K STATIC 

64K > | 

16K >DYNAMIC 

4K J 

1.8 MHz ONLY 

1.8 MHz ONLY 

0.9/1. B MHz 1 TRANSPARENT 




FFE4 


( = 0) 






FFE3 








FFE2 










MEMORY 

(USUALLY 

ROM ) 

(S=l) 


FFE1 








FFEO 
















FFDF 


S* 


TY 


MAP 

TYPE 








FFDE 


C 












FFDD 


S 


Ml 


MEMORY 
SIZE 




1 


1 
















FFDC 


C 














FFDB 


S 


MO 




1 





1 





1—0.9 MHz ONLY 1 REFRESH 




FFDA 


C 


I 






FFD9 


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Rl 


MPU 
RATE 




1 


1 














FFD8 


C 






MEM 
(S = IF 
(S = 7 IF 


ORY 
R/W =1) 
R/W=0) 

I , 


FFD7 


S 


RO 




1 





1 









FFD6 


C 






FFD5 


S 


PI 


PAGE #1 


\ MPU ADDRESSES FROM 0000 TO 7FFF 
J APPLY TO PAGE #1 IFPl = 'l' 




FFD4 


C 




FFD3 


S 


F6 


DISPLAY 
OFFSET 

(BINARY) 


1 

> 






FFD2 


C 


1 ADDRESS OF " UPPER- LE FT-HAND DISPLAY ELEMENT 




FFD1 


S 


F5 


' = 0000 + (1/2 K • OFFSET) 




FFDO 


C 






DMA 

G6R, G6C 

G3R 

G3C 

G2R 

G2C 

GIC, GIR 










(S»7J / 1 


FFCF 


S 


F4 








FFCE 


C 












/ / ' 
/ / ' 
/ / ' 

| 


FFCD 


S 


F3 








FFCC 


C 














FFCB 


S 


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FFCA 


C 










FFC9 


S 


Fl 








FFC8 


C 














FFC7 


s 


FO 


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FFC6 


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FFC5 


s 


V2 


VDG 
MODE 

(SAM) 




1 


1 


1 


1 


















FFC4 


C 










FFC3 


s 


VI 




1 


1 








1 


1 












FFC2 


C 






FFC1 


s 


VO 




1 





1 





1 





1 









FFCO 


c 






FFBF 


RESERVED 
: DO NOT USE! 










J REGISTERS OR SPECIAL I/O 




FF60 




A 


FF5F 


' EXTERNAL CS 
l/0 2 












(S-6) /, 


FF43 








FF42 






— 


4K 

■ 1 




'/// 


FF41 






FF40 






7/A 


FF3F 


PIA 1 
I/O] 












(S=5) / 


FF23 






FF22 








'/// 


FF21 
FF20 


'NO TE: 

M.S. 2 MOST SIGNIFICANT 




///> 


FF1F 


? PIA 

l/0 (0.9 MHz) 


L.S. s LEAST SIGNIFICANT 






V J 




r — p 








(S^)'// 

/// 


FF03 


S = SET BIT 1(ALL BITS ARE CLEARED 
C = CLEAR BIT J WHEN SAM IS RESET.) 






FF02 




FF01 








/// 


FFOO 











Figure 9: Memory map of the Color Computer address space. The general division of addresses is provided at the left, while the 
SAM programming registers and the processor-interrupt vectors are expanded at the right. 



122 March 1981 © BYTE Publications Inc 





4* 



A microcompuf er 
for everyone at 

a Micr o Price 

The UlicrofkeJ - a new generation of 

miniature computers 

A COMPLETE COMPUTER 
for $149.00 for 1K Kit 



The unique 

and valuable 

components of the MicroAce 

The MicroAce is not just another personal 
computer. Quite apart from its exceptionally low 
price, the MicroAce has two uniquely advanced 
components: the powerful BASIC interpreter, and 
the simple teach yourself BASIC manual. 

The unique versatile BASIC interpreter offers 
remarkable programming advantages: 

• Unique 'one-touch' key word entry: the 
MicroAce eliminates a great deal of 
tiresome typing. Key words (RUN, PRINT, 
LIST, etc.) have their own single-key entry. 

• Unique syntax check. Only lines with correct 
syntax are accepted into programs. A cursor 
identifies errors immediately. This prevents 
entry of long and complicated programs with 
faults only discovered when you try to run 
them. 

• Excellent string-handling capability takes up 
to 26 string variables of any length. All strings 
can undergo all relational tests (e.g. 
comparison). The MicroAce also has string 
input to request a line of text when 
necessary. Strings do not need to be 
dimensioned. 

• Up to 26 single dimension arrays. 

• FOR/NEXT loops nested up 26. 

• Variable names of any length. 

• BASIC language also handles full Boolean 
arithmetic, conditional expressions, etc. 

• Exceptionally powerful edit facilities, allows 
modification of existing program lines. 

• Randomise function, useful for games and 
secret codes, as well as more serious 
applications 

• Timer under program control. 




PEEK and POKE enable entry of machine code 
instructions, USR causes jump to a user's 
machine language sub routine. 

• High resolution graphics with 22 standard 
graphic symbols. 

• All characters printable in reverse under 
program control. 

• Lines of unlimited length. 

'Excellent value' indeed! 

For just $149.00 (including handling charge) you 
get everything you need to build a personal 
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Yet the MicroAce really is a complete, powerful, 
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The MicroAce is programmed in BASIC, and you 
can use it to do quite literally anything, from playing 
chess to managing a business. 

The MicroAce is pleasantly straightforward to 
assemble, using a fine tipped soldering iron. It 
immediately proves what a good job you've done: 
connect it to your TV ... link it to the mains adaptor 
... and you're ready to go. 

Fewer chips, compact design, 
volume production-more power 
per Dollar! 

The MicroAce owes its remarkable low price to its 
remarkable design: the whole system is packed on 
to fewer, newer, more powerful and advanced LSI 
chips. A single SUPER ROM, for instance, contains 
the BASIC interpreter, the character set, operating 
system, and monitor. And the MicroAce IK byte 



Post and Packing FREE 
(Add 6% Tax for Shipments inside California) 

RAM (expandable to 2K on board) is roughly 
equivalent to 4K bytes in a conventional computer 
typically storing 100 lines of BASIC. (Key words 
occupy only a single byte.) 

The display shows 32 characters by 24 lines. 

And Benchmark tests show that the MicroAce is 
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No other personal computer offers this unique 
combination of high capability and low price. 

The MicroAce teach-yourself 
BASIC manual. 

If the features of the BASIC interpreter mean 
little to you-don't worry. They're all explained in the 
specially written book free with every kit! The book 
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represents a complete course in BASIC 
programming-from first principles to complex 
programs. (Available separately purchase price 
refunded if you buy a MicroAce later.) 
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The MicroAce Kit: 

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$169.00 with 2K 

Demand for the MicroAce is very high: use the 
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your kit, we will repair it for a fee of $20.00, post and 
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MicroAce as received within 14 days for a full 
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doubt and we have no doubt that you will be. 



Z80 A microprocessoi 
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Sockets lor 
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ROM, 




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contains... 

• Printed circuit board, with 
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Complete components set, 
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manufactured by selected 
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New rugged keyboard, 
touch sensitive, wipe clean. 
Ready-moulded case. 
Leads and plugs for 
connection to domestic TV 
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(Programs can be SAVEd 
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Mains adaptor of 600 mA 
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unregulated. 
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programming and user 
manual. 



JOIN THE REVOLUTION - DON'T GET LEFT 
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Send Check, Money Order or quote your Credit Card No. to: 
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or phone (714) 547 2526 quoting your Credit Card Number. 



Quantity 



Description 



TOTAL 





MicroAce Kit 1K 


$149.00 






MicroAce Kit 2K 


$169.00 






Manual 


$10.00 






IK Upgrade Kit 


$29.00 




Shipmen 
add 6% 


Is inside California 
TAX 


TOTAL 





Amex. 
Diners 
Check 

Money Order 
Master Charge 
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I 
I 

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Circle 67 on inquiry card. 



BYTE March 1981 



123 















Synchronous Address 


Mode 


Video Display Generator Signal 


s M 


ultiplexer 


Signals 










GMO 












G/A 




GM2 

X 


GM1 

X 


EXT/1 




CSS 

X 


v 2 


v, 


Vo 


Internal alphanumeric 











External alphanumeric 





X 


X 


1 


X 











Semigraphic-4 





X 


X 





X 











Semigraphic-6 





X 


X 


1 


X 











Full graphic 1-C 













X 








1 


Full graphic 1-R 










1 


X 








1 


Full graphic 2-C 







1 





X 





1 





Full graphic 2-R 







1 


1 


X 





1 


1 


Full graphic 3-C 




1 








X 










Full graphic 3-R 




1 





1 


X 







1 


Full graphic 6-C 




1 


1 





X 




1 





Full graphic 6-R 




1 


1 


1 


X 




1 





Direct memory access 


X 


X 


X 


X 


X 




1 


1 


Table 7: Mode correspondence 


between the 


SAM an 


d the VDG. 



A15 A14 A13 A12 All A10 A9 AB A7 A6 A5 A4 A3 A 2 Al AO 



<=s 


F5 


F4 


F3 


?2 


Fl 


PO 






























MSB LSB 

Figure 10: Mapping of the video-display refresh address. The 
SAM uses a 7-bit offset to determine the start of video-display 
memory. This allows the use of 512-byte "pages" for display 
refreshing, making it possible to page through memory to create 
fast animation effects, etc. 



Text continued from page 120: 

graphics and can also allocate more memory for multiple 
pages, up to eight. It provides graphic operations, such as 
LINE, DRAW, and CIRCLE, that are fast enough to 
allow the programming of real-time games using the 
joysticks as controllers. 

Memory type is self-explanatory. The SAM must be 
programmed for the type of memory devices used in the 
system to produce the correct timing signals. If 16 K-bit 
circuits (MCM4116 or the equivalent) are used, pin 35 
can be used for RASl. This is needed to select a second 
bank of devices to provide 32 K bytes of memory. One 
way to do this on the Color Computer is to piggyback a 
second set of eight MCM4116s on top of the existing in- 
tegrated circuits, paralleling all the pins except for the 
RAS pin. When this is jumpered to pin 35 on the SAM, 
the system then has 32 K bytes of user-programmable 
memory. 

The microprocessor clock rate is also programmable. 
There are three modes, as shown in figure 9. In mode 0, 
the clock rate is fixed at one-sixteenth the crystal frequen- 
cy. In this case, that is 895 kHz. Mode 2 gives a fixed rate 
of one-eighth the crystal frequency, or 1.8 MHz. This can 
be used with an MC68B09E, a 2 MHz version of the 
microprocessor. However, there are no memory or VDG 
addresses output in this mode, so don't use it. 

Mode 1 is the most interesting. It gives a dual-rate 
clock of 895 kHz or 1.8 MHz depending on the address 
used in the bus cycle. When the processor accesses 
addresses from hexadecimal 0000 to 7FFF and FF00 to 
FFlF, the lower rate is used, allowing for slower memory 
and peripherals. When all other addresses are accessed, 
the processor runs at 1.8 MHz. Using fast ROMs will 
almost double the speed of the system because a majority 
of the microprocessor's memory references are to fetch op 



codes. If you want to try this, execute the following 
BASIC statement: 

POKE 65495,0 

This will set bit R0 of the microprocessor rate register at 
location hexadecimal FFD7 and put the SAM into the 
dual-rate mode. If your microprocessor can run at the 
higher speed (a pretty good bet), you will see the 
changing-color cursor flashing about twice as fast as nor- 
mal. Your BASIC programs will now run about twice as 
fast, too. There is one problem, though — don't try to use 
the SOUND, CLOAD, or CSAVE statements in this 
mode. The PIA used by these statements is at location 
hexadecimal FF20 and it will probably not run at the 
higher speed. 

The other two registers do not apply to the Color Com- 
puter. The Map Type bit chooses a mixed 
programmable/read-only type of system such as the 
Color Computer or a fully programmable system such as 
a disk-based one. The Page bit allows two 32 K-byte 
pages of memory to be accessed between locations hexa- 
decimal 0000 and 7FFF. This can't be done on this 
system. 

Keyboard Scanning 

The keyboard is configured as an 8 by 7 matrix of keys. 
The Color Computer uses a software routine to encode 
the keyboard in a manner similar to that of the TRS-80 
Model I. This is done by shifting a through the B port of 
PIA IC8. The B port drives the 8 rows of the keyboard; 
the 7 columns are connected to the A port of IC8. The A 
port has internal pull-up resistors that provide a logic 1 
level unless a key is depressed. When the shifted occurs 
on the row of the closed key contact, the low level is 
passed to port A. By repeating the scanning procedure 
several times, debounced inputs are recognized. 

If you need to monitor the keyboard during a program, 
a function (INKEYS) is provided. The BASIC statement 

A$ = INKEYS 

will return a character if a key is closed when the function 
is called. An example use of this function would be to 
monitor the keyboard during a 'Tank" game for direction 



124 



March 1981 © BYTE Publications Inc 



Circle 76 on inquiry card. 



The largest selection 
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IKHNO.19 

Write for our catalog. 



LANGUAGES 



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DISK OPERATING SYSTEMS 

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BUGANDuBUG 


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WORD-MASTER 


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No matter what is on your word proces- 
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of? Microspell will be your dictionary, too. 

Microspell has a basic 20,000 word dictionary, and you can add 
to it yourself. Add technical words, create auxiliary dictionaries, 
special expressions, and acronyms. 

Complete with full dictionary, all utilities, and a demonstration 
file, Microspell from Lifeboat costs $249. 



JOB COSTING (GD) 
PAYROLL (PTREE) 
PAYROLL (SSG) 



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muMATH 



STATPAK 
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STANDARD TAX 



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ACCOUNTS PAYABLE & ACCOUNTS 
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THE CP/M HANDBOOK 
THE C PROGRAMMING LANGUAGE 
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FLIPPY DISK KIT 
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Program names and computer names are 
generally trademarks or servicemarks of the 
author or manufacturing company. 

All software products have specific re- 
quirements forhardware and additional as- 
sociated software (e.g. operating system or 
language). 

All products are subject to terms and condi- 
tions of sale. 



Copyright @ 7987 Lifeboat Associates. No 
portion of this advertisement may be repro- 
duced without prior permission. 



Ordering Information 



COMPUTERS SUPPORTED WITH MEDIA FORMAT ORDERING CODES. 



ADDS Multivision 

AVL Eagle ... 
Altair 8800 

AllDS 

Apple CP/M 13 Sector . 
Apple CP/M 16 Sector 
BASFSystem 7100 
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Blackhawk Single Density 

CDS Versatile 3B 

CDS Versatile 4 ... 
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CSSN Backup . 

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Digital Microsystems . A1 

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Research Machines 5 25 in 



Research Machines 8 in 

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STANDARD 
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5 25 in 



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A4 ZenrthA89 * Lifeboat CP/M P4 

Zenith Z89 • Magnolia 

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: lifeboat Associates; 

THE 

I scrrwARS 

SUPER- 
MARKET 



Lifeboat Associates, 1651 Third Avenue, N.Y.; N.Y 10028 
f212) 860-0300 International Telex: 220501, Domestic Telex: 640693 



In Germany, ^ 

Intersoft GmbH, Schlossgartenweg 5, 

D-8045 Ismaning Telephone 089/966-444 Telex: 5213643 isof 

In Switzerland, 

Lifeboat Associates GmbH, Aegeristr. 35, CH6340 Baar, 

Telefon: 042/31 2931, Telex: 865265 MICO CH 



■ 






keys and a "Fire" key. This would allow you to play a 
'Tank" game without having a set of joysticks. 



This type of converter is accurate to ± Vi the least signifi- 
cant bit, or in this case ±39 mV. 



Digital-to-Analog Converter 

The D/A (digital-to-analog) converter allows the 
Color Computer to send analog waveforms. These 
signals are used for the cassette output, sound to the 
video modulator, and as a reference signal for A/D 
(analog-to-digital) conversion. 

Six of the eight port A lines are configured as outputs 
and buffered to drive a resistive adder network for analog 
signal generation, as shown in figure 11. The resultant 
analog signal ranges from V to +5 V in 78 mV steps. 



PART OF IC4 
MC6821P 



PA2 
PA3 
PA4 
PA5 
PA6 
PA7 



IC2 
MC14050B 



'~l 



$> 



> 



i> 



> 



> 



> 



2 320K 
WA — i 



15 



160K 
-WV\ — l 

80K 
-AAA — * 



12 



40K 
-AAA — * 



20K 
-VW- 



10 10K 

VA 1 



-o 



ANALOG 
OUTPUT 



I I 



Figure 11: Schematic diagram of the Color Computer's digital- 
to-analog converter. In a rather simple scheme, the output lines 
of a parallel port drive a resistive adding network to provide 
conversion. The resulting analog signals are used for recording 
on a cassette, providing the video modulator with sound, and 
also as part of the analog-to-digital converter. 



IC4 

MC6821 



u 



:> 



DIGITAL TO ANALOG 
CONVERTER 
(FIGURE 11) 




\ AFMALUt. 

/level 

FROM 
JOYSTICKS 



C21 

1/2 MC14529 



Figure 12: Diagram for the analog-to-digital converter circuit. 
Also used as the joystick interface, this circuit applies the 
successive-approximation method (see figure 13) to change 
analog signals to digital form. 



Cassette Port 

The Color Computer has a cassette port which con- 
nects to a low-cost recorder. Motor-control capability is 
included that allows the cassette recorder to be started or 
stopped as required. The motor can be turned on and off 
with the statements MOTOR ON and MOTOR OFF. 
This allows the user to fast-forward or rewind tapes 
without having to unplug connections to the Color Com- 
puter. 

Data is output to the recorder from the D/A converter. 
If an oscilloscope is connected to the data-output line, pin 
5 of the cassette jack, an 800 mV 1500 bps signal will be 
seen. 

When data is loaded from the cassette recorder, the 
playback signal can be routed to the modulator sound in- 
put in a manner that allows you to monitor the cassette 
signal via the speaker of a television set. This is done with 
the AUDIO ON and AUDIO OFF statements. 

The cassette data-output can be used for an analog out- 
put level because the D/A converter can be controlled by 
a user program. The motor-control relay can be used to 
control loads up to 6 V DC at 500 mA. 

Joystick Interface 

Two joystick ports are provided which allow full x,y 
directional control. Each joystick has a pushbutton for 
use with games (eg: paddle control for the Pinball game). 
Each joystick consists of two potentiometers, each con- 
nected across +5 V and ground. The wiper of each 
potentiometer is connected to the input of an analog 
multiplexer controlled by PIA IC8. The voltage level 
from each of the four potentiometers is routed to the A/D 
converter to get a digital value for the position. This 
value will range between and decimal 63. The 
JOYSTK(j) function returns the digital value of the 
joystick position. 

Analog voltage levels from the joysticks are digitized 
using a successive-approximation technique. This is one 
of the more popular methods of A/D conversion. The 
6-bit D/A converter is used in a feedback loop to 
generate a known analog signal to which the unknown 
analog joystick input is compared. This technique is not 
as fast as a flash converter, nor is it as slow as a binary 
counter. 

Figure 12 shows the block diagram for the successive- 
approximation converter circuit. Figure 13 shows a 
flowchart for this approach. The D/A converter inputs 
are controlled by the microprocessor to form a 
successive-approximation register. The analog output is 
compared to the analog joystick input by the MLM339 
comparator whose output is monitored by the MC6809E. 

At the start of a conversion the MSB (most significant 
bit) of the D/A converter is turned on by the 
microprocessor, producing an output equal to half the 
full-scale value. This output is compared to the analog in- 
put and if it is greater than the joystick voltage, the 
microprocessor turns the MSB off. However, if the D/A 
output is less than the joystick voltage, the MSB remains 
on. 

Following the trial of the MSB, the next most signifi- 
cant bit is turned on and again the comparison is made 



126 March 1981 © BYTE Publications Inc 



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Circle 68 on inquiry card. 



BYTE March 1981 127 



between the converter's output and the joystick voltage. 
The same criteria apply and this bit is either kept on or 
turned off. This procedure of testing each bit continues 
four more times until the 6 bits of the D/A converter 
have been set to the proper level. 

Once the conversion is complete the microprocessor 
reads the joystick output by reading port A of PIA IC4. 
The internal structure of port A allows a read of the port 
to sample the output logic levels. Now the Color Com- 
puter has the digital value for the joystick voltage. The 
time necessary to do this conversion is constant and does 
not vary with the analog voltage level. 

Note that the Color Computer has an on-board A/D 
converter that accepts a signal between +5 V and ground 
and can digitize it with less than a 40 mV error. This 
means you can use the appropriate joystick inputs to 
monitor various analog voltages. The switch inputs are 
connected to the PIA (the left switch to IC8 pin 3, PAl; 
and the right switch to IC8 pin 2, PAO). You can write a 
progam to monitor these bits for use with external 
devices. Figure 14 shows the connectors for the joysticks 
(which are not shown in the TRS-80 Color Computer 
Operation Manual). 



usable. 

Expansion Port 

The expansion port provides the capability to interface 
almost anything to the Color Computer. Table 8 lists the 
pins and their functions. Note that the entire address bus 
is brought out. There is also a decode-defeat pin which 
disables the 74LS138 that decodes ROMs and peripherals. 
This allows the expansion port to redefine the memory 
map. For instance, a flip-flop could be toggled to remove 
the BASIC and Extended BASIC ROMs from the memory 
map and replace them with programmable memory. A 
disk-controller board could also contain 48 K bytes of 
memory to fill the system from address hexadecimal 0000 
to FF60. 

The Vector Graphic company makes a wire-wrap pro- 
totype board (part number 4609) that fits the expansion 
connector of the Color Computer. This allows you to 
build your own peripheral boards. We are working on an 
interface to the General Instrument "Cricket" sound 
generator. The output from this circuit can be routed to 
the video modulator through a pin on the expansion con- 
nector. If you want, you can also build your own game 



RS-232 Interface 

An RS-232 interface is also provided. This allows you 
to connect all manner of devices to the Color Computer. 
The standard RS-232 Transmit Data, Receive Data, and 
Carrier Detect signals are provided. This is the funda- 
mental signal subset used by most devices. Tandy sells an 
off-the-shelf line of printers and a modem that are readily 



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Q 



START SUCCESSIVE 
APPROXIMATION ROU 



TING / 



CLEAR IC4, PORT A 
= D/A INPUTS 



-J 



SET BIT I OF 
D/A INPUTS 




RESET BIT I OF 
D/A INPUTS 



1 = 1-1 




READ IC4 PORT A 
(AND SHIFT RIGHT 
TWO BITS) FOR 
DIGITAL LEVEL 



c 



END 



D 



Figure 13: Flowchart of the successive-approximation algorithm 
used by the Color Computer. 



128 



March 1981 © BYTE Publications In 



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X TAP OF JOYSTICK 

Y TAP OF JOYSTICK 

GROUND 

SWITCH TO GROUND 

CONNECTED TO +5V 
THROUGH 100JI RESISTOR 



Figure 14: Pin designations of the Color Computer joystick con- 
nectors. The connectors will mate with a standard 5-pin DIN 
plug, and any signal within the A/D converter's range may be 
monitored under program control. 





Expansion Port Pin 


Description 


pin 


function 




pin 


function 


1 


-12 V 




2 


+ 12 V 


3 


HALT 




4 


Nonmaskable Interrupt 


5 


RESET 




6 


E 


7 


Q 




8 


CB1 of IC4 


9 


+ 5 V 




10 


DO 


11 


D1 




12 


D2 


13 


D3 




14 


D4 


15 


D5 




16 


D6 
R/W 


17 


D7 




18 


19 


AO 




20 


A1 


21 


A2 




22 


A3 


23 


A4 




24 


A5 


25 


A6 




26 


A7 


27 


A8 




28 


A9 


29 


A10 




30 


A11 


31 


A12 




32 


C000 thru FEFF 


33 


Ground 




34 


Ground 


35 


Analog In 




36 


FF40thru FF5F, CS 


37 


A13 




38 


A14 


39 


A15 




40 


Decode Defeat 


Table 8 


Signals ava 


table 


at the expansion port. 



cartridges. If you want them to auto-start like the Tandy 
cartridges, connect pins 7 and 8 together. This runs the Q 
clock into the CB1 input of PI A IC4, causing an FIRQ 
interrupt. The FIRQ interrupt-service routine jumps to 
hexadecimal C000 and starts execution. There is also a 
device select on pin 32 that is decoded from hexadecimal 
C000 to FEFF. 

Summary 

We have tried to completely describe the architecture 
of the Color Computer and deduce the reasoning behind 
the design trade-offs. Tandy certainly is to be com- 
plimented on the amount of "bang for the buck" — every 
part is fully used and several innovative design ideas are 
evident. We believe that the Color Computer has the 
capability to surpass the Model I in sales. 

In a later article we will take a detailed look at the 
Extended BASIC and discuss its capabilities. We are cur- 
rently implementing several popular video games in 
BASIC. Once the algorithms are proven, we plan to con- 
vert them to machine language to increase the speed, 
although with the power of the Extended BASIC we may 
not have to.B 

Circle 70 on inquiry card. 



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February 1981. Vol. 1 Issue #9 




A comparison 
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The first in a series of articles by 
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A review of MACRO-80 by Micro- 
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A tip on how to save substantial 
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Current up-to-date information on 
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'VisiCalc i s a trademark of Personal Software, inc. 
CP/M and MAC are trademarks of Digital Research, Inc. 
The CP/M Users Group is not affiliated with Digital Research. 
T/MAKER is a trademark of P. Roizen. 



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BYTE March 1981 



131 



What Is Good Documentation? 



Jim Howard 

150 Ramona Place 

Camarillo CA 93010 



As more and more people discover 
the joys of owning a microprocessor 
the need for good documentation will 
continue to grow. Information will be 
needed at all levels, from detailed 
hardware and software documenta- 
tion to descriptions of which buttons 
to push to play your favorite game. 

Who will provide this information? 
The simple answer is that those who 
know will tell those who don't know. 
It sounds simple, but it's not. Every- 
where, complaints are made about 
documentation — "inadequate," "er- 
roneous," "over my head," "bad or 
nonexistent," and so on. All too of- 
ten, companies market excellent sys- 
tems with poor or sketchy documen- 
tation, resulting in unhappy cus- 
tomers and unsatisfactory sales. 

It's a common mistake to believe 
that because somebody is an expert in 
a subject, he can explain it to others. 
For example, it's assumed that a pro- 
fessor who knows a subject inside and 
out can pass on this information to 
students. However, whether he can 
or cannot depends on something else 
besides his knowledge of the subject. 
It depends on his ability to put 
himself in the place of the users, the 
students, to begin where they are, 



using their language and their know- 
ledge level. (Of course, if there is a 
failure to communicate, it is the stu- 
dents who fail, not the professor!) 

The microprocessor industry is a 
classic example of the communication 
problem. Aside from a few shining 
lights, microprocessor literature suf- 
fers from a bad case of "the jargons." 
The problem was not as serious while 
the technology was being pursued by 
only a few hobbyists, who like to 
work things out for themselves. Now 



Aside from a few 

shining lights, 

microprocessor 

literature suffers from 

a bad case of "the 

jargons." 

that the public is becoming involved 
in large numbers, the information 
must adapt to the customer, not the 
other way around. 

Many could undoubtedly do a 
better job of communicating if they 
followed a few principles. But doing 



this requires conscious dedication. 
And, of course, it requires principles. 
Those principles are what this article 
is about. 

To translate the jargon of the ex- 
pert into terms meaningful to the rest 
of the world, we need an interpreter. 
Such an interpreter is similar to the 
compiler or interpreter used in com- 
puters, which translates the source 
language into one the machine under- 
stands. In both cases, the source 
language is provided by the computer 
expert. The machine is the user in one 
case, the public in the other. 

Information Design 

The interpreter we require can best 
be referred to as information design. 
This term is better than the common 
term "technical writing," in that it in- 
dicates what really is re- 
quired — conscious, step-by-step de- 
sign. Writing is just one aspect of pre- 
senting understandable information. 
In fact, technical writing is similar to 
writing code for a computer program. 
If the planning and structure are 
sound, the writing almost takes care 
of itself. 

There are many aspects of informa- 
tion design, not all of which can be 



• Content defines the breadth and 
depth of the material in a docu- 
ment, and is best specified by a 
topic diagram. Consistency and 
uniformity of treatment are re- 
vealed by such a diagram: One 
topic should not be treated in great 
detail and others of equal impor- 
tance hardly mentioned. The 
breadth and depth should fit users' 
needs — all relevant material in- 
cluded, no unnecessary redundan- 
cies, and sufficient detail to allow 
users to understand the explana- 
tion or perform the job. 

• Organization gives shape and 



Information Design Principles 

direction. The users always know 
where they are, where they have 
been, and where they are going. 
Indexes and headings make the 
organization visible to users, so 
that information is located easily 
and quickly. Material is grouped 
and sequenced to flow logically 
and naturally from one topic to 
another. A top-down approach is 
used, to provide an overall struc- 
ture before confusing users with 
details. Introductions and sum- 
maries tie pieces together both for- 
ward and backward, and reinforce 
for long-term memory. 



• Format makes the information 
understandable through language 
and illustrations. Language speaks 
to one half of the brain — the ver- 
bal, linear side. Simple vocabulary 
and short, direct sentences make 
for ease of understanding. Illustra- 
tions speak to the other half of the 
brain — the nonverbal, spatial side. 
Illustrations are most effective 
when they are near the relevant 
text and are keyed to it through 
call-outs and highlights. Working 
together, words and illustrations 
present the whole "picture" as 
neither can alone. 



132 March 1981 © BYTE Publications lnc 



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covered here. What is necessary is 
that a few key principles are made 
clear. 

The basic objective of information 
design is usability. Whatever the user 
intends to do — write a program, as- 
semble a piece of hardware, learn 
how a system works — the documen- 
tation must serve this purpose. 

Although this may sound trivial, if 
you're writing a technical document, 
it's surprising how easy it is to lose 
sight of this overall requirement after 
page 1. The presentation can become 
an ego trip without your realizing it. 
On the other hand, it's hard to go 



wrong if you consistently keep the us- 
ability objective in mind. 

How do we determine if a docu- 
ment is usable? Whatever the type of 
document — operator's manual, main- 
tenance procedure, reference manual, 
training program — it has some pur- 
pose. Its purpose may be to explain a 
concept, describe the operation of a 
piece of equipment, or guide a person 
through an assembly procedure. 

To be usable, the document must 
take the users from a state of in- 
complete knowledge about some sub- 
ject to a condition of more complete 
knowledge. If it's a procedure, the in- 



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formation must guide the users 
through the task. In any case, the 
document must take them from 
"here" to "there." 

That's what information design 
does: It starts where the users are and 
builds step by step. The information 
designer first asks who the users are. 
Then he puts himself in their place 
and asks, "What will they under- 
stand, with their experience? What is 
their technical knowledge and 
vocabulary? How can they best be 
helped?" 

Next, he builds step by step. He 
breaks up complicated subjects into 
simpler parts. He leads the users 
gradually into new territory, helping 
them make their own discoveries. 
With each step their confidence grows 
and they want to learn and do more. 
At the end, the users know they have 
succeeded — and, therefore, so has the 
information designer. 

The Elements of Information 
Design 

If we are going to start where the 
users are and build step by step, we 
need a plan of action. We need to 
decide: 

• what information to include in the 
document 

• how to organize it 

• how to present it so it's understand- 
able 

We'll discuss these aspects under the 
headings of Content, Organization, 
and Format. 

Content 

The content of a document is the 
specific technical material contained 
in it. This should be carefully defined 
by boundary lines set down by the in- 
formation designer. 

Content really has two aspects: 
what information is included 
(breadth) and what is its level of 
detail (depth). A simple example will 
illustrate the important difference be- 
tween breadth and depth: An opera- 
tor's manual for a computer system 
might tell you to "remove and replace 
the printer's print wheel as 
necessary." The subject of print wheel 
replacement is thus "covered" in the 
manual; that is, in terms of breadth, 
it is part of the content. However, the 
lack of "how to" details may make 
this information of little use to many 

Circle 73 on inquiry card. 



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Circle 74 on inquiry card. 



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printer users. Thus the proper depth 
of information is not part of the con- 
tent. 

A good tool to help a writer of 
documentation analyze breadth and 



depth is a topic diagram (figure 1), 
which is an arrangement of topics in 
boxes at different levels, with lines 
joining related topics. It serves a pur- 
pose similar to that of an outline, but 



BREADTH 





SUBJECT OR 

PROJECT 

INTRODUCTION 
































TOPIC 1 




TOPIC 2 


















































1.1 




1.2 




1.3 




2.1 




2.2 



Figure 1: A topic diagram is a useful tool for determining the breadth, depth and con- 
sistency of a piece of writing. Although similar in content to an outline, the topic 
diagram provides a clearer visual check on how topics are handled. As shown, topics 1 
and 2 are major topics at the same level. Neither is a subtopic of the other and both will 
be treated equally when the writing is done. Subtopics represent breakdowns of each 
major topic. As additional topics and subtopics are added the diagram can extend 
downward and to the left and right. 



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provides an easier visual check on 
such elements as breadth, depth, and 
consistency of treatment. 

In figure 1, topics 1 and 2 are major 
topics at the same level in the 
diagram. They might be two major 
components of a system, or groups of 
software, or procedures. Neither is a 
subtopic of the other and they will be 
treated equally in the presentation. 

Subtopics are shown under each 
major topic: 1.1, 1.2, 1.3 under topic 
1, and 2.1 and 2.2 under topic 2. 
These represent breakdowns of each 
major topic. The diagram can con- 
tinue on down to further depths of 
subdivision and can also be extended 
to the left and right as additional 
topics are added at a given level. 

We can see that the breadth of the 
topic diagram, particularly at the ma- 
jor topic level, tends to indicate the 
breadth of content. The depth of the 
diagram indicates the depth of con- 
tent. While this should not be con- 
sidered an infallible guide, it is useful 
in preliminary planning. 

Another use of a topic diagram is 
that it gives an idea of consistency of 
coverage. A glance at figure 1 will tell 
the writer if topics at the same level 
are being treated with some con- 
sistency in how they are subdivided, 
or if one topic is being pursued to 
greater levels of detail than others. 
Without such a guide, it's easy to 
cover one topic in great detail and 
give other topics at the same level on- 
ly token treatment or overlook them 
completely. 

Definition of content is as impor- 
tant for what is not included as for 
what is. Many technical documents 
include irrelevant information. This 
can be particularly annoying in pro- 
cedural documents, when users are 
trying to accomplish an exacting task. 
They want to get on with it, but are 
continually being interrupted with ex- 
traneous remarks that belong in some 
other part of the document or should 
be left out entirely. 

Figure 2 shows a topic diagram for 
this article. As you can see, in addi- 
tion to defining content, such a 
diagram shows a preliminary 
organization or structure. 

Organization 

To proceed step by step, we need to 
know where we are going and a route 
to get there. In other words, we need 
structure, or organization. Informa- 



138 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



139 



disordered 
ping list, 
everything 



tion must be grouped, sequenced, and 
related in order to be understood. 
Otherwise, it is merely a jumble of 
facts or ideas — a "shop- 
If we had to learn 
by rote memory from 
shopping lists, we'd be in big trouble. 
Once a good structure is established, 
all kinds of details can be hung on it 
and they will be understood and 
remembered. 

Organization is also what makes 
information in a document easily ac- 
cessible. Accessibility depends on 
both the overall structure of the docu- 
ment and how this structure is made 
visible to the user through indexing 
and headings. If information is organ- 
ized properly, the user will be able to 
turn quickly to the information he 
wants. Once there, he will be able to 
continue with a minimum of routing 
to other parts of the document. 

The importance of structure or or- 
ganization can be illustrated by a 
very simple example — a telephone 
book. Have you ever stopped to 
think how useless a telephone book 
would be if the names were listed ran- 
domly rather than alphabetically? 
The important aspects of structure or 
organization include indexing and 
headings, grouping and sequencing, 
routing, and introductions and 
reviews. 



Indexing and Headings 

Indexing and headings are the 
means by which the organization of 
the document is made easily visible to 
users. A writer may actually have a 
good organization, but if it is not 
clear to users, it will not really have 
served its purpose. 

Indexing as used here includes both 
the standard type of index found at 
the end of a document and the table 
of contents. The index should be set 
up with the idea that users will 
sometimes look for items alphabeti- 
cally, as in a dictionary. Many items 
that are too small or too specific to be 
included in the table of contents are 
made accessible with a good index. 

Often a table of contents can be 
usefully constructed in two parts: an 
overall table in front and more de- 
tailed tables with each major section 
of the document. This avoids an un- 
wieldy table up front. Figure 3 pro- 
vides an example of a two-part table 
of contents. The main table (on the 
left in the figure) would appear in the 
front of the document. Each major 
section would start with its own table 
of contents (on the right in figure 3) 
showing the more detailed headings 
and subheadings in the section. 

A consistent set of headings serves 
to make information accessible. 
Headings also help users remember 





WHAT IS GOOD 

DOCUMENTATION 

? 














INFORMATION 
DESIGN 














ELEMENTS OF 
INFORMATION 
DESIGN 
































CONTENT 




ORGANIZATION 




FORMAT 
































SUMMARY 





Figure 2: A topic diagram written for this article. 

140 March 1981 © BYTE Publications Inc 



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where they are, which is just as 
important. Thus high-level headings 
should be repeated frequently, for 
example as a running head at the top 
of each page. Having the relevant 
headings always in front of the user 
makes the structure visible, and de- 
tails are then assimilated more easily. 

Grouping and Sequencing 

The overall organization of the 
document is established by how the 
content material is grouped and se- 
quenced. Again, the topic diagram is 



useful during the planning stages in 
making visible the planned organiza- 
tion of the document. 

Whether the document is pro- 
cedural or descriptive, grouping of 
the topics should be based on a 
logical pattern and the relevance of 
different items. For example, pro- 
cedural tasks normally performed 
together (such as the various steps re- 
quired to start up a computer system) 
should be grouped together. In a 
system description, the individual 
descriptions of system components 



CONTENTS 
LIST OF FIGURES 
LIST OF TABLES 

1. INTRODUCTION 



2. SYSTEM COMPONENTS 



3. SYSTEM OPERATION 

4. COMMUNICATIONS 



2. SYSTEM COMPONENTS 

2.1 CENTRAL PROCESSING UNIT 

CONTROL PANEL 
MICROPROCESSOR 
DIRECT MEMORY ACCESS 

2.2 DISK DRIVES 

DRIVE CONTROLS 
NUMBER OF DRIVES 
DRIVE COMBINATIONS 

2.3 VIDEO TERMINAL 

DISPLAY SCREEN 
KEYBOARD 



Figure 3: An example of a two-part table of contents. By using an overall table in the 
front of the document, and a more detailed table later, an initial unwieldy table is 
avoided where a user would be subjected to unwanted detail. 



LONG-TERM MEMORY 



SHORT-TERM MEMORY 





Figure 4: Summaries and long-term memory. In the human brain, memory is divided 
into short-term memory and long-term memory. Although the capacity of long-term 
memory is large, all information must first pass through a short-term memory. When 
writing, the inclusion of summaries, reviews, and question-and-answer sections is an ef- 
fective way of passing information into long-term memory. 



would normally be grouped together, 
as in the example table of contents 
shown in figure 3. 

Sequencing is one of the most 
critical parts of the structure. The 
user is being led step by step from the 
known to the unknown, from the 
simple to the complex. Here the top- 
down structuring principle frequently 
used in writing computer programs 
also applies. The sequence should 
begin at the top and give the readers 
the big picture before engulfing them 
with details. It is not unusual to begin 
reading a document and find yourself 
up to your ears in technical details 
before you really know what's going 
on. 

Most equipment operations and 
human activities have a natural or 
normal sequence that should be 
preserved in the documentation. For 
example, you normally gather to- 
gether all the tools and supplies re- 
quired for an activity before starting; 
therefore, this information should 
logically precede the activity descrip- 
tion. It is disconcerting to have to 
stop in the middle of a task and run to 
the hardware store to buy some item. 

Routing 

Once you start using a document it 
is inconvenient to have to refer to 
other parts of the document, or to 
other documents. The more often you 
are routed, and the more pages you 
have to thumb through to get there, 
the less useful the document. On the 
other hand, if all information is 
repeated at each point of need, a 
bulky document can result. Obvious- 
ly, judgment is required in weighing 
these trade-offs. For example, you 
wouldn't want to tell a user how to 
solder a particular type of joint every 
time it came up — you would set aside 
a special section for this purpose. 
However, if a safety precaution ap- 
plies to a number of different tasks in 
the document, it is better to accept 
the redundancy and repeat the 
precaution. 

Introductions and Reviews 

A general rule is to prepare users 
for what is coming and to remind 
them of where they have been. Pro- 
ceeding through a document, users 
may forget where they are, forget 
what has gone before — and decide 
they didn't really want to learn this 
anyway. Information should be 



142 March 1981 © BYTE Publications Inc 



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designed to help users relate 
backward and forward and recognize 
and retain key points along the way. 

Further, readers need introductory 
instructions to help them find and use 
information. For example, the 
numbering schemes for tasks or il- 
lustrations, the use of safety symbols, 
notes, cautions, and warnings, and 
the treatment of information about 
tools and supplies should be briefly 
explained. If these instructions are 
backed up by consistent information 
presentation (see Format section), 
users will quickly learn what to ex- 
pect, no matter where they are in the 
document. 

Simple reviews at key points rein- 
force information and help users re- 



tain it in memory. Human memory, 
to put it simply, consists of two parts, 
"short-term" and "long-term." 
Whereas capacity is very limited in 
STM (short-term memory), the 
capacity of LTM (long-term memory) 
is large indeed. The catch is that in- 
formation can get to LTM only 
through STM. Summaries and re- 
views and question-and-answer ses- 
sions are effective ways of establish- 
ing information firmly in LTM. This 
important concept is illustrated in 
figure 4. 

Format 

Format usually has the rather nar- 
row meaning of "physical layout of 
the page." Here the term is meant also 



to include the rules that govern text 
and illustrations — that is, how infor- 
mation is presented on a page. 

The general rule is that language 
and illustrations should work 
together. Each is an effective way of 
presenting certain kinds of informa- 
tion, and relatively ineffective for 
other kinds. When combined proper- 
ly, they form a powerful presentation 
technique. 

People will readily admit that pic- 
tures can do things that words cannot 
and vice versa. And yet it is surpris- 
ing how often we find ourselves 
reading words, words, words, when a 
visual or two would have helped the 
presentation considerably. Many 
ideas become clearer with an illustra- 



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BYTE March 1981 



145 



tion, and some kinds of information 
can hardly be communicated at all 
without one. If you want to tell some- 
one what something looks like, show 
a diagram or a photograph. 

It is known that the left and right 
sides of the brain are quite different. 
For most people, the left side is domi- 
nant and works mostly with linear, 
sequential logic (like a computer). It 
is also the verbal side and controls 
language. 

The right side specializes in images, 
music, pictures — it deals in spatial 
and visual concepts, in contrast to the 
linear, verbal left brain. Schools, 
with their traditional emphasis on 
verbal skills, have tended to neglect 
the right side of the brain. People 
who are less adept with their left 
brain have suffered as a result. Ein- 
stein, for example, was a poor stu- 
dent in language, but had a great 
ability to visualize (see figure 5). 

The ideal combination is words 
and pictures working together, each 
doing what it does best. In a pro- 
cedure, for example, words can tell 
readers what to do and how to do it; 
pictures can tell them what it looks 




^BpW'* V LEFT HALF (WORDS) 

V 

f |V x 




Figure 5: The left and right sides of the human brain are very different. In most 
humans, the left side, which works mostly with linear and sequential logic, is dominant. 
The left side also controls verbal communications. The right side of the brain deals in 
spatial, visual, and more holistic concepts. One of the best ways of imparting informa- 
tion to the reader is through a combination of both words and pictures, thus enabling 
the reader to use both sides of the brain. 



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146 March 1981 © BYTE Publications Inc 



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like and where it is. For descriptive 
material, words and diagrams will do 
a good job of explaining and describ- 
ing, provided they are working 
together. When you decide to use pic- 
tures to communicate with readers, 
follow the flow through step by step. 
Don't be content with offering an oc- 
casional "amazement diagram" and a 
"see figure so-and-so." You can 
perhaps wake up the right half of the 
reader's brain this way, but to get it 
working with the left half as a 
unit — whole-brain learning — make 
the words and pictures work 
together. 

Here are some guidelines on how to 
do this, discussed under the following 
headings: keying text to illustrations, 
positioning text and illustrations, and 
limiting information density. 

Keying Text to Illustrations 

The mutual reinforcement of text 
and illustrations can be strengthened 
by keying the text to the illustration. 
This can be done by a liberal use of 
highlights and call-outs, which are 
"talked to" in the text. 

For complicated diagrams, an in- 
dexing system can be used. An exam- 
ple of this common technique is 
shown in figure 6. Three parts of an 
electrical unit are designated A, B, 
and C in the picture on the right. 
These same letters are used in the text 
on the left to refer to these specific 
parts. This method can be used with 
fairly complex diagrams without con- 
fusing the reader. The alphabetical or 
numerical symbols take up little room 
on the diagram and can be ordered 



(for example, clockwise in figure 6) to 
make it easy to locate any symbol. 

Highlights and call-outs help the 
user zero in on the main items of in- 
terest in a picture. A heavy outline or 
shading or color, together with a call- 
out of the item of interest, can make 
the text and illustration mutually sup- 
port each other and help the user 
relate illustration to text. 

Consistent, standard nomenclature 
should be used in linking text to il- 
lustration, and indeed throughout the 
document. Information becomes less 
accessible and less understandable if 
the same item is referred to by dif- 
ferent names. 

Positioning Text and Illustrations 

Because the text and related pic- 
tures should work together, they 
should be positioned close together. 
Ideally, the user should be able to 
work back and forth between text 
and illustration without having to 
turn a page. While this ideal is 
sometimes impractical, it is usually 
possible to keep the illustration close 
to the relevant text. For important, 
frequently referenced figures, fold- 
outs are sometimes the answer. 

Limiting Information Density 

Information is like food. If readers 
eat too fast, or too much at one time, 
they get indigestion. If information is 
presented too fast or in too large 
doses, readers will get confused. This 
is because of the limited capacity of 
short-term memory. Therefore, like 
food, information must be broken up 
into "bite-size" pieces to be digestible. 




Figure 6: Keying text to illustrations. The mutual reinforcement of text and illustrations 
(as shown in figure 5) can be strengthened by keying the text to the illustrations through 
the use of highlights and call-outs which are "talked to" in the text. 



148 



March 1981 © BYTE Publications Inc 



Circle 84 on inquiry card. 



Accurate. 

Up-to-the-minute. 

Easy to read. 

More people choose microcom- 
puter tutorials from Osborne/ 
McGraw-Hill than any other source. 
That's because Osborne/McGraw- 
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What's more, at Osborne/ 
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Osborne/McGraw-Hill has a best 
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Your best sellers will be rushed 
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Look for the 
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□ 26-8 An Introduction to 
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second edition. Adam Osborne. #1 best- 
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Buyer's Guide -NEW. 
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Yes! Please rush me the book titles I have checked above. 



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Good format does this. 

Language should be simple and 
direct. Only words the reader 
understands should be used, with 
new words explained as they are in- 
troduced. Explanations are easier to 
read and understand if sentences are 
short and simple, and if words have 
few syllables. 

Illustrations should not be cluttered 
with unnecessary information. If they 
are too "busy," pictures become con- 



(7a) 



fusing and are less useful. To avoid a 
profusion of details, illustrations can 
be used in a progression from simple 
to more complex. This is related to 
top-down sequencing. An initial 
overall figure can give the "big pic- 
ture," which is easy to understand 
and serves as a beginning structure 
for proceeding to more detailed il- 
lustrations. In forming such progres- 
sions, it's important to preserve the 
relative locations of the parts of 



v. 



DATA BUS 



n 



nrai 



MEMORY 



T> 



ADDRESS BUS 



CONTROL LINES 








I )"° Bus 

^ 1/0 BUS 



•CONTROL 



(7b) 



whatever is being pictured. For exam- 
ple, if a simple block diagram of a 
microprocessor leads off the series, 
subsequent more detailed diagrams 
and schematics should show the 
various parts of the blocks in the 
same relative positions as the original 
block. An example is shown in figure 
7. Note that the lower detailed 
diagram preserves the relative posi- 
tions, established by the upper figure, 
of the major parts of the system. 

Earlier we said that microprocessor 
literature is suffering from a bad case 
of "the jargons." However, you'll see 
by now that there is much more to 
good documentation than avoiding 
jargon. You probably have had the 
experience of reading something and 
finding that it was very difficult to 
follow, even though you seemed to 
understand all the words. In this case, 
the author managed to avoid 
technical terminology but failed in 
other important areas. Good 
technical documentation requires a 
highly disciplined approach, and that 
approach is provided by information 
design. Those who adopt a go-as- 
you-please approach may score a suc- 
cess now and then, but it will be by 
accident. They have no way of know- 
ing whether they have really reached 
their audience. In many cases they 
have not.B 



RESTART 



TSC 



RES 



til 

VMA R/W 

IRQ 



VMA 02 



T^S 



A10 



All 



A12 



ROM 



CS 
CS 
CS 
CS 



AO-9 



A7 



A8 



A9 



A10 



L2. 



R/W 

CS 

CS 

CS 

CS 

CS 



AO-6 



ADDRESS BUS 



A12 



• CSO 



A13 



« CS1 



A1A 



RES 



PIO 



CS2 

E 
R/W 



IRQA IRQB 



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3 PORT B 



Figure 7: To avoid reader confusion, illustrations should be used in a progression from less detail to more. An initial block diagram 
(7a) can give the overall picture before going into greater detail (7b). When forming these progressions, it's important to keep parts in 
the same relative positions. 



150 March 1981 © BYTE Publications Inc 



Circle 85 on inquiry card. 



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Programming Quickies 



Computing the 
Determinant of a Matrix 

Brian Flynn, 1704 Drewlaine Dr, Vienna VA 22180 



Matrix inversion is often used in solving sets of 
simultaneous equations and in performing multiple 
linear-regression analysis. But what determines whether 
or not a matrix can be inverted? The answer is its deter- 
minant does. More specifically, if the determinant of a 
matrix is 0, the matrix is singular and can't be inverted. 

A Radio Shack Level II BASIC program for calculating 
the determinant of a matrix is presented here. The 
algorithm uses the upper-triangular technique and 
switches rows, when necessary, to insure that the deter- 
minant is always calculated, within the limits of the com- 
puting capability of the TRS-80 Model I. 

A matrix is a rectangular array of numbers or variables 
(usually displayed in brackets). A square matrix is two- 
dimensional with as many rows as columns. A character- 
istic of a square matrix is its determinant. Determinants 
are defined only for square matrices, just as only square 
matrices are invertible. Unlike a matrix, a determinant is 
written as an unbracketed, single number — a lone, lorn 
creature such as 5, 0.03, or —1. The symbol for a deter- 
minant is sometimes det, but more often two parallel ver- 
tical lines: | | . (This latter symbol is also used for ab- 
solute value. The circumstance in which | | appears 
determines whether it means absolute value or determi- 
nant.) 

It's relatively easy to calculate a second-order determi- 
nant, that is, the determinant of a second-order (2 by 2) 
matrix: tally the product of the principal diagonal 
elements and subtract from this the product of the off 
diagonal elements. The principal diagonal is the imagi- 
nary line segment running from the "northwest" corner to 
the "southeast" corner of the matrix. The off diagonal, on 
the other hand, is the one which connects the "northeast" 
and "southwest" corners. The process of calculating a 
second-order determinant is illustrated in table 1. 

Tallying a third-order (3 by 3) determinant is a bit 
more difficult than tallying one of the second order. If the 
elements of the matrix are not too unwieldy, however, 
the calculation can still be made by hand without much 
trouble. This is shown in table 2. But for matrices of 
order four and higher, the business of determining the 




°11 a 22 - a l2°2l 



2 • 9-5-3 • 18-15-3 



Table 1: The general method for evaluating a 2 by 2 matrix 
and an example. The elements of the principal or major 
diagonal are multiplied (a u a 22 ), as are the elements of the off 
or minor diagonal (a 12 a 21 ). Then the product of the off 
diagonal is subtracted from the product of the principal 
diagonal. 




' °11 °22 33 +0 12 23°31 ♦°13°32 21 

- on o 32 o 2 3 -012O21O33 -013022031 



5 2 4 
1 3 7 

6 9 9 



-5-3- 
- 5-8 



9+2- 
7-2 



7-6 
1-9 



+ 4-8 
-4-3- 



Table 2: The method for evaluating a third-order determi- 
nant is an extension of the method used for second-order 
determinants. Note that plus signs are associated with the 
three products formed by solid lines, and minus signs are 
associated with the three products formed by dashed lines. 



152 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



153 



Programming Quickies 



determinant can get really complicated. Indeed, 
calculating a fourth-order determinant one time by hand, 
using the popular Laplace expansion, is usually sufficient 
to elicit the plea, "Isn't there an easier way?" 

Fortunately, there is. The upper-triangular method is a 
straightforward, computer-compatible technique for 
tallying a determinant of any order. The process, il- 
lustrated in table 3, is in two steps: 

• Transform the matrix so all of the elements below the 
principal diagonal are Os, using elementary row opera- 
tions. Anticipate division by 0, and switch rows of the 
matrix to avoid it. 

• Calculate the product of all elements along the 
transformed principal diagonal. This product is the deter- 
minant. 

If you ever determine to determine the determinant of a 
matrix, I hope you find the upper-triangular method 
useful.! 




STEP 1 . TRANSFORM THE ELEMENTS OF THE LOWER TRIANGLE INTO 

0s: TRANSFORM THE 8 INTO BY MULTIPLYING THE ELEMENTS 
OF ROW #1 BY -2 THEN ADDING THEM TO THE CORRESPONDING 
ELEMENTS OF ROW #2. 



4 


© 



TRANSFORM THE CIRCLED 2 INTO BY ADDING 
ROW #1 TO ROW #3. 



3 

-5 
4.5 



TRANSFORM THE 8 INTO 0. IF THE ABOVE PATTERN WERE FOL- 
LOWED. -8/0 TIMES ROW #2 WOULD BE ADDED TO ROW #3. 
TO AVOID DIVISION BY 0, SWITCH ROWS 2 AND3. THIS CHANGES 
THE ARITHMETIC SIGN OF THE DETERMINANT (LINE 4060 OF 
THE PROGRAM ). 



4.5 
-5 



STEP 1 IS NOW FINISHED SINCE THE ELEMENTS OF THE LOWER 
TRIANGLE ARE ALL 0s. 

STEP 2. TALLY THE PRODUCT OF ALL ELEMENTS ALONG THE PRINCIPAL 
DIAGONAL. 

DETERMINANT = - [4-8- (-5)] =160 

Table 3: The upper-triangular method f or evaluating higher- 
order determinants consists of two steps: first, transform the 
elements of the lower triangle into 0s, then find the product 
of the principal diagonal. 



Listing 1: The program for determining the determinant of a 
matrix. 

10 REM CALCULATING THE DETERMINANT OF A 

MATRIX 

20 REM UPPER TRIANGULAR METHOD 

30 REM BRIAN I. FLYNN; FALL 1980 

40 REM MOD 1: INITIALIZE & ENTER DATA 

50 GOSUB 1000 

60 REM MOD 2: CALCULATE DETERMINANT 

70 GOSUB 2000 

80 REM MOD 3: PRINT DETERMINANT 

90 GOSUB 3000 

100 GOTO 9999 

1000 REM MODULE 1 

1010 REM VARIABLES 
1020 REM C = USED IN TRANSFORMING 

MATRIX 
1030 REM DT = DETERMINANT 

1040 REM HOLD = USED IN SWITCHING ROWS 

1050 REM K = ORDER OF THE MATRIX 

1060 REM SIGN = + 1 OR - 1 

1070 REM X = MATRIX 

1080 REM INITIALIZE 

1090 DEFDBL C,D,H,X:SIGN = 1:DT = 1:CLS 

1 100 PRINT "THIS PROGRAM COMPUTES THE 

DETERMINANT OF A MATRIX." 
1 1 10 PRINT:INPUT "HOW MANY ROWS (COLUMNS) 

ARE IN YOUR MATRIX";K 
1120 DIMX(K.K) 

1130 REM ENTER DATA 
1140 FOR 1=1 TO K 

1150 CLS:PRINT "PLEASE ENTER DATA." 

1160 PRINF'ROW f';I;":" 

1170 FORJ=lTOK 

1180 PRINT'OOL r';J:INPUT X(I,I) 

1190 NEXT J, I 

1200 RETURN 

2000 REM MODULE 2 

2010 REM CHECK FOR 1ST-ORDER DETERMINANT 
2020 IF K= 1 THEN DT = X(l,l):GOTO 2180 

2030 REM FILL LOWER TRIANGLE WITH s 
2040 FORL=lTOK-l 

2050 FORI = LTOK-l 

2060 REM AVOID DIVISION BY 

2070 IF X(L,L) = THEN GOSUB 4000 

2080 IF DT = THEN 2180 

2090 C = X(I+1,L)/X(L,L) 

2100 FORJ=lTOK 

2110 X(I+1,J) = X(I+1,J)-X(L,J)*C 

2120 NEXT J,I,L 

2130 REM TALLY PRODUCT OF PRINCIPAL DIAGONAL 

ELEMENTS 
2140 FOR 1=1 TO K 

2150 DT = DT*X(I, I) 

2160 NEXT I 

2170 DT = DT-SIGN 

2180 RETURN 

3000 REM MODULE 3 
3010 PRINT"DETERMINANT = ";DT 

3020 RETURN 

4000 REM SUBROUTINE: SWITCH ROWS 
4010 FORM = L+lTOK 

4020 IF X(M,L) = THEN 4070 

4030 FOR Q = 1 TO K 

4040 HOLD = X(L,Q):X(L,Q) = X(M,Q):X(M,Q) = HOLD 

4050 NEXT Q 

4060 SIGN = -SIGN.-GOTO4100 

4070 NEXT M 

4080 REM DETERMINANT = 

4090 DT = 

4100 RETURN 

9999 END 



154 March 1981 © BYTE Publications Inc 



Languages Forum 



A Coding Sheet 
for FORTH 



John O Bumgarner, 17370 Hawkins La 
Morgan Hill CA 95037 

FORTH is a new programming language to most 
people, and, while it has many advantages over other 
languages, it does have an unconventional appearance. 
FORTH is not an intrinsically difficult language, but the 
unfamiliar appearance, the use of a last-in-first-out stack 
for parameter passing, and a unique approach to problem 
solving require you to reorient your thinking a bit. 

When I was learning FORTH, I often used to stop and 
sketch the appearance of the parameter stack as I defined 
a "word" (portion of a program) to help me get every- 
thing in place at the right time. It helped me, the novice 
FORTH programmer, to have a graphic representation of 
what the parameter stack looked like at each step. Later, I 
needed to document programs, so I expanded my sketchy 
method and made a proper FORTH-style coding sheet 
that provided the graphic parameter-stack representa- 
tion. 

The need for documentation never 

seems to go away, so I still use the 

coding sheet regularly. 

Now, while I rarely need help visualizing the stack, the 
need for documentation never seems to go away, and so I 
still use the coding sheet regularly. It has occurred to me 
that other FORTH programmers, new or otherwise, 
would find it useful too. 

The coding sheet is shown full-sized in figure 1 and is 
meant to be copied for use by the reader. The form is 
deliberately simple to make it as flexible as possible. I 
have tried to strike a balance between the size of the 
spaces for words, the size of the spaces for stack items, 
and the number of stack items. 

In actual practice, eight stack items on the form are suf- 
ficient because most FORTH words do not manipulate 
the stack outside of the range of the normal stack 
operators (which work from three to six words deep). In 
fact, a rule of thumb for good FORTH programming dic- 
tates that, if you get in a situation with the parameter 
stack that cannot be handled by normal stack operators, 
you are doing something wrong. You should stop and ex- 
amine your methods to see how you can avoid the prob- 
lem. In my experience, this is true; a better way results 
from a little thought, and it usually is simpler, to boot! 

The space for words used in the definition is left a bit 
wide, as it is common to put short phrases on one line. 
This not only saves space but also allows frequently used 
short phrases such as fetching from or storing to a 

Text continued on page 162 



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March 1981 © BYTE Publications Inc 155 



Languages Forum. 



DATE 



LOCATION 



WORD 



WRITER 



VOCABULARY 









STACK 








TOP 



















































































































































































































































































































































































































































WORDS 



J.O.B.80 



Figure 1: A coding sheet for FORTH used to show the effect of words in a FORTH definition on the parameter stack. 

156 March 1981 © BYTE Publications Inc 



Languages Forum. 





Z.Z. Aft*;/ so i+k fl. £~xpacr *«S ? pBLETg 

DATE LOCATION WORD 

WRITER VOCABULARY 

STACK TOP WORDS 






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CC -t«.k 


c? <**\ 








Cld 


HtLKU 


: EKTZCJf 






,5 LAO.) 
ber cow 


<X\A.cl <*- 


v t 




a.d 


HU.IM 





p 


l\ -t-We* 


UCCCft 












a.ef- 


■po -* 1 








><?4 iV\»\i»tq 








<susL 


ch 


Key 














a.dL 


*k 


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Ov/ETZ 




IW£0"V»iH 


^ keypfi 


'■tt) 




A << 


ck 


«^ 


X 


X 














*«* 


^k 


-uf' 


+■ 


















a.d. 


c! 


















,ai<~L 


LOOp 


■ 
















— 


T>ROp 


















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Kex. 
















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.* P p&lste: 




Cvic* 7 


f \9 "■ 


"PEL ch< 


Urac+fO 




£k 


7F 


7F 












tk 


7F 


^k 


CA/eC 




?-pELE 


T£ a« 


eH"* a. 






<^k 


T/F 


~ 




cUarac' 


er ow.+l 


LC Hack. 




cM 


T/F 


T/F 


x>op 




duel ret 


'Ci*^ * 'i 


KtfC' \/4ll 


e 


( <r— 


ck 


T 


XF _j 






CMlif if 


*ke c ka 


■Acter 




1 


-r 


cW 


^t/JM 7 






UJA^ °- 


VtLcWc 


rae-ter. 




41 




T 


TPRoP 






6>tk€ru)"i 


?e if r« 


torw^ 




jl . 




T 


TUero ' 


1 


'•"k 


f* 




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t<fr- 










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1 




















































1 

r 

P 

e 

z 

t 

i 
c 


"able 1: An example using the FORTH coding sheet. In this example and that of table 2, FORTH words or phrases are listed in th 
ightmost column, reading from top to bottom. The stack area on the same line represents zero or more parameters on th 
arameter stack after the word or phrase has been executed; the rightmost entry in the stack area is always the top-of-stack, wit 
ntries below it on the stack listed to the left. A dash represents an empty stack. "T/F" represents a flag of either true (nonzer 
lalue) or false {zero value) pushed to top-of-stack as the result of some comparison operation. Arrows represent the flow of cor 
rol due to either a loop construct or the outcome of an IF construct. Note that, in the definition of { 7DELETE }, the stack exit 
he definition with two values on the stack if the comparison made evaluates as false, but only one value if the comparison is trui 
tee listing 1 for details. 


e 
e 
h 



- 
s 

y 



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Circle 88 on inquiry card. 



BYTE March 1981 



157 



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Circle 89 on inquiry card. 



Languages Forum. 






£? APR. 80 

DATE 
WRITER 



i* //. 



COUA/TE#_ 



LOCATION 



WORD 



VOCABULARY 









STACK 










TOP 


r 






iefc? 


<M i»c<: 


u^Utoi 




— 








^etl»p 


another 


one 




— 
























•VWe via 


nte of -V 


k[$ root 


iV\£ 


— 












r 




o 








cU^ 


r + l\£ 




o 


aJJr, 








CLCCUl 


•Muld+or 


J 




— 


















o 
















o 


a. c&(Xr*j 












i 


^. 




— 
















— 


Pet*: 


-H posh 


£ *? a nic 


i^oCr (" 


u«)fo 


fop-o-H 


-tack 


Viavw 














W»(>vi 


HU.W 












WKtH 


K1U.IM 


c? 


trutf 


i^ VI lU 


* <: o 








niuw 


^/f 
















viat^l 










f 




YltllVl 


/ 






tk-Ut 


p4\r"t" 


i 


MU.W1 


1 


Adcir. 










I 






/mwi 
















MUkM 










c 




tfuw 


1 






$<K\4e- 


fart 


A 


V»H.KVl 


1 


addr2 
















WUJVt 
















muw 


t«f 


-for e*i 


d cov\d 


I'Tfoyx ( 


tlHHI^O 


) 




T /p 


loop 


ufltil 


Itue 










- 



















WORDS 



1 o \/Atf/Afr£E ME6-ATiv/e 


o VAfclAljLe NON-WfC- 




; ^oofj-r&^- 


o 


rsiE6-ATW& 


1 


o 


NON-MEfr 


1 


T2.p6-|i\ v- 








F£Tc-H 




-y^F 




o 




< 




Jf FALSE 




/ 






MG6-A-TW£. 






+ / 








£u*>g 


\ 


r 




1 






Norvi-rsJtfr 






*-l 






T-M^nJ 1 


If 




o «" 




I1N71! 








'■» 



Table 2: Another example using the FORTH coding sheet. See listing 1 for details. 



160 March 1981 © BYTE Publications Inc 



Solution\s6 J lu-shun\n[ME,fr.MF s fr.L solution-] 
la: An answer to a problem. 





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Languages Forum. 



Listing 1: A block of FORTH code. The FORTH words EXPECT 
sheets in tables 1 and 2. 



7DELETE ] , and COUNTER are explained on the coding 



( Character and data input words) 
1 

2 ( EXPECT accepts n ch's putting them at given address) 

3 ( Use: address n EXPECT ) 

4 : EXPECT DO KEY OVER I + C! LOOP DROP ; 

5 HEX ( change base to HEX for the following word) 

6 ( 7DELETE returns only T if given ch. is a DEL ) 

7 ( otherwise it returns the given ch. and a F on the top) 

8 : 7DELETE 7F OVER = DUP IF SWAP DROP THEN ; 

9 DECIMAL 

10 VARIABLE NEGATIVE VARIABLE NON-NEG 

1 1 ( COUNTER counts the number of negative and non-negative) 

12 ( numbers and exits if given a zero. FETCH supplies §'s) 

13 : COUNTER NEGATIVE ! NON-NEG ! BEGIN 

14 FETCH DUP < IF 1 NEGATIVE +! ELSE 1 NON-NEG +! 

15 THEN 0= UNTIL ; 



Text continued from page 155: 

variable to read better. Such condensed definitions are 
also useful to keep as documentation. (See table 2.) 

[Editor's note: I have used John's sheet and found it 
very helpful in the design and documentation of FORTH 
words. I like to indent my entries in the "WORDS" col- 
umn to show if... then... else constructs and loops. I have 
also been working with a similar diagram that allows a 
line to run across the long dimension on a page; this gives 
me more room for indenting FORTH words and docu- 
menting what they do....GW] 

Listing 1 is an example of a typical FORTH block of 
code. If it were part of a bigger listing, there would be 



three such blocks on one page and the page would be 
called a triad. If you wanted to see this block or edit it at 
your terminal, you would type { 123 LIST }. [The 
braces are not part of the FORTH phrase, but are the 
standard BYTE delimiters that isolate FORTH words that 
include punctuation and FORTH phrases from the sur- 
rounding text. ...GW] 

The FORTH coding sheets show the detailed structure 
of each of the three words defined in block 123. The cod- 
ing sheets in tables 1 and 2 show the words in great detail. 

I hope that this coding sheet is of use to fellow FORTH 
enthusiasts. It certainly helped me learn FORTH, and 
allows me to produce clear documentation. ■ 



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162 



March 1981 © BYTE Publications lnc 



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BYTE March 1981 163 



BYTE's Bits 



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164 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



165 



A Beginner's Guide 
to Spectral Analysis, Part 2 



Mark Zimmermann 

9410 Woodland Dr 

Silver Spring MD 20910 



In Part 1 of this article, I introduced 
some of the ideas behind the Fourier 
transform in one dimension. Here, I 
will try to extend those ideas to two- 
dimensional space. I will introduce a 
few of the many uses of two-dimen- 
sional spectral analysis, with par- 
ticular emphasis on image processing. 
The main computer program that ac- 
companies this article (see listing 1) is 
a 6502 assembly-language program 
that performs a two-dimensional 
transformation on a 25- by 40-pixel 
image. The program is specifically 
adapted to run on the Commodore 
PET microcomputer with 8 K bytes 
of programmable memory, but it 
should be a reasonably straightfor- 
ward process to modify the code to 
work on other comparable machines. 
Several floating-point arithmetic 
routines are used from the PET's 
BASIC ROM (read-only memory); a 
table is included that describes what 
each routine does, so that it may be 
replaced by your own arithmetical 
procedures if necessary. 

Components of Waves 

As you will recall, the whole no- 
tion of Fourier, or spectral, analysis is 
to take a signal that is, for example, a 
function of time, and resolve it into 
its components (ie: the various fre- 
quencies that make up the whole). A 
chord played on a piano may produce 
a sound that is very complicated 
when plotted on an oscilloscope 
screen, but when the chord is Fourier 
analyzed, the individual notes (com- 
ponent frequencies) stand out. 



It is mathematically possible to ex- 
press any reasonable function as a 
sum of sines and cosines of various 
frequencies. The mathematical recipe 
for finding how much of each sine 
and cosine went into making the 
original signal is a fairly simple pro- 
cess that is discussed in many books 
(see references on page 198). Instead 
of going into the math here, however, 
I'd rather discuss the "feel" of Fourier 
transforming, with the objective of 
helping you develop some instincts 
about what a transform should look 
like and what it means. 



Any reasonable 

function may be 

expressed as a sum of 

sines and cosines of 

various frequencies. 



Figure 1 on page 168 shows several 
pairs of graphs. In each pair, the 
graph on the left represents a function 
of time. It could be showing, for in- 
stance, the difference between normal 
atmospheric pressure and the instan- 
taneous pressure in a passing sound 
wave. 

The graph on the right shows the 
Fourier transform (a function of fre- 
quency) of the graph on the left. It 
plots the amount of the components 
needed at each frequency to make the 
left-hand graph. The amount of sine 
wave is shown as a dashed line; the 



amount of cosine wave is a solid line. 
The horizontal axis runs from zero 
frequency (where it's intercepted by 
the vertical axis) to high frequencies. 
If the amount graphed on the right 
goes negative, it simply means that 
the original signal needs to have some 
amount of the function —sine or 
— cosine added to it. In other words, 
the original signal contained some 
sine waves that were 180° out-of- 
phase with the standard sine wave (so 
there's nothing special or mysterious 
about having a negative amount of a 
given frequency component). 

What kind of insights can you get 
by examining the graphs in figure 1? 
First, it's clear that any function of 
time which is symmetric with respect 
to the t = (vertical) axis is made up 
only of cosine waves, and any func- 
tion that is asymmetric with respect 
to t = is made of only sines. Every 
cosine wave is symmetric about the 
origin of time, so a sum of cosines 
should certainly be symmetric; every 
sine wave is asymmetric. A function 
that is neither perfectly symmetric 
nor perfectly asymmetric requires 
both sines and cosines in its constit- 
uent frequencies. 

A second fact which becomes ap- 
parent from a study of figure 1 is that 
functions of time which have some 
net area (area between the curve and 
the horizontal axis) always have some 
amount of component with zero fre- 
quency plotted in their transforms. A 
zero-frequency wave doesn't wave at 
all; it's a constant number as time 
goes by, like cosine(O). Contrariwise, 



166 March 1981 © BYTE Publications Inc 



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Figure 1: Graphs on the right (functions of frequency) plot Fourier transforms for the 
specific functions on the left (functions of time), indicating the amount of each compo- 
nent frequency present in the original. Abrupt changes with respect to time (figures la 
thru Id) are reflected in the transforms by the presence of higher-frequency energy. 
Graphs of functions exhibiting periodicity (figures le thru Ih) produce peaks centered 
on the frequency of this oscillation in the associated transform. 



if a function of time has no net area, if 
it is positive just as much as it is 
negative, then its Fourier transform 
has no zero-frequency component. 
This component, in fact, is just the 
average value of that signal. 

Let's examine several specific pairs 
of graphs. The transform of a square 
pulse (figure la) contains a number of 
low-frequency cosines (to build up 
the area under the pulse and create 
the flat-topped sections which ob- 
viously change little with time), but 
in addition, a fair amount of high- 
frequency cosine energy is required to 
make the square pulse. A triangular 
pulse of the same area has similar 
low-frequency requirements, but 
needs fewer higher-frequency waves 
(see figure lb). A Gaussian (bell- 
shaped) curve requires very little 
high-frequency contribution to make 
its smooth function of time (see figure 
lc). 

This correlation between "abrupt- 
ness" and high frequencies in the 
Fourier transform is, in fact, quite 
general. Functions that change 
abruptly with time, like the square 
wave, or that have a lot of fine detail 
(the sharp edges), are not composed 
only of low-frequency, slowly chang- 
ing waves; the jumps require a lot of 
high frequencies to define them. As a 
square wave becomes narrower and 
narrower, more and more high 
frequencies are necessary: a falling 
body's thud, if replayed at a high 
enough speed, can sound like an 
abrupt gunshot. Signals that don't 
have sudden jumps, like those 
represented in the triangular graph, 
can be made using fewer high- 
frequency components, but the sharp 
corners where the slope of the 
triangle's sides changes still require 
high-frequency sinusoids. Smooth 
curves like the Gaussian, where there 
isn't much detail, require the least 
amount of high frequencies. 

Finally, look at the graphs in 
figures le thru lh. The functions of 
time (on the left) all show some sort 
of periodic behavior. Their trans- 
forms all reveal this by a peak at or 
near the frequency of oscillation. The 
more cycles of oscillation that the 
temporal function goes through, the 
sharper the peak in frequency space. 
This effect is not just math- 
ematical—you can hear it. A heavily 
damped bell that rings for very few 
cycles produces an abrupt note 



168 March 1981 © BYTE Publications Inc 



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BYTE March 1981 169 



Listing 1: The 6502 machine-language program 2DFT performs two-dimensional 
Fourier transform of images on the Commodore PET's video display. SINTAB is a table 
of sin (x) for x = 0, it/ 20, 2ir/20, ..., thru 1 9ir/20, in PET floating-point notation (5 bytes 
per number). Numbers may be scaled up or down for normalization; one good choice is 
to divide each sine by the square root of 32. ROWSXFRMD is a table of transformed 
rows from the screen, beginning with row 0, frequency 0, real (cosine) transform, then 
row 0, frequency 0, imaginary (sine) transform, then row 0, frequency 1, real 
transform, then imaginary, and so on, ending with row 24, frequency 20, imaginary 
transform. 

; enter here to transform rows of screen data 
;do 24+1 rows (all of them) 

;point to bottom row pf screen 



.point to bottom of answer area for storage 



:DONE = RTS instruction, to return to BASIC control 



DOROWS: 


LDA 


#18 




STA 


ROWCOUNT 




LDA 


#C0 




STA 


ROWO 




LDA 


#83 




STA 


R0W0+1 




LDA 


#FB 




STA 


ANSO 




LDA 


#1F 




STA 


ANSO+1 


L00P1: 


JSR 


ROWTRANSFORM 




DEC 


ROWCOUNT 




BMI 


DONE 




SEC 






LDA 


ROWO 




SBC 


ins 




STA 


ROWO 




BCS 


OVER1 




DEC 


ROWO+1 


0VER1: 


JMP 


LOOP1 


DONE: 


RTS 




ROWTRANSFORM: 


LDA 


#64 


L00P2 : 


STA 


FREQ 




LDA 


#C3 




STA 


POINT 




JSR 


ONEFREQ 




JSR 


STOREIT 




LDA 


#91 




STA 


POINT 




JSR 


ONEFREQ 




JSR 


STOREIT 




LDA 


FREQ 




SEC 






SBC 


#5 




BPL 


L00P2 




RTS 




STORE IT: 


LDX 


ANSO 




LDY 


ANSO+1 




JSR 


DAA6 




LDA 


ANSO 




SEC 






SBC 


#5 




STA 


ANSO 




BCS 


OVER2 




DEC 


ANSO+1 


OVER 2: 


RTS 




ONEFREQ: 


LDA 


#27 




STA 


COLNUM 




LDX 


#5 




LDA 


#0 


L00P3: 


STA 
DEX 


MYACC-l.X 




BNE 


LOOP3 


TOP: 


LDY 


COLNUM 




LDA 


(ROWO) ,Y 




TAY 






LDA 


#0 




JSR 


D278 




LDY 


#STABPG 




LDA 


POINT 




JSR 


D8FD 




LDY 


#0 




LDA 


#MYACC 




JSR 


D73C 




LDY 


#0 




LDX 


#MYACC 




JSR 


DAA6 




DEC 


COLNUM 




BMI 


DONE 




LDA 


POINT 




SEC 






SBC 


FREQ 




BCS 


OVER3 




ADC 


#C8 


0VER3: 


STA 


POINT 




JMP 


TOP 



;back up to prior row (40 elements /row) 



;number in FREQ is 5 times frequency (5 bytes /number) 
; initially set to maximum frequency .. .count down to 

,set pointer for sine (imaginary part) transform 



;set pointer for cosine (real) transform 



;decrement frequency being analyzed for 
;do all frequencies 0-20 inclusive 



;setup for PET utility subroutine 
;store P at X+256Y 



;move answer pointer back to a free space 



;set column counter to maximum = 39 



; MYACC is 5 adjacent page zero . locations 
;clear them out here 



;get screen character at current row & column 



;convert integer 256A+Y to floating in P 

;point to page of sine table 

,256STABPG+POINT points to a sine to be multiplied in 

;(sine)*P is calculated and stored in P 

;point to MYACC, my accumulator's 5 bytes 
;(MYACC)+P is put into P 



; (P) gets rounded & transferred to 256Y+X (my ace.) 
:quit when all columns done 

;move pointer a distance FREQ through table 
;work modulo 200, to stay on table 

Listing 1 continued on page 174 



without a well-defined musical pitch. 
A tuning fork that rings for 
thousands of cycles makes a clear, 
precise tone. 

Contemplation of some graphs of 
Fourier-transform function-pairs can 
lead to a number of other useful in- 
sights. The illustrations in figure 1 
were adapted from Ron Bracewell's 
excellent book, The Fourier Trans- 
form and Its Applications (see refer- 
ences), which is worth looking at for 
further inspiration. 

Adding a Dimension 

Many signals, like sound, or light 
from a star, are essentially one-di- 
mensional, and the techniques dis- 
cussed above and in the earlier part of 
this article are immediately applicable 
to them. But there are other, extreme- 
ly interesting signals which are two, 
three, or more dimensional when 
they arrive. Rather simple extensions 
of the concepts involved in one-dim- 
ensional spectral analysis will allow 
multidimensional signals to be trans- 
formed, analyzed, and manipulated. 
Ill discuss the two-dimensional case 
because problems with more dimen- 
sions can be attacked by completely 
analogous methods. 

What function does a two-dimen- 
sional Fourier transform serve? For 
one thing, it can help solve many 
three-dimensional problems which 
have translational symmetry; that is, 
problems in which one of the three 
spatial dimensions can be trivially 
factored out. An obvious example is a 
system like a coaxial cable, or a cylin- 
drical waveguide, where everything 
looks the same as you move along the 
length of the device. Two-dimen- 
sional Fourier transforms can give the 
electrical characteristics of such 
systems. To some extent, problems 
involving thin layers like the Earth's 
atmosphere can be dealt with using 
two-dimensional transforms. 

If that were all, a few people might 
play around with two-dimensional 
spectral analysis, but it wouldn't be a 
huge industry. However, there's 
another class of problems that are of 
overpowering interest. These prob- 
lems are in the field of imaging, or 
remote sensing. Ever since evolution 
came up with the first rudimentary 
eye-spots, creatures have been using 
electromagnetic radiation to probe 
their environments. With the devel- 
opment of lenses that form a two- 

Text continued on page 178 



170 



March 19B1 © BYTE Publications lnc 



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assistance of a Big Eight 
accounting firm, a financial package for 
microcomputers which accommodates 
the needs of both the very small- 
businessman and the household budget 
manager, and costs far less than you 
would imagine. 

The FINANCIAL PARTNER™ contains all 
essential accounting functions, and yet is 
easy to use. It also has built-in flexibility: 
Programming expertise and valuable time 
are not needed to get the FINANCIAL 
PARTNER™ ready to use. And most 
important, this is a complete package, 
containing the programs, language, 
operating system, and supplies. 
The beauty of the FINANCIAL 
PARTNER™ is that you don't have to be a 
professional bookkeeper or accountant to 
use it. Controller Jim Vogt says, "It is one 

The FINANCIAL PARTNER™ is available from your 
local dealer or you can direct inquiries to: 

THE DENVER SOFTWARE COMPANY 

MANUFACTURERS OF MICROCOMPUTER SOFTWARE 



ofthe 

simplest accounting systems I have ever 
worked with, and it has a great ability to 
produce timely and accurate financial 
statements for small business or home 
use." All the necessary "how-to" is 
detailed in a well-written, step-by-step 
reference manual. 

The FINANCIAL PARTNER™, which 
operates from menu selections, collects 
and organizes information for all of the 
standard categories: Assets, liabilities 
(including accounts payable), normal 
living expenses, deductible expenses 
(including all six deductions for personal 
Federal Income Tax returns), earned 
income (for both the wage earner and the 



self-employed), 
and other income 
and expenses. 
The provided chart of accounts 
is tailored for most users, but it can 
easily be modified by adding new 
accounts or changing descriptions. The 
FINANCIAL PARTNER™ generates 
standard financial reports — including a 
detail trial balance, income statement, 
and balance sheet — as well as 
batch proof listings, check register, 
vendor payable reports, and chart of 
accounts reports. 

The FINANCIAL PARTNER™ is available 
for Apple, Atari, Commodore, Ohio 
Scientific, Texas Instruments, Radio 
Shack, Zenith, and most other 
microcomputers. 

Minimum hardware requirements are: 48 K 
RAM, 1 40 K on-line storage, 40 x 24 or 
80 x 24 display device, and almost any 
80-column printer (optional). 




36 Steele Street, Suite 19 • Denver, Colorado 80206 
Dealer inquiries welcome. 303 321-4551. 



i&Bhlilfrj 



you're ciluKMjs 
<i winner! 



NINE GAMES FOR 
PRE-SCHOOL CHILDREN 

by George Blink 

16K. . S-80 19.95 

KEYBOARD VIDEO PRINTER 
EXTENDER (KVP) 

by Lance Mkkkji 

0/16. . S-80 119.95 

C/4. . .S-80 J14.95 

RPN CALCULATOR 

by RusioH Starkly 

C/16. .S-80 $9.95 

STBO-UC 

by Lino Mlcklui 

4/M. .S-80 124.95 

ST-BOD SMART TERMINAL 

by Line* Mlcklui 

C/16. .S-80 S49.95 

0/32. .s-80 $79.95 

STAD 

by PiulVindirEljk 

16/M. . S-80 124.95 



TINY COMP 



D/32. . S-80 

STAR TREK 

by Land Micklus 

C/16. .. S-BO 

APL80 



D. .S-80 

C. . S-80 

TRS-80* MEMORY 
DIAGNOSTIC 

by Dave Stambaugh 
0/16. . S-80 

KRIEGSPIEL II 
by Ron Polkin 

C/16. . S-80 

UP PERISCOPE 

by Ron Polkin 

C/16 . .S-BO. . . . 
X-WING II 

by Chris Fret 

C/16. .S-80. . . 



CCA-DM 

Pinonil Sollwln 

C/S-80 $74.95 

C/Apple $99.95 

DESK TOP PLANNER 

Pinoml Soltwore 

O/Apple $99.95 

MONTY 

Psnonll Sotlwlrs 

C/S-80 $24.95 

C/Apple $27.95 

O/S-80 $27.95 

O/Apple $27.95 

LEVEL III BASIC 

Microsoft 

C/S-80 $49.95 

MuMATH 

Mlcroiolt 

O/S-80 $74.95 

EDITOR-ASSEMBLER 

Mlcroiolt 

C/S-80 $29.95 



OLYMPIC DECATHLON 

;oll 

C/S-BO $24.95 

D/S-BO S24.95 

BASIC COMPILER 

Microsoft 

O/S-80 S195.00 

ADVENTURE MICROSOFT 

Mlcroiolt 

C/S-80 $29.95 

C/Apple S29.95 

A.L.D.S. 

Microsoft 

D/S-80 S95.00 

FORTRAN 

Microsoft 

O/S-80 S95.00 

NEWDOS 80 

Apparat 

D/S-80 $149.95 



SCREEN MACHINE 

Solum Inc. 

C/Apple $19.95 

O/Apple $29.95 

APPLE TALKER 

Sotlipi Inc. 

C/Apple $15.95 

DUNGEON CAMPAIGN 

Synirglttlc Soltwiri 

O/Apple $17.50 

C/Apple $14.95 

WILDERNESS & DUNGEON 
CAMPAIGN 

Synorgltllc Soltwiri 

O/Apple $32.50 

WILDERNESS CAMPAIGN 

Synergistic Sotlwiri 

C/Apple $17.50 

O/Apple $19.95 

ODYSSEY 

Synorgltllc Soltwiri 

O/Apple $29.95 



HIGHER TEXT 

Synergistic Software 

D/Apple $35.00 

HIGHER GRAPHIC 

Synergistic Software 

D/Apple $24.95 

MODIFIABLE DATA BASE 

Synergistic Software 

D/Appla $79.50 

MAILING LIST DATA BASE 

Synergist 

D/Apple $34.50 

PROGRAM LINE EDITOR 

Synergistic Software 

D/Apple . .$40.00 

BISMARCK 

Strategic Simulations 

C/S-80 $49.95 

D/S-BO $59.95 

D/Apple . .$59.95 



SUPER NOVA 

Big Five Software 

C/S-80 $14.95 

GALAXY INVASION 

Big Five Sottwlrl 

C/S-80 $14.95 

HELLFIRE WARRIOR 

Automated Simulations 

O/S-80 $29.95 

O/Apple $29.95 

C/S-80 $24.95 

STARFLEET ORION 

Automited Slmulillont 

C/S-80 $19.95 

C/Apple $19.95 

C/Pet $17.95 

O/S-80 $24.95 

O/Apple $24.95 

RESCUE AT RIGEL 

Automited Slmulillont 

O/S-80 $24.95 

O/Apple $24.95 

C/S-80 $19.95 

C/Apple $19.95 

C/Pet $19.95 



MORLOC'S TOWER 



)/S-BO 


.$19.95 


)/Apple 


$19.95 


:/S-80 


.$14.95 


;/Apple. ...'.... 


$14.95 


:/Pel 


.$14.95 


TEMPLE OF APSHA 




Automated Simulations 




:/s-8o. , .-. 


$24.95 


:/Pel 


.$24.95 


3/S-BO 


$29.95 


J/Apple 


.$29.95 


DATESTONES OF RYN 


Automated Simulations 




J/S-BO 


.$19.95 


l/Apple 


.$19.95 


;/s-bo 


.$14.95 


;/Apple 


.$14.95 


I/Pet 


$14.95 



VISICALC 

Radio Shack 

O/S-80 $95.00 

3 D GRAPHIC 

Sebrais Computing 

C/Alarl $29.95 

HI-RES MYSTERY HOUSE 

On Line Syitemi 

O/Apple $32.95 

HI-RES WIZARD & 
PRINCESS 

On Line Syttemt 

O/Apple $24.95 

3 MILE ISLAND 

Muse Software 

O/Apple $39.95 

BEST OF MUSE 

Mule Softwlrl 

O/Apple $39.95 

GLOBAL WAR 

Mull Softwiri 

C/Apple $17.95 

O/Apple $24.95 



INVASION OF ORION 

Aulomitid Slmulitiont 

O/S-80 $24.95 

O/Apple $24.95 

C/S-80 $19.95 

C/Apple $19.95 

C/Pel $19.95 

ADVENTURELAND 

Advinture Internlttonll 

C/S-80 $14.95 

C/Apple $14.95 

PIRATE'S COVE 

Advinture Internitlonll 

C/S-80 $14.95 

C/Apple $14.95 

MISSION IMPOSSIBLE 

Adventure Internitlonll 

C/S-80 $14.95 

C/Apple $14.95 

MYSTERY FUN HOUSE 

Advinturl Intemetlonil 

C/S-80 $14.95 

C/Apple $14.95 



SUPER TEXT II 

Muse Software 

D/Apple $150.00 

THE VOICE 

Muse Software 

D/Apple $39.95 

U-DRAW II 

Muse Software 

D/Apple $39.95 

APPILOT II EDU-DISK 

Muse Software 

D/Apple $99.95 

BEST OF BISHOP 

Soflape Inc. 

D/Apple $39.95 

EDITOR ASSEMBLER 

Kayden Software 

D/Apple $49.95 

SUPER APPLE BASIC 

Hayden Software 

D/Apple $39.95 



SARGON II 

Hayden Software 

O/S-80 $34.95 

O/Apple $34.95 

C/S-80 $29.95 

C/Apple $29.95 

AIR TRAFFIC CONTROLLER 

Sensatlonel Sotlwiri 

C/S-80 $9.95 

C/Apple $9.95 

SUPER INVASION 

Sensitionil Sottwire 

C/Apple $19.95 

SPACE WAR/SUPER 
INVASION 

Sinutlonil Sottwire 

O/Apple $29.95 

DATA FACTORY 

Micro Lib 

O/Apple $100.00 

DOGFIGHT 

Micro Lib 

O/Apple $29.95 



PINBALL 

Acorn Sottwire 

C/S-80 $14.9 

O/S-80 $20.9 

DUEL-N-DROIDS 

Acorn Sottwire 

O/S-80 $20.9 

C/S-80 $14.9 

PIGSKIN 

Acorn Sottwire 

C/S-80 $9.95 

SUPER SCRIPT 

Acorn Sottwlrl 

O/S-80 $29.9! 

MIDWAY CAMPAIGN 

Anion Hill 

C/S-80 $15.01 

C/Apple '. . . .S15.I 

C/Pet S15.C 

PLANET MINERS 

Avilon Kill 

C/S-80 $15.01 

C/Apple $15. ( 

C/Pet $15.01 



NUKEWAR 

Avilon Hill 

C/S-BO 

C/Apple 

C/Pet 

B-1 BOMBER 

Avilon Hill 



NORTH ATLANTIC CONVOY 



INTRODUCTION TO 
PROGRAMMING IN BASIC 

Atari 

C/Atari $19.9! 

3 TIC TAC TOE 



CHESS 

Atari 

C/Atarl $39.9! 

STAR RAIDERS 

Atari 

C/Atari $15.9! 

SUPER BREAKOUT 

Atari 

C/Atarl $39.9! 

EDITOR ASSEMBLER 

Atari 

C/Atarl $15.9! 

VIDEO EASEL 

Atari 

C/Atari $39.9! 

INVESTMENT PORTFOLIO 

Small Syttemt Sotlwire 

C/S-80 $49.9 

WALL STREET CHALLENC 

Image Computer Product! 

C/Atari $14.9 



WARPATH 

by Ron Potkln 

C/16. S-80 $14.95 

MAGIC PAINTBRUSH 

MirkPelciirtkl 

0/32 /A ROM $29.95 

THREE-D GRAPHICS 

Mirk Ptterinkl 

0/48/A ROM $29.95 

PORK BARREL 

George Blank 

C/16 /A $9.95 

AUTOMATED DISK 
DIRECTORY 

Ramwaro 

C/[2]/32/S-80 $19.95 

PATHWAYS THROUGH THE 
ROM 

SeftSkfe PubHcaflone 

plui $1. thlpping . . .$19.95 



VISICALC 

Pinonil Sotlwiri 

O/Apple $149.95 

O/Atarl S199.95 

INTERLUDE 

Syntonic Softwiri 

C/S-80 $16.95 

C/Apple $16.95 

O/S-80 $19.95 

O/Apple $19.95 

SPECIAL DELIVERY EXTRACT 

Quillty Softwan Dlltrlbutort 

O/S-80 $125.00 

FORTH II 

Sottipe Inc. 

O/Apple $49.95 

APPLE LISTENER 

Softlpe Inc. 

C/Apple $19.95 



T SHORT 

Web Internitlonll 

C/S-80 S9.95 

ULTRA MON 

Interpro 

C/S-80 $24.95 

AMBUSH 

Strlleglc Slmulitiont 

O/Apple $59.95 

BASKETBALL 

Aliri 

C/Alarl $39.95 

MUSIC COMPOSER 
Ann 

C/Atarl $59.95 

BLACKJACK 

Atari 

C/Atarl $14.95 

HANGMAN IN BASIC 

Atari 

C/Atarl $14.95 



PYRAMID OF DOOM 

Adventure International 

C/S-80 $14.95 

C/Apple .$14.95 

VOODOO CASTLE 



C/S-BO $14.95 

C/Apple $14.95 

THE COUNf 



C/S-80 $14.95 

C/Apple $14.95 

STRANGE ODYSSEY 



C/S-80 $14.95 

C/Apple $14.95 

FIN-PLAN 



D/S-BO. . . 
SCRIPSIT 



SOFT MUSIC 

Computer Light & Sound 

C/S-80 $24.95 



D/S-BO $150.00 

GALACTIC EMPIRE . 

Broderbund Software 

D/Apple $24.95 

GALACTIC REVOLUTION 

Broderbund Software 

D/Apple $24.95 

GALACTIC TRADER 



Broderbui 

D/Apple $24.95 

ASTEROIDS IN SPACE 



.$74.95 D/Apple 

FASTGAMMON 



.$65.00 C/S-80 

.$95.00 C/Apple 



MIND MASTER 

Image Computer Products 

C/Atari 

SKILL BUILDER I 

Image Computer Products 

C/Atari 

STRATEGY PACK I 



C/Atari 

STRATEGY PACK II 



ALL STAR BASEBALL 



Circle 98 on inquiry card. 



TRS-80 Model li, 64K RAM 
TRS-80 Model III, 16KRAM 
TRS-80 Model III, 48K RAM 
TRS-80 Model III, 48K RS232, 2-drives 
TRS-80 COLOR Computer, 4K RAM 
TRS-80 COLOR Computer, 16K RAM 
TRS-80 COLOR Comp. 16K, Ext. BASIC 
APPLE II PLUS, 48K RAM 
ATARI 400, 8K RAM 
ATARI 400, 16K RAM 
ATARI 800, 16K RAM 
ATARI 800, 48K RAM 



$3599.00 (#26-4002) 

$919.00 (#26-1062) 

$1039.00 (#26-1062-)-) 

$2299.00 (#26-1063) 

$359.00 (#26-3001) 

$399.00 (#26-3001 + ) 

$529.00 (#26-3002) 

$1119.00 (#47-203) 

S439.0D (#36-400) 

S499.00 (#36-401) 

$829.00 (#36-800) 

$1089.00 (#36-802) 




TRS-80* 

COLOR COMPUTER 

4K $359.00 

16K with extended 

BASIC $529.00 



TRS-80* 
MODEL III 



16K $919.00 
48K with two drives $2299.00 





ATARI 800 

$829.00 

ATARI 400 

$439.00 



ATARI 1 16K RAM $119.50 

AXLON 32K RAM $259.00 

APPLE II + 
48K $1119.00 




SUP-R-MOD RF Modulator 

APPLE II Disk Drive w/controller 

MICROSOFT Z-80 SoftCard 

MICROSOFT RAMCard 

PASCAL Language Card 

Mountain Computer ROMWriter 

Mountain Computer ROM Plus + w/Filter 

Mountain Computer Expansion Chasis 

CCS Arithmetic Processor 

CCS Calendar/Clock Module 

KURTA Graphics Table w/lnterface 

VERSAWRITER 

ALF AM II Music Synthesizer 

NEC 12" Monochrome Monitor - 



$34.95 
$579.00 
$279.00 
$169.00 
$469.00 



(#47-100) 

(#47-004) 

(#47-80) 

(#47-81) 

(#47-PAS) 



$169.00 (#47-MH003) 
$189.00 (#47-MH007) 
$609.00 (#47-MH024) 
$399.95 (#47-7811C) 
$125.00 (#47-7424A) 
$659.00 (#47-1000) 
$239.00 (#47-1100) 
$189.00 (#47-1200) 
$239.00 (#5-200) 



LYNX 



MAKES YOUR COMPUTER A WHOLE NEW ANIMAL 
LYNX is more than a telephone coupler. LYNX is a one-piece total 
telephone linkage system for TRS-80 Level I or Level II or APPLE II com- 
puters. No RS-232 required for true originate/answer direct-connect 
telephone operation. DOS-compatible EMTERM terminal software is fur- 
nished on cassette. 

TRS-80 Model-I (Level I or Level II), 4K $229.00 (#19-80) 

APPLE II or APPLE II PLUS, 16K min $239.00 (#19-85) 




DISK-80 



Disk Controller (up to 4 drives) 

Data Separator 

Incl. 16K of RAM 

Provision for an additional 16K RAM 

TRS-BUS Connector for future expansion 

ONLY $369.00 



$449.00 


(#9-MX70) 


$519.00 


(#9-MX80) 


$499.00 


(#9-80) 


$669.00 


(#9-82) 


$999.00 


(#9-83) 


$3795.00 


(#9-300) 



PRINTERS 

EPSON MX-70 
EPSON MX-80 
OKIDATA Mlcrollne 80 
OKIDATA Mlcrollne 82 
OKIDATA Mlcrollne 83 
OKIDATA Slimline 300 



TERMS: Print and apocltlcitloni Hi iub|td to changi HAROSIOE Kcapta VISA 
» MASTERCARD, CartlfMd chKki and Monay Orders: Paraonalchocki accaptad 
(takat 3 woaks to ckw) HARDSIDE piyi ill shipping clurgit (within tin 48 
ititu) on •« PREPAID ordtri OVER J100.00.0n ill ordtnundtr S1O0 • S2.50 
handling clurgo mint bo iddid. COD ordort accoptod (ordari ovw $250 raqulrt 
25'/'. dopnlt) thera It • $5.00 handling clurgo. UPS Bluo Labol, and Air Frolght 
ivaHabk) it aitra coat. 

"TRS-M, APPLE and ATARI ara tradamarka of Tandy, Appw Computar Co., 
ind Warnar Comrnu mutton, mpocttvary. 



(O 



TS€JHARDSID€ 

6 South St .Milford. NH 03055 (603)673-5144 
TOLL FREE OUT-OF-STATE 1-800-258-1790 



Circle 99 on inquiry card. 



Circle 100 on inquiry card. 



If you're looking for 

the best prices 
in the U.S.A. on 




TRS-80 

MICROCOMPUTERS 

We have consistently offered the 
TRS-80 line at savings up to 20%, 
which means you can save $150 
to $1 500 by buying directly from 
Computer Discount of America. 

TRS-80 Model II, 64K System, 
with disc drive only $3385.00 

Other TRS-80 Model II, or Model 
III computers and systems, Color 
Computers, and Pocket Computers 
are in stock at similar savings. 

Our savings are as big on expan- 
sion interfaces, printers, diskettes - 
everything for your TRS-80 System. 



ATARI 

MICROCOMPUTERS 




We have the full line of ATARI 
personal computers and systems, 
including Models 400 and 800. 
The computers, accessories, and 
hardware are brand new, in 
factory sealed cartons, and carry 
a full factory warranty. 
Most models are in stock for 
immediate delivery (usually 
within 7-10 days), and a price 
quote is as near as your phone. 
So if you're looking for the best 
prices in the U.S.A., for micro- 
computers and accessories, call 
Computer Discount of America, 
Inc., West Milford, New Jersey 
07480. 201-728-8080. NO TAX ON 
OUT-OF-STATE SHIPMENTS. 



TOLL FREE 800-526-5313 



Computer 



of America 



Authorized TRS-80 dealer, store B-282. 



174 March 1981 © BYTE Publications lnc 



Listing 1 continued: 



D0C0LS : LDA 


#14 


STA 


C0LNUM 


L00P4 : LDA 


#3C 


STA 


FREQ 


JSR 


FTC6.D 


DEC 


COLNUM 


BPL 


L00P4 


RTS 




FTC&D : LDA 


COLNUM 


CLC 




ADC 


#D3 


STA 


RDISP 


LDA 


#83 


STA 


RDISP+1 


LDA 


#13 


SEC 




SBC 


COLNUM 


STA 


LDISP 


LDA 


#80 


STA 


LDISP+1 


LDA 


COLNUM 


ASL 


A 


STA 


ADRS 


ASL 


A 


ASL 


A 


ADC 


ADRS 


ADC 


#2E 


STA 


STASH 


LOOP 5: STA 


ADRS 


LDA 


#1F 


STA 


ADRS+1 


LDA 


#91 


STA 


POINT 


JSR 


COLXFRM 


LDX 


#5 


L00P6: LDA 


MYACC-l.X 


STA 


C0SACC-1.X 


DEX 




BNE 


L00P6 


LDA 


#1F 


STA 


ADRS+1 


LDA 


STASH 


CLC 




ADC 


#5 


STA 


ADRS 


LDA 


#C3 


STA 


POINT 


JSR 


COLXFRM 


LDY 


m 


LDA 


It COSACC 


JSR 


D95E 


JSR 


D728 


JSR 


DADE 


LDA 


#0 


STA 


SGNCOMPR 


LDA 


B0 


JSR 


D900 


LDY 


#0 


LDX 


# COSACC 


JSR 


DAA6 


LDA 


#LF 


STA 


ADRS+1 


LDA 


STASH 


STA 


ADRS 


LDA 


#C3 


STA 


POINT 


JSR 


COLXFRM 


LDX 


#5 


1.00P7: LDA 


MYACC-l.X 


STA 


SINACC-1 ,X 


DEX 




HNF. 


LOOP 7 


LDA 


#1F 


STA 


ADRS+1 


LDA 


STASH 


CLC 




ADC 


#5 


STA 


ADRS 


LDA 


#91 


STA 


POINT 


JSR 


COLXFRM 


LDY 


ItO 


LDA 


if SINACC 


JSR 


D73C 


JSR 


DADE 


LDA 


#0 


STA 


SGNCOMPR 



;enter here to transform and display 20' ; 2 columns 

j 60 / 5 = 1 2 is maximum frequency which can be shown 
;begin at 12 and do frequencies through -12 
;fourier transform column &. display 



;when finished , go back to BASIC control 



jpoint to screen address of right-hand column to 
;be displayed (zero at center) 



;point to left-hand display column 

; (column 20 is only displayed on right... see below) 



;temporary storage for multiplication 10*C0LNUM 



;now we have 10-C0LNUM 

;and now accumulator points to low byte of the real 

;part of the last R0WSXFRMD table entry for this column 

;high part of end of R0WSXFRMD table address in 8K PET 



;pointer set for cosine transform of real part of data 
ireturns answer in MYACC and in P 



; transfer answer to COSACC on page zero, 5 bytes 



;reset data pointer before doing sine transform 
;stash holds result of low byte address calculation 

;add 5 to get to point to imaginary part of data 
;there is never a carry 

;point setup for sine transform of imag. data 



; transfer COSACC to S 

;calculate S-P and leave result in P 

;copy P to S 

;set sign comparison (address BE) to + 
;must call PET subroutine with (B0) in A 
;(P)*(S)=(P)**2 is calculated and left in P 



; transfer P to COSACC 

jpoint to real data again 

;setup for sine transform of real data 

; transfer answer to SINACC on page zero 



jpoint to imaginary data 
;and do cosine transform 



;add (SINACC) -+-(P) and store in P 
;copy P to S 



Listing 1 continued on page 176 
Circle 101 on inquiry card. » 



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XEROX® E a trademark of XEROX CORPORATION. 



Circle 102 on inquiry card. 



NEW 



for 



CP/M 



Software Tools That Work 

• proven 

• cost-effective 

■ thousands in use 

Available In standard 8-Inch format for 
most CP/M systems, and 5-Inch CP/M 
and HDOS formats for Heath/Zenith sys- 
tems. 

Written by computer professionals who 
demand the same high standards In 
their microcomputer software as they 
get on bigger machines, these pro- 
grams have built a reputation for qual- 
ity, reliability, and performance. The 
HDOS versions are sold by Heath/Zenith 
dealers nationwide as well as through 
independent distributors internationally. 

Programs available on standard 8" 
CP/M, 5" Heath CP/M and HDOS disks: 

Programming Languages 

C/80 

C Compiler $39.95 

RATFOR 

Fortran language extension . .$39.95 
LISP/80 

LISP interpreter $39.95 

UVMAC/Z80 

Macro assembler for Z80 $29.95 

UVMAC/8080 

Macro assembler for 8080 , . .$29,95 

Word Processing & Utilities 

TEXT 

Text formatter $34.95 

PACK/CRYPT 

File compression/encryption. .$24.95 

Available for the H89, H8, and Z89 in 
Heath 5" CP/M and HDOS formats only: 

Graphics & Word Processing 

PIE 

Full screen text editor $29,95 

ED-A-SKETCH 

Full screen graphics editor . . .$29,95 

Utility Programs 

CATALOG SYSTEM/UTILITIES 
(HDOS only) 

Catalog disk library; file 

dump, compare, etc $19.95 

REACH (HDOS only) 

Modem and file transfer $19.95 

Entertainment 

AIRPORT 

Real time action game $19.95 

INVADERS 

Action video game $19.95 

MYCHESS 

Chess champion $34.95 

ORDERING INFORMATION: Specify 
program name and disk format. Check 
program listing above for format avail- 
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Tfie Software ^Toolwdrk^ 

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Dealer inquiries invited. 

CP/M is a registered trademark of Digital Research, Inc. 



Listing 1 continued: 





LDA 


BO 




JSR 


D900 




LDY 


#0 




LDA 


#COSACC 




JSR 


D73C 




JSR 


DE24 




LDA 


BO 




CMP 


#89 




BCS 


LIMITER 




JSR 


D0A7 




LDA 


BA 




JMP 


OVERLTD 


LIMITER: 


LDA 


#FF 


OVERLTD: 


LDY 


#0 




STA 


(RDISP), Y 




TAX 






LDA 


RDISP 




SEC 






SBC 


#28 




STA 


RDISP 




BCS 


0VER4 




DEC 


RDISP+1 


0VER4: 


LDA 


COLNUH 




CMP 


#14 




BEQ 


0VER5 




TXA 






STA 


(LDISP) ,Y 




LDA 


LDISP 




CLC 






ADC 


#28 




STA 


LDISP 




BCC 


0VER5 




INC 


LDISP+1 


0VER5: 


LDA 


FREQ 




CMP 


#C4 




BEQ 


D0NE2 




SEC 






SBC 


#5 




STA 


FREQ 




LDA 


STASH 




JMP 


LOOP b 


D0NE2: 


RTS 




COLXFRM: 


LDA 


m 




LDX 


lib 


LOOPS: 


STA 
DEX 


MYACC-1 ,X 




BNE 


L00P8 




LDA 


#19 




STA 


ROWNIJM 


L00P9: 


LDY 


ADRS+1 




LDA 


ADRS 




JSR 


DA74 




LDY 


#STABPG 




LDA 


POINT 




JSR 


D8FD 




LDY 


#0 




LDA 


#MYACC 




JSR 


D73C 




LDY 


#0 




LDX 


t'MYACC 




JSR 


DAA6 




DEC 


ROWNUM 




BEQ 


DONE2 




LDA 


POINT 




SEC 






LDX 


FREQ 




BMI 


NECFREQ 




SBC 


FREQ 




BCS 


0VER6 




ADC 


#C8 


0VER6: 


STA 


POINT 




JMP 


NXTADR 


NECFREQ: 


SBC 


#C8 




CMP 


FREQ 




BCC 


OVER7 




SBC 


FREQ 




JMP 


0VER6 


0VER7: 


LDA 

SEC 


POINT 




SBC 


FREQ 




JbS 


0VER6 


NXTADR: 


■ LDA 
SEC 


ADRS 




SBC 


#D2 




STA 


ADRS 




BCS 


0VER8 




DEC 


ADRS+1 


0VER8: 


JMP 


L00P9 



;square of P is now in P 

;(C0SACC)+(P) is in P 

;SQR(P) . . .now we have fourier amplitude to be plotted! 

;must avoid overflow, so check exponent of answer 

; take branch if result is bigger than 255 
;convert P to an integer in B3,B4 
;but B3 is zero, by limiting process 

^replace overflow by 255 

;display it on the screen! ! --£ ir s t, right column 



^subtract 40 to point to previous row 



;check column number, and don't plot column 
;number 20 (no room on screen!) 

;plot result in left column here 



;add 40 for next row 

;see if we've reached frequency of -12 yet... 

^decrement frequency 

; go back and do it again at new frequency 

;clear out MYACC ' s 5 bytes 

;initialize counter of rows 

;'transfer column member pointed to by ADRS to P 
;point to sine table page 

; (sine) 1 '? in P 

; (MYACC)-f(P) in P 

; (P) to MYACC 

;return when all 25 are done 

:musr. handle movement of pointer carefully 
;work modulo 200, stay in table 



; f or FREQ less than zero, this section 
;moves pointer while staying within table 



;back up 210 to previous column member 



176 March 1981 © BYTE Publications Inc 



SHORTEN THE JOURNEY TO KNOWLEDGE. 



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BYTE March 1981 



177 



Circle 104 on inquiry card. 



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Text continued from page 170: 

dimensional image on the retina, 
remote sensing took a giant step for- 
ward. 

When conditions are good, the im- 
ages that develop on photographic 
plates or inside vidicons (television- 
camera tubes) can be used just as they 
are. But often, noise or other in- 
terference makes the original image 
low-quality. When astronomers look 
up, or spy satellites look down, they 
want to squeeze every possible bit of 
information out of their sensors, to 
"milk" every photon. That's one ma- 
jor reason for all the progress in im- 
age analysis and two-dimensional 
signal processing that has been made 
in the past few decades. 



Advantages of 
transforming a visual 
image into the frequen- 
cy domain overcome all 
the limitations of the 
photographic medium. 



The advantages of transforming a 
picture into the frequency domain, 
where the elemenfs of the image that 
vary periodically are gathered and 
grouped together, are numerous, just 
as were the advantages of analyzing a 
one-dimensional signal in frequency 
space (as discussed last month in Part 
1). By working digitally inside a com- 
puter, you overcome all the limi- 
tations of the photographic medium. 
It's easy to enhance or mute contrasts, 
to intensify edges of objects (high 1 
spatial frequencies) or to take out 
distracting large-scale brightness 
variations (low-spatial frequencies). 
The wonderful images that come 
back from NASA's planetary probes 
are automatically processed by these 
kinds of techniques before anyone 
sees them. 

If, after all this build-up, you're ex- 
pecting to hear that the two-dimen- 
sional Fourier transform is an arcane, 
incomprehensible mathematical pro- 
cess, I'm sorry, but I have to disap- 
point you. To take a two-dimensional 
transform, you merely need to choose 
a pair of perpendicular coordinate 
axes (x and y). First do a one- 
dimensional Fourier transform in the 



x direction, and then do a one- 
dimensional transform on the result 
of that, in the y direction. That's ail 
there is to it! 

The 2DFT Program 

The 6502 assembly-language pro- 
gram in listing 1 performs two-dimen- 
sional Fourier transforms. The pro- 
gram takes as its input data the con- 
tents of the Commodore PET micro- 
computer's video-display screen: 1000 
numbers, arranged in 25 rows of 40 
integers, each one in the range thru 
255. The results of the transformation 
are displayed on the screen. Only the 
amplitude of the transform is shown; 
all phase information (whether the 
wave is sine, cosine, or a mixture) is 
suppressed. 

I'd like to take a little time now to 
describe how the program works, and 
the choices and compromises I had to 
make in implementing it. This discus- 
sion should help you if you need to 
adapt 2DFT to run on a different 
microcomputer, and it should also be 
a useful starting point for modifica- 
tions and improvements of my pro- 
gram. After the discussion, 111 return 
to the uses of the program, the in- 
sights that you can achieve by play- 
ing around with it, and the fascinat- 
ing topic of holography, and how to 
do it with this program. 

First, concerning the fundamental 
algorithm used to do the transforms: 
as mentioned above, a true two-dim- 
ensional Fourier transform results 
after you perform separate one- 
dimensional transformations on each 
row of a matrix, and then perform 
separate one-dimensional transfor- 
mations on each resulting column of 
data. 2DFT does that. The routine 
DORO WS finds the amount of cosine 
phase necessary at each frequency, as 
well as the amount of sine. Those 
numbers are stored in memory for 
each row. Then, the routine DO- 
COLS does the same thing for each 
column of stored half-transformed 
data, and puts the amplitude of each 
resulting frequency-space point onto 
the screen. The amplitude is simply 
the square root of the sum of the 
squares of the cosine component and 
the sine component (like finding the 
hypotenuse of a right triangle). 

To do the one-dimensional row 
and column transformations, DO- 
ROWS and DOCOLS call subrou- 
tines ROWTRANSFORM and COL- 



178 March 1981 © BYTE Publications Inc 



Software for the Apple II and Apple II Plus* 




ASTEROIDS IN SPACE" 

By Bruce Wallace 

An exciting space action game! Your space ship is 
traveling in the middle of a shower of asteroids. Blast 
the asteroids with lasers, but beware — big asteroids 
fragment into small asteroids! The Apple game paddles 
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From time to time you will encounter an alien space 
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effects add to the arcade like excitement that this 
program generates. Runs on any Apple II with at least 
32K of RAM and one disk drive. 

On Diskette - $19.95 





Cassette 



FASTGAMMON" By Bob Christiansen. 
Sound, hi res, color, and musical cartoons have 
helped make this the most popular backgammon 
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entertaining features fool you — FASTGAMMON 
plays serious backgammon. Runs on any Apple II 
with at least 24K of RAM. 
$19.95 Diskette - $24.95 



ASTROAPPLE'" by Bob Male. 
Your Apple computer becomes your astrologer, 
generating horoscopes and forecasts based on the 
computed positions of the heavenly bodies. This 
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entertain friends. ASTROAPPLE produces natal 
horoscopes (birth charts) for each person based 
on his or her birth data. Any two people may be 
compared for physical, emotional, and intellectual 
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BASIC with machine language subroutines. It 
requires either RAM or ROM Applesoft and at least 
32K of memory. 

Cassette - $14.95 Diskette 




$19.95 




SSpfe FRACAS" by Stuart Smith. 



A fantastic adventure game like no other! Up to eight 
players can participate in FRACAS at the same time. 
Journey in the land of FAROPH, searching for hidden 
treasure while warding off all sorts of unfriendly and 
dangerous creatures. You and your friends can compete 
with each other or you can join forces and gang up on the 
monsters. Your location is presented graphically and sound 
effects enliven the battles. Save your adventure on diskette 
or cassette and continue it at some other time. Both integer 
BASIC and Applesoft versions included. Requires at least 
32K of RAM. 



Cassette- $19.95 Diskette - $24.95 



BENEATH APPLE MANOR'" by Don Worth. 
Descend beneath Apple Manor into an under- 
ground maze of corridors, rooms, and secret 
passages in quest of rich and powerful treasures. 
The dungeon complex consists of many floors, 
each lower level more dangerous than the last. If 
you can reach the lowest level, you may even find 
the ultimate object of your quest, the fabled 
golden apple of Apple Manor. Strategy is extreme- 
ly important as you deal with a variety of monsters, 
each with its own characteristics. Written in 
integer BASIC with machine language sub- 
routines. Requires integer BASIC and at least 16K 
of RAM on cassette or 32K of RAM on diskette. 

Cassette - $14.95 Diskette 




$19.95 



BATTLESHIP COMMANDER" by Erik Kilk and Matthew Jew. 



A game of strategy. You and the computer each start out by positioning five ships of 
different sizes on a ten by ten grid. Then the shooting starts. Place your volleys skillfully 
— a combination of logic and luck are required to beat the computer. Cartoons show 
the ships sinking and announce the winner. Sound effects and flashing lights also add 
to the enioyment of the game. Both Applesoft and integer BASIC versions a re included. 
Requires at least 32K of RAM. 

Cassette - $14.95 Diskette - $19.95 



BABBLE" by Don Worth. 
Have fun with this unique software. You write a 
story, entering it as a BABBLE program. As you 
write the story you specify certain words to be 
selected by the computer or entered from the key- 
board at execution time. Run the program and 
watch BABBLE convert your story into an often 
hilarious collection of incongruities. The ways in 
which BABBLE can entertain you are limited only 
to your imagination. You can compose an 
impressive political speech or write poetry. You 
can plan a dinner menu. You can even form 
images on the screen or compose musical tunes 
with the help of BABBLE. The cassette version 
requires at least 16K of RAM and the diskette 
version requires at least 32K of RAM. BABBLE is 
written in machine language and runs on any 
Apple II computer. 

Cassette - $19.95 Diskette 



My SISTER'S pencil anftp,p- 
E.NCR LOVES YOUR ANTEATER, 
AND THE CP.ABGRASS IS AT- 
TACKING THE FRIENDLY 1 MATADOR. 




BABBLE 



$24.95 



LINKER by Don Worth. 

Turn your Apple II or Apple II Plus into a powerful and productive 
software development machine with this superb linking loader/editor 
package. LINKER does the following and much more: 

• Dynamically loads and relocates suitably prepared machine 
language programs anywhere in RAM. 

• Combines a main program with subroutines. You can assemble a 
subroutine once and then use it with as many main programs as you 
wish. 

• Produces a map of all loaded routines, giving their location and the 
total length of the resulting module. 

• Contains a library of subroutines including binary multiplication and 
division, print text strings, delay, tone generator, and random 
number generator. 

Linker works with virtually any assembler for the Apple II. Requires 32K 
of RAM and one disk drive. 

Diskette - $49.95 
Manual Only - $19.95 




QUflLny SOFTW71R6 

6660 Reseda Blvd., Suite 105, Reseda, CA 91335 

(213) 344h6599 

Now exclusive distributors for products from The Software Factory, Newhall, California 
*Apple II and Apple II Plus are trademarks of Apple Computer. Inc 



WHERE TO GET IT: Call us at (213) 344-6599 forthe name of the Quality Software 
dealer nearest you. If necessary you may order directly from us. Mastercard and 
Visa cardholders may place orders by telephone. Or mail your check or bankcard 
number to Quality Software, 6660 Reseda Blvd., Suite 105, Reseda, CA 91335. 
California residents add 6% sales tax. SHIPPING CHARGES: Within North America 
orders must include $1.50 for first class shipping and handling. Outside North 
America the charge for airmail shipping and handling is $5.00. Pay in U.S. 
currency. 



Circle 105 on inquiry card. 



BYTE March 1981 



179 




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The MICROCONDUCTOR'" is not jusr o file manager bur o rrue Dora 
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DATA FILES — No limir on rhe number of records o file con hove. 

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^Registered Trade Mark of Apple® and Radio Shack. 




180 



BYTE March 1981 



TRS-80® Model III Owners . . . 



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BYTE March 1981 181 



XFRM, respectively. These simply 
use the old, classical, straightforward 
method of calculating a Fourier 
transform— no fast-Fourier-trans- 
form subtleties! 

I've avoided talking about the 
mathematical mechanism for moving 
from ordinary space to the frequency 
domain in these articles so far, 
because there are ample technical 
references which explain such matters 
in great detail, and because the cal- 
culation tends to get in the way of the 
real substance of the subject, especial- 
ly in an introduction such as this one. 
Here, let me just say that the trans- 
forms are accomplished by multiply- 



ing each row (or column) element by 
a sinusoidally varying factor, and 
adding up the results of those multi- 
plications at each frequency. To find 
out how much cosine phase at fre- 
quency / is in a given row, multiply 
each row element r(x) by cos(27r/;c) 
and sum those products for the whole 
length of the row. The amount of sine 
wave is found by multiplying r(x) by 
sin(27r/;c) and summing those results. 
You can unite the cosines and sines 
into a set of complex numbers, with 
the cosines making the real parts and 
the sines the imaginary parts. Then, 
usual complex-number algebra helps 
keep track of how to add and subtract 



S 

B8 
B9 
BA 
BB 
BC 
BD 
BE 
BF 



P 

BO 
B1 
B2 
B3 
B4 
B5 



Contents 
exponent + 80 
fractions MSB 
frac. byte 2 
frac. byte 3 
fraction LSB . 
sign 

sign comparison 
roundoff byte 



S = e 
82 
AD 

F8 
54 
59 
00 
FF 
00 



P= -ir/2 
81 
C9 
OF 
DA 
A2 
FF 



Note: +,-,*,/, and 1 must be called with 
S in B8 thru BD, sign comparison set 
to (B5) XOR (BD), and (B0) in A 



Constants in floating (merged sign) nota- 
tion: 

E024 

DDE3 

E01A 

CDBC 

E01F 



'I. 

■Klz 



IT 

2w 



0000 USR(P) 

CED6 SORP 

CED9 S AND P 

D264 FRE(P) 

D285 POS(P) 

D349 STR$ 

D5C4 CHR$ 

D5D8 LEFTS 

D604 RIGHTS 

D60F MIDS 

D654 LEN 

D663 ASC 

D685 VAL 

D6E6 PEEK 

D728 S - P 

D73C JSR D95E, then S + P 

D73F S + P 

D7AC normalize P 

D8BF LOG(P) 

D8FD JSR D95E, then S * P 

D900 S * P 

D95E [A + 100Y]— S, separating sign, set sign comparison, return with (B0) in A 

D9E4 S/P 

DA74 [A + 100YJ-P, separating sign 

DAA6 roundoff(P)-[X + 100Y], merging sign 

DACE S-P 

DADE P-S, with rounding 

DAE1 P—S, without rounding 

DAED roundoff(P) 

DAFD SGN(P)-A 

DB0B SGN(P) 

DB2A ABS(P) 

DB9E INT(P) 

DE24 SQR(P) 

DE2E S I P 

DEA0 EXP(P) 

DF45 RND(P) 

DF9E COS(P) 

DFA5 SIN(P) 

DFEE TAN(P) 

E048 ATN(P) 

Conversions: D0A7 P-integer in B3,B4 [100B3 + B4] 
D278 integer in A,Y [100A + Y] - P 

Table 1: Entry points for Commodore PET ROM functions, including floating-point 
subroutines that are utilized directly by the author's program. 



components during the transforma- 
tion process. 

None of this is anything for a non- 
mathematically inclined person to 
worry about; it's just a recipe for the 
machine to follow in order to crank 
out the answers. There's no more 
need to follow the details of the pro- 
cess than there is to follow the details 
of how your pocket calculator com- 
putes exponentials or logarithms. In 
ten or twenty years, as the power of 
computers grows and their cost 
shrinks, there will probably be single- 
keyword instructions to perform 
Fourier transforms, just as most 
machines now have EXP and LOG 
routines available. Some people will 
still work with the nitty-gritty, low- 
level algorithms and procedures, just 
as some engineers work with in- 
dividual transistors today. But most 
human work will be done using 
higher-level languages, where it's 
easier to invent new concepts and 
prove theorems. Machines will han- 
dle the low-level dirty work. 

Besides the specific algorithm I 
chose to use, some other important 
decisions went into the design of 
2DFT. First, to avoid all danger of 
arithmetic overflow and underflow, I 
use floating-point procedures except 
at the final stage where the results of 
the transformation are displayed. At 
that point, the floating numbers are 
converted into fixed-point integers 
and any results greater than 255 are 
truncated to equal 255. (There are 
never any negative results because the 
square root of the sum of the squares 
is always positive or zero.) 

To save program space and avoid 
the headaches of writing my own 
routines, I call the floating-point pro- 
cedures in the PET's BASIC ROM. 
Table 1 is a list of hexadecimal ad- 
dresses of the entry points to these 
routines, and includes short descrip- 
tions of what each routine does and 
how to call it. (Driven by my need for 
machine-language floating-point cap- 
abilities, I found the locations of these 
subprograms, and I don't think that 
there can be anything wrong with 
PET owners using the subroutines in 
their programs, as I've done. I should 
also note, however, that Commodore 
and Microsoft may change the ad- 
dresses given in table 1 in future pro- 
duction of PETs and other machines.) 

A second important choice that 
was made in the design of 2DFT was 



182 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



183 



to use the same scales for the horizon- 
tal and vertical axes in the Fourier 
transform. This is not as obvious a 
choice as it might seem. Because the 
video display screen isn't square, it 
might seem to be better to squeeze the 
vertical scale, so that as many high 
frequencies could be plotted in the 
vertical direction as are plotted 
horizontally. The resulting distortion 
would be perfectly acceptable math- 



ematically, but it would make the pic- 
tures harder to look at and might be 
responsible for some mistaken no- 
tions on the part of naive viewers. 
Additionally, choosing different 
scales for horizontal and vertical 
transformations would require the 
use of a different set of sines and 
cosines for each dimension. 

I chose instead to make the scales in 
the frequency domain equal. The re- 



Listing 2: This program calls 2DFT and helps translate its results to a form more easily 
viewed by a human. A picture can be drawn on the screen, using the usual cursor- 
control characters. Hitting the exclamation-mark key turns the picture into a form that 
2DFT can read, where each cell has in it a number (from thru 255) proportional to the 
magnitude of the image at that cell. The quote key turns the numbers back into a 
"density plot" where the brightness of each cell is proportional to its magnitude. 

5 REM»*POKE 135,6 BEFORE RUNNING TO PROTECT MACHINE-LANGUAGE 2DFT PROGRAM 

10 DATA 32, 58,59 ,103, 106, 118, 225., 245, 244, 229, 160:F0R 1-1 TO 10:READ Gt : NEXT 

20 TPINT "HIT -RETURN- TO TRANSFORM SCREEN" 

30 PRINT " -QUOTES- TO MAKE DENSITY PLOT" 

40 PRINT " - ! - TO TURN DENSITY TO NUMBERS" 

100 GET AS: IF AS""" GOTO 100 

110 I-ASC(AS ): IF 1-13 GOTO 200 

120 IF I'34 GOTO 600 

130 IF 1-33 GOTO 900 

140 PRINT AS;:GOTO 100 

200 FYS(1536 ) : SYS( 171 3 ) : GOTO 100 

BOO FOR 1-32768 TO 33767 : A=PEEK( I ): POKE I , Gt( A/2 5 ) : 

900 FOR 1=32768 TO 33767 : A-PEEK( I ) : B=l : FOR J=0 TO 

910 NEXT:POKE I , 25 «B : NEXT : GOTO 100 

020 REM"POKE 135,32 WHEN FINISHED TO REGAIN ACCESSIBILITY TO ALL MEMORY 



: NEXT : GOTO 100 

:IF A-G1,(J) THEN B=J:J = 




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quired sines and cosines are stored in 
a table (on PET memory page 
STABPG, in listing 1); a pointer 
moves through the table, allowing the 
transformation subroutines to read 
off the trigonometric functions with a 
minimum amount of computational 
overhead. The effect of making the 
scales equal in both directions is that 
instead of using a 25- by 40-pixel 
(picture-element) screen, the program 
is really transforming a 40 by 40 im- 
age. The extra 15 rows are presumed 
to be filled with zeroes before every 
transformation. After transforming, 
the high frequencies that fall outside 
the bounds of the video screen are not 
calculated. (This is not a devastating 
loss; as you may have heard, you can 
cut off and throw away part of a 
hologram and still reconstruct the 
whole original image from the re- 
maining fragment. The only cost is a 
loss of resolution and sharpness in the 
reconstructed image. More on this 
later.) 

The third significant choice I made 
in writing 2DFT was to display the 
amplitude of the Fourier transform: 
the square root of the sum of the 
squares of the sine and cosine com- 
ponents. A photographic plate has a 
sensitivity that is proportional to the 
light energy which falls in any given 
area. Taking the square root adds 
mathematical complexity and com- 
putational time to the transformation 
process. On the other hand, the 
square-root operation makes it a lot 
easier to look at and interpret the 
transform results on the video screen. 
It prevents almost all overflows 
because any number between and 
65,535 is mapped into the range to 
255 automatically. The cost in time is 
an additional 10% or so, which is ac- 
ceptable for the benefits that result. 
Finally, the nonlinearity of the square 
root turns out not to interfere much 
with the holographic process, in my 
experiments. 

The video-character generator used 
in the PET is capable of storing a 
number between and 255 in each of 
the thousand screen locations, but for 
human viewing, this kind of a display 
isn't very good. In the BASIC driver 
program which calls and controls 
2DFT, I've included short routines to 
convert the screen contents to and 
from a "density plot," where each pix- 
el on the display is filled with a 
character with brightness propor- 



184 



March 1981 © BYTE Publications Inc 



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Photo 1: Photo la shows a simple image 
of low-frequency components present 
along the length of the stripes. Perpen- 
dicular to the stripes, strong periodicity 
occurs at frequencies that are multiples of 
the spacing frequency. The resulting 
transform is shown in photo lb. 



tional to the number formerly stored 
in that cell (see listing 2). The density- 
plot display uses only eleven distinct 
symbols, so it's as if the 8 bits stored 
in each screen location have been 
truncated to about 3Vz bits. The loss 
of precision is not severe, and the 
density plots are much easier to look 
at and understand than the raw data. 

Experimenting with 2DFT 

As I have implemented it, the 2DFT 
program takes about 4 minutes to do 
a single complete two-dimensional 
Fourier transform of the contents of 
the PET's screen and display the 
results. (It runs faster if the input data 
contains many zeroes, since the float- 
ing-point multiplication routine in the 
PET knows how to multiply by zero 
quite rapidly!) The columns of the 
answers are plotted as soon as they 
are calculated. After a computation, 
5250 bytes of PET memory are left 
containing the results of the row 
transformations in floating-point 
notation (5 bytes per number). 
Because the input data was a set of 
strictly real numbers, fifty of the sine 
components are always exactly zero 
(two zeroes per row), and so there are 



1000 independent numbers in mem- 
ory—precisely as many independent 
numbers as there were cells on the 
screen. This is not coincidental; the 
Fourier-transformation process "con- 
serves information," so it had to turn 
out that way. 

For your first experiments, and to 
confirm that the program is working 
correctly, I recommend that you 
transform simple pictures. A good 
test is a picture made up of parallel 
stripes (see photo 1). The picture, like 
a picket fence, has only low-fre- 
quency components present in the 
direction along the length of the 
stripes. Perpendicular to the stripes, 
there is a strong periodicity, at fre- 
quencies which are multiples of the 
fundamental spacing frequency. Log- 
ically, the transform should be a 
series of bright spots running along a 
line perpendicular to the original 
stripes. 

Another good test is to transform a 
sharp spike— a picture with only one 
cell illuminated. Such a sharp point is 
made up of equal amounts of sine 
waves at all frequencies and in all 
directions. Thus, the result of 
transforming a spike should be a 




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186 March 1981 © BlrTE Publications Inc 



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BYTE March 1981 



187 



screen with equal intensities in every 
cell. 

One of the first things that you 
should discover when experimenting 
with 2DFT is that the absolute loca- 
tion of a picture on the screen doesn't 
matter. Shifting a picture changes the 
phases of the sines and cosines that go 
into making that image, but it does 
not change the amplitude of the fre- 
quency spectrum of that picture. 
Because only the amplitude and not 
the phase is displayed, two pictures 
which differ only by some shift 
should give the same transforms. 
(This insensitivity to shifts is one 
reason for the usefulness of Fourier 
transforms in pattern-recognition 
problems!) 



Another thing to notice about 
2DFT is the relative overall intensity 
of a picture and its transform. This 
intensity, of course, is somewhat ar- 
bitrary, since by multiplying each ele- 
ment of the transform's sine table by 
some constant, the whole trans- 
formed picture gets multiplied by the 
square of that constant. (The con- 
stant shows up squared because the 
sine table is used two times, once to 
transform the rows and once for the 
columns.) 

If none of the transformed image 
was lost because of the nonsquare 
screen, it would be possible to adjust 
the constant that multiplies the sine 
table so that the sum of the squares of 
the pixels before a transform equals 



the sum of the squares after 
transforming. The multipler is 
1/SQR(L), where L is the length of a 
side of the square screen. 

In my implementation of 2DFT, I 
tried multiplying every element of the 
sine table by 1/SQR(32) and have 
found it to work well. Thirty-two is a 
reasonable mean value between the 
length of a row and the length of a 
column. The exact choice of the con- 
stant isn't critical unless you want to 
be able to read off quantative 
mathematical transformation results. 
For experimental purposes, any value 
that keeps the picture elements from 
growing too bright or too dim is ac- 
ceptable. 

An obvious quality of the transfor- 




WESIKO 













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mations produced by 2DFT is that 
they are symmetric about a cell near 
the center of the video screen. The 
cell around which everything seems 
to revolve is the (0,0) cell, the center 
of the frequency domain. It contains 
the sum of all of the cells in the un- 
transformed picture multiplied by 
any factors that were chosen for the 
sine table. It's also the cell which is 
most likely to suffer from an 
overflow problem because all of the 
pixels in each original image were 
positive numbers and add together to 
make a large zero-frequency total. 
(2DFT displays overflows as a 
character of maximum brightness, for 
the number 255.) The rest of the 
transformed image is symmetric 



about the central cell, in the sense 
that each cell contains the same 
number as the cell an equal distance 
away on the opposite side of the 
middle. 

This follows mathematically from 
the fact that the original image was 
entirely real, with no imaginary 
(complex-number) part. You can 
think of it as just a convention, if you 
like; to avoid sharp edges which 
might cut off parts of a picture, we 
have plotted "negative frequencies" as 
if they had the same energy as the 
corresponding positive frequencies. 

It works out then that you can 
think of the opposite edges of the 
screen as being joined, so that 
something moving off the screen at 



the right-hand side comes in 
automatically at the left edge. (Be- 
tween the top and bottom edges, 
there are 15 unseen lines, however, in 
order to make the imaginary screen 
square.) Because there are an even 
number of columns, one column on 
each side of the central (zero) column 
is not duplicated. That column is 
plotted as the rightmost one on the 
screen. 

It's a good idea to take some time 
now to draw pictures on the screen, 
transform them, and try to develop 
some instincts about what the trans- 
forms tend to look like. Many of the 
results from one-dimensional Fourier 
analysis carry over to two dimen- 
sions. For example, we noted that an 




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All software has specific requirements for proper operation such as computer 
type, equipment configuration and support software. 

Check the following codes for system requirements to be certain yoursystem 
will accept the software offered. 

(A) CP/M version 1.4 or higher. 

(B) CP/M version 2.0 or higher. 

(C) CBASIC-2. 

(D) MBASIC version 4.51. 

(E) BASIC-80 version 5.0 or higher. 

(F) 48K memory or greater. 

(G) 56K memory or greater. 
(H) 64K memory. 

(I) Business system: 48K memory, 200K dual disk drives, cursor address- 
able terminal, and 132 column printer. 
(K) Cursor addressable terminal. 
(L) signed license required for shipment. 
(O) specify 8080, Z80, or CDOS. 
(P) giveCP/M serial number. 
(T) serial port and modem. 
(Z) Z80CPU. 



Choose any of 4 ways to order: 

• Write Westico, Inc., 25 Van Zant Street, Norwalk, CT 06855. 

• Call (203) 853-6880. 

• Telex 643-788. 

• Dial-up our 24-hour computer (300 baud) (203) 853-0816. 

Specify prepaid, C.O.D., Master Charge, or VISA. (Please give credit card 
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Specify disk format: North Star Single or Double, Micropolis Mod I or 
Mod II; 8" single density, or Ohio Scientific. 

Prices do not include shipping and C.O.D. In CT add 7'/;% sales tax. 

'Manual price will be credited against later purchase of software. 

CP/M is a trademark of Digital Research. 
Z80 is a trademark of Zilog. Inc. 
PASCAL/M is a trademark of Sorcim. 
PASCAL/MT» is a trademark of MT Micro Systems. 
PEACHTREE is a trademark of Retail Sciences. Inc. 
S-BASIC is a trademark of Topaz Computing. 
SELECTOR IV is a trademark of Micro-Ap. Inc. 

Copyright • 1981 Westico. Inc. 




(2b) 



(2c) 



(2d) 



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T "JVWVZMX-!E«XUVQU-K<3(*)SHTMJIBECa 



image with very fine detail (sharp 
spikes or narrow lines) in one dimen- 
sion requires many high-frequency 
sinusoidal waves to define it; the 
same is true for two-dimensional pic- 
tures. A picture that repeats only a 
few times across the screen width will 
have strong low-frequency com- 
ponents in it (components that show 
up in frequency space near the central 
zero-frequency cell), while a picture 
that repeats many times across the 
screen will have strong components 
at the higher frequency of repetition. 
(In your experiments, don't forget 



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that you're not seeing the highest ver- 
tical frequencies, which fall outside 
the screen's height.) 

You should realize that even 
though the program uses horizontal 
and vertical axes to do the mathemat- 
ical transform, those axes are ar- 
tificial and not part of the initial or 
final picture. So, if you're looking at 
an image which has strong structure 
trending along a line from northwest 
to southeast, feel free to tilt your head 
and define your own personal axes in 
such a way as to make the image and 
its transform easier to think about. 



Photo 2: This sequence illustrates some of 
the properties of the holographic transfor- 
mations as done by the 2DFT program. 
Photo 2b is the hologram produced from 
the simple image in 2a. In 2c, the image is 
reconstructed from the hologram. Note 
the mirror duplication of the original im- 
age and the spreading of the reference spot 
due to the cut-off of high vertical fre- 
quencies by 2DFTs algorithm. A substan- 
tial portion of the hologram is zeroed in 
photo 2d (indicated by the @ symbol), 
giving the reconstructed image in photo 
2e. This reconstruction is fainter and 
"noisier" than photo 2c, but no part of the 
overall image is missing. 



Holography and Very-Long- 
Baseline Interferometry 

One of the most exciting and 
valuable developments of technology 
in the past thirty years has been that 
of holography. Holograms can store 
information at densities far greater 
than normal photography, and with 
far better immunity to noise and loss 
of data from scratches, dust, etc on 
the film. An equally exciting develop- 



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190 March 1981 © BYTE Publications Inc 



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merit in modern astronomy has been 
the discovery of what's called very- 
long-baseline interferometry, or 
VLBI. In a VLBI observation, radio 
telescopes thousands of kilometers 
apart look at the same object. The 
signals which they receive are com- 
bined, and by this combination, give 
a resolving power equal to that of a 
single telescope as large as the separa- 
tion between receivers— a telescope 
as large as the Earth, in some cases! 

Even working at wavelengths very 
long compared to optical light, VLBI 
techniques enable astronomers to see 
objects that are hundreds or thou- 
sands of times smaller than the largest 
optical telescopes can resolve. The 
vast increase in astronomical 
information-gathering capability has 
produced new insights during the last 
few years concerning the structure of 
distant galaxies and the early history 
of the universe. 

Both holography and VLBI rely on 
the same secret: the two-dimensional 
Fourier transform. Using the 2DFT 
program presented here, it's easy to 
make and reconstruct one type of 
hologram, the "Fourier-transform 
hologram," which is most useful for 
storing and retrieving two-dimen- 
sional information. (Holograms to 
record three-dimensional objects 
work on similar principles. See some 
of the references for more informa- 
tion.) It's also easy to use this pro- 
gram package to experiment with and 
learn about some of the interferome- 
try problems that radio astronomers 
face. 

Briefly, the results of a very-long- 
baseline-interferometry observation 
consist of a map of the object in the 
sky— a map not in the usual sense, 
but of the frequency domain. As the 
Earth's rotation moves the radio- 
telescope antennas relative to the 
stars, the signals that the telescopes 
receive sample different points in the 
Fourier-transformed plane. With 
enough observations, using enough 
antennas, reasonably complete 
coverage of this transformed map can 
be achieved. 

The big problem in VLBI is to 
deduce what the astronomical object 
looks like before transforming. If in- 
formation about the relative phases 
of points in the frequency domain 
were available, it would be possible 
to unambiguously invert the observa- 
tions and produce a picture of the ob- 
ject. 



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The secret of 

holography and its 

sophisticated ability to 

retain information is 

the two-dimensional 

Fourier transform. 



Unfortunately, VLBI can't (as of to- 
day) produce enough phase informa- 
tion. The astronomers have to look at 
an image in Fourier-transformed 
space which contains only amplitude 
information, just like the image that 
the 2DFT program produces. In some 
cases, it's not too hard to guess what 
the object that produced that trans- 
form looked like, but observers often 
must fall back on model making and 
try to fit the simplest reasonable ap- 
proximation they can think of to the 
data. This is a tough subject, but an 
important one. A lot of research is 
going on now in an attempt to find 
better solutions. 

Fourier-transform holography is 
also a subject for vigorous current 
research. One reason for the interest 
is that holograms could possibly pro- 
vide huge, ultra-fast memories for 
computer systems. Ordinary micro- 
film is a very inefficient way to record 
data. It fails to take advantage of the 
information-storage ability of high- 
resolution photographic film, and if 
the bit density is pushed up, the 
microfilm technique becomes unac- 
ceptably vulnerable to film defects, 
dust particles, etc. Conventional 
photographic methods are too highly 
localized for each bit that is writ- 
ten—it's like trying to transmit infor- 
mation over a noisy phone line 
without a decent error-detection and 
correction code! 

A hologram, on the other hand, 
shares many of the best properties of 
sophisticated error-preventing tech- 
niques. Each bit of the original record 
is spread out over the entire holo- 
graphic image. A speck of dust can't 
clobber a particular bit; all it can do is 
add a slight overall noise to the re- 
covered analog signal, and even that 
noise can be entirely removed by a 
simple digitizing process. If half of a 
photograph is cut off and thrown 
away, half of the picture is lost 
forever. If half of a hologram is re- 
moved, the whole picture is still 
there! The sharpness of the picture is 



reduced, but no particular region is 
lost at all. 

How can a hologram work? Photo- 
graphic film records only the intensi- 
ty, not the phase, of the light that hits 
it. The secret is simple: put a phase 
reference into the original object that 
is being holographed! This phase ref- 
erence is just a bright, pointlike spot 
in the original. When transformed, 
the bright spot by itself turns into a 
constant signal over the whole fre- 
quency versus space plane because (as 
mentioned above) a sharp spike is 
made up of equal amounts of sinu- 
soids at all frequencies. 

This constant background signal 
provides a reference against which 
the sines and cosines of the other 
parts of the original object can in- 
terfere, constructively and destruc- 
tively. The background provides the 
reference phase; the rest of the 
Fourier-transformed image adds and 
subtracts relative to that background, 
and so an intensity recording (as on a 
photographic plate) includes enough 
phase information to allow the orig- 
inal image to be reconstructed. 

The reconstruction algorithm is 
simple: just do another Fourier 
transform of the hologram to return 
to ordinary space! Mathematically, if 
phase information is recorded, the 
operation of Fourier transforming is 
its own inverse, like the operation of 
inverting is for numbers. The recon- 
structed image comes back twice, 
symmetrically situated about the cen- 
tral zero-frequency spike, but it's easy 
to mask off one of the two images if 
necessary . 

The 2DFT program is quite capable 
of taking simple holograms and re- 
constructing them. Because the trans- 
formation is done on a 40 by 40 grid, 
but only the central 25 rows of forty 
elements are kept and displayed, 
some of the high vertical frequencies 
in the original image will be lost. 
(That explains the vertical spreading 
of some of the reconstructions, 
especially noticeable in the central 
region.) It's best not to try to recover 
images with too much fine detail. If 
the original is made of lines at least 
two cells thick, it usually comes back 
quite recognizably. 

Note that the bright pointlike spot 
that provides the reference phase 
should be brighter than the rest of the 
original image being transformed; 
otherwise, the rest of the image tends 
to act as a (poor) reference phase for 



194 March 1981 © BYTE Publications Inc 



Circle 121 on inquiry card. 



The new 1421 
by Hazeltine: 

It can wear many faces. 




Looks can be deceiving. The 
new Hazeltine 1421 is more 
than a terminal — it's a 
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Hazeltine 1421 works with 

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So, even if your software 

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Getting to know the Hazeltine 1421 is easy. 
For the name of your nearest Hazeltine 
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Hazeltine Corporation, Computer Terminal 
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Telex: 96-1 435 

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Answers for XheAJUS,^ 




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(4) MOD-II UTILITY PACKAGE (Racet Computes)... 
adds important utilities to TRSDOS.. .copy files 
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repair bad directories. ..displays sorted directory of 
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disk ID. ..and more. ..$150. 

(5) ADVENTURE #1-#9 (Scott Adams - Adventure 
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your way through a maze of obstacles in order to 
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package includes all 9 Adventures written by Scott 
Adams. ..$99. 95. 

(6) GSF (Racet Computers)... Generalized Subroutine 
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utilities that can be called from a BASIC program (no 
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items in under 5 seconds.. .allows PEEK and POKE 
statements ..move data blocks.. .compress and un- 
compress data. ..works under TRSDOS ..$50. 

(7) DSM (Racet Computes)... Disk Sort Merge ...sorts 
and merges large multiple diskette files on a 1 to 4 
drive system... NOT AN IN MEMORY SORT...can 
actually alphabetize (or any other type of sort) 4 disk 
drives worth of data. ..sorts one complete disk of 
information in 10 minutes. ..information is provided to 
use DSM with the RS MAILING PROGRAM. ..works 
under TRSDOS. ..$150. 

(8) RSM (Small Systems Software) ...a machine 
language monitor and disassembler.. .can be used to 
see and modify memory or disk sectors. ..contains all 
the commands found on the Model-I version plus 
some additional commands for the MOD-II. ..works 
under TRSDOS... $39.95. 

(9) BLINK BASIC LINK FACILITY (Racet Computes).. 
Link from one BASIC program to another saving all 
variables... chain programs without losing variables 
...$50. 

(10) BASIC CROSS REFERENCE UTILITY (Racet 

Computes) ...lists all variables and strings used in a 
program (with the line numbers in which they appear) 
...lists all GOTO's and GOSUB's (with the line num- 
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variables or strings (with the line number in which 
they appear). ..$50. 

(1 1> DEVELOPMENT PACKAGE (Racet Computes)... 
SUPERZAP (to see. print or change any byte on a 
diskette)... Disassembler and MOD-II interface to the 



MICROSOFT EDITOR ASSEMBLER PLUS including 
uploading services and patches for Disk l/0..assemble 
directly into memory. ..save all or portions of source 
to disk... dynamic debug facility (ZBUG)...entended 
editor commands. ..$125. 

(12) HARD/SOFT DISK SYSTEM (Racet Computes)... 
The software essential to interface any of the popular 

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megabytes oistorage (and larger). ..directory expand- 
able to handle thousands of files ...$400. 

(13) CAMEO HARD DISK DRIVE CONTROLLER. 

coming soon (November 1?) 

(14) HARD DISK DRIVES... coming soon (Nov. 17). 

(15) H & E COMPUTRONICS, INC. SHARE-A- 
PROGRAM DISKETTE #1... works under TRSDOS... a 
collection of programs written by MOD-II owners... 
programs include data base management ...a word 
processor. ..mail system. ..mortgage calculations... 
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a program that can be added to the SHARE-A-PRO- 
GRAM DISKETTE. 

(16) WABASH CERTIFIED DISKETTES.. $39.95 (per 
box of 10). 

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plates and adjustable spacing. ..$44 95. 

(18) MASTER PAC 100. ..100 essential programs... 
BUSINESS.. .PERSONAL FINANCE.. . STATISTICS- 
MATH. ..GAMBLING... GAMES., includes 125 page 
manual and 2 diskettes... $99.95. 

(19) BUSINESS PAC 100. .100 essential business 
programs. .INVENTORY CONTROL.. PAYROLL... 
BOOKKEEPING SYSTEM ...STOCK CALCULA- 
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COUNTS RECEIVABLE.. .ACCOUNTS PAYABLE... 
includes 1 25 page manual and twodiskettes... $149. 95. 

(20) EDITOR ASSEMBLER (Galactic Software Ltd.)... 
the first user oriented Editor Assembler for the 
MODEL II and was designed to utilize all the features 
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...$229.00. 

(21) BASIC COMPILER (Microsoft) ...changes your 
source programs into machine language. ..increases 
program execution by 3-10 times.. ,$395. 

(22) MAIL/FILE SYSTEM from Galactic Software Ltd. 
stores 2,500 names per disk. No sorting time is 
required since the file is automatically sorted by first 
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alphanumerica Zip. Supports a message line. Comes 
complete with user-oriented documentation (100- 
page manual). Allows for company name and individ- 
ual of a company and complete phone number (and 
extension). ..works under TRSDOS. ..$199.00 

(23) INCOME TAX PAC ...Professional income tax 
package. ..most forms and schedules. ..output to video 
or line printer... automatic memory storage of all 
information ... data can be loaded from diskette, 
changed and edited. ..built in errorchecking... $199.95. 

(24) COMPUTER GAMES (SBSG)...Mean ChBCker 
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(1) CP/M (Lifeboat Associates) an alternative 

operating system for the MOD-II that allows MOD-II 
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available under CP/M... $170. 

(2) CP/M HANDBOOK...(Sybex)...a step-by-step 
guide to CP/M ...takes the reader through each of the 
CP/M commands... numberous sample programs... 
practical hints., reference tables. ..$13. 95. 

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ACCOUNTS PAYABLE, INVENTORY CONTROL, 

AND PAYROLL(PeachtreeSoftware)...requires CP/M 
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modules or as a coordinated system ..$500 per 
module.. $2500 for the complete system. 

(4) WORD-STAR... The ultimate word processor.. .a 
menu driven word processing system that can be used 
with any printer. All standard word processing 
commands are included. ..plus many unique com- 
mands only found on WORD STAR. ..requires CP/M 

..$495. 

(5) MAIL LIST MERGE. ..An add on package that 
allows the user to send form letters (created on 
WORD-STAR) to any compiled mailing list (using any 
CP/M based MAIL program such as the PEACHTREE 
MAIL PROGRAM). ..requiresCP/M, WORD STAR and 
andy CP/M based mail program. ..$150. 

(6) SELECTOR III (Micro-Ap)...complete data 
management system... user defined fields and codes... 
manages any list defined by the user. ..includes 
additional modules for simplified inventory control. 
accounts receivable and accounts payable. ..requires 

, CBASIC-2„.$295. 

(7) SELECTOR IV (Micro-Ap)...the ultimate data 
management system. ..all features use the SELECTOR 
III plus, .data file format conversions... full page report 
formatter. ..computations. ..global search and replace 
...hard disk compatible., data/text merging. ..$550. 

(8) GLECTOR (Micro-Ap)...add on package to the 
SELECTOR ..general ledger that allows the user to 
define a customized chart of accounts ...$350. 

(9) CBASIC-2 a non-inte*active BASIC used for 
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make more efficient use of disk files. ..eliminates the 
use of most line number references. ..require on such 
programs as the SELECTOR. ..$120. 

(10) MICROSOFT BASIC. ..an enhanced version of the 
MICROSOFT BASIC found on TRSDOS...adds 

i commands such as chaining (allows the user to LOAD 
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the BASIC COMPILER to speed up programs (3-10 
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(11) MASTER TAX (CPAids) ...professional tax 
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payroll register. W2's and payroll checks. ..$450. 

(13) ELECTRIC PENCIL (Michael Shrayer Software) 
.Complete word processor with extensive editing 

and printer formatting features.. .$275 (Standard 
printer version)...$300 (DIABLO. NEC or OUME 
version). 

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source programs into machine language. ..increases 
program execution by 3-10 times. .5395. 

• (CP/M IS A REGISTERED TRADEMARK 
OF DIGITAL RESEARCH) 



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$ll/year Cor 12 issues) 



Circle 122 on Inquiry card. 



THE ORIGINAL MAGAZINE FOR 
OWNERS OF THE TRS-80 ™* MICROCOMPUTER 



SOFTWARE 

FOR TRS-80 - 

OWNERS 



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MONTHLY 

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FOR TRS-80 
OWNERS 



MONTHLY NEWSMAGAZINE 

Practical Support For Model I, II & HI 



PRACTICAL APPLICATIONS 
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GAMBLING • GAMES 
EDUCATION 
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BEGINNERS CORNER 
NEW PRODUCTS 
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MARKET PLACE 
QUESTIONS AND ANSWERS 
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AND MORE 



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PROGRAMS AND ARTICLES PUBLISHED IN OUR FIRST 12 ISSUES 
INCLUDE THE FOLLOWING: 

A COMPLETE INCOME TAX PROGRAM (LONG AND SHORT FORM) 

INVENTORY CONTROL 

STOCK MARKET ANALYSIS 

WORD PROCESSING PROGRAM (FOR DISK OR CASSETTE) 

LOWER CASE MODIFICATION FOR YOUR VIDEO MONITOR OR PRINTER 

PAYROLL (FEDERAL TAX WITHHOLDING PROGRAM) 

EXTEND 16 DIGIT ACCURACY TO TRS-80"' FUNCTIONS (SUCH AS 

SQUARE ROOTS AND TRIGONOMETRIC FUNCTIONS) 

NEW DISK DRIVES FOR YOUR TRS-80'" 

PRINTER OPTIONS AVAILABLE FOR YOUR TRS-80'" 

A HORSE SELECTION SYSTEM***ARITHMETIC TEACHER 

COMPLETE MAILING LIST PROGRAMS (BOTH FOR DISK OR CASSETTE 

SEQUENTIAL AND RANDOM ACCESS) 

RANDOM SAMPLING***BAR GRAPH 

CHECKBOOK MAINTENANCE PROGRAM 

LEVEL II UPDATES***LEVEL II INDEX 

CREDIT CARD INFORMATION STORAGE FILE 

BEGINNER'S GUIDE TO MACHINE LANGUAGE AND ASSEMBLY 

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LINE RENUMBERING 

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DATA MANAGEMENT SYSTEM Complete file management for your TRS-80". 
CLEANUP Fast action Maze Game. 

ADVENTURE Adventure »0 by Scott Adams (From Adventureland International). 
* All programs are supplied on cassette (add $3 for Diskette Version - add $5 for modified Mod-ll Version). 



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Texas Instruments 



INCORPORATED 





Stock market programs, oil field 
calculations, real estate software, and 
data for insurance rates are some of 
the many programs originally written 
for the TI 59/58 calculator and 
then converted to a custom Solid 
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or individuals can permanently 
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their unique software in this 
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The services at American Micro 
range from shipping finished modules 
created from submitted formulas or 
programs to renting and selling the 
emulator software system that 
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COSTS 

Programs less than 

1000 steps $26/module 

Programs between 1000 and 

2000 steps $36/module 

Programs between 2000 and 

5000 steps $48/module 

Minimum order is 250 modules 

705 Bowser ^ILi'-VA 

Richardson, Texas 75080 
(214) 238-1815 

198 March 1981 © BYTE Publications Inc 



the bright spot. Also note that some 
errors come in due to overflow and 
truncation, as only 8 bits of the 
hologram are recorded on the dis- 
play. If you want to, you can turn the 
holographic display of numbers into 
a density-plot image for inspec- 
tion—but the resulting truncation to 
about 3V2 bits means still more noise 
in the reconstructed image. 

It's quite educational to delete a few 
points (or a sizable fraction) of the 
hologram, and still see the entire 
original picture be reconstructed from 
the remaining fragment. (It may be 
desirable to change the density-plot- 
ting gray-scale factors in some cases, 
as the image reconstructed from a 
partially removed hologram is fainter 
than the usual result.) These are only 
a few suggestions — try inventing ex- 
periments of your own! 

A final word about very -long-base- 
line interferometry: if it is known that 
the astronomical object under obser- 
vation contains a bright, pointlike 
source in or near itself, it is possible 
to completely reconstruct a map of 
the original source. The bright spot 
acts as a phase reference for the radio 
astronomers. In fact, what they're re- 
constructing is just a Fourier-trans- 
form hologram — but on a galactic 
scale! 

Further Work 

After a program is written, it's 
always possible (and sometimes prof- 
itable) to go back and see how it 
could have been done differently, and 
perhaps better. The 2DFT program is 
no exception; I have several ideas for 
improvements and modifications, 
some of which you may wish to try. 
First, now that I know not to be 
afraid of cutting off parts of the 
holographic image, I've wondered 
whether a 64- by 64-cell transform 
would be the best step up. Since the 
dimensions are powers of two, it 
would be possible to use the fast- 
Fourier-transform algorithm and save 
time by at least a factor of 6 (the 
logarithm of 64 to the base 2) over the 
slow method. I also think that it 
might be worthwhile to use fewer bits 
during the transform, since overflows 
haven't been as deadly as I feared 
before starting the project. Perhaps 
integer arithmetic with 1 or 2 bytes 
for the numbers would work; it 
would certainly save space and time 
over the 5-byte floating-point meth- 



ods that are used by the PET's firm- 
ware algorithms. (BASIC integer 
operations on the PET are actually 
done almost entirely in floating-point 
arithmetic; the only benefit of in- 
tegers that I know of is to save 
memory in large arrays.) 

I've seen comments about 1-bit 
Fourier transforms in some refer- 
ences. If that is a reasonable tech- 
nique, you could use the Vi-cell 
graphics capabilities of the PET 
screen to display 50- by 80-pixel 
transformed images. 

Finally, there must be a better way 
to find the amplitude of the trans- 
formed data than to take the square 
root of the sum of the squares of the 
sine and cosine parts. (The PET's 
floating-point square-root algorithm 
simply raises the argument to the 
Vz power, by taking a logarithm, 
multiplying, and exponentiating. It's 
not overly fast!) Perhaps a little table 
lookup could get a fast square root 
with sufficient accuracy for display 
purposes. 

There are surely other improve- 
ments to be made on 2DFT. But as it 
is, it has provided me with a powerful 
learning tool. I've developed a more 
intuitive understanding of holo- 
graphy and the Fourier-transform 
process than I ever had before... and 
it's been fun! I hope you enjoy it as 
much.B 



References 

1. Beasley, M J. Lasers and Their Applica- 
tions. Taylor & Francis Ltd, 1976. 

2. Bracewell, Ron. The Fourier Transform 
and Its Applications. New York: McGraw-Hill, 
1965. 

3. Cathey, W Thomas. Optical Information 
Processing and Holography. New York: John 
Wiley & Sons, 1974. 

4. Cohen, Marshall H. "High-Resolution 
Observations of Radio Sources." Annual 
Reviews of Astronomy and Astrophysics, 
volume 7, 1969. 

5. Collier. Robert J, Christoph B Burckhardt, 
and Lawrence H Lin. Optical Holography. 
Academic Press, 1971. 

6. DeVelis, John B and George O Reynolds. 
Theory and Applications of Holography. 
Reading MA: Addison-Wesley, 1967. 

7. Gabor, Dennis. "Holography, 1948-1971." 
Lecture givenon the acceptanceofthe Nobel 
Prize in physics, 1971. Reprinted in Laser 
Devices and Applications, edited by Ivan P 
Kaminow and Anthony E Siegman, IEEE 
Press, 1973. 

8. Ryle, M. "Radio Telescopes of Large 
Resolving Power." Lecture given on the ac- 
ceptance of the Nobel Prize in physics, 1974. 
Reprinted in Reviews of Modern Physics, 
volume 47, number 3, July 1975. 



Who will be first 
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BYTE March 1981 



199 



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Editorial. 



Text continued from page 10: 

listed at the end of this editorial. 

"It looks like too much trouble": Most of the things 
you'll need to do are easy and make sense. After a while, 
they will become so natural that you'll wonder how you 
ever did without them. 

"/ don't have the time to spare — I'm on a tight 
deadline": You have time to debug, don't you? And you 
have time to fix that bug that appears six months after 
you wrote the program. Actually, the techniques of 
design (which include structured programming during the 
program design and implementation) take up less time 
due to decreased time in testing, debugging, and 
maintenance. In fact, what you're doing is spending more 
time in design (doing it right) and less time in testing and 
debugging (finding and fixing what you didn't do right 
the first time). 

"It takes all the fun (or mystery) out of programming": 
This is a difficult question to answer because there's an 
element of truth in it. But what do you mean by "fun"7 If 
you mean surprises or adventure, you're right — there's 
less of that because you know more of what is going to 
happen before you start coding; on the other hand, 
there's less frustrating debugging. There's less exultation 
when a program finally works — but there's also quite a 
bit of pride in the knowledge that it will stay working. 
Proper design takes some of the mystery out of program- 
ming. Programming becomes a skill, but it is designing 
that becomes the art. 

Finally, if you are programming for a living, 
haphazard programming may be "fun," but can you af- 
ford such fun? Untraceable bugs and unreliable programs 
decrease your productivity and your effectiveness. Can 
you and your company afford that? 

Some Design Tools 

The following briefly describes three design tools that 
have been available for at least five years. Data flow 
diagrams (DFDs) are usually used on large projects, 
although they can help clarify your thinking on simpler 
ones. They force you to clarify what information is being 
manipulated and how it "flows" through the project. On 
a level of design several steps closer to coding, structure 




Figure 2: An example of a data flow diagram (DFD). The circles 
represent processes (or actions) we are interested in within a 
system. The boxes represent external systems. The parallel lines 
represent data files (often called data stores), and the lines repre- 
sent groupings of data that are transformed by the process. 



200 



March 1981 © BYTE Publications Inc 



Circle 125 on inquiry card. 



Volume II 



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Editorial. 



charts are hierarchical models of a system that emphasize 
the tasks and subtasks to be performed and the data that 
passes among them. Finally, on the lowest level of design 
before coding, structured pseudocode is an informal 
English-like coding that allows you to experiment with 
implementing the logic of a program without being 
bothered with the narrow grammar of a particular com- 
puter language. Although I'll give an example and a short 
explanation of each method, you should refer to some of 
the books described at the end of this editorial for further 
details. 

An example of a data flow diagram is given in figure 2. 
The circles represent processes we are interested in (ac- 
tions being performed, not states of the system), and the 
arrows represent some grouping of data that is being 
transferred from one activity to another. The rectangular 
boxes represent other systems that interact with our 
systems but that are not of interest to us. If the arrows 
lead out of these boxes, they are called sources; if the ar- 
rows lead in, they are called sinks. The two parallel lines 
represent data files (also called "data stores") that store 
information for later use; depending on the file, arrows 
may go in both directions. 

Data flow diagrams are usually used in groups, with 
one diagram representing the interaction of the system 
with external systems (one circle interacting with several 
boxes) and each of the other diagrams representing one 
circle from a "higher" diagram. For example, figure 3a 
shows an overview DFD of (a simplified version) the in- 



teraction between the BYTE editorial department and the 
rest of the world. Figure 3b shows an expansion of the 
single circle in figure 3a. Further data flow diagrams can 
be used (if needed) to subdivide a given process. 

When a set of DFDs covers several levels, the circles in 
the subordinate diagram reflect the identity of the parent 
circle. For example, the processes (circles) in a diagram 
representing process 1 of figure 3b ("log in and schedule 
manuscripts") would be numbered 1.1, 1.2, 1.3, and so 
on; similarly, subordinate processes of 1.3 would be 
labeled 1.3.1, 1.3.2, 1.3.3, and so on. 

A data flow diagram is useful only when it meets cer- 
tain criteria. Although I can't give all the dos and don'ts, 
the following points are helpful: First, take care that 
circles represent meaningful data transformations and ar- 
rows represent meaningful collections of data. For exam- 
ple, "read card deck" is not a meaningful transformation, 
but "classify incoming orders" is. 

Second, with one exception, the inputs and outputs to 
a given diagram must be the same as those for the single 
process the diagram represents in the next higher 
diagram. This rule makes sense, and checking diagrams 
for compliance often alerts you to some data flow you've 
ignored. The one exception to this rule is that arrows for 
rejected data on one level are not shown in the next 
higher level (for example, see "manuscripts with no name 
or return address" coming out of process 1 in figure 3b); 
the reason for this convention is to avoid cluttering up 
the diagrams. 




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202 March 1981 © BYTE Publications Inc 



Circle 126 on inquiry card. 



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BYTE March 1981 



203 



Editorial, 

(3a) 





NCOMING 
MANUSCRIPTS 


BYTE 

EDITORIAL 
DEPARTMENT 1 










FINISHED 
1 MANUSCRIPT 




AUTHORS 


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REJECTED I 
MANUSCRIPT \ 
WITH LETTER^ 












ACCEPTANCE 
LETTER AND CHECK 







MANUSCRIPTS WITH 
PRIMARY EDIT DONE 




Figure 3: Overview and detailed data flow diagrams. Figure 3a shows an overview data flow diagram of the interaction of the BYTE 
editorial of fice with the rest of the world. Figure 3b is a detailed data flow diagram showing the workings of circle in figure 3a. (The 
system shown has been simplified for purposes of illustration.) 



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BYTE March 1981 205 



Editorial. 



Third, data flow diagrams should show the logical 
flow of data, not its physical flow in an existing 
system — a DFD is not a flowchart. For example, circle 1 
in figure 3b should not be labeled "Karen," even though 
she logs all incoming manuscripts. 

In conclusion, the data flow diagram is a planning tool 
used in the early stages of design. It can clarify the flow of 
data in either an existing or a proposed system. You'll 
probably draft many versions of a data flow diagram 
before you arrive at a satisfactory version — this is a nor- 
mal and unavoidable consequence of your increased 
understanding of the system and the improvements you 
are making in its design. 

It's particularly important to use data flow diagrams 
when you are working for someone other than yourself 
(for example, a partner or client) because DFDs give you 
an easily understood document from which the other per- 
son can contribute at an early stage in the design process. 
This early feedback can often prevent costly backtrack- 
ing in the later stages of system implementation. 

The Structure Chart 

Structure charts are used later in the design process, 
when you know what a system (or program) is to do but 
want to organize the design and interaction of modules. 
Structure charts can be used to design either a single pro- 
gram or a system of programs; if you are designing a 
system, a finished structure chart will suggest logical 
ways in which to group the modules of the system into 
programs. 

In a structure chart (see figure 4), rectangular boxes 
represent modules that perform a given action. The 
organization of the modules is determined by the arrows 
interconnecting them; the one being pointed to is used by 
the one doing the pointing to carry out its task. The 
modules communicate in much the same way as people 
do in a military hierarchy: the higher (calling) modules 
are organizers, sending orders to the ones below; the 
lower (called) modules are workers, performing their 
tasks (often calling modules that they command) and 
reporting back to their superiors. However, in this situa- 
tion, it is the data that is transmitted up and down be- 
tween modules. The structure chart records this move- 
ment. The arrow that begins with an outline circle 
represents data being passed (eg: an employee record, a 
part number), and an arrow beginning with a filled-in cir- 
cle represents a logical flag (eg: transaction-valid or 
invalid-account-number flag). 

Figure 5 i s a n example of a structure chart a t work. The 
task being illustrated (top box) is the writing of an (im- 
aginary) order for a final article payment to a BYTE 
author. Note that the data can pass both up and down, 
depending on the situation, but that logical flags almost 
always pass yes/no-type control information up to a call- 
ing module. The vertical lines on the box "get valid article 
record" (in the second row of figure 5) indicate that it is a 
library module that can be used as is from an existing 
library of routines. 

A structure chart shows the subdivision of a system in- 
to modules, the hierarchy of those modules, and the data 
that passes among them. It does not imply anything 
about the method used to implement a module, nor does 
it imply a left-to-right execution sequence for modules on 



the same row. Again, the main benefit of structure charts 
is the clarity of design they produce. Creating the struc- 
ture chart forces you to be precise about what needs to be 
done. Once completed, the structure chart gives you the 
opportunity to find logical design flaws and to check for 
overall completeness. As with the data flow diagram, 
you'll probably write several versions of the structure 
chart before you get one that will satisfy you; but, in do- 
ing so, you'll create a design that will lead to a much 
better system or program. 

Structured Pseudocode 

Structured pseudocode is used only after you've passed 
the boundary from system design to program design. By 
the time you're ready to use structured pseudocode, you 
have already specified the function of the program and 
some of its implementation details. Writing structured 
pseudocode is like writing a program for an imaginary 
machine that understands English-like phrases; it is a 
"test run" for the real thing, coding the actual program in 
the strict grammar of BASIC, FORTRAN, or some other 
computer language. Structured pseudocode tells what is 
to be done, the order it is done in, and how it is done. 
Once the structured pseudocode has been written, 
studied, and rewritten to your satisfaction, you can easily 
code your computer program from the pseudocode. 

Listing 1 gives a short example. The hypothetical task 
is to find the lump-sum payment for an article from a 
lookup table, given the classification number of the 
desired article (which is the key field of the lookup table). 
We'll assume that the lookup table has two fields, a 
classification number and a payment amount, and that a 
sequential search of the table is made to find the ap- 
propriate line. 

Listing 1 shows what's being done more clearly than an 
equivalent BASIC (or even Pascal) program because it's 
not concerned with rigorously expressing the algorithm 
in the narrow (and therefore less meaningful) grammar of 
the computer language. Still, since the pseudocode 
follows (or should be written to follow) the style of the 
target language, writing the actual program is simply a 
matter of expanding the lines of pseudocodes to take care 
of all the necessary details. For more information on con- 



CALLING 
MODULE 



DATA USED JO 

• FL 



DATA USED 




LOGICAL FLAG 
RETURNED 



Figure 4: An example of a structure chart. The boxes represent 
modules that perform specified actions, with the higher boxes 
pointing to the subordinate boxes that they use. An arrow with 
an outline circle represents a grouping of data, while an arrow 
with a filled circle represents a logical flag that transmits the 
results of some yes/no-type evaluation. 



206 March 1981 © BYTE Publications Inc 



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208 



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MICROPROCESSOR PROGRAM- 
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with diagrams, tables, and index. 
Tracks through the subject with 
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209 



Editorial ____^_— ^_^— _ 

verting structured pseudocode to BASIC, see my article, 
"Applied Structured Programming," in the book Pro- 
gram Design: Programming Techniques, Volume I (listed 
at the end of this editorial). 

At this point I'd like to break my earlier promise and 
say a few good words about structured programming, 
which is the design philosophy behind structured 
pseudocode. Structured programming asserts that any 
program can be written as a combination of three pro- 
gramming structures: a sequence of events, one of two 
events chosen by the value of a condition (the 
if. ..then... else construct), and an event repeated as long 
as a condition is true (the while... do construct). Struc- 
tured programming goes hand-in-hand with top-down 
design (also called programming by stepwise refinement), 
which says that you solve a programming problem by 
breaking it into subproblems and continually subdivide 
these subproblems until each one can be easily coded. 
This process results in manageable, modular programs 
that are easy to understand, debug, modify, and main- 
tain. The importance of such advantages cannot be 
overemphasized, especially if you program for a living. 

Some Good Books 

You will find the following books helpful if you're in- 
terested in structured programming, program design, or 
system design. The first books deal primarily with struc- 
tured programming and program design, while the latter 
ones go deeper into long-range design. 

Programming Proverbs by Henry F Ledgard (Hayden 
Book Company, Rochelle Park NJ, 1975): This is a 



friendly, but thorough, folk classic on methodical pro- 
gramming. It contains 26 proverbs with examples and 
some additional material on top-down design, and it can 
be read and understood by almost everyone with some 
programming experience. The languages used in the ex- 
amples are ALGOL 60 and PL/ 1. The author, along with 
several coauthors, has tailored the same material for dif- 
ferent books that emphasize FORTRAN, COBOL, 
BASIC, and Pascal. The titles are: FORTRAN (or 
COBOL or BASIC or Pascal) with Style: Programming 
Proverbs. All are published by Hayden Book Company. 

The Elements of Programming Style, Second Edition 
by Brian W Kernighan and P J Plauger (McGraw-Hill, 
New York NY, 1978): Written in the style of Strunk and 
White's Elements of Style (the English language style 
book), it is slightly more formal and not as folksy as Pro- 
gramming Proverbs. It covers its material more 
methodically than Programming Proverbs does. 

A Collection of Programming Problems and Techni- 
ques, by H A Maurer and M R Williams (Prentice-Hall, 
Englewood Cliffs NJ, 1972): I've always enjoyed leafing 
through this book because of all the tidbits of informa- 
tion it possesses. It includes such diverse information as 
the Ackermann function, algorithms involved with 
reverse Polish notation, and information on generating 
magic squares and solving simultaneous equations by the 
Gauss-Seidel method. An excellent book for problem 
ideas if you're teaching programming or need a short, 
nontrivial problem to illustrate a point. 

Software Debugging for Microcomputers, by Robert C 
Bruce (Reston Publishing Co, Reston VA, 1980): 



WRITE ARTICLE 
CHECK ORDER 



ARTICLE 
NUMBER 



1REC0RD- 
NOT-FOUNC 
FLAG 



ARTICLE 
RECORD 



CLASSIFICATION- ♦ 
INVALID FLAG | 



GET VALID 

ARTICLE 

RECORD 



CLASSIFICATION 
NUMBER 



LOOKUP 
TABLE 



CALCULATE 
CHECK AMOUNT 
FOR LUMP-SUM 
ARTICLE FROM 
LOOKUP TABLE 



ARTICLE 
RECORD 



CHECK 
AMOUNT 



CALCULATE 
CHECK AMOUNT 
FOR PER-PAGE 
ARTICLE 




ARTICLE 
RECORD 



CHECK 
AMOUNT 



WRITE ORDER 
FOR CHECK 



GROSS AMOUNT 
FOR CHECK 



DEDUCT AMOUNT 
ALREADY PAID 



Figure 5: Another example of a structure chart. The (hypothetical) action illustrated is the generation of an order for a check for final 
payment to a BYTE author for an article. The vertical bars on the first and last boxes in the middle row represent predefined modules 
that can be used in different situations. 



210 March 1981 © BYTE Publications Inc 



dBASE II vs. the Bilge Pumps. 



by Hal Pawluk 

V\fe all know that bilge pumps suck. 

And by now, we've found out— the hard 
way— that a lot of software seems to work the 
same way. 

So I got pretty 
excited when I ran 
across dBASE II, an 
assembly-language rela- 
tional Database Man- 
agement System for 
CP/M. It works! And 
even a rank beginner 
like myself got it up 
and running the first 
time I sat down with it. 

If you're looking 
for software to deal with 
your data, too, here are 
some tips that will help: 

Tip #1: Database Management 
vs. File Handling: 

Any list or collection of data is, loosely, 
a data base, but most of those "data base man- 
agement" articles in the buzzbooks are really about 
file handling programs for specific applications. 
A real Database Management System gives you 
data and program independence (no repro- 
gramming when data changes), eliminates data 
duplication and makes it easy to turn data into 
information. 

Tip #2: Assembly 
Language vs. BASIC: 

This one's easy: if you're setting up a 
DBMS, you're going to be doing a lot of sorting, 
and Basic sorts are s-l-o-w. Run a benchmark on 
a Basic system like S*-IV against a relational 
DBMS like dBASE II and you'll see what I mean. 
(But watch it: I've also seen one extremely slow 
assembly-language file management system.) 

Tip #3: Relational vs. Hierarchal 
& Network DBMS. 

CODASYL-like hierarchal and network 
systems, around since the 1960's, are being 
phased out on the big machines so why get stuck 
with an old-fashioned system for your micro? A 
relational DBMS like dBASE II eliminates the pre- 
defined sets, pointers and complex data structures 
of a CODASYL-type DBMS. And you don't need 
to be a programmer to use it. 




dBASE II vs. everything else. 

dBASE II really impressed me. 
Written in assembly language (with no 
need for a host lan- 
guage), it handles up to 
65,000 records (up to 32 
fields and 1000 bytes 
each), stores numeric 
data as packed strings 
so there are no round- 
off errors, has a super- 
fast multiple-key sort, 
and supports ISAM 
based on B* trees. 

You can use it 
interactively with 
English-like commands 
(DISPLAY 10 PROD- 
UCTS), or program it 
(so when you've set up the formats, your secretary 
can do the work). Its report generator and user- 
definable full screen operations mean that you can 
even use your existing forms. 

And if all this makes your mouth water, but 
you've already got all your data on a disk, that's 
okay: dBASE II reads your ASCII files and adds 
the data to its own database. 

Right now, I'm using dBASE II with my 
word processor for budgeting, scheduling and 
preparing reports for my clients. 

Next come job costing, time billing and 
accounting. 

An Unheard-of Money-Back 
Guarantee. 

dBASE II is the first software I've seen 
with a full money-back guarantee. 

To check it out, just send $700 (plus tax in 
California) to Ashton-Tate, 3600 Wilshire Blvd., 
Suite 1510, Los Angeles, CA 90010. (213) 666-4409. 
Test dBASE II doing your jobs on your computer 
for 30 days. If, for some strange reason, you don't 
want to keep it, send it back and they'll refund 
your money. 

No questions asked. 

They know you don't need your bilge 
pumped. 



AshtonTate 



©AshtonTate 1980 



Circle 131 on inquiry card. 



BYTE March 1981 



211 



Editorial , 



Although this book has little to do with structured pro- 
gramming or design, I mention it because of its thorough 
treatment of debugging techniques. If you're interested in 
such debugging techniques as forcing, block debugging, 
snapshots, and patching, you should read this book. 

Listing Is Structured pseudocode for a routine to find a value 
from a lookup table. The lookup table contains two fields, 
classification-number and check-amount , and this routine finds 
the appropriate check-amount by matching a given classifica- 
tion number to the classification numbers in the table. A sequen- 
tial search is used, starting at the top of the table. If a 
classification-number match is made, the check-amount needed 
is the check-amount entry in the same line, and the error-flag 
(for the information of the calling routine) is cleared. If no 
match is made, check-amount is set to zero and the error-flag is 
set. 

while not-at-end-of-file and match-not-found 

compare classification number of current line with classification 

number sought 

ii the two are equal 

check-amount sought is check-amount field in current line 
eke 

add 1 to table-index 
endil 
endwhile 

ii no-match-found 
set error-flag 
eke 
check-amount = 
clear error-flag 
endil 
return (to calling routine) 



Program Design: Programming Techniques, Volume I, 
edited by Blaise W Liffick (BYTE Books, Peterborough 
NH, 1978): This book contains new material and articles 
reprinted from BYTE. Subjects include "Top-Down 
Modular Programming;" "Some Words About Program 
Structure" (both by Albert D Hearn); "Applied Struc- 
tured Programming" (by me); "Decision Tables: How to 
Plan Your Programs" (by Thomas G Bohon), and several 
other helpful articles. My only regret is that several ar- 
ticles include what are called "Warnier-Orr diagrams," a 
program design technique I do not recommend. 

A Primer on Structured Program Design, by Gary L 
Richardson, Charles W Butler, and John D Tomlinson 
(Petrocelli Books, New York NY, 1980): This book 
covers structured programming and program design, but 
it also touches on the larger elements of system design. 
One nice feature is that it briefly lists several different 
design tools in order to help you choose the one you like 
best. 

Classics in Software Engineering, edited by Edward 
Nash Yourdon (Yourdon Press, New York NY, 1979): I 
cannot say enough good things about this book. It is a 
compilation of all the pivotal papers in the fields of struc- 
tured programming (both theory and practice), program 
and system design, and other related fields. Not only is it 
extremely convenient to have these articles gathered 
together, it's also the only way most people will ever see 
them (since many of the articles appeared in the pro- 
ceedings of computer conferences as many as 15 years 
ago). By reading the articles (and the excellent introduc- 




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BYTE March 1981 213 



GET THE 

SOFTWARE THAT'S 

GOING PLACES. 

THE UCSD p-SYSTEM: 

You want a copy of the exciting software system that's 
going places. Professionals everywhere are using the 
UCSD p-System. Now, you can have it. The UCSD 
p-System offers: a complete software development system, 
your choice of languages, and a portable system that 
runs on your microcomputer today and tomorrow. Send in 
the coupon below and join the pros today. Phone orders 
accepted with Visa or Master Card. 

Yes, I want the software system that's going places— 
the UCSD p-System. Here's my order: 

UCSD p -System* (Version I V.O) including documentation: 

□ with UCSD Pascal™ Compiler $500.00 

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□ with UCSD Pascal and FORTRAN-77. $750.00 

□ BASIC Compiler Add-On $150.00 

□ Assemblers Package (cross-assemblers) 

for Z-80, 6502, 6800, 6809, 
8080, 9900, Z8, PDP-11™/ 
LSI-11™ $250.00 

□ Complete UCSD p-System with UCSD Pascal 

Documentation Set $50.00 

□ Send me more information (general) 

□ Send distributor information 

□ Send information on the availability of systems for the 
6800, 6809, and/or 9900 processors 

My system has: (check only one) 

□ CP/M® Version 1.4 

□ CP/M Version II.O with 128-byte sectors 

□ 8080 or Z80 processor without CP/M (requiring some 
assembly language programming) 

□ 6502 processor (requiring some assembly language pro- 
gramming) 

□ PDP-11 with D RX01 □ RX02 (check one) 

□ LSI-11 with □ RX01 □ RX02 (check one) 

NOTE: (pertaining to two items above) For availability of RK05 and RL01 disk 
drivers, contact SofTech Microsystems. 

*System requires 48K contiguous RAM. Software is 
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Allow six weeks for delivery. 



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Corporation. LSI-11 and PDP-11 are trademarks of Digital Equipment Corporation.) 

La ^^ <^B M <^» <^» ^^ <^» W <^B <^» MM ^B <^» ^^ M^J 



Editorial. 



tions to each article, written by Mr Yourdon), you can 
see how the key ideas in the field formed and grew. The 
highly theoretical article, "Flow Diagrams, Turing 
Machines, and Languages with Only Two Formation 
Rules," by C Bohm and G Jacopini, contains the 
theoretical rigorous proof that any program can be writ- 
ten using only sequence, choice (if... then... else), and 
iteration (while. ..do). Although I don't have the room to 
list all the articles in this 424-page book (most of which 
are remarkable in some way), I must mention "The Hum- 
ble Programmer," by Edsger Dijkstra; "Revolution in 
Programming: An Overview," by Daniel McCracken, 
and the monumental "Structured Programming with go 
to Statements," by Donald Knuth. 

The Practical Guide to Structured Systems Design, by 
Meilir Page-Jones (Yourdon Press, New York NY, 1980): 
This is a very readable book explaining the latest design 
techniques. I enjoyed reading it, and I referred to it con- 
stantly while writing this editorial. It covers the three 
techniques discussed above, as well as several I didn't 
have room for (the concept of a "data dictionary," for 
one), and it is greatly enhanced by the inclusion of a com- 
plete case study of a system designed using the methods 
given in the book. The book concentrates on the design 
process and talks only briefly of structured programming 
and program design. Also, it presents much the same 
material as the next two books (which come before it 
chronologically), with a slight reduction in complexity 
and a slight increase in readability. I recommend that you 
read this book first. 

Structured Analysis and System Specification by Tom 
DeMarco (Prentice-Hall, Englewood Cliffs NJ, 1979): 
This book covers much the same material as the 
preceding book, but it treats the subjects covered more 
rigorously and a bit more formally. It also addresses the 
special problem of modeling and designing very large 
systems that don't yet exist. 

Structured Design: Fundamentals of a Discipline of 
Computer Program and Systems Design, by Edward 
Yourdon and Larry C Constantine (Prentice-Hall, 
Englewood Cliffs NJ, 1979): This book is the parent of the 
two just described (the first publication of this book was 
in 1975, and the authors of all three books come from the 
same school of design). Because it was written to describe 
its design techniqes for the first time, the notation used is 
a bit cluttered (compared to the streamlined design used 
in the last two books), but this book is easily the most 
comprehensive and the most theoretical; it attacks the 
problem of program design on the broadest level. Par- 
ticularly important are the ideas of coupling and cohesion 
among program modules, each of which have separate 
chapters in the book. 

Conclusions 

If I had to give you one word to associate with the con- 
cept of design, that word would be forethought. Design is 
forethought — it's as simple as that. Few people would say 
that they program without forethought, but program- 
ming at the keyboard (or with a coding sheet) without 
design is the same as playing the piano without sheet 
music — more improvisation than rendition. So the ques- 
tion is no longer, "Is this really necessary?" It's "can you 
afford not to?"B 



214 March 1981 © BYTE Publications Inc 



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BYTE March 19B1 215 



Technical Forum 



DATALINE 



Daniel S Hunt, 829 Presidio Dr, Costa Mesa CA 92626 

There is a certain pleasure in writing assembly- 
language subroutines for my Microsoft BASIC system; 
however, the dismal tedium involved in hand-converting 
object code into BASIC data statements is unmatched. 

There are alternatives: one method is to put the object 
code into a data file and read it into memory for execu- 
tion by the program. The disadvantage with this method 
is that one must keep a separate file for what is in essence 
a subroutine. Besides, the file may be lost in a backup 
operation or during insouciant copying of the BASIC 
code to another disk. 

My solution for this problem was to write DATALINE. 
DATALINE is a BASIC program that takes freshly 
assembled object code and moves it into DATA 
statements so that the code can be integrated with the 
BASIC mainline source code. 

This program assumes that you are able to move object 
code into a memory area protected from BASIC. If you 
do not have the ability to move blocks of object code in 
this way, the concatenation routine can be joined with an 



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algorithm to read a .COM file character by character. 

To use DATALINE, load the object code into an area 
protected from BASIC. The program will prompt you for 
the load address, length of the program in 64-byte 
segments, a file name, and a starting line number. It 
peeks the object code byte by byte and concatenates a 
string conversion of each byte to a line composed of line 
number, " DATA ", plus appropriate spaces and com- 
mas between each byte value. Eight bytes are put on each 
data line. The line is filed serially, and it appears to 
BASIC to be a program file saved in "A" mode. You can 
merge the data lines with your BASIC program by using 
the MBASIC MERGE command. 

This program includes one of my most used library 
routines. This is a procedure that takes a hexadecimal- 
value input at the keyboard and converts it to decimal 
representation which can be used in PEEK and POKE 
statements. As the MBASIC 5.1 interpreter is intolerant 
of integer overflow, the conversion is to single-precision 
floating-point base 10, rather than integer. While integer 
conversion is possible, the extra speed gained in the exer- 
cise is not worth the extra code or the increased com- 
plexity. 

If your BASIC is an older version of Microsoft, merely 
reduce the length of the variable names where your inter- 
preter rejects one here. 



Listing 1: Written in Microsoft BASIC, this short routine takes 
the drudgery out of writing assembly-language subroutines for 
BASIC programs. The program rewrites object code as BASIC 
DATA statements, as shown in listing 2. 



MBASIC DATALINE WRITER 



Written by Daniel S. Hunt, April 25, 1980 
MBASIC 5.1 INTERPRETER / Sol-20 



10 REM 

100 ' 

110 

120 ' 

130 ' 

140 ' 

150 WIDTH 64 

160 PERSE = &HCOD5 : 'SOLOS CLEAR SCREEN CALL 

170 CALL PERSE:PRINT:PRINT 

180 PRINT "— MACHINE CODE / DATA LINE WRITER — ":PRINT 

190 INPUT "Enter hex base address of oject code ",HXIN$ 

200 GOSUB 350 :' CONVERT HEX STRING TO REAL DEC. 

210 DBASE = BASETEN 

220 INPUT "Routine length in 64-byte segments ".PAGES : 

LENGTH = PAGES * 64 
230 INPUT "Enter name of data statement file ",DFILE$ 
240 OPEN "0",1,DFILE$ 

250 INPUT "Enter line number of starting data statement ",LNUM 
260 LASTBYTE = DBASE + (LENGTH -1) 
280 GOSUB 570 :'CREATE DATA LINES 
290 CLOSE 
310 ' 
320 ' 

330 REM - CONVERTS HEX INPUT STRING TO DECIMAL — 
340 ' 

350 CUME = 

360 HDATJ = "0123456789ABCDEF" 
370 CHARPOS% = LEN(HXINS) 
380 FOR 1% = 1 TO LEN(HXIN$) 
390 ADDER =0 

400 FOR 1% = 1 TO LEN(HDATS) 

410 IF MID$(HXIN$,I%,1) = MID$(HDAT$,I%,1)THEN 

ADDER = J% - 1 Listing 1 continued on page 218 



216 March 1981 © BYTE Publications Inc 



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BITE March 19B1 217 



Circle 138 on inquiry card. 



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Technical Forum, 

Listing 1 continued: 

420 
430 

440 



450 

460 

470 

480 
490 
500 
510 
520 
530 
540 
550 
560 
570 
580 
590 
600 
610 
620 
630 



640 
650 
660 
670 
680 
690 
700 
710 
999 



NEXT 

' { CASE CHARPOS% OF } 
IF CHARPOS% = 4 THEN 

CUME = CUME + (ADDER * 4096) 
IF CHARPOS% = 3 THEN 

CUME = CUME + (ADDER * 256) 
IF CHARPOS% = 2 THEN 

CUME = CUME + (ADDER * 16) 
IF CHARPOS% = 1 THEN 
CUME = CUME + ADDER 
' { END CASE } 

CHARPOS% = CHARPOS% - 1 
NEXT 

BASETEN = CUME 
RETURN 



-CONVERTS OBIECT CODE TO BASIC DATA LINES- 



FOR I = DBASE TO LASTBYTE STEP 8 
LNUM$ = STRJ(LNUM) + " " 
DATL$ = LNUMJ + "DATA " 
FOR J = TO 7 

BYTE - PEEK(I + J) 



IF I = 7 THEN 

BYTES = STRS(BYTE) 
ELSE 
BYTE$ = STRS(BYTE) 



+ CHR$(44) + 



DATL$ = DATL$ + BYTES 

NEXT 

PRINT DATL$ :' TO CRT 

PRINT #1, DATL$ :' TO FILE 

LNUM = LNUM + 10 
NEXT 
RETURN 
END 



Listing 2: A "verification run" of DATALINE in a CP/M operating-system environ- 
ment shows that assembly-language object code is converted into DATA statements for 
embedding in a BASIC program. 



A>asm qtab.aax 
CP/M ASSEMBLER 



VER 1.0 



ROUTINE TO INITIALIZE TAB STOPS ON QUME 



9000 = 
00F8 = 
00F9 = 
0040 = 
0080 = 
001 B = 
0020 = 
000D = 
000A = 
0009 = 
0001 = 
000F = 
000E = 
000A = 

9000 



9000 210000 

9003 39 

9004 226890 



ASEG 
'*'*' DECLARATIONS *** 
CACHE EQU 



ROUTINE ORIGIN 



SERSTAT 

SERDAT 

SDR 

STBE 

ESC 

SPC 

CR 

LF 

HT 

ONE 

SI 

SO 

NUMTBS 



EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 

ORG 



BEGIN MAIN PROGRAM" 
NIT: 

LXI H.0000H 

DAD SP 

SHLD OLDSTK 



9000H 
0F8H 
0F9H 
40H 
80H 
27D 
32D 
13D 
10D 
09H 
01H 
15D 
14D 
10D 

CACHE 



;ZERO REGISTER SO THAT 

;VALUE PASSED TO H = SPC 

SETTING 

;SAVE OLD STACK POINTER 

ADDRESS Listing 2 continued on page 222 



218 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



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Technical Forum. 



Listing 2 continued: 
9007 317A90 LXI 

MAIN: 
900A 215190 LXI 



SP.STKTOP 



;SET UP LOCAL STACK 



H.PMODE ;THIS PUTS QUME IN PRO- 
GRAM MODE 
900D CD4190 CALL SCAN ;READ SERIES LINE AND SEND 

IT 

TAB0: ;ACTUAL MESSAGE LOAD BEGINS HERE 



9010 B7 

9011 1E0A 

TAB1: 
9013 215790 
9016CD4190 
9019 216090 
901C CD4190 



ORA A ;CLEAR FLAGS 

MVI E.NUMTBS ;SETS FOR CARRIAGE WIDTH 

LXI H.TAB8SP 

CALL SCAN 

LXI H,SETTAB 
CALL 



A>asm qtab.aaz 

CP/M ASSEMBLER — YER 1 .0 

907A 

003H USE FACTOR 

END OF ASSEMBLY 

A > type qtab.hex 

1090000021000039226890317A90215190CD419011 
10901000B71E0A215790CD4190216090CD41901DFF 
10902000C21390215490CD4190216390CD41903155 
109030006890C30000DBF8E680CA3590C979D3F99F 
10904000C9B77EFE24C84FCD3590CD3D9023C34196 
1 090500090 1 B0E24 1 B0F24202020202020202024C 1 
06906000 1 B3 1 240D0A245F 
0090000070 

A>ddt qtab.hex 
SID VERS 1.4 
NEXT PC END 
9066 9000 677F 
#g0 



A>b: 

B> basic dataline 

BASIC Rev. 5.1 

[CP/M Version] 

Copyright 1977, 78, 79, 80 (C) by Microsoft 

Created: 14-Jan-80 
5595 Bytes free 

—MACHINE CODE / DATA LINE WRITER— 

Enter hex base address of object code 9000 
Routine length in 64-byte segments 2 
Enter name of data statement file bytes.dat 
Enter line number of starting data statement 5000 
5000 DATA 33, 0, 0, 57, 34, 104, 144, 49 
5010 DATA 122, 144, 33, 81, 144, 205, 65, 144 
5020 DATA 183, 30, 10, 33, 87, 144, 205, 65 
5030 DATA 144, 33, 96, 144, 205, 65, 144, 29 
5040 DATA 194, 19, 144, 33, 84, 144, 205, 65 
5050 DATA 144, 33, 99, 144, 205, 65, 144, 49 
5060 DATA 104, 144, 195, 0, 0, 219, 248, 230 
5070 DATA 128, 202, 53, 144, 201, 121, 211, 249 
5080 DATA 201, 183, 126, 254, 36, 200, 79, 205 
5090 DATA 53, 144, 205, 61, 144, 35, 195, 65 
5100 DATA 144, 27, 14, 36, 27, 15, 36, 32 
5110 DATA 32, 32, 32, 32, 32, 32, 32, 36 
5120 DATA 27, 49, 36, 13, 10, 36, 0, 
5130 DATA 0, 0, 0, 0, 0, 0, 0, 
5140 DATA 0, 0, 0, 0, 0, 0, 0, 
5150 DATA 0, 0, 0, 0, 0, 0, 0, 
OkB 



222 March 1981 © BYTE Publications Inc 



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BYTE March 1981 223 



Technical Forum 



Addition and Subtraction: 
The 1802 Versus the Z80 

Stephen Merrin, 4470 NW Alpha PI, Apt 6, Corvallis OR 97330 



Binary arithmetic is inherently simple because it in- 
volves only 0s and Is. But recently, while I was trying to 
understand the instruction sets of two very different 
microprocessors, the 1802 and the Z80, I became con- 
fused when examining addition and subtraction opera- 
tions. The confusion arose primarily over the notion of 
"borrow" in subtraction. 

When you perform multiple-byte additions and sub- 
tractions, instructions like ADD WITH CARRY and 
SUBTRACT WITH BORROW (CARRY) are needed. In 
the 1802 User Manual the instruction SUBTRACT MEM- 
ORY WITH BORROW is defined as performing the 
following: 

D - M(R(X)) - (NOT DF) - DF,D 

Here, 8-bit arithmetic is being performed. DF is the bor- 
row (carry) bit and M(R(X)) and D are 8-bit operands. 
On the other hand, in the Z80, you have the instruction 
SBC s, SUBTRACT WITH CARRY, which accomplishes: 



A - A - s 



CY 



This operation involves the 8-bit operands A and s, and 
CY is the borrow (carry) bit. 

If you are a programmer at the assembly- or machine- 
language level, you are aware that ambiguity in the de- 
scription of the instruction set cannot be tolerated. You 
need to know such things as: Is the 1802 DF bit or 1 if 
the result of subtracting two positive numbers is nega- 
tive? Is the Z80 flag CY or 1 if the result of subtracting 
two positive numbers is negative? (Oddly enough, even 
though CY and DF serve the same purpose in both micro- 
processors, the answer for the 1802 is opposite that of the 
Z80.) 

My objective for this exercise was to explain to myself 
exactly what was happening at the bit level during these 
addition and subtraction operations. I also wanted to for- 
mulate a simple model of the operation. As it turned out, 
in the 1802, all addition and subtraction operations are 
very neatly and cleanly lumped into one category. In the 
Z80, however, the picture is not so simple. While the Z80 
has a large and powerful instruction set which I prefer to 
that of the 1802, the 1802 has a certain elegant simplicity. 

What I wanted to do was to first set up a model for 
binary addition and subtraction, without reference to 
any particular processor, then show how the 1802 and 
Z80 addition and subtraction operations could be inter- 



preted in terms of my model. I wanted my model to re- 
flect the inherent simplicity that I ascribed to binary 
arithmetic. 

In addition to 8-bit arithmetic operations, the Z80 also 
allows for 16-bit and even 4-bit operations, the latter be- 
ing used in BCD (binary-coded decimal) manipulations 
(the half-carry flag H is the analog of the other carry flag 
CY). In the 1802, except for incrementing and decremen- 
ting the 16-bit registers R(N), all arithmetic operations 
use 8-bit operands. In my model, I am concerned only 
with 8-bit operations and how they can be used to imple- 
ment multiple-byte additions and subtractions. 

A unified model for addition and subtraction is possi- 
ble because a subtraction operation can actually be 
viewed as an addition operation. Addition and subtrac- 
tion can be accomplished with the same hardware, pro- 
vided there are circuits to do complementation. 

Let X and Y be 8-bit quantities. Y will denote the 
one's complement of Y ( Tis again an 8-bit quantity, ob- 
tained by replacing each 1 with a and each with a 1). 
Let c,- and c„ denote 1-bit values, called respectively 
"carry in" and "carry out." In my general model, all 8-bit 
additions and subtractions take the form: 

X + Y + c,~ c„SUM 

Here, SUM is the 8-bit quantity resulting from the addi- 
tion of X, Y, and c,. If a carry is generated, then c = 1; 
otherwise c„ = 0. This is shown in figure 1. 

For single-precision (1-byte) additions and subtrac- 
tions, c, = for addition and c, = l for subtraction. For 
multiple-byte operations, c f will take on the value of c„ 
generated in the last performed operation. The results of 
an addition or subtraction will be in two's complement 
form. The 8-bit quantity Y+l (and throw away the 
carry, if there is one) is the two's complement of Y. 

If you wish to add X and Y, you do X+Y+Ci with 
c,=0; if you wish to compute the difference X—Y, you 
do X+ Y + Ci with c, = l (ie: add the two's complement of 
Y to X). Thus, as advertised, both the sum and difference 
of X and Y can be regarded as taking the form of an addi- 
tion. The distinction is that, for subtraction, c, has a dif- 
ferent value and the one's complement Y is used. Some 
examples are shown in figure 2. 

The following is how multiple-byte sums are done. 
Suppose we have X = X m ,X„,.,...Xi (an m-byte sequence) 
and Y=Y m ,Y m -u..Y l , where each X k and Y„ is 8 bits. Let's 
say that you want to compute the multiple-byte sum 
X+ Y. You first perform Xi + Yi + c, with c, = 0. Then do 



224 



March 1981 © BYTE Publications Inc 



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©onComputing, Inc. 1981 



Technical Forum 





X 




Y 


+ 


H 


E 


SUM 



Figure 1: A pictorial model 
of the addition of X, Y, and c. 
to give SUM and the carry bit 



X2 + Y2 + C, where c t = c of the previous sum. And so 
forth until you finally do X m + Y„ + c,, with c L = c a 
resulting from the immediately preceding sum of X m - t and 

Multiple-byte subtractions are similar. Again, suppose 
X and Y are given as above, but now you want to com- 
pute the multiple-byte difference X — Y. First, perform 
Xi + Y.+c, with c, = l. Next do X 2 + Y 2 + c, with c t = c 
of the preceding sum; and so on until you finally do 
X„-f- Y m -r-c, with Ci = c„ resulting from the immediately 
preceding sum of X m - t and Y m _i. Notice that X—Y is com- 
puted by adding the two's complement of Y to X in a 
multiple-byte fashion. 

Let me summarize the addition /subtraction model I 
have just presented. Whether you choose to add or sub- 
tract, or whether you want multiple-byte or single-byte 
operations, in all cases the fundamental operation is a 
sum of the form X+ Y+c.-c, SUM. 




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X = 5 

Y = 6 

Find X + Y 

00000101 

00000110 

+ 



X 
Y 
c, 



00001011 


X + Y 


c o = 




X = 5 




Y = 6 




Find X-Y 




00000101 


X 


11111001 


Y 


+ 1 


c, 


11111111 


X- 


c = o 




X = 6 




Y = 5 




Find X-Y 




00000110 


X 


11111010 


Y 


+ 1 


c, 



Figure 2: Some examples of a 
unified model for binary ad- 
dition and subtraction, c. and 
i 

c o are 1-bit values called 
"carry in" and "carry out." If 
a carry is generated by the 
addition of X and Y, then c 

' o 

= 1; otherwise c = o. 



00000001 
c = 1 



X-Y 



The 1802 processor fits this model perfectly. In the 
1802, both c, and c„ correspond to the 1-bit register DF. 
Just before the addition or subtraction operation is per- 
formed, DF is the c,. Just after the operation, DF is loaded 
with c . (Incidentally, table 1 is a complete list of the 1802 
arithmetic operations.) WITH CARRY and WITH BOR- 
ROW operations take c, to be whatever value that cur- 
rently resides in DF (ie: c, is determined by c a of the 
previous operation). Otherwise, as discussed in my 
model, c, must be for an addition and 1 for a subtrac- 
tion operation. 

Table 1 is important for two reasons. First, it reve als 
exactly what each operation does. (D + M(R(X)) + 
DF-DF,D is much clearer than D-M(R(X))-(NOT 
DF) — DF,D.) Second, it is obvious that, without excep- 
tion, each addition and subtraction operation has the 
form X+Y-f-c,— c„,SUM. This last fact is no accident, 
since (presumably) the same hardware is used for all 
operations. 

In the Z80, the 1-bit carry flag CY serves the same 
function as the DF flag does in the 1802. In contrast with 
the 1802, where the DF bit corresponds exactly with the 
model's c, and c„, there is a distinction in the Z80 between 
an addition and a subtraction as far as the role of the CY 
is concerned. Consider this example that points out this 
distinction. Is the computation 5 — 3 the same as 
5 + ( — 3)7 That is, in the Z80, is there any difference in 
the outcome between the assembly-language sequences 
(LD A,05 SUB 03) and (LD A,05 ADD FD)7 (FD is the 
two's complement representation of —3, written in hexa- 
decimal.) While the end result is 02 in A for both com- 
putations, the final value of CY is not the same. When 
you do 5-3, CY = 0. When you do 5 + (-3), CY = 1. If 
you do analogous operations in the 1802, DF = 1 in both 
cases. How do you make sense out of all this? 

Table 2 describes what occurs within the Z80 in terms 
of my model. Four classes of operations are shown in the 
table: add, add with carry, subtract, and subtract with 
carry. X and Y are arbitrary 8-bit operands within the 



226 March 1981 © BYTE Publications Inc 



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S16LT 
S18LT 
S20LT 
S22LT 
S24LT 
S28LT 
S40LT 



1+ 25+ 100 + 



LOW-PROFILE GOLD 



1+ 25+100-1 



Part* 

S8LG 30 27 24 

SULG 34 31 27 

S16LG 39 35 31 

S18LG 45 40 36 

S20LG .50 45 ,40 

S22LG 53 48 42 

S24LG 59 53 47 

S2BLG 67 61 54 

S40LG 99 88 75 

WIRE-WRAP SOLDER TIN 



Part* 

sawT 

S14WT 
S16WT 

stawT 

S20WT 
S22WT 
S24WT 

S28WT 
S40WT 



1+ 25+ 100 + 



WIRE-WRAP GOLD 



Pan* 

SBWG 
S14WG 
S16WG 
SiBWG 
S20WG 
S22WG 
S24WG 
S28WG 
S40WG 



1 + 25 + 100 + 



$550. 



74LSTTL 



Part* Price 

74LS00 30 

74LS01 30 

74LS02 30 

74LS03 30 

74LS04 30 

74LS05 30 

74LS08 32 

74LS09 35 

74LS10 .30 

74LS11 32 

74LS12 36 

74LS13 30 

74LS14 55 

74LS15 30 

74LS20 30 

74LS21 34 

74LS22 34 

74LS26 32 

74LS27 .35 

74LS2B 39 

74LS30 30, 

74LS32 38 

74LS37 38 

74LS38 38 

74LS40 38 

74LS42 70 

74LS47 95 

74LS4B V15 

74LS51 ,30 

74LS54 .30 

74LS55 30 

74LS73 .45 

74LS74 45 

74LS75 59 

74LS76 .50 

74LS83 .55 

74LS85 1.20 

74LSB6 45 

74LS90 .69 

74LS92 75 

74LS93 ,75 

74LS95 88 

74LS107 45 

74LS109 45 

74LS112 .45 

74LS113 45 

74LS114 49 

74LS123 98 

74LS124 99 

74LS125 70 

74LS126 ,70 

74LS132 .90 

74LS136 45 

74LSI38 .75 

74LS139 .75 

74LS145 1.25 

74LSI47 245 

74LS14B 145 

74LS151 70 



74LS152 

74LS153 
74LS154 

74LS157 

74LS158 

74LSI60 

74LS161 

74LSI62 

74LSI63 

74LS164 

74LS165 

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74LS173 

74LS174 

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74LS190 

74LS191 

74LS192 

74LSI93 

74LSI94 

74LS195 

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74LS221 

74LS240 

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74LS373 

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74LS375 

74LS377 

74LS386 

74LS390 

74LS393 

81LS95 

81LS96 

81LS97 

81LS98 



CRYSTALS 

(P*rtN includes (requency In MHZ) 



Pari* 

SYI 

SYl 8432 
SY2 

SY2 4576 
SY3.579 
SY4 

SY5 068 
SY6 

SY6.144 

SYB 

SY10 
SY12 

SY14.3181E 



575 
5 75 
575 
5 75 
575 



'AWT & ViWT CARBON FILM 
5% RESISTORS 



200K 
220K 
240K 



3 3K 33K 330K 
3.6K 36K 360K 
3.9K 39K 390K 

4 3K 43K 430K 
470K 



1 3M 
1 5M 
1 6M 



22M 
24M 

2 7W 
3M 

3 3M 
3 6M 
3 9M 



5 6K 

6 2K 
6 8K 



910 



5I0K 
560K 
620K 
680K 
750K 

s;ok 



MINIMUM ORDER PER TYPE: 5 pes — 
any qty 5 pack @ $.25 

MINIMUM ORDER PER TYPE: 100 pes 
Price Per 100 Pk: 

QTY WWT 'AWT 

lOOup SI. 70 S1.80 

1.000 up 1.50 l 60 

5.000 up 1.30 1.40 

10.000 up 1,10 1,20 



TRANSISTORS 



2N2219A 

2N2222A 

2N2905A 

2N2907A 

2N2369A 

2N3904 

2N3906 

PN2222A 

PN2907A 



.19 



VOLTAGE 
REGULATORS 

Part* Cose Price 



DIODES 

Swllehlno 
121$ 1 00 

12(H00 



7BL05 
7BL12 
78L15 
79L05 
79L12 
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78I2P 
7815P 
7905P 
7912P 
7915P 
7805K 
7812K 
7815K 
790 SK 
7912K 
7915K 
309 H 
309K 
317P 



T092 

T092 

T092 

T092 

T092 

T092 

TO220 

TO220 

TO220 

TO220 

TO220 

TO220 

T03 

T03 

T03 

T03 

T03 

T03 

T039 

T03 

TO220 

T03 

T03 

TO220 



2.95 
550 
2.40 



ZENER 

DIODES 

Vi WT 

Pari* Pric 

1NS231B .21 

1N5239B 2C 

1N5242B 2C 

1N5245B 2C 

1N5248B 2C 

1N5250B 2C 

1N5252B 2C 

1N5255B 2C 



1N4733A 
1N4739A 
1N4742A 
1N4744A 
1N4746A 
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CERAMIC DISC 
CAPACITORS 50V 



10pl 
22pl 

33d! 

39pl 

47pl 

68pt 
100p( 
I50pl 

220p' 

2V0pl 

330pl 

470pl 

,001ml 
0022ml 
0033ml 

,0047ml 

,01ml 
022ml 
033ml 
047ml 



SOLID DIPPED TANTALUM 
CAPACITORS 20% 

Value Volts 1+ 25+ 100 + 



2716 * b\ 
TMS27I6 
2732 



EPROMS 

S 7 95 
12 50 



RECTIFIERS (1A) 



1N4001 
1N40O2 
1N40O3 
1N4O04 
1N4005 
1N4006 
1N4007 



LINEAR 
M = 8 PIN 
N = 14/16 PIN 

Pan* Price 

LF355M I 10 

LF356M 1 10 

LF357M 1 10 

LM301A.M 35 

LM307M 35 

LM308M 1 00 

LM3HM 85 

LM3l8M 195 

LM324N 90 

LM339N 99 

LM377N 2 40 

LM380N 125 

LM331N i 95 

LM555M 39 

LM556N 95 

LM56SN 1 25 

LMS66M 1 65 

LMS67M 1 25 

LM709N 29 

LM710N 75 

LM711N 39 

LM741M 35 

LM747N ,79 

LM1458M 55 

LM3900N 69 

LM4136N 1 25 



Part* 

7406 

7407 

7416 

7417 

7423 

7425 

7445 

7446 

7460 

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7480 

7489 

7494 

7497 

74100 

74104 

74105 

74 116 



2 95 
2 95 
2 95 



MICROPROCESSORS & SUPPORT 

Part* Price Q? 



8216 
8224 
8226 



5 95 
3 25 
5 95 
3 25 
3 95 
3 25 



8228 5 50 

8238 5 50 

8251 7 50 

8255 8 95 

8257 i 7 95 

Z80A 1 2 95 
Z80ACTC 12 95 



ZBOA-PIO 

6BO0 

6BI0 

6B2I 

6850 

6502 

6522 



2 95 

3 95 
595 
7 50 
6 95 



4000 CMOS 
B SERIES ONLY 



4022 
4023 
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4050 
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4068 



MIN ORDER: $10.00 SHIPPING: ADD $2 
GA RESIDENTS ADD 3% SALES TAX 



00 



MASTER 
VISA 



mailordersSOUTHERN SEMICONDUCTORS I 

BOX 986 

LAWRENCEVILLE, GA. 30246 PHON 

OEM AND INSTITUTIONAL INQUIRIES INVITED (404) 



CARD AND 
WELCOME 

NC. 

E ORDERS: 
963-3699 



Circle 144 on inquiry card. 



BYTE March 1981 



227 



Technical Forum 











Operan 


ds 


Used That Match 








Operation 




the 


Formula: 




Operation 




Code 


X 


+ 


Y 


+ c,-c„,SUM 




ADD 




F4 


M(R(X)) 


+ 


D 


+ 


0-DF.D 




ADD IMMEDIATE 




FC 


M(R(P)) 


+ 


D 


+ 


O-DF.D 




ADD WITH CARRY 




74 


M(R(X)) 


+ 


D 


+ 


DF-DF.D 




ADD WITH CARRY IMMEDIATE 




7C 


M(R(P)) 


+ 


D 


+ 


DF-DF.D 




SUBTRACT D 




F5 


M(R(X)) 


+ 


D 


+ 


1-DF.D 




SUBTRACT D IMMEDIATE 




FD 


M(R(P» 


+ 


D 


+ 


1-DF.D 




SUBTRACT D WITH BORROW 




75 


M(R(X)) 


+ 


D 


+ 


DF-DF.D 




SUBTRACT D WITH BORROW IMMEDIATE 


7D 


M(R(P» 


+ 


D 


+ 


DF-DF.D 




SUBTRACT MEMORY 




F7 


D + 


M(R(X)) 


+ 


1-DF.D 




SUBTRACT MEMORY IMMEDIATE 




FF 


D + 


M(R(P» 


+ 


1-DF.D 




SUBTRACT MEMORY WITH BORROW 


77 


D + 


M(R(X)) 


+ 


DF-DF.D 




SUBTRACT MEMORY WITH BORROW IMMEDIATE 


7F 


D + 


M(R(P)) 


+ 


DF-DF.D 




Table 1: Arithmetic operations 


of the 1802 microprocessor 













Operation 


X + Y 


X - Y 


performed 


X + Y with carry 


X - Y with carry 


Equivalent 


CY-0 


CY-0 


sequence of 






steps taken 


C-CY c-CY 


C— CY c.-CY 


within the 


SUM=X + Y + c, SUM=X + Y + c 


SUM=X+ Y +c, SUM = X+ Y + c, 


Z80 to perform 


CY-c„ CY-c„ 


CY- cT CY- c7 


the given 






operation 






Table 2: Addition and subtraction operations in 


the Z80 microprocessor. 



No More Puns 



From BD Software, available 
'through Lifeboat Associates for a measly 
j145. While this compiler is only a subset of 
the incredible Unix* C, it is a subset de- 
signed to fit comfortably on CP/M systems and 
be maximally useful for non-number-crunching 
applications; i.e., thereare no inherent floating 
point or long variable types. You do get: fast 
and reasonably short object code, quick 
'^compilation and linking, powerful hooks 
into CP/M, plus plenty of docs and 
^sample programs. — ^r~° 



k Try it and . . . 
er, ahem 



you know. 



Unix is 3 trademark 
ol Bell Laboratories. 



CP/M is a trademark 
ol Digital Research. 



LIFEBOAT ASSOCIATES,1 651 3rd Ave., N.Y., N.Y. 10028 
Ph: (21 2) 860-0300. Telex: 640693. 



Z80. Notice that the "with carry" operations (ADC, SBC) 
are distinguished from the others only in that CY is not 
initially zeroed. The peculiar feature of table 2 (in com- 
parison with table 1) is that, when doing a subtraction, 
the CY bit is complemented beforehand to obtain c,. 
Following the operation, c„ is complemented to yield the 
final value for CY. This explains why 5—3 and 5 + (—3) 
are not equivalent in the Z80 (as far as the end result of 
CY is concerned). When the operation performed is a 
subtraction, CY takes on the complement of c . 

As an illustration of the importance of the above con- 
siderations, suppose that you want to compute X—Y 
(where X and Y are 8-bit positive values). Then you want 
to branch according to whether the result is negative or 
positive. In the 1802, DF = 1 means that the result was 
positive, and a branch is made based on the value of DF. 
Suppose in the Z80 you wish to branch according to CY 
(the branching could also be done according to the sign 
bit; however, there are cases when using CY is more con- 
venient, such as a shift operation that follows a subtrac- 
tion). The problem is not so straightforward now, 
because in the Z80, it is crucial to know whether or not 
X — Y was computed using a subtraction operation. If so, 
flag CY = means the result was positive. ■ 



Technical Forum is a feature intended as an interactive 
dialog on the technology of personal computing. The subject 
matter is open-ended, and the intent is to foster discussion and 
communication among readers of BYTE. We ask that all cor- 
respondents supply their full names and addresses to be printed 
with their commentaries. We also ask that correspondents supply 
their telephone numbers, which will not be printed. 



228 



March 1981 © BYTE Publications Inc 



Circle 145 on inquiry card. 



Circle 146 on inquiry card. 



COMPUTERS-TERMINALS-MODEMS! 



MODEMS AND COUPLERS 



Connect your Apple, TRS-80 or any other computer or terminal to the phone lines! 



Penril 




Penril 
300/1200 



Penril 300/1200— Bell 212A style $799 

Bell 2 12A style. 1200 baud and 300 baud. Manual origi- 
nate, auto-answer. Full duplex. RS232. Direct connect 
to phone lines via RJ11C standard extension phone 
voice jack. 1 year warranty. 




U.S. Robotics 

USR-330A 

Bell 103/113 style 

USR-330D 

Bell 103/113 style 



USR-330D $339 

Bell 103/113 style. 330 baud. Manual originate, auto- 
answer. Half/full duplex. RS232. 1 year warranty. Direct 
connect to phone lines via RJ1 1C standard extension 
phone voice jack. 

USR-330A $399 

Same as USR-330D but includes auto-dial capability. 




U.S. Robotics 

The 

Phone Link 
Acoustic 
Modem 



Bell 103/113 style $179 

300 baud. Sleek, low profile. Originate and answer cap- 
ability. Half-full duplex. Self-test. RS232. Light displays 
for On, Carrier, Test, Send Data, Receive Data. 15 oz. 

Perkin-Elmer Corporation 

Bantam 550B .... $694 

Compact. Silent. Upper/lower 
case. 80th col. wrap-around. 
Bell. Integrated numeric pad. 
Printer port. Transparent 
mode. Editing features. 
Tabbing. 

Bantam 550E... $755 

Same as 550B plus 
separate numeric key- 
pad and cursor direction 
keys. 

Bantam 550S $879 

Same as 550E plus block mode. 8 function keys, and 
protected fields, reverse video fields, half intensity 
fields, blinking fields. 

550 Options 

20mA Current Loop Interface $70 

Non-Glare Screen $25 

2nd page of memory (550S only).. $100 




Digital Equipment Corporation 



DECVT100 



DECVT100 ...$1668 

Detachable keyboard. Separate numeric keypad with 
function keys. Business forms character set. Reverse 
video. Selectable double-size characters. Bidirectional 
smooth-scrolling. 80 cols or 132 cols. Split screen. Set- 
table tabs. Line drawing graphic characters. Status line. 
Key-Click. 



HARDCOPY TERMINALS 



Teletype 
Model 43 



CRT's 




Perkin-Elmer 
Corporation 



Superowl 1251 



Perkin-Elmer Superowl 1251 $1564 

Intelligent, editing CRT. Detachable keyboard. 32 fully 
programmable function keys. Intelligent printer part. 
Business forms character set. Block mode. Protected 
fields. Blinking fields. Numeric fields. Reverse video. 
Half intensity. Polling. Down line loading of options. Re- 
mote control of all options by host computer. Settable 
tabs. Status line. Separate numeric keypad. Transpar- 
ent mode. _ 




Teletype 
Corporation 



Teletype Model 43 KSR with RS232 
and Connector Cable $999 

30 CPS. Dot matrix. 1 32cols.Truedescenders on lower 
case. Excellent print quality for dot matrix printer. Pin 
feed. 




NEC Corporation 
NEC Spinwriter 5510 & 5520 




5520 KSR Spinwriter $3088 

55 CPS. Impact printer. Selectric print quality. Change- 
able print fonts. 110, 300 and 1200 baud data rate. Nu- 
meric keypad. Friction and tractor feed. 

5510 Spinwriter $2754 

55 CPS. Impact printer. Selectric print quality. Change- 
able print fonts. 110, 300 and 1200 baud data rate. Fric- 
tion and tractor feed. 



& PRINTERS 



DECLA120 

Digital Equipment 
Corporation 



DECLA120... $2388 

180 CPS. Dot matrix. Upper/lowercase. 1K buffer. De- 
signed for 1200 baud communications. 30 character 
answerback message. Adjustable line spacing. Adjus- 
table character sizes including double sized characters. 
Settable horizontal and vertical tabs. Top-of-form capa- 
bility. RS232. 




Perkin-Elmer 
Corporation 



Pussycat 650/655 
CRT Screen Printer 



650/655 Pussycat CRT Screen Printer. $899 

100 CPS. Extremely compact and quiet. 110 to 9600 
baud rate. 2K buffer. Ideal for producing rapid, reliable 
hardcopyof your CRT screen display. Can be added to 
any CRT with our interface option. 




*0*# 




Digital 

Equipment 

Corp. 



DECLA34DA... $939 

30 CPS. Dot matrix. Upper/lower case. 4 character 
sizes. Up to 217 cols per line. 6 lines per inch settings. 
Friction feed. Settable tabs. RS232. 

DECLA34AA $1095 

30 CPS. Dot matrix. Upper/lower case. 8 character 
sizes including double size characters. 6 lines per inch 
settings. Up to 217 cols per line. Friction feed. Settable 
horizontal and vertical tabs. Top-of-form capability. 

Options for LA34AA and LA34DA 

Tractor Feed Mechanism $114 

Numeric Keypad w/ Function Keys . . $69 

Pedestal .' $100 

Paper Out Sensor $25 

APL Capability with APL Keycaps .. $499 
2K Buffer with Text Editor and 1200 Baud 
Communications Capability $499 



52 



Leasing rates and lease/purchase plan information is available on request. 

All equipment is shipped with a 10 day money back guarantee. 

We offer full service, on site maintenance plans on all equipment. 

All equipment in stock. 



203N]. WABASH SUITE I7IB CHICAGO, ILL 60SQI 



SALES 

GENERAL OFFICES 

SERVICE 



C312) 346-5650 
r.312) 3-46-5651 
C312] 733-0497 






Desk-Top Wonders 



Hunt the Wumpus with Your HP-41C 



Hank Librach, 52 Bulkley Dr, Fairfield CT 06430 



Are you envious of all the people on your block who 
have their own microcomputer systems with fancy dis- 
plays, sound effects, and all sorts of goodies? You needn't 
feel inferior any more. With the Hewlett-Packard HP- 
41C programmable calculator, you can do all these things 
by considering the display to be a one-lire video display 
with 12-character capability. It will prompt you, make 
different-frequency sounds, and scroll its alphanumeric 
display. 

You have probably played the popular Hunt the Wum- 
pus game (in BASIC) on a microcomputer system. Now, 
you can hunt him on your HP-41C. This version of Hunt 
the Wumpus has all the excitement of the big game, in- 
cluding the ability to throw gas cans, get snatched by 
bats, or fall into a pit. You'll also be warned when the 
Wumpus, a pit, or bats are near. 

The program will easily fit into an unexpanded HP- 
41C. With added memory modules and a bit of ex- 



perimentation, many refinements are possible. 

Playing the Game 

After entering the program as shown in listing 1 (on 
page 232), set the following: 

• SIZE 018 (eighteen registers are used) 

• FIXO 

• Enter the register data as shown in table 1 

• ASN WUMP XEQ (assigns program to XEQ key) 

• Put HP-41C in USER mode 

• Press XEQ 

At this point, you will be prompted with "SHOOT?" 
Enter your choice, YES or NO (you will automatically be 
in the ALPHA mode), and press RUN. You will be asked 
which room you wish to enter. Continue until you win or 
lose. Happy hunting! ■ 



LSI-1 1 SYSTEMS FROM ANDROMEDA 

Any size you want. 




No matter what your LSI-1 1 system 
needs are, Andromeda can satisfy 
them. 

For example, the 1 1/M1 system shown 
on the right weighs only 14 pounds yet 
contains 102kb of mini disk storage 



(expandable to 389kb), 64kb of RAM, 
space for up to 16kbof EPROM, 4 serial 
ports, and the LSI-11/2 CPU. All of this 
for less than $4000. While the 11/M1 
will run the RT-11 operating system, it 
is best suited fordedicated applications 
where its small size but large processing 
power are needed. 

Near the other end of the scale is the 
11/H23-DDF system shown at the left. 
The mobile enclosure includes the 
LSI-11/23 processor, 256kb main 
memory, 10mb of storage onthedouble 
density RK-05 cartridge disk and 
1.2mb on the double density floppy 
disks. This system also has 4 serial 
ports and 7 empty dual width slots for 
additional interfaces. The $22,500 price 
includes the video terminal shown, a 
150 CPS matrix printer, and the RT-11 
operating system. 

These are just two examples of the 
many LSI-1 1 based systems available 
from Andromeda. And the standard 
systems are just starting points; we 
will provide any combination of pack- 




age, processor, memory, interfaces, 
and peripherals to meet your require- 
ments. In addition to general purpose 
systems, we also have turnkey pack- 
ages for word processing, time-sharing, 
data acquisition, and graphics. 

We also provide individual boards, 
software and accessories to support 
LSI-1 1 systems. 

LSI-1 1 . RT-11, and RK-05 are trademarks of the 
Digital Equipment Corp. 

/INDROMGD^ 
5V51GME 



9000 Eton Ave. 



INC. 



Canoga Park, Calif. 91304 
Phone: 213/709-7600 
TWX: (910) 494-1248 

Prices are domestic U.S.A. only. 



230 March 1981 © BYTE Publications Inc 



Circle 147 on inquiry card. 



LOWEST PRICE - BEST QUALITY 



NORTH STAR 




North Star Horizon 2 

2-5V4 Disk Drives 
32K Double Den 
Factory assem. & tested 
Factory guaranteed 
List 3095 

only 



$2274 



POWERFUL NORTH STAR BASIC FREE 
SUPERB FOR BUSINESS & SCIENCE 

FACTORY ASSEMBLED & TESTED LIST ONLY 

HORIZON-1-32K-DOUBLE DEN $2695 $1980 

HORIZON-2-32K-QUAD DENSITY 3595 2674 

HORIZON-2-64K-QUAD + HARD DISK 9329 7149 

HORIZON RAM ASSM 16K=$389. 32K = $579 

HORIZON RAM KIT SALE! 16K = $314 32K = $469 

HORIZON DISK DRIVE SALE DOUB DEN SAVE! 315 

NORTH STAR HARD DISK 18 Mb 4999 $3929 

PASCAL-PLUS 14,18 OR 36 DIGITPRECISION 249 

SUPERBRAIN 



ZENITH 




SUPERBRAIN QD 64K 

List $3995 only $2995 



Z-89 48K 

List $2895 only $2299 



TERMINALS Z-1 9 $725 

INTERTUBEIII om y $725 

DIP-81 PRINTER m y $395 




MICROTEK $675 

NEC PRINTER $2569 
TRACTOR, THIMBLE, RIBBON 



InterSystems 

ITHACA INTERSYSTEMS 2A 




List $3595 You Pay Only 



Z-80A CPU 4 MHz 
64K Dynamic RAM 
Front panel 
V I/O— with interrupts 
FDCII Disk Controller 
20 slot motherboard 

$2795 



PASCAUZ + THE FASTEST PASCAL $375 

GET READY FOR ITHACA'S Z-8000 

8086 16 BIT CPU & SUPPORT CARD SEATTLE $575 

MORROW 8" DISK 

DISCUS 2D -I- CP/M® 600K ONLY $938 
DISCUS 2 + 2 + CP/M® 1.2 MEGA B. $1259 
ADD DRIVES 2D = $650 2 + 2 = $975 
2D-DUAL + CP/M® ONLY $1555 



MORROW HARD DISK 

26,000,000 BYTES!! 

LIST $4995 ONLY $3995 

CP/M® IS INCLUDED! 



SAVE ON MEMORY AND PROGRAMS 




SYSTEMS MEMORY 64K A & T 4mHz 

$599 
SYSTEMS MEMORY 64K BANK SELECT 
$789 
CENTRAL DATA 64K RAM $599 

ITHACA MEMORY 8/1 6-blt 64K $845 

SEATTLE MEMORY 8/16 BIT 16K 4Mhz 
$275 
SSM KITS Z-80 CPU $221 

VIDEO BRDV834Mhz $412 

ANADEX PRINTER DP-9S00-1 $1349 

CAT NOVATION MODEM $169 

TARBELLDISKCONTROLLERDD $445 
ECONORAM2A8KASSM $179 

NSSE 1-22 & P01 TERRIFIC PROGRAMS 
ONLY $10. EACH 
NORTHWORD 294 MAILMAN 234 
INFOMAN $364 

TARBELL COMPUTER-PHONE 



RC A-COSM AC VP-1 1199 RCA-COSMAC 
VP-711 $199 

COLOR1 RAINBOW 385 
SPECTRUM $289 

E2-80 Machine Language Tutor $25 
EZ-CODER Translates English to BASIC 
$71 
ECOSOFT FULL ACCOUNTING PKG 

$315 
BOX OF DISKETTES $29 

SECRETARY WORD PROCESSOR 

The Best! $99 

TEXTWRITER III Book Writing Program 

$112 

GOFAST NORTH STAR BASIC Speeder 

Upper $71 

Which Computers are BEST? 

BROCHURE FREE 

North Star Documentation refundable 

w/HRZ $20 



AMERICAN SQUARE COMPUTERS BEATS ADV. PRICES 



square 

American [|j] Computers 

919-889-4577 KIVETT DR. JAMESTOWN N.C. 27282 919-883-1105 



CP/M Is a registered trademark of Digital Research, Inc. 



Circle 148 on inquiry card. 



BYTE March 1981 231 



Circle 149 on inquiry card. 



The 

reachable 

star. 



The STAR puts a quality 300 
bps RS232 modem within reach 
of the small computer user...the 
same modem selected by IBM, 
GE, RCA, and ADR The price? 
Under $200! 

VVeVe designed this compact 
modem with exclusive tripleseal 
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2050 Research Drive, Livermore, CA 94550 



232 March 1981 © BYTE Publications Inc 



Desk-Top Wonders. 



Register 


Contents 


Comments 


R0 


_ 


Your location, generated randomly 


R1 


2345 " 






R2 


158 10 






R3 


1467 






R4 


1357 






R5 


124 10 


> 


Room layouts, enter these values 


R6 


3789 




in ALPHA mode 


R7 


3469 






R8 


269 10 






R9 


678 10 






R10 


2589 




R11 


3 


Number of cans of gas, generated by program 


R12 


seed 


Used for random number generation 0<s<1 


R13 


_ 


Wumpus position 


R14 


— 


Bat positions (all generated randomly) 


R15 


— 


Pit position 


R16 


YES 


Enter letters in ALPHA mode; used for string comparison 


R17 


NO 


Enter letters in ALPHA mode; used for string comparison 


Table 1: 


Register data used 


in the Hunt the Wumpus game for the HP-41C. A dash 


indicates data that varies from game to game. See the text for details on using the 


program 







Listing 1: Hunt the Wumpus for the HP-41C programmable calculator. 



Si*LBL "viUr-lP" 


38 X<=Y? 


75 'V CANS' 


112 GTO 89 


82 3 


39 GTO 95 


76 RVIEH 


113*LBL 32 


83 STG 11 


48 "WUMPUS NEAR' 


77 PSE 


114 "FELL IH- 


H4 X£y 9; 


41 RVIEH 


78 "SHOOT?" 


ll 5 RVIEH 


95 STG i3 


42+LBL 85 


79 ARCL 16 


116 STOP 


86 XEQ "I 


43 RCL 14 


88 "r-" 


117+LBL 13 


87 STO 14 


44 XEQ 86 


81 ARCL 17 


118 "TO ROOM: - 


98 XEQ 91 


45 X<=Y? 


82 RVIEH 


119 ARCL IHD 88 


89 STO 15 


46 GTO 87 


83 PSE 


128 AVI EH 


18+LBL 93 


47 "BATS HEAR" 


84 RON 


121 PSE 


11 XEQ 91 


43 RVIEH 


85 STOP 


122 RTH 


12 RCL 13 


49*LBL 87 


86 ASTO X 


123+LBL 86 


13 X=Y? 


58 RCL 15 


87 AOFF 


124 1 


14 GTG 99 


51 XEQ 86 


88 RCL 16 


125 ST- 11 


15 XOY 


52 X<=Y? 


89 X=Y? 


126 XEQ 13 


16 STO 69 


53 GTO 14 


96 GTG 68 


127 STOP 


17+LBL 89 


54 "PIT NEAR" 


91 XEQ 13 


128 STO 88 


18 XEQ 93 


55 A VI EH 


92 STOP 


129 RCL 13 


19 GIG 92 


56 GTO 14 


93 STO 88 


136 - 


28 GTG 14 


57*LBL 66 


94+LBL 84 


131 X=8? 


2ULBL 91 


58 RCL m 


95 RCL 88 


132 GTO 18 


22 RCL 12 


59 - 


96 RCL 14 


133 RCL 11 


23 PI 


68 ABS 


97 - 


134 X=8? 


24 ♦ 


61 3 


98 X=8? 


135 GTO 15 


25 21 


62 RTH 


99 GTO 11 


136 "HISSED" 


26 * 


63*LBL 83 


188 RCL 88 


137 AVIEH 


*57 rn,- 

u rr-.L- 


64 RCL 89 


181 RCL 15 


138 GTO 99 


28 STG 12 


65 "YOU ARE IN ROOM" 


162 - 


139+LBL 18 


29 19 


66 "h HO:" 


183 X=8? 


148 "GOT Hlh" 


36 * 


67 ARCL X 


184 GTO 12 


141 AVIEH 


31 IHT 


68 RVIEN 


185 GTO 69 


142 BEEP 


32 i 


69 PSE 


186+LBL 11 


143 STOP 


33 + 


78 PSE 


187 XEQ 81 


144+LBL 15 


34 RTH 


71 RTH 


188 STO 88 


145 "LOST" 


35+LBL 92 


72*LBL 14 


189 "SNATCHED TO." 


146 AVIEH 


36 RCL 13 


72 "GOT" 


118 ARCL 88 


147 TONE 1 


37 XEQ 86 


74 ARCL 11 


111 RVIEH 


148 END 



Circle 150 on Inquiry card. 



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Floppy Disks Mag Cards Cassettes Computer Tapes Disk Packs Computer Peripherals 






Technical Forum 



Build a Simple 
Video Switch 



Richard C Hallgren, Department of Biomechanics, 

College of Osteopathic Medicine, Michigan State University, 

East Lansing MI 48824 



Although I know that there are many sophisticated 
ways of building a video switch, I am hard pressed to 
think of one that is easier to build, as inexpensive, or 
works as reliably as mine. In the process of building a 
CAI (computer-aided instruction) system, I needed a 
logic-controlled device to switch video to a video display 
at appropriate times. Because I had to transfer the video 
signal without excessive attenuation, I knew that the 
switch required a series impedance of less than 50 ohms at 
10 MHz. 

Motorola Semiconductor manufactures a quad bilat- 
eral switch (MC14016B) that is able to transfer frequen- 
cies up to 54 MHz, but the series resistance of each switch 
is in the neighborhood of 300 ohms. As I considered other 
alternatives, it occurred to me that if I took two of the 
devices and connected all eight of the switches in parallel, 
the series impedance would be approximately 37.5 ohms. 

Figure 1 shows the schematic diagram of the video 
switch. Dropping the control line to ground opens the 
switch, and raising the control line to +5 V closes the 



Quad Analog Switch/Quad Multiplexer 

• High on/off output voltage ratio — 65 dB typical 

• Quiescent current = 0.5 nA/package typical at 5 VDC 

• Low crosstalk between switches — 80 dB typical at 1 .0 MHz 

• Diode protection on all inputs 

• Supply voltage range = 3.0 VDC to 1 8 VDC 

• Transmits frequencies up to 54 MHz at 5 VDC 

• Linearized transfer c haract eristics 

• Low noise — 1 2nV/\/Cycle, f > 1 kHz typical 

• Pin-for-pin replacement for CD4016, CD4066 



Maximum Ratings (voltage referenced to V ss ) 



Rating 


Symbol 


Value Unit 


DC supply voltage 


Vdd 


-0.5 to +18 VDC 


Input voltage — all inputs 


v in 


-0.5 to V DD +0.5 VDC 


DC current drain per pin 


1 


10 mADC 


Operating temperature range 
AL device 
CL/CP device 


T A 


-55 to + 125 °C 
- 40 to + 85 


Storage temperature range 


Tstg 


-65 to +150 °C 


Table 1: Technical data for th 


e MC14016B. 



switch. Since the units are bilateral, it doesn't matter 
which line is the input or output. I have used the switch in 
this form for over a year, and it has performed so well 
that there hasn't been a need to replace it with a more 
elegant design. ■ 



VIDEO 
IN/ OUT 



Ot 



VIDEO 
OUT/IN 



o- 



VIDEO/ 

CONTROL 

GROUND 



C^ 



+ 5V 
A 



MC14016B 
Nl V CC 



01 
02 
IN2 
C2 
C3 
GROUND 



CI 
C4 
IN4 

04 
03 
IN3 



10 



CONTROL O- 



MC14016B 
INI V CC 



01 

02 

IN2 

C2 

C3 

GROUND 



CI 
C4 

IN4 
04 
03 

IN3 



14 



13 



Figure 1: Schematic diagram of a simple video switch. The MC14016B integrated circuit is a Quad Analog Switch/Quad Multiplexer 
manufactured by Motorola Semiconductor. 



234 March 1981 © BYTE Publications lnc 



DEALERS: By now you know that it takes 



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TO SELL 

COMPUTERS 



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Circle 151 on inquiry card. 



BYTE March 1981 



235 



System Notes 



Software Addressing 
Modes for the 8080 



Dragan Bozinovic 

25 Wood St Apt 810 

Toronto, Ontario M4Y 2P9 Canada 



If you have ever had to write a nontrivial program in 
Intel 8080 assembler, you probably missed the conve- 
nience of more sophisticated addressing modes such as in- 
dexed, indirect, and relative addressing. You may have 
also wished that you had an easy way to access data 
stored below the top of the stack. 

Let's briefly review what Intel 8080 hardware offers 
in the area of addressing, along with suggestions for im- 
provement: 

1. Direct addressing: All 3-byte instructions are direct, 
with the absolute address stored in the last 2 bytes of the 
instruction. If you do not have a relocating assembler and 
loader, you must specify absolute starting addresses in 
your subroutines. This will force you to reassemble them 
whenever you have to change addresses. It would be con- 
venient to have relative addressing instead, which would 
specify the displacement (positive or negative) of the 
referenced address relative to the address of the referenc- 
ing instruction. Assemblers can easily calculate these 
displacements for you. All addresses in your subroutine 
will be independent of its starting location, allowing you 
to move the object code anywhere in memory. Relative 
addressing tends to confuse beginners, but they soon find 
that it is worth the effort to overcome the initial confu- 
sion. 

2. Implicit addressing: Most instructions can reference 
the byte pointed to by the "data counter" (register pair 
HL), while a few accumulator-oriented instructions can 
use other registers as data counters. A nicer arrangement 
would be one in which any memory location could serve 
as a data counter, freeing the processor registers for more 
useful work. This is where indirect addressing comes in. 

3. Stack pointer addressing: You can readily access the 
last 2 bytes stored in the stack, but if you think about 
retrieving bytes stored previously you may get a 
headache. 

4. Immediate data: The instruction itself contains the 
data byte instead of an address. 



What can software do to enhance the choice of ad- 
dressing modes? If you're not overly concerned about ex- 
ecution speed, you may use software routines to create 
the illusion of having any addressing mode you desire. 
You will also need a few bytes of programmable 
(writable) memory. 

How does it work? Just CALL the routine implement- 
ing the particular addressing mode, followed immediate- 
ly by the instruction to be executed using that mode. That 
instruction will not be executed as is, but will provide the 
operation code and information necessary for EA (effec- 
tive address) calculation. Instructions that are to be ex- 
ecuted by hardware will be formed in programmable 
memory. After execution, control returns to the instruc- 
tion following the pseudo-instruction unless it was a suc- 
cessful CALL or JMP. None of the registers are changed 
unless they are modified by the instruction to be ex- 
ecuted. 

Listing 1 contains detailed specifications of each 
routine and its source code. Concerning the program- 
ming conventions used, it may be noted that routines 
were developed using the Intel MAC80 assembler, which 
has only one location counter ($). To define data storage 
close to the routines that use it, and still separate it 
physically into programmable memory, three predefined 
labels, PROG, DATA, and TEMP, are used to keep track 
of the addresses. 

The basic idea behind the approach described here is 
that of covering hardware by a layer of software rou- 
tines, creating an illusion of a machine that is easier to 
program. In fact, this is the concept behind the creation 
of a virtual machine. It can be expanded far beyond the 
basic addressing modes, particularly in the area of I/O 
(input/output) handling. This approach was developed 
to hide peripheral devices from the programmer, but the 
application to addressing modes is likely to be better 
understood by a wider circle of programmers. ■ 

Listing 1 and text box on pages 238 and 240. 



236 March 1981 © BYTE Publications Inc 



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(216)382-7599 



System Notes 



Listing 1: Sophisticated addressing modes may be emulated on 
an Intel 8080 microprocessor with the use of these subroutines. 
They are passed values interpreted as pseudo-code, each setting 
up the proper absolute addresses, freeing the programmer from 
the bind of limited addressing. Similar routines could easily be 
developed for other processors. 



Location 


Object 
Cods 


Label 


AODC 






AODC 




RELAT: 


AODC 


E3 




AODD 


FS 




AODE 


D5 




AODF 


CD27A1 




A0E2 


2B 




A0E3 


2B 




A0E4 


2B 




A0E5 


C31DA1 




OOOC 




LENGTH 


A0E8 




PROG 


A0E8 




* 


A0E8 




SPNDX: 


A0E8 


E3 




A0E9 


F5 




AOEA 


D5 




AOEB 


EB 




AOEC 


210600 




AOEF 


39 




AOFO 


EB 




A0F1 


D5 




A0F2 


C319A1 




000D 




LENGTH 


A0F5 




PROG 


A0F5 




* 


A0F5 




SPDEX: 


A0F5 


E3 




A0F6 


F5 




A0F7 


D5 




A0F8 


E5 




A0F9 


210800 




AOFC 


39 




AOFD 


E3 




AOFE 


CD39A1 




A101 


El 




A102 


C31DA1 




0010 




LENGTH 


A105 




PROG 


A105 




INDRX: 


A105 


E3 




A106 


F5 




A107 


D5 





Operation 


Operand 


ORG 


PROG 


XTHL 




PUSH 


PSW 


PUSH 


D 


CALL 


EMSUB 


DCX 


H 


DCX 


H 


DCX 


H 


JMP 


EMEND 


SET 


S-RELAT 


SET 


$. 


ORG 


PROG 


XTHL 




PUSH 


PSW 


PUSH 


D 


XCHG 




LXI 


H,6 


DAD 


SP 


XCHG 




PUSH 


D 


JMP 


EMI 


SET 


S-SPNDX 


SET 


$ 


ORG 


PROG 


XTHL 




PUSH 


PSW 


PUSH 


D 


PUSH 


H 


LXI 


H r 8 


DAD 


SP 


XTHL 




CALL 


EMS1B 


POP 


H 


JMP 


EMEND 


SET 


S-SPDEX 


SET 


$ 


XTHL 




PUSH 


PSW 


PUSH 


D 



A 108 


E5 




A109 


EB 




A10A 


5E 




A10B 


23 




A10C 


56 




A10D 


EB 




A10E 


E3 




A10F 


C319A1 




000D 




LENGTH 


A112 




PROG 


A112 




' 


A112 




INDEX: 


A112 


E3 




A113 


F5 




AIM 


D5 




A115 


D5 




A116 


C319A1 




0007 




LENGTH 


A119 




PROG 


A1I9 






A119 




EMI: 


A119 


CD27A1 




A11C 


El 




A11D 




EMEND: 


A11D 


19 




A11E 


22F167 




A121 


Dl 




A122 


Fl 




A123 


El 




A124 


C3F0B7 




A127 




EMSUB: 


A127 


7E 




A128 


32F0B7 




A128 


23 




A12C 


5E 




A12D 


23 




A12E 


56 




A12F 




EMSBR: 


A12F 


3E 




A130 


C3 




A131 


32F387 




A134 


23 




A135 


22F4B7 




A138 


C9 




A139 




EMS1B: 


A139 


7E 




A13A 


32F0B7 




A13D 


C32FA1 




0027 




LENGTH 


A140 




PROG 


B7F0 






B7F0 




EMINS: 


B7F3 




EMRTN: 


B800 






B800 




DATA 



PUSH 


H 


XCHG 




MOV 


E,M 


INX 


H 


MOV 


D,M 


XCHG 




XTHL 




JMP 


EMI 


SET 


S-INDRX 


SET 


$ 


ORG 


PROG 


XTHL 




PUSH 


PSW 


PUSH 


D 


PUSH 


D 


JMP 


EMI 


SET 


S-INDEX 


SET 


$ 


ORG 


PROG 


CALL 


EMSUB 


POP 


H 


DAD 


D 


SHLD 


EMINS + 1 


POP 


D 


POP 


PSW 


POP 


H 


JMP 


EMINS 


MOV 


A,M 


STA 


EMINS 


INX 


H 


MOV 


E,M 


INX 


H 


MOV 


D,M 


DB 


03EH 


DB 


0C3H 


STA 


EMRTN 


INX 


H 


SHLD 


EMRTN + 1 


RET 




MOV 


A,M 


STA 


EMINS 


JMP 


EMSBR 


SET 


S-EM1 


SET 


$ 


ORG 


TEMP 


DS 


3 


DS 


3 


ORG 


DATA 


SET 


$ 




S2 SORCIM 

1333 Lawrence Expressway, Suite 418 
Santa Clara, C A 95051 
(408)248-5543 



the SORCIM Report 

the past three years, Sorcim's professionals have scored a string of software successes. These 
lude: 

* PASCAL/M™ , a complete implementation of the Wirth PASCAL language that 
supports the ISO standard. 

* TRANS 86™ , a microprocessor code translator that converts existing 8080 or Z80 
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* The A.C.T.™ series of cross assemblers that support virtually all popular CPUs. 

* Custom software for specific businesses, as well as standard programs for OEM 
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In the months to come, Sorcim will introduce additional software tools that will continue our tradition 
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Sorcim products will be delighted to see what we'll be introducing in the future. Watch for our 
upcoming ads - there are more software success stories yet to come. 

Sorcim is the source for microcomputer software tools. 



238 March 1981 © BYTE Publications Inc 



Circle 153 on inquiry card. 



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IN THIS SMALL SPACE... 

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The Quasar Data QDP-100H is a larger version with 
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Phone: 216/526-0838 / 526-0839 
Telex: 241596 



Circle 154 on inquiry card. 



BYTE March 1981 239 



System Notes 



Interface Specifications 

Family: EMUL 

Routines: RELAT, INDEX, INDRX, SPNDX, 
SPDEX. 

Purpose: This family of routines EMULates several 
addressing modes not implemented by Intel 8080 hard- 
ware. 

Description: Routines consist of separate CALLable 
prefixes of code, common subroutine (EMSUB), and 
final processing routine (EMEND), grouped under the 
name EMUL (see listing 1). Prefixes of unnecessary 
routines may be removed. All routines share a com- 
mon temporary data area defined in EMUL. In this 
work area two instructions are constructed and ex- 
ecuted: 

1. Instruction to be emulated 

2. Return jump 

CALLing interface basic description: 

CALL entry-point 

op address-parameter 

The instruction to be emulated is one of Intel 8080's 
3-byte instructions: LDA, ST A, LHLD, SHLD, LXI, 
JMP's and CALLs. Any other instruction is illegal and 
will produce incorrect results. Return is made after the 
emulated instruction (except for JMP and CALL). The 
instruction is not executed as coded, but serves as an 
argument to emulation routines. The value expected in 
the address field of the emulated instruction and the 
method of forming EA as well as eventual additional 
parameters are all described for each routine. Some of 
the routines are redundant and can be simulated by 
others from this family. Users will have to decide 
which to use depending on the concern for program- 
ming convenience, calling sequence storage re- 
quirements, and execution speed. If applicable, alter- 
nate ways of accomplishing each effect are given under 
the description of each routine. 



Side Effects: The current stack is used three to four 
words deep and restored before return. None of the 
processor registers are changed (including PSW) unless 
modified by the emulated instruction. 

Routine: RELAT 

Purpose: This routine is provided to facilitate 
writing of PIC (position-independent code). It 
emulates addressing relative to PC (program counter). 

Use: // you are writing a module that must be 
capable of executing anywhere in memory you may 
reference a label in the same module as follows: 



CALL 
op 



RELAT 
label-S 



The displacement label-$ will be added to the content 
of PC to form the effective address and the instruction 
will be executed. The only precondition is to have 
RELAT code or JMP to it on the fixed absolute address 
known at assembly time. 

Routine: INDEX 

Purpose: This routine emulates addressing relative 
to the content of the register pair DE. Effective address 
is formed as: 

EA = (DE) + displacement 

Displacement is taken from the address field of the 
emulated instruction and can be either positive or 
negative. 

Routine: INDRX 

Purpose: This routine emulates addressing relative 
to content of the word pointed to by register pair DE. 
Effective address is formed as: 



EA = ((DE)) + displacement 


Calling sequence: 




LXI 

CALL 


D, address 
INDRX 


is equivalent to: 




LHLD 

XCHG 

CALL 


address 
INDEX 



Routine: SPNDX 

Purpose: Sometimes you may wish to access not the 
top word o,f the current stack fosing POP, XTHL, or 
PUSH), but a previously stored word or byte. This 
may be accomplished by calling this routine if the posi- 
tion of the desired word or byte relative to the top of 
the stack is known at assembly time. The word that is 
referenced by POP is accessed using an offset of zero 
(low byte zero, high byte one). The offset is found in 
the address field of the instruction to be emulated. It is 
not and cannot be checked against the current depth 
of the stack. The SP content is not changed. 

Routine: SPDEX 

Purpose: This routine has the same purpose as 
SPNDX, but the offset is found in register pair DE in- 
stead of the address field of the following instruction. 
This permits the offset to be dynamically changed, 
even if the program is to be ROM (read-only memory) 
resident. The calling sequence of this routine is dif- 
ferent from the general model. It is: 



; $ being the current location 
counter value 



LXI 

CALL 

DB 



D, off set 

SPDEX 

op-code 



or equivalent 



octal 



hex 



240 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



241 



BYTELINES 



News and Speculation About Personal Computing 

Conducted by Sol Libes 



•Software Copyright 
Law Enacted: Congress 
has passed the Computer 
Software Copyright Act of 
1980. It protects the rights of 
individuals and companies 
who develop, sell, and lease 
computer programs. The law 
adds computer programs to 
the list of "writings" in 
which exclusive rights may 
be granted for "limited 
times," which generally is 
until 50 years after the 
author's death. 

The law gives the author 
exclusive rights to copy the 
work and to transfer owner- 
ship rights, including sale 
and leasing arrangements. 
Piracy is punishable by fines, 
civil damages, or criminal 
penalties. Work does not 
have to be registered with 
the Copyright Office to be 
protected; it is protected 
once it is in "any tangible 
medium of expression." 

Before the passage of this 
law, the copyright status of 
computer software was 
unclear. 



■ Irst 68000 System 

Introduced: S-100-bus 
personal-computer users can 
now step up to the most 
powerful 16-bit micro- 
processor—the Motorola 
MC68000. Management 
Analysis & Control Inc, 3530 
C Street NE, Auburn WA 
98002, is the first manufac- 
turer to announce a 
68000-based personal- 
computer system. Its new 
processor card will sell for 
$2095. (That's more than I 
paid for my entire S-100 
cabinet and contents!) As 
yet, no software has been 
announced. 



iJhugart Offers 

5 Megabyte Hard-Disk 
System For Under 
S2000: If you're looking 
for a hard-disk system and 



can do some minimal inter- 
facing, you'll be interested 
in Shugart Associates' 
special deal, called the 
"Success Kit." The kit is real- 
ly an evaluation offer for 
OEMs considering the 
design of a Shugart hard-disk 
drive into their computer 
systems; however, there are 
no restrictions on the offer, 
hence anyone can buy just 
one Success Kit. For $1950 
you can get an SA1002 
8-inch, 5-megabyte Win- 
chester-technology drive, an 
SA1400 intelligent con- 
troller, cables, and 
documentation. The con- 
troller provides backup on 
single- or double-sided 
floppy-disk drives. For more 
information, call (800) 
824-7888; in California (800) 
852-7777 (operator 12). 



■ CC Grants Apple and 
Heath Extensions: The 

FCC has granted Apple Com- 
puter Inc and Heath Com- 
pany a 3-month extension on 
compliance with the January 
1, 1981 deadline for RF 
(radio-frequency) radiation 
regulations. Each unit now 
carries a label warning that 
the equipment can interfere 
with radio and television 
reception and that the user 
is responsible for correcting 
it. 

This is the second exten- 
sion of the original July 1980 
deadline given the com- 
panies by the FCC. Both con- 
tended that more time was 
needed to make the 
necessary product changes. 

MtST Plans Home- 
Video Data Base: AT&T 
has disclosed that it is about 
to begin a year-long test of 
an electronic telephone dir- 
ectory. The test will involve 
700 color-video terminals in 
homes and businesses 
throughout Austin, Texas. 



The terminals will be con- 
nected to telephone lines 
and used to access white- 
and Yellow-Pages listings. 
Users will also be able to 
store personal information. 

A similar test involving 
eighty-three participants was 
conducted earlier in Albany, 
Texas; it involved black-and- 
white terminals. AT&T is 
conducting another testwith 
the Knight-Ridder News- 
paper group, in Coral 
Cables, Florida. That system 
includes news reports, home 
banking, and a home-shop- 
ping service. 

If these tests are suc- 
cessful, it will be three to 
four years before the system 
is widely available. 



v apaneie Sales Of US- 
Made Personal Com- 
puters Drop Sharply: 

Feedback From Fujitsu, a 
Japanese computer-industry 
newsletter, reports that the 
sales of US-made personal 
computers in that country 
have dropped sharply. It 
says that until recently, 
Tandy/Radio Shack, Com- 
modore, and Apple manu- 
factured over 90% of the 
6000 to 7000 personal com- 
puters sold monthly in 
Japan. However, their share 
of the market has fallen to 
20% as Hitachi, NEC (Nip- 
pon Electric Company), and 
Sharp have moved into the 
manufacture and sale of per- 
sonal computers. 

Apple and Tandy have 
formed joint ventures with 
Japanese concerns in an at- 
tempt to combat these in- 
roads on US sales. Com- 
modore is reportedly study- 
ing a similar move. 



vapanese Establishing 
Foothold In US Personal 
Computing: The Japanese 
presence is being felt in the 
American personal-comput- 



er market. For example, all 
142 Computerland stores 
will soon carry Japanese per- 
sonal computers. Com- 
puterland is currently 
negotiating with Casio, NEC, 
Panasonic, and Hitachi. 
Several other distributors are 
flirting with Japanese per- 
sonal computers. Apple, Tl 
(Texas Instruments), and 
Atari appear to be the 
primary losers of valuable 
showroom space. 



I ermlnals To Replace 
Phone Directories: The 

French government is pre- 
paring to launch a bold ef- 
fort to give every telephone 
subscriber in France a mini- 
video terminal. Initially it 
will provide on-line tele- 
phone directories. The ter- 
minal will have a 7- to 8-inch 
diagonal screen with 24 lines 
of 40 characters each, solid- 
state keyboard, and a mo- 
dem to send data at 75 bps 
(bits per second) and receive 
at 1200 bps. The PTT (Postal 
Telephone and Telegraph 
Authority) expects the ter- 
minal to cost $75 to $100. 
Over the next ten years, the 
PTT expects to procure more 
than 30 million terminals at 
a cost of $3 billion, which it 
estimates is less than the 
cost of printed directories 
and directory-assistance op- 
erators. 



M. 



I ore Hobby Robot- 
ics Activities: Add these 
developments to previously 
listed sources of robotics in- 
formation. 

The United States Ro- 
botics Society, Palo Alto, 
California, is resuming 
publication of its ROVOX 
newsletter. Membership is 
$20 per year. The Computer- 
world Store, Van Nuys, 
California, has published the 
Robotics Catalog. Also, the 
International Institute of 



242 March 1981 © BYTE Publications Inc 



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T^/SOP evW °"' trademark Carolina Business Computers 

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of CPU Int'l Pascal/M. ACT & TRANS 86 trademarks Sorcim 

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Business Applications Textwriter, Datebook & Milestone trademarks Organic Software 

Ultrasort-ll & FABS trademarks Computer Control Systems Magic Menu trademark of Charles Merrirt 

Copywriter, Copyproof & Diction trademarks Systronics Microstot trademark Ecosoft S-Basic trademark Topaz Programming 

Spellguard trademark ISA CP/M & MP/M trademarks Digital Research TRS-80 trademark Tandy Superbrain trademark Intertec Data 

Systems UCSD Pascal trademark of Regents of University of California WordStar trademark Micro Pro Int'l Spellbinder trademark Lexisoft 

For shipping add S5. in US; S10. outside US per package California residents add appropriate state sales tax Terms: Prepaid check, 

M/C or VISA or in US COD (UPS) Dealer inquiries invited Prices quoted do not include dealer installation & training Prices effective until May 1, 1981 



-sectoi 



ed)t> s 



(jWtttSW 



00) w 5 " 



Circle 156 on inquiry card. 



BYTE March 1981 



243 



BYTELINES 



Robots in Pelahatchie, 
Mississippi, has resumed 
publication of its quarterly 
newsletter. 



w 



rlstwatch-Slzed 
Computer Proposed: Ten 

years ago, who would have 
conceived of the table-top 
computer or, better yet, the 
pocket computer? Yet they 
are realities today. Current 
dreams envision something 
much smaller: the Novem- 
ber 1980 Computer carried a 
detailed proposal by 
Stephen Kearney for a com- 
puter to be worn on your 
wrist. Kearney has overcome 
the I/O (input/output) prob- 
lem with a clearly thought 
out display and keyboard. 
The LCD (liquid-crystal 
display) is 27 characters by 8 
lines (for a total of 216 
characters), with uppercase, 
lowercase, and special char- 
acters, in a space 1 % by 3 
inches. The unit has a 9-key 
keyboard capable of upper- 
and lowercase alphanumer- 
ics and special characters. 
The keyboard measures '/, 
inch by 2 inches. 



w, 



hlch Computer Is 
The Fastest?: Datamation 
recently conducted a survey 
to determine which comput- 
ers are the fastest in produc- 
tion. The measurement used 
was KOPS (thousands of op- 
erations per second). This 
was felt to be a better mea- 
sure than MIPS (millions of 
instructions per second). The 
top three were: Cray-1 
(800,000 KOPS), CDC Cyber 
205 (800,000 KOPS), and 
CDC 7600 (10,000 KOPS). 
The fastest IBM computer 
was the IBM 1088 (2X) with 
1160 KOPS. 

The KOPS rating is deter- 
mined by measuring how 
long it takes the computer to 
execute a prescribed mix of 
programs; the measurement 
ignores I/O and operating- 
system considerations. As 
such, KOPS measures only 
processor speed and not sys- 
tem speed. 

Jmart Wheelchair 
Shown: The Rehabilita- 



tion Engineering Center of 
the Veterans Administration 
Hospital, Palo Alto, Califor- 
nia, has demonstrated a pro- 
totype microprocessor- 
controlled wheelchair for 
severely incapacitated per- 
sons. Using autofocus ultra- 
sonic-ranging detectors aim- 
ed at the head, a person can 
direct the wheelchair's 
movements by moving his 
head. Sensors are included 
to detect objects in the 
chair's path and to gauge 
distance to walls so that the 
chair can track a wall at a 
fixed distance. Cruise con- 
trol is provided so that the 
user can relax until a change 
in velocity is wanted. The 
developers expect this unit 
to add only $100 to $200 to 
the cost of a standard 
wheelchair. 



■ lat-Panel Display 

Update: There are over 2 
million video terminals in 
use. It's expected that yearly 
shipments will top the mil- 
lion-unit level by the 
mid-1980s. However, they 
have some big disad- 
vantages. They're bulky, 
they waste a lot of desk 
space, consume too much 
power, annoy users with re- 
flected light, and are dam- 
aged easily. 

More than a dozen com- 
panies are developing flat- 
panel displays. Some are al- 
ready in production. Most 
successful are the plasma 
displays. LCD and ELD (elec- 
troluminescent displays) are 
also being developed. 

The Japanese are working 
on flat-panel displays. Fujit- 
su, Hitachi, Matsushita, and 
Seiko Denki have all pro- 
duced plasma and LCD pro- 
totypes. Hycom Corpora- 
tion, a US subsidiary of 
Sharp, has developed an 
ELD for the US Army in por- 
table battlefield terminals. 
Exxon Corporation, through 
its Kylex and Electrophoretic 
Information Display divi- 
sions, is also developing flat 
displays. Kylex is already 
producing an 8-line LCD 
panel, and it is rumored that 
this will soon be expanded. 

There is no doubt that by 



the end of the decade flat- 
panel displays will dominate 
the terminal- and television- 
display markets. They will 
offer low power consump- 
tion, high daylight visibility, 
and the shock resistance 
necessary to make the true 
portable computer and intel- 
ligent terminal a reality. 



^» an A Computer Have 
Worms7 Several years ago 
rumor had it that an enter- 
prising computer hacker had 
gained access to a DOD 
computer from a remote ter- 
minal. Once inside, he 
entered a program that re- 
wrote its data into all of the 
computer's memory, des- 
troying the computer's soft- 
ware and data base. In other 
words, the program was like 
the shapeless monster from 
the classic science-fiction 
thriller, The Blob. 

Now, from Xerox's Palo 
Alto (California) Research 
Center, comes the "Worm." 
The Worm is a series of pro- 
grams that wiggles through a 
computer network at will, 
copying itself into inactive 
systems in the network. The 
Worm coordinates the oper- 
ation of all the computer 
systems in the network. It 
delegates tasks to unused 
machines and coordinates 
the operation of machines in 
the network. Any complex 
computations are handled 
by harnessing multiple pro- 
cessors. 

The Worm is still in the ex- 
perimental stage. As such, it 
may be the precursor of 
much more powerful auton- 
omous programs that, like 
the Blob, could take over 
and control entire networks. 



Vomputer Contest To 
Aid The Handicapped: 

The National Science Foun- 
dation, Johns Hopkins 
University, and Radio Shack 
have announced a nation- 
wide competition for com- 
puter aids for the physically 
or mentally handicapped. 
(See "National Search to Aid 
the Handicapped Through 
Personal Computers," page 
316.) The grand prize is 



$10,000, with runner-up 
prizes of equipment and 
money. There are several in- 
centives to encourage par- 
ticipation, including 
separate entry categories for 
students, amateurs, and pro- 
fessionals. For more infor- 
mation, contact Personal 
Computers for the Hand- 
icapped, Johns Hopkins 
University, POB 670, Laurel 
MD 20810. 



R. 



obot Destroys Itself: 

An experimental robot at the 
University of Florida went 
out of control, destroying 
itself before a graduate stu- 
dent could press its cutoff 
button. The robot's arm was 
driven into its supporting 
body, ripping its shoulder 
off. 



#«erox Introduces First 
Ethernet System: Xerox 
has been talking about 
Ethernet for two years, and I 
have reported on its progress 
many times. Finally, it has 
introduced the first system 
hardware. Called the Xerox 
System 8000, it allows users 
to create, file, print, and 
distribute documents and 
data to any and all users on 
the system. It allows many 
types of office equipment to 
be linked into an integrated 
local system via coaxial 
cable, and the system can be 
tied in to other external net- 
works. 

Without a doubt, many 
manufacturers will in- 
troduce hardware and soft- 
ware interfaces for the 
Ethernet system. IBM, 
Wang, Exxon, AT&T, and 
M/A-COM are working on 
their own local network 
systems. 



I 



BM Opens Retail 

Stores: Philadelphia and 
Baltimore are the sites of 
IBM's two new storefront 
sales outlets. Several more 
are planned. 

The stores carry type- 
writers, copiers, word pro- 
cessors, small-business com- 
puters, and supplies. IBM is 
following in the footsteps of 



244 March 1981 © BYTE Publications Inc 




TOMORROW'S answers 
for the H8 TODAY! 



DG Electronic Developments provides the only enhancements to put the 
Heath " H8 ahead TODAY while maintaining its high standards, broad 
flexibility and high reliability. 

DG-80 (Z80" Based CPU) 

The DG-80 offers the BEST foundation for the H8 to build on for the future. 
Compare the DG-80 to your current Heath" 8080 CPU and see the 
advantages of the DG-80's superior speed and flexibility. The Z80 gives twice 
the processing speed coupled with twice the instruction set making your H8 a 
truly professional microsystem. DG-80 aids the efficient writing of utility 
programs, user routines, sub-routines and use of assemblers. 

DG-80 $249. (Documentation only $25.) 

DG-FP8/ADP4 (DG80 Front Panel Monitor) 

The DG-FP8/ADP4 firmware/hardware package brings the world of 
standardization to your H8. The FP8/ADP4 allows the full use of currently 
available "STANDARD" CPM software, with 4 MHz operation. You can still 
use your HDOS and all its related software, by simply putting a disk in your 
drive. The DG firmware package gives you use of the full 64K of RAM available 
on the 64D or 64D5. The FP8/ADP4 firmware also offers many extras 
including hexadecimal O R split octal display; simplification of register and 
memory contents display; and the full use of all Z80 registers (more than twice 
the number of registers in the 8080). Plus, the unique front-panel single-step 
feature is maintained to aid in software troubleshooting. 
DG-FP8 $69.95. DG-ADP4 $19.95. Purchased together $79.95. 

(Documentation only — source code not included $ 1 5.) 

DG-64D (64K RAM Memory Board) 

The DG-64D is THE BEST memory board available for the H8! Along with 
the DG-80 CPU, the 64D gives a full 64K of addressable memory. Its built-in 
flexibility ensures future compatibility. Multi-user configurations can be 
achieved accessing up to eight 64D's on line with the hardware/software bank 
select features. Memory contents are maintained and protected during 
extended wait states by asynchronous refresh. 

DG-64D priced from $333 (0K) to $529 (64K). (Documentation only $15.) 

DG-64D5 (5-Volt Power Supply 64K RAM) 

The DG-64D5 memory board offers the ultimate in low power consumption 
for the H8 computer! The 64D5 is primarily designed for use with the Heath 
Color Graphics board. In addition to offering ALL of the features of the 
standard 64D, the 64D5 utilizes single-supply 5-volt-only dynamic RAMs and 
allows the use of extended wait states. 

Priced from $333 (0K) to $799 (64K). (Documentation only $15.) 

Chip Sets (8-45 1 7 dynamic RAMS) $ 1 50. 

CP/M (Standard V2.2 Disk Operating System) 

The final component for the "STANDARD" H8 system is Digital Research's 
CP/M " V2.2. Our full line of H8 enhancements in combination with CP/M gives 
the user unparalleled flexibility and puts thousands of CP/M software programs 
at your fingertips. 

CPM V2.2 $ I 30. (Documentation only $25.) 

All products supplied with complete documentation. 
Please call or write for additional information. 

Heath' and H8" are registered trademarks ot Heath Corporation. Benton Harbor. Michigan. CP/M- is the registered trademark of Digital 
Research ot Pacific Grove. California. Z80 ■ is the registered trademark of Zilog Corporation. 
















D-E 



Ordering Information: Products listed available from DG Electronic 
Developments Co., P.O. Box 1124. 1827 South Armstrong, Dentson, Tx. 
75020. Check, Money Order, VISA or MasterCard accepted. Phone orders 
(charge only) call (214) 465-7805. No COD's. Freight prepaid. Allow 3 weeks 
for personal checks to clear. Texas residents add 5%. Foreign orders add 
30%. Prices subject to change without notice. 



Circle 157 on inquiry card. 



BYTE March 1981 



245 



BYTELINES 



DEC, even though DEC 
closed two of its retail 
outlets and has put a halt to 
its retail expansion. 

In a related development, 
Hewlett-Packard has 
entered into an agreement 
to sell its HP-1000L small- 
business computer through 
ABC Computers Inc's 350 
retail outlets. 



I rogrammer Fined 
For Copying Software: A 

Mobile County, Alabama, 
circuit court has fined a pro- 
grammer $50,000 for copy- 
ing his former employer's 
software and using it in a 
competing business he 
started. A jury decided that 
a theft had occurred, even 
though nothing material was 
taken. The prosecution 
maintained that the former 
employee could not have re- 
created the identical pro- 
grams in such a short period 
of time. The defense said he 
had done so. The program- 
mer plans to appeal. 



I ersonal Computing 
On Corporate Machines: 

Federal auditors discovered 
over 200 government 
employees at the Sandia 
Nuclear Weapons Research 
Center in Albuquerque, New 
Mexico, using the facility's 
Control Data Corporation 
systems for personal use. 
Sources report that 456 
unauthorized files were 
located, including several 
hundred games such as Star 
Trek and Adventure, as well 
as poetry, jokes, personal 
letters, a beer-can collection 
catalog, and bowling-team 
rosters. One employee was 
caught helping local gam- 
blers run a bookmaking 
operation. 



Uoes Computer Crime 
Pay? It certainly does... 
according to Paul Nolan, 
supervisory special agent in 
the FBI's White Collar Crime 
Section. He estimates that 
non-computer-aided embez- 
zlement averages $23,000 
per occurrence, while 
computer-aided embezzle- 



ment averages $430,000. By 
the way, bank robbers 
average only $3000. 



w olume Production 
For 64 K-BIt Memories: 

Within two months, sup- 
pliers will start shipping the 
new 64 Kbit programmable 
memories to manufacturers 
and distributors. Prices will 
be in the $25 to $30 range; 
they'll drop under $20 in 
July. Fifteen suppliers have 
announced devices, al- 
though some of the spec- 
ification sheets are ten- 
tative. 

It's not yet clear when 
personal-computer manu- 
facturers will start using the 
64 K-bit chips in place of 
16 K-bit circuits. Many will 
stick with the 16 K-bit de- 
vice until the 64 K units 
show a significant price 
drop. 

Intel has let it be known 
that its 64 K-bit memories 
will use redundant bits for 
increased yield, the same 
technique used by IBM and 
Western Electric in their in- 
house circuits. Intel uses a 
"ROM-fuse" technique (an 
internal programmable read- 
only-memory) to decode ad- 
dresses and replace one or 
more defective cells. 



#Tda Status Report: It 

is estimated that the DOD 
(Department of Defense) 
uses over 500 general-pur- 
pose computer languages 
and that $3 billion is spent 
each year for software de- 
velopment, whose control is 
a nightmare. That's what led 
the DOD to subsidize the 
Ada language project. The 
department wants Ada to be 
its only language. 

In 1975, a DOD group 
undertook the task of 
evaluating twenty-three 
existing languages to find a 
standard language. None 
were found suitable. In 
mid-1978, the group invited 
specification recommenda- 
tions from around the world 
and sponsored a competi- 
tion among seventeen organ- 
izations. The Green lan- 
guage (later dubbed Ada), 



developed by Cii Honeywell 
Bull (a French subsidiary of 
Honeywell), emerged the 
winner. Initial specifications 
were released in mid-1979 
and refined and completed 
by mid-1980. 

A fully functional Ada 
compiler for the entire 
language is expected to be 
available next year. Many 
private and educational in- 
stitutions are currently 
developing Ada compilers, 
including Carnegie-Mellon 
University and the Universi- 
ty of Karlsruhe, West Ger- 
many. Other schools study- 
ing various aspects of Ada 
include Stanford, Harvard, 
MIT, and the Universities of 
Texas, Massachusetts, 
Southern California, Penn- 
sylvania, York (England), 
Tokyo, London, and the 
Technical University of Den- 
mark. 

The DOD has requested 
that the Ada compiler run on 
the DEC (Digital Equipment 
Corporation) VAX 11/780 and 
produce code for the VAX, 
the DEC PDP-11, and the 
military AN/GYK-12. 

A number of institutions 
already have "Little Ada" 
compilers running, and it's 
likely that we'll see a "Tiny 
Ada" implementation for 
8080/Z80 systems by year's 
end. 



V/hlo Scientific Sold: 

Ohio Scientific Inc (OSI), 
one of the early pioneers in 
personal-computing sys- 
tems, has been purchased 
for an undisclosed sum by 
M/A-COM Inc of Burlington, 
Massachusetts. M/A-COM 
manufactures business com- 
munications equipment. OSI 
had sales of $14.8 million for 
the 10-month period ending 
October 1980. Mike Cheiky, 
OSI founder, will remain as 
vice-president of develop- 
ment. In all likelihood OSI 
will move away from per- 
sonal computing and into 
the small-business market. 



R 



andom Rumors: 

Apple is rumored to be fran- 
tically working on a 16-bit 
computer system using the 



Motorola 68000.... Sony and 
Canon are about to intro- 
duce computers using the 
Motorola 6809 8-bit micro- 
processor.... Radio Shack 
may introduce a disk system 
for the TRS-80 Color Com- 
puter system.... According to 
insiders, Texas Instruments 
will soon have a low-cost 
system and a Viewdata-type 
terminal. Tl is concerned 
over Radio Shack's growing 
domination of the consumer 
communications market.... 
Experts predict that Radio 
Shack will have 40,000 
people hooked up to data 
bases through their equip- 
ment by year end.... 

The Apple III appears to 
be designed to accept one of 
the new 5 Va -inch Win- 
chester hard disks in place 
of its 514 -inch floppy-disk 
drives.... Informed sources 
say that Zilog is at last ship- 
ping fully functional Z8000s. 
Reportedly, the first four 
versions had some op codes 
that did not execute correct- 
ly... Sony and Matsushita 
are expected to introduce 
portable microcomputer 
products that fit into your 
briefcase. They are intended 
for electronic mail and data- 
base access applications. 
(See "The Panasonic and 
Quasar Hand-Held Com- 
puters," by Gregg Williams 
and Rick Meyer January 
1981 BYTE, page 34.) ...Ex- 
pect a CP/M-like operating 
system for Atari's 800 per- 
sonal computer.... Okidata 
will unveil a 35 cps overlap- 
ping dot-matrix printer for 
under $1000 at the National 
Computer Convention in 
May.... 



MAIL: I receive a large number 
of letters each month as a result 
of this column. If you write to 
me and wish a response, please 
include a self-addressed, 
stamped envelope 

Sol Llbes 
POB 1192 
Mountainside NJ 07081 



246 March 1981 © BYTE Publications Inc 



The Text Solution for APPLE II® 

Now APPLE II® Owners Can Solve Text Problems 

With VIDEOTERM 80 Column by 24 Line Video Display 

Utilizing 7 X 9 Dot Character Matrix 

Perhaps the most annoying shortcoming of the Apple II® is its limitation of displaying only 40 columns by 24 lines of 
text, all in uppercase. At last, Apple II® owners have a reliable, trouble-free answer to their text display problem. 
VIDEOTERM generates a full 80 columns by 24 lines of text, in upper and lowercase. Twice the number of characters as 
the standard Apple II® display. And by utilizing a 7 by 9 character matrix, lower case letters have true descenders. But 
this is only the start. 



VIDEOTERM, MANUAL, 
SWITCHPLATE 




VIDEOTERM 



Pascal 



Other 
Boards 



' ; - * in '()* + ,-. / 

B123456789: ;< = >? 
f ft B C D E F G H I J K L H N 
P R 5 T U V W X Y Z [ \ ] A . 
'abcdefjhijklmnD 
pqrstuvwxyzt i ) * I 



7X12 MATRIX 
18X80 OPTIONAL 



MIIII '()»♦>-. / 
I1ZJ4567B9: i < = >? 

IJIC0EF6H I JKIMHO 

possTuvuxrzc\it_ 

'jtcdefjiiijklino 
pqrstuvwxyzt! )'i 



7X9 MATRIX 
24X80 STANDARD 



Advanced 
Hardware 
Design 



Available 
Options 



VIDEOTERM lists BASIC programs, both Integer and Applesoft, using the entire 80 
columns. Without splitting keywords. Full editing capabilities are offered using the 
ESCape key sequences for cursor movement. With provision for stop/start text 
scrolling utilizing the standard Controls entry. And simultaneous on-screen display 
of text being printed. 

Installation of VIDEOTERM in slot 3 provides Pascal immediate control of the 
display since Pascal recognizes the board as a standard video display terminal and 
treats it as such. No changes are needed to Pascal's MISC. INFO or GOTOXY fiies, 
although customization directions are provided. All cursor control characters are 
identical to standard Pascal defaults. 

The new Microsoft Softcard' is supported. So is the popular D. C. Hayes Micro- 
modem II" , utilizing customized PROM firmware available from VIDEX. The power- 
ful EasyWriter" Professional Word Processing System and other word processors 
are now compatible with VIDEOTERM. Or use the Mountain Hardware ROMWriter' 
(or other PROM programmer) to generate your own custom character sets. Natural- 
ly, VIDEOTERM conforms to all Apple OEM guidelines, assurance that you will have 
no conflicts with current or future Apple II' expansion boards. 

VIDEOTERM's onboard asynchronous crystal clock ensures flicker-free character display. 
Only the size of the Pascal Language card, VIDEOTERM utilizes CMOS and low power con- 
sumption ICs, ensuring cool, reliable operation. All ICs are fully socketed for easy 
maintenance. Add to that 2K of on-board RAM, 50 or 60 Hz operation, and provision of power 
and input connectors for a light pen. Problems are designed out, not in. 

The entire display may be altered to inverse video, displaying black characters on a white 
field PROMs containing alternate character sets and graphic symbols are available from 
Videx. A switchplate option allows you to use the same video monitor for either the 
VIDEOTERM or the standard Apple IP display, instantly changing displays by flipping a 
single toggle switch. The switchplate assembly inserts into one of the rear cut-outs in the 
Apple IP case so that the toggle switch is readily accessible. And the Videx KEYBOARD 
ENHANCER can be installed, allowing upper and lower case character entry directly from 
your Apple IP keyboard. 

1K of on-board ROM firmware controls all operation of the VIDEOTERM. No machine 
language patches are needed for normal VIDEOTERM use. 



Characters 7x9 matrix 
Options 7 x 12 matrix option; 

Alternate user definable 
character set option; 
Inverse video option. 



Firmware Version 2.0 
Display 



24 x 80 (full descenders) 

18 x 80(7 x 12 matrix with full descenders) 



Want to know more? Contact your local Apple dealer today for a demonstration. VIDEOTERM is available 
through your local dealer or direct from Videx in Corvallis, Oregon. Or send for the VIDEOTERM Owners 
Reference Manual and deduct the amount if you decide to purchase. Upgrade your Apple II* to full terminal 
capabilities for half the cost of a terminal. VIDEOTERM. At last. 



Apple II' is a trademark of Apple Computer Inc. 
ROMWriter' is a trademark at Mountain Hardware Inc 
Micromodem II" is a trademark of D. C. Hayes Associaies 
Soltcard' Is a trademark at Microsoft 
EasyWrilef is a trademark of Information Unlimited Soltw 



> VIDEOTERM includes manual $345 

• SWITCHPLATE S 19 

■ MANUAL refund withpurchase. 5 19 

• 7x12CHARACTERSET $ 39 

• MICROMODEM FIRMWARE S 25 



APPLE II® OWNERS! 

introducing the 

KEYBOARD & DISPLAY 

ENHANCER 

■ PUT THE SHIFT AND SHIFT LOCK BACK WHERE IT BELONGS 
»SEE REAL UPPER AND lower CASE ON THE SCREEN 
• ACCESS ALL YOUR KEYBOARD ASCII CHARACTERS 



Videx has the perfect companion for your 
word processor software: the KEYBOARD 
AND DISPLAY ENHANCER Install the 
enhancer in your APPLE II and be typing in 
lower case just like a typewriter. If you want an 
upper case character, use the SHIFT key or the 
CTRL keyfor shift lock. Not only that, but you 
see upper and lower case on the screen as you 
type. Perfectly compatible with Apple Writer 
and other word processors like, for example. 
Super-Text. 

If you want to program in BASIC, just put it 
back into the alpha lock mode; and you have 
the original keyboard back with a few im- 



provements. Now you can enter those elusive 9 
characters directly from the keyboard, or re- 
quire the Control key to be pressed with the 
RESET to prevent accidental resets 

KEYBOARD AND DISPLAY 

ENHANCER is recommended for use with all 
revisions of the APPLE II. It includes 6 ICs. and 
EPROM and dip-switches mounted on a PC 
board, and a jumper cable. Easy installation, 
meaning no soldering or cutting traces. Alter- 
nate default modes are dip-switch selectable. 
You can even remap the keyboard, selecting an 
alternate character set. for custom applications. 




PRICE • KDE-700 (REV. 7 or greater) J 129. 

■ KDE-000 (REV. 6 or less) S 129. 

Apple 11* is a trademark of Apple Computer. Inc. 




VIDEX 
897 N.W. Grant Avenue 
Corvallis, Oregon 97330 
Phone (503) 758-0521 



Circle 158 on inquiry card. 



BYTE March 1981 247 



iTSSvEPi 

WITH DSC'S 10% CLUB 

• YOU CAN BUY HARDWARE, SOFTWARE, 
AND SUPPLIES AT 10% ABOVE 
WHOLESALE 

• JOIN NOW: $15.00 ANNUAL 
MEMBERSHIP FEE INCLUDES $10.00 
CREDIT TOWARD FIRST PURCHASE AND 
CATALOG OF PRODUCTS 

• TERMS — PREPAYMENT, CASH, CERTIFIED CHECK, M.O., 
M.C. AND VISA ADD 4%, FOB PHI LA., PA. 

• WARRANTIES — ALL EQUIPMENT CARRIES 
MANUFACTURER'S WARRANTY AND WILL BE SERVICED 
BY MANUFACTURER OR REPRESENTATIVE 



COMPUTERS 

Intertec - SuperBrain 32K 

SuperBrain64K 

SuperBrain QD 64K 

Intertube III 

Atari - 400 Computer 

SOOComputer 

815Dual Disk Drive 

Applell + Apple II Plus-16K 

32K 

48K 

Drives- Lobo for Apple- 5%" with controller 

VRData- 40tk1side 

80tk 1side 

40 tk 2 side 

80tk2side 
8" CDC 9404B, Mod II comp. 
16K memory 

Modems - D-Cat direct connect 

Lexicon acoustic 

Radio Shack - Mod. I Expansion Interface 

Model III 16K 

Model MI32Kw/2Drives 

ColorComputer4K 

ColorComputer 16K 

PRINTERS 

Centronics -730-1 parallel 

730-3 serial 

737-1 parallel 

737-3 serial 

704-9 RS-232 serial 

Anadex-8000 

NEC-5510w/tractor 

C. Itoh Starwriter25cps parallel 
SUPPLIES 

Verbatim Diskettes -5'/4" MD-01 DataLife 

550-01, DD 

8"FD-34-9000-DataLife 

Nashua Diskettes -5V4" (high quality) 

8"DD,FD-1D-WP 

Dysan-5%"SS-SD 
ALL BRANDS OF HARDWARE, SOFTWARE, 
SUPPLIES AND BOOKS ARE AVAILABLE. 



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PERIPHERALS, 



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CHARGE O MASTER CHQ. 
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EXPIRATION DATE 



Software Received 



SDisk Supply Co. _ 
SUITE 439, 111S. OLIVE ST. MEDIA, PA 19063 
(215)461-5437 ^^Bl 



Apple II, PET, and 
TRS-80 

B-l Nuclear Bomber, 

historical strategy game for 
the Apple, PET, and 
TRS-80. Cassette, $14.95. 
Avalon Hill Game Com- 
pany, 4517 Harford Rd, 
Baltimore MD 21214. 

Planet Miners, strategy 
game for the Apple, PET, 
and TRS-80 (three versions 
sold together). Cassette, 
$14.95. Avalon Hill Game 
Company (see above). 

TRS-80 

Disk Editor/Assembler, 

line editor and relocatable 
machine-language assembler 
for the TRS-80. Floppy disk, 
$99.95. Radio Shack, 1 Tan- 
dy Ctr, Fort Worth TX 
76102. 

FORTRAN, programming 
language and utilities for the 
TRS-80. Floppy disk, 
$99.95. Radio Shack (see 
above). 

Lost Ship Adventure, 
Adventure program for the 
TRS-80. Cassette, $14.95. 
The Programmer's Guild, 
POB 66, Peterborough NH 
03458. 

Profile, general-purpose 
data base and report writer 
for the TRS-80. Floppy disk, 
$79.95. Radio Shack (see 
above). 

Real Estate Volume II, 
mortgage analysis program 
for the TRS-80. Cassette, 
$29.95. Radio Shack (see 
above). 

Scripsit, word-processing 
package for the TRS-80. 
Floppy disk, $99.95. Radio 
Shack (see above). 



Standard & Poor's 
Stockpak and Portfolio 
Management System, stock- 
analysis program for the 
TRS-80. Floppy disk, 
$49.95. Radio Shack (see 
above). 

Star Trek 4.0, action 
game for the TRS-80. 
Cassette, $14.95. The Pro- 
grammer's Guild (see 
above). 

Superdisk, collection of 
utility programs for the 
TRS-80. Floppy disk, 
$49.95. The Programmer's 
Guild (see above). 

VisiCalc, numerical com- 
putation and forecasting tool 
for the TRS-80. Floppy disk 
$99.95. Radio Shack (see 
above). 

Texas Instruments 99/4 
Early Learning Fun, 

educational activity for 
children for the TI 99/4. 
Floppy disk, $30. Texas In- 
struments, 13500 N Central 
Expy, Dallas TX 75231. 

Personal Record Keeping, 
computer-based filing system 
for the TI 99/4. Program 
cartridge, $50. Texas In- 
struments (see above). 

Speech Editor, speech syn- 
thesis aid for the TI 99/4. 
Program cartridge, $45. 
Texas Instruments (see 
above). 

Other Computers 

Nevada COBOL, version 
of the COBOL language for 
CP/M systems. Eight-inch 
floppy disk, $99.95. Ellis 
Computing, 1480 17th Ave, 
San Francisco CA 94122. 



This is a list of software packages that have been received by 
BYTE Publications during the past month. The list is correct to the 
best of our knowledge, but it is not meant to be a full description 
of the product or the forms in which the product is available. In 
particular, some packages may be sold, for several machines or in 
both cassette and floppy-disk format; the product listed here is 
the version received by BYTE Publications. 

This is an all-inclusive list that makes no comment on the quality 
or usefulness of the software listed. We regret that we cannot 
review every software package we receive. Instead, this list is 
meant to be a monthly acknowledgment of these packages and 
the companies that sent them. Companies sending software pack- 
ages must include the suggested list price of the packages and 
(where appropriate) the alternate forms in which they are avail- 
able. 



248 March 1981 © BYTE Publications Inc 



Computer experts 
(the pros) usually have big 
computer experience. 
That's why when they shop 
system software for ZBO 
micros, they look for 
the big system features 
they're used to. And that's 
why they like Multi-User 
OASIS. You will too. 



DATA INTEGRITY: FILE & 
AUTOMATIC RECORD LOCKING 



The biggest challenge 
for any multi-user system 
is co-ordinating requests 
from several users 
to change the same record 
at the same time. 

Without proper 
co-ordination, the 
confusion and problems 
of inaccurate or even 
destroyed data can be 
staggering. 

Our File and Automatic 
Record Locking features 
solve these problems. 

For example: normally 
all userscan view a 
particular record at the 
same time. But, if that 
record is being updated 
by one user, automatic 
record locking will deny all 
other users access to the 
record until the up-date is 
completed. So records 
are always accurate, 
up-to-date and integrity 
is assured. 

Prosdemandfile& 
automatic record locking. 
OASIS has it. 



SYSTEM SECURITY: 
LOGON, PASSWORD 
& USER ACCOUNTING 



Controlling who gets on 
your system and what they 
do once they're on it is the 
essence of system security. 



(THEN COMPARE.) 



Without this control, 
unauthorized users could 
access your programs and 
data and do whatthey like. 
A frightening prospect 
isn't it? 

And multi-users 
can multiply the problem. 

Butwiththe Logon, 
Password and Privilege 



Level features of Multi-User 



OASIS, a system manager 
can specify for each user 
which programs and files 
may be accessed — 
and for what purpose. 

Security is further 
enhanced by User 
Accounting — a feature that 
lets you keep a history 
of which user has been 
logged on, when and 
for how long. 

Pros insist on these 
security features. 
OASIS has them. 



EFFICIENCY: 
RE-ENTRANT BASIC 



A multi-user system 
is often not even practical 
on computers limited 
to 64K memory. 

OASIS Re-entrant 
BASIC makes it practical. 

How? 

Because all users use a 
single run-time BASIC 
module, to execute their 
compiled programs, less 



memory is needed. Even 
if you have more than 64K, 
your pay-off is cost saving 
and more efficient use 
of all the memory you have 
available— because it 
services more users. 

Sound like a pro feature? 
Itis.AndOASIS hasit. 



AND LOTS MORE. 



Multi-User OASIS supports 
as many as 1 6 terminals 
andean run in as little as 
56K memory. Or, with 
bank switching, as much 
as 784K. 

Multi-Tasking lets each 
user run more than one 
jobatthe sametime. 

And there's our BASIC- 
a compiler, interpreter and 
debugger all in one. 
An OASIS exclusive. 

Still more: Editor; Hard 
& Floppy Disk Support: 
Keyed (ISAM), Direct & 
Sequential Files: Mail-Box; 



Scheduler; Spooler; 
all from OASIS. 

Our documentation is 
recognized as some of the 
best, most extensive, in the 
industry. And, of course, 
there's plenty of 
application software. 

Put it all together and it's 
easy to see why the real 
pros like OASIS. Join them. 
Send your order today. 




OASIS IS AVAILABLE FOR 

SYSTEMS: Altos; Compucorp. Cromemco; 
Delta Producls: Digital Group; Digital 
Microsystems. Dynabyte Godbout: IBC; 
Index; Intersyslems; North Star. Onyx; 
SD Systems; TRS BO Mod II. Vector 
Graphic. Vorimex 

CONTROLLERS: Bell Controls: Cameo 
Corvus; Konan; Micromation; Micropolis: 
Tarbell; Teletek; Thinkertoys; X Comp 

Wnle (or complete. 

Iree Application Software Directory 



1 PLEASE SEND ME: 






Price 






with 


Manual 


■ Product 


Manual 


Only 


I OPERATING SYSTEM 






(Includes: 






EXEC Language; 






m File Management; 






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■ Device Drivers; 






| Print Soooler; 






■ General Text 






■ Editor, etc ) 






1 SINGLE-USER 


S150 


SI 7.50 


| MULTI-USER 


350 


17 50 


■ BASIC COMPILER/ 






■ INTERPRETER/DEBUGGER 


too 


1500 


' RE-ENTRANT BASIC 






■ COMPILER/INTERPRETER/ 






" DEBUGGER 


150 


15.00 


- DEVELOPMENT PACKAGE 






' (Macro Assembler; 






_ Linkage Editor; 






1 Debugger} 


150 


25.00 


■ TEXT EDITOR S 






| SCRIPT PROCESSOR 


ISO 


15.00 


| DIAGNOSTIC & 






CONVERSION UTILITIES 






| (Memory Test; 






Assembly Language; 






1 Conveners: File 






Recovery: Disk Test; 






1 File Copy from 






' ' otner OS; etc ) 


100 


15.00 


m COMMUNICATIONS 






■ PACKAGE 






; (Terminal Emulalor; 






■ File Send S Receive) 


too 


15.00 


■ PACKAGE PRICE 






p (All of Above) 






SINGLE-U5ER 


500 


60.00 


[1 MULTI-USER 


850 


6000 


I FILE SORT 


too 


15.00 


■ COBOL-ANSI '7« 


750 


35.00 



Order OASIS from: 

Phase One Systems, Inc. 

7700 Edgewater Drive, Suite 830 

Oakland, CA 94621 

Telephone (415) 562-8085 
TWX 910-366-7139 

NAME 

STREET (NO BOX =) 

CITY 

ZIP 



STATE 

AMOUNTS 

{Attach system description; 

add S3 for shipping; 

California residents add sales tax) 

□ Check enclosed D VISA 

□ UPS C.O.D. □ Master-charge 

Card Number 

Expiration Date 

Signature 



MAKES MICROS RUN LIKE MINIS 



Circle 160 on inquiry card. 



BYTE March 1981 



249 



6809 
SOFTWARE 



uTwrq ; i ini] 



BY MICROWARE* 1 



OS-9™ MULTIPROGRAMMING 
OPERATING SYSTEM 

Vm true multitasking, real time operating system for 
/ M timesharing, software development, database, 
L m process control, and other general applications. 
This versatile OS runs on almost any 6809-based computer. 

■ UNIX™ -like file system with hierarchical directories, 
byte-addressable random-access files, and full file security. 
Versatile, easy-to-use input/output system is hardware in- 
dependent and expandable. 

■ Powerful "shell" command interpreter features: I/O 
redirection, multiple job stream processing, and more. In- 
cludes a complete set of utility commands. 

■ OS-9 Level Two uses hardware memory management 
and can address over one megabyte of memory. Also 
includes pipes and filters for inter-process data transfers. 

■ OS-9 Level One runs on systems without memory 
management hardware having up to 56K memory. 

□ OS-9 Level Two $495* □ Level One $195 

BASIC09™ PROGRAMMING 
LANGUAGE SYSTEM 

Extended BASIC language compiler/interpreter with 
integrated text editor and debug package. Runs 
standard BASIC programs or minimally-modified 
PASCAL programs. 

■ Permits multiple named program modules having local 
variables and identifiers. Modules are reentrant, position 
independent and ROMable. 

■ Additional control statements for structured 
programming: IF . . . THEN . . . ELSE, FOR . . . NEXT, 
REPEAT . . . UNTIL, WHILE ... DO, LOOP . . . ENDLOOP, 
EXITIF . . . ENDEXIT. 

■ Allows user-defined data types and complex data 
structures. Five built-in data types: byte, integer, 

9 digit floating-point, string and boolean. 

■ Runs under OS-9'" Level One or Level Two. D$195* 

OTHER OS-9™ FAMILY SOFTWARE 

■ Stylograph™ Screen-Oriented Word Processor 

■ Interactive Assembler ■ Macro Text Editor 

■ Interactive Debugger 

BASIC09 and OS-9 are trademarks of Microware® and Motorola. UNIX is 
a trademark of Bell Laboratories.* Most software is available on ROM or 
diskette in versions for many popular 6809 computers. Contact 
Microware® for specific availability. 




MICROWARG® 

Microware Systems Corp., Dept. B2 

5835 Grand Avenue, Des Moines, Iowa 50304 

(515) 279-8844 • TWX 910-520-2535 



Could you pass 

this Red Cross 

swimming test? 



SWIM: 

1. Breaststroke - 100 Yds. 

2. Sidestroke-lOOYds. 

3. Crawl stroke -100 Yds. 

4. Back crawl — 50 Yds. 

5. On back (legs only) -50 Yds. 

6. Turns (on front, back, side). 

7. Surface dive — underwater swim — 20 Ft. 

8. Disrobe — float with clothes — 5 mins. 

9. Long shallow dive. 

10. Running front dive. 

11. 10-minute swim. 



Anybody who's taken a Red Cross swim course knows 
how tough it can be. There's a good reason. 

We believe drowning is a serious business. 

Last year alone, we taught 2,589,203 Americans not 
to drown— in the seven different swim courses we offer 
all across the country. (Incidentally, most of the teaching — 
as with almost everything American Red Cross does — 
is done by dedicated volunteers.) 

A good many of the youngsters not only are learning 
to keep themselves safe. Thousands upon thousands of 
them are learning to become lif esavers. 

And the life they save — may be your own. 




Red Cross 
counting 
on you. 



A Public Service of This Magazine & The Advertising Council &*« 



250 



March 1981 © BYTE Publications Inc 



Circle 161 on inquiry card. 




32K Board Pictured Above 



Why Not the Best? 

From The Dynamic RAM Company. 



2MHz 


4MHz 


16K— $249 


$259 


32K— $375 


$395 


48K— $500 


$530 


64K— $625 


$665 



We have now been shipping 
our 2MHz dynamic RAM boards 
for over two years. Hundreds of 
4MHz boards have been going 
out every month since early 
1979. Our reliability is proven in 
the thousands of systems which 
contain our board. Many quality- 
minded systems houses across 
the country and overseas are 
using our boards for their 
equipment. 

Our prices still beat all. 
Despite rising 16K memory chip 
prices (at least from reputable 
suppliers), Central Data continues 
to give you the best buy in 
memory today. Nobody offers a 
board with a capacity of 64K, 
assembled, tested, and guaranteed 
for a full year at the price we do. 

Circle 162 on inquiry card. 



Deselect around PROMs. Our 

boards have the important deselect 
feature which lets you overlap any 
fixed memory in your system with 
no interference. 

Our features make the board 
easily used and expanded. You 
address our boards on 1 6K 
boundaries with mini-jumps (small 
shorting plugs that slide over wire- 
wrap pins) near the top of the 
board for easy access. If you want 
to expand your board after you 
have purchased it, all that you 
need to do is add memory. We 
can supply you with expansion 
packages ($150-2MHz, 
$1 60-4MHz) which include eight 
RAMs that you can depend on as 
well as two mini-jumps for 
addressing. And of course, our 
board never generates wait states. 

Low power consumption keeps 
your computer running cool and 
reliable. The total power 
consumption of our 1 6K board is 
typically less than 4 watts (+8V @ 
300ma, +1 6V @ 1 50ma and 



-16V @ 20ma). Boards with 
additional memory typically 
increase power consumption only 
1 watt per 16K! 

Standard S-100 Interface. Our 
board is designed to interface with 
any standard S-1 00 CPU. All of 
the timing of the board is 
independent of the processor chip, 
and the board is set up for 
different processors by changing 
two plugs on the board. 

Call or write us today. That will 
guarantee a fast response with 
more information on the board. Or 
make an order — you'll probably 
have the board in two weeks! If 
you're interested, also ask for a 
catalog on our Z8000 16-bit 
processor board designed for the 
MULTIBUS. All of these products 
are available to your local dealer, 
also. 

Central Data Corporation, 713 
Edgebrook Drive, PO Box 2530, 
Station A, Champaign, IL 61820. 
(217) 359-8010 



Central Data 



BYTE March 1981 



251 



Circle 163 on inquiry card. 



TERMINALS FROM TRANSNET 



DEC 



PURCHASE PLAN -12-24 MONTH FULL OWNERSHIP PLAN • 36 MONTH LEASE PLAN 

PURCHASE PER MOUTH 

DESCRIPTION PRICE 1ZMOS. 24MOS J6MOS, 

LA36DECwrllerll $1,695 S16Z S 90 S 61 

LA34 OECwrlter IV 1,095 105 58 40 

LA34 DECwrller IV Forms Ctrl. .. 1,295 124 68 46 

LA120DECwrilerlllKSR 2,295 220 122 83 

LA120 DECwrilerllIRO 2,295 220 122 83 

VT100CRTDECscope 1,695 162 90 61 

VT132 CRT DECscope 2,295 220 122 83 

TI745 PortableTerminal 1,595 153 85 58 

TI765 Bubble Memory Terminal . 2,595 249 138 93 

TI783 Portable KSR, 120 CPS . . . 1 ,745 167 93 63 

TI785 Portable KSR, 120 CPS . . . 2,395 230 12B 86 

TI787 Portable KSR, 120 CPS . . . 2,845 273 152 102 

TI810RO Printer 1,895 182 102 69 

TI820 KSR Printer 2,195 211 117 80 

730 DeskTop Printer 715 69 39 26 

737 W/P Desk Top Printer 895 86 48 32 

704 RS232-C Printer 1,795 172 96 65 

6081 High Speed Band Printer .. 5.495 527 293 198 

DTB0/1 CRT Terminal 1,695 162 90 61 

DT80/1L15"ScreenCRT 2,295 220 122 83 

DT60/5APLCRT 2,095 200 112 75 

DT80/5L APL 15" CRT 2,595 249 138 94 

ADM3A CRT Terminal 875 84 47 32 

ADM31CRTTerminal 1,450 139 78 53 

ADM42 CRT Terminal 2,195 211 117 79 

1420 CRT Terminal 945 91 51 34 

1500 CRT Terminal 1,095 105 58 40 

1552 CRT Terminal 1,295 125 70 48 

.,., , ., : _ Letter Quality KSR, 55 CPS 3,395 326 181 123 

> " ■ Letter Quality RO, 55 CPS 2,895 278 154 104 

2621A CRT Terminal 1,495 144 80 54 

2621 P CRT Terminal 2,650 255 142 96 

FULL OWNERSHIP AFTER 12 OR 24 MONTHS • 10% PURCHASE OPTION AFTER 36 MONTHS 
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TEXAS 
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R A NSlYET corporation 

1945 ROUTE 22 ■ UNION, N.J. 07083 • (201) 688-7800 

TWX 710-985-5485 




Books Received 



Basic Computer Programs 
for Business, Volume I, 
Charles D Sternberg. 
Rochelle Park NJ: Hayden 
Book Company Inc, 1980; 
25 by 20 cm, 264 pages; 
softcover, ISBN 
0-8104-5162-X, $9.95. 

Basic FORTRAN, James S 
Coan. Rochelle Park NJ: 
Hayden Book Company Inc, 
1980; 15.5 by 23 cm, 248 
pages, softcover, ISBN 
0-8104-5168-9, $8.95. 

Communicating with 
Microcomputers, Ian H 
Witten. London, England: 
Academic Press Inc Ltd, 
1980; 15.5 by 23 cm, 164 
pages, hardcover, ISBN 
0-12-760750-1, $18; soft- 
cover, ISBN 0-12-760752-8, 
$10.50. 

Computers and Program- 
ming Guide for Scientists 
and Engineers, second edi- 
tion, Donald D Spencer. In- 
dianapolis IN: Howard W 
Sams & Company Inc, 1980; 
14 by 22 cm, 463 pages, 
softcover, ISBN 
0-672-21693-0, $15.95. 

The Computer in the 
School: Tutor, Tool, Tutee, 
Robert Taylor, editor. New 
York: Teachers College 
Press, 1980; 15.5 by 23.5 
cm, 274 pages, softcover, 
ISBN 0-8077-2611-7, $14.95. 

Computer/Law Journal, 
Volume II, Number 2, Jay 
Becker, editor. Los Angeles 
CA: Center for Comput- 
er/Law, 1980; 17.5 by 25.5 
cm, 469 pages, softcover, 
ISSN 0164-8756, $16. 

Designs of VMOS Circuits 
with Experiments, Robert T 
Stone and Howard M 
Berlin. Indianapolis IN: 
Howard W Sams & Com- 
pany Inc, 1980; 14 by 22 
cm, 174 pages, softcover, 
ISBN 0-672-21686-8, $10.95. 

A Guide to FCC Equip- 
ment Authorizations, 
Willmar K Roberts. New 
Smyrna Beach FL: Willmar 



This is a list of books received at BYTE Publications during this 
past month. Although the list is not meant to be exhaustive, its 
purpose is to acquaint BYTE readers with recently published titles 
in computer science and related fields. We regret that we cannot 
review or comment on all the books we receive; instead, this list is 
meant to be a monthly acknowledgment of these books and the 
publishers who sent them. 



K Roberts, 4637 Van Kleeck 
Dr, 1980; 21.5 by 27.5 cm, 
142 pages, softcover, ISBN 
none, $24.50 in North 
America, $29.50 elsewhere. 

Introduction to Pascal, In- 
cluding UCSD Pascal, 
Rodney Zaks. Berkeley CA: 
Sybex, 1980; 18 by 23 cm, 
421 pages, softcover, ISBN 
0-89588-050-4, $12.95. 

Introduction to TRS-80 
Level II BASIC and Com- 
puter Programming, Michael 
P Zabinski, PhD. Engle- 
wood Cliffs NJ: Prentice- 
Hall Inc, 1980; 22.5 by 29 
cm, 186 pages, hardcover 
ISBN 0-13-499970-3, $14.95; 
softcover, ISBN 
0-13-499962-2, $10.95. 

Micromatics, Steven K 
Roberts. Elmwood CT: 
Scelbi Publications, 1980; 22 
by 29 cm, 190 pages, hard- 
cover, ISBN none, $19.95. 

Modern Microprocessor 
System Design, Daniel R 
McGlynn. Somerset NJ: 
John Wiley & Sons, 1980; 
22.5 by 29 cm, 295 pages, 
hardcover, ISBN 
0471-06492-0, $21.95. 

The Nature of Computa- 
tion: An Introduction to 
Computer Science, Ira Pohl 
and Alan Shaw. Rockville 
MD: Computer Science 
Press Inc, 1981; 16 by 23.5 
cm, 397 pages, hardcover, 
ISBN 0-914894-12-9, $16.95. 

Owning Your Home 
Computer, Robert L Perry. 
New York: Everest House, 
1980; 19 by 25.5 cm, 224 
pages, softcover, ISBN 
0-89696-093-5, $10.95. 

Personal Computers 
Handbook, Walter H 
Buchsbaum, Sc D. In- 
dianapolis IN: Howard W 
Sams & Company Inc, 1980; 
14 by 22 cm, 286 pages, 
softcover, ISBN 
0-672-21724-4, $11.95. ■ 



252 March 1981 © BYTH Publications Inc 



Circle 164 on inquiry card. 



H 



CQIYIPUTRQNICS 



N 
C. 



• • • EVERYTHING FOR YOUR TRS-80 • • • 

TRS-ftO In a irHdcmnrk of (he H;»<tlo Shnck Division of Tandy Corporation 

1980 INCOME TAX PAC 

Completely Revised • Latest Tax Tables • Fully Tested • Complete Manual and Documentation 
• • The New Version Of The Income Tax Pacs Are Full Of Error Catching Codes • • 

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• INCOME TAX PAC A 

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FOR LEVEL II with or without Printer, Cassette or Disk Has all features 
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Circle 165 on inquiry card. 



BYTE March 19B1 253 



Circle 166 on inquiry card. 



FULL COLOR 

GRAPHICS 

The original 256- color imaging system with 
high resolution video FRAME GRABBER 
for the S-100 bus. r ^A 

Capture and digitize a video frame in 1 /60 of a 
second. Select the best resolution for your , a 
application, from 256 to 1280 pixels ^ 
per TV line. Display your digitized y' 
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Compact two-board 
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Features: 

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• Choice of 1, 2, 4, 8, 16 or 32 bits per pixel 

• 32K-byte Image memoiy on the basic system 

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^ 441 California Ave., Palo Alto, CA 94306 



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From S-lOO to 
IEEE-488 




P&T-488+ S-100 computer = Intelligence 
for your Instrumentation System 

The P&T-488 permits an S-100 computer to operate as a talker, 
listener, or controller on the IEEE-488 instrumentation bus for 
less than half the cost of calculator-based systems. Software 
packages which give access to the 488 bus from high level lan- 
guages such as BASIC are available for CP/M, North Star DOS 
/BASIC, and Cromemco CDOS. Or "roll your own" system 
with the custom system package of assembly language drivers. 
P&T-488, assembled and tested, + any 
software package: $450 (domestic USA) 



TSoof 



Ask BYTE 



Conducted by Steve Ciarcia 



PICKLES & TROUT 

P.O. BOX 1206. GOLETA. CA 93017. (805) 967-9563 



Modem Modification 

Dear Steve, 

I read "A Build-It-Yourself 
Modem for Under $50" 
(August 1980 BYTE, page 
22) with great interest, as I 
do so many of your arti- 
cles. Can the circuitry be 
modified easily to provide 
either originate or answer 
operation at the flick of a 
switch? From your article, it 
seems that the only dif- 
ference between the origi- 
nate and answer modes is 
the value of two capacitors 
in both the modulator and 
demodulator. If the values 
of these capacitors are 
switch-selected, then the 
modem could be either an 
originate- or an answer-only 
unit, as desired. 

I have an uneasy feeling 
about several aspects of this 
scheme. Since you say that 
the capacitances are critical, 
will the switch capacitances 
cause trouble? Secondly, 
will the variable poten- 
tiometer settings be unique 
to each mode of operation, 
thus necessitating separate 
potentiometers for each 
switch setting? 

It seems much more ap- 
pealing to get expanded 
capability by buying a few 
additional components than 
by buying another complete 
set of components for both 
the modulator and 
demodulator. 
Jonathan K Davis 

An originate/ 'answer 
modem is more complicated 



to build than it might seem 
at first. While, in theory at 
least, the answer functions 
can be added to the design 
by changing a few capaci- 
tors and resistors, the logis- 
tics of doing this presents a 
problem. The wires neces- 
sary to add these com- 
ponents and connect them 
through switches act like an 
antenna. Due to the high 
impedances in the circuit, it 
would probably become 
"swamped" with noise and 
cease reliable operation. 

The only effective way to 
connect these components is 
through CMOS (comple- 
mentary metal-oxide semi- 
conductor) switches such as 
the 4052 dual l-of-4 analog 
multiplexer, which are 
mounted close to the 
modem board. Separate 
potentiometer settings for 
answer and originate modes 
are necessary as well. If 
done as a printed circuit, the 
result is a more complicated 
and expensive board. 

I won't tell you that 
simply installing components 
with a switch will not work, 
but I hesitate to suggest it. 
Success depends on your 
construction abilities. 

As for the kit mentioned 
in the article, many ex- 
perimenters seem to be pur- 
chasing two kits at once 
(they are still available). Ap- 
parently they intend to 
change a few components 
on the second board to 
make it "answer. " 

Also, instead of two 
speakers and two rubber 



In "Ask BYTE," Steve Ciarcia answers questions on any area of 
microcomputing. The most representative questions received 
each month will be answered and published. Do you have a nag- 
ging problem? Send your inquiry to: 

Ask BYTE 

c/o Steve Ciarcia 

POB 582 

Glastonbury CT 06033 
If you are a subscriber to The Source, send your questions by 
electronic mail or chat with Steve (TCE3I7) directly. Due to the 
high volume of inquiries, personal replies will be given as time 
permits. Please enclose a self-addressed, stamped envelope, and 
be sure to include "Ask BYTE" in the address. 



254 March 1981 © BYTE Publications Inc 



Circle 167 on inquiry card. 



CHRISLIN YEARS AHEAD IN 
MEMORY DESIGN 




WE'VE DONE IT AGAIN — State of the Art Multibus® Memory Design. First to offer up to 51 2K on one board, and CHRISLIN again brings pricing 
sanity to the memory market. Why pay over $2000 for our competitor's 64K x 8 memory board when we will give you the CI 8086 1 28K x 9 memory 
for just $1500 or better yet, the CI-8086 512K x 9 memory module for $4700. 

Up to 512K bytes in a single option slot. Available in 64K. 96K, 128K, 256K, or 5 12K configurations. On board parity generator checker, for both 8 bit 
or 16 bit systems. Off shelf deliveries. 





CI-6800-2 — 16KB to 64KB. Plugs directly into 
Motorola's EXORciser I or II. Hidden refresh up to 1.5 
Mhz. Cycle stealing at 2 Mhz. Addressable in 4K 
increments with respect to VXA or VUA. On board 
parity. 64K x 9 $750.00. 



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Multibus is a trademark of the Intel Corp. LSI II is a trademark of Digital Equipment Corp. EXORciser is a trademark ot Motorola 

Circle 168 on inquiry card. BYTE March 1981 255 



Circle 169 on inquiry card. 



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Ask BYTE 



cushions in the coupler kit, 
MicroMint is shipping (at no 
extra cost) a ceramic micro- 
phone in place of one 
speaker. Even though 1 de- 
signed the prototype using 
an 8-ohm speaker as the 
"mike, " the ceramic unit is 
far more reliable.... Steve 



Communications 

Dear Steve, 

I am working on convert- 
ing your biphase encod- 
ing/decoding circuits to use 
8- instead of 4-bit words. 
(See "Hand-Held Remote 
Control for Your Computer- 
ized Home," July 1980 
BYTE, page 22.) This ap- 
proach looks promising, but 
I am not sure which com- 
munications medium I 
should use the circuits for. 
Radio is a possibility, but I 
really don't like the idea of 
having its interference. In- 
frared also looks good, but I 
am not sure about achieving 
long-range communications 
with it. To the best of my 
knowledge, the same holds 
true for ultrasonics. Can 
you suggest a particular 
system? 

Also, in figure 3 of your 
article, there is a note next 
to the FSK OUTPUT saying 
that it can be connected to 
figure 5's input; however, 
figure 5 has two inputs 
labeled audio input modula- 
tion, plus and minus. Why? 
Arthur Allen Gleckler 

Any of the systems you 
list will work. For the most 
part, ultrasonics and in- 
frared communication are 
limited to use in one room. 
If the experience of model- 
airplane builders is worth 
anything, 49 MHz radio 
control may be your best 
bet. Interference presents 
less of a problem if you use 
the "smarts" available with a 
microprocessor. Perhaps you 
should require that, for any 
command to be acted upon, 
it must be received correctly 
with a synchronization word 
before and after the com- 
mand. 

There are many coding 
schemes that insure you 



don't lose data. Rather than 
sending a single bit, you 
could send the same bit 
eight successive times. This 
makes for slow but reliable 
reception. Heathkit sells a 
variety of radio-control 
equipment that is adaptable 
to the task. 

Finally, in figure 5, the 
plus (+) lead would be con- 
nected to the biphase output 
of figure 3 and the minus 
( — ) lead would be con- 
nected to ground.... Steve 



BSR X-10 

Dear Steve, 

I read with interest your 
article "Computerize a 
Home." (See the January 
1980 BYTE, page 28.) 

Can you suggest refer- 
ences or other aids for pur- 
suing the option of directly 
synthesizing the command- 
console waveform and trans- 
mitting it directly onto the 
AC line? This approach may 
be useful in an application 
for which I'm developing a 
product. 
Jim Konsevich 

It so happens that the 
cover article of the 
September 1980 issue of 
Radio Electronics is about 
the BSR X-10. The article 
fully describes how to syn- 
thesize waveforms for direct 
injection into the AC line. It 
also has schematics of the 
command console and 
typical receivers. It should 
be just what you need. 

By the way, I wrote the 
article.... Steve 



Reference Needed 

Dear Steve, 

In your article 
"Computer-Controlled 
Security for Your Home" 
(January 1979 BYTE, page 
56) you indicate an MM5369 
in figure 4. I cannot find 
any reference or cross- 
reference for this device. It 
looks like an interesting 
unit; where can I get one 
and who manufactures it? 
James Bush 



256 



March 1981 © BYTE Publications lnc 



Circle 170 on inquiry card. 



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BYTE March 1981 



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Ask BYTE 



Radio Shack sells the 
MM5369 as part number 
276-1769, for 52.89. Radio 
Shack calls it an oscillator/ 
divider. Be aware that the 
+ 12 V and ground-pin 
connections were listed in- 
correctly in the power- 
connection table. Pin 8 is 
the ground and pin 2 is 
+ 12 V.... Steve 



Character 
Descension 

Dear Steve, 

I own a Radio Shack 
TRS-80 Level II with 16 K 
bytes of memory, and I 
have installed an uppercase/ 
lowercase kit. 

If you have seen a system 
with this kit, you probably 
noticed that the lowercase 
letters p, q, and y do not 
descend below the line. Ac- 
tually, they are the same 
size as the uppercase letters. 
This can be irritating. To 
cure this, the character 
generator must be changed, 
but I have yet to find a 
compatible device to replace 
the old one. It must have 
the same characters 
(graphics, etc) and of 
course, the new p, q, and y. 
Please tell me where I can 
get such a device and its ap- 
proximate cost? 
Mark T Cruse 

Apparently the device 
that you want is made by 
Motorola, but is proprietary 
to Radio Shack. The stan- 
dard MCM6670 installed in 
TRSSOs is only available in 
quantities of 5000 or greater. 
There is the preprogrammed 
MCM6674 that is available, 
but it is a 5 by 7 matrix. 
Try ordering a new char- 
acter generator directly from 
Radio Shack. I do not see 
any 5 by 9 dot -matrix 18-pin 
horizontal-scan character 
generators in the Motorola 
data manuals that would be 
applicable. 

I asked a few non-Radio 
Shack TRS-80 dealers about 
this, and some expect to 
eventually carry it. All the 
new TRSSOs have a revised 
character generator installed, 
even though the descenders 



cannot be used without the 
uppercase/ lower case 
option Steve 



Home Control 

Dear Steve, 

I work in software de- 
velopment for a videotext/ 
electronic publishing con- 
cern. Hardware is not my 
area of expertise; however, I 
have done some minimal 
automation of my home, in- 
cluding a humidity-con- 
trolled bathroom fan. I an- 
ticipate using a computer- 
controlled BSR X-10, but 
mine will be different from 
yours. (See "Computerize a 
Home," January 1980 BYTE, 
page 28.) I plan to have my 
ultrasonic controller run 
through the computer to the 
X-10 unit. I hope to talk to 
the X-10 unit through an op- 
toisolator that would replace 
the microphone in the unit. 

The same technique can 
be applied to any remotely 
controllable consumer 
device. It avoids the poten- 
tial conflicts between the 
various ultrasonic and in- 
frared control methods used 
in televisions, turntables, 
cassette decks, and other 
products. In the future, a 
videodisk, a Telidon video- 
tex terminal, and an elec- 
tronic-music library will join 
the list of controlled devices. 
There will be an ultrasonic 
receiver in each room. To 
complement the computer 
control, each device will re- 
tain its local controls. 

I am working on a com- 
puter-controllable pre- 
amplifier for my stereo, in- 
corporating reed-switch 
relays and a voltage- 
controlled amplifier. Crown 
has a unit on the market, 
but it's a little too expensive. 
The preamplifier will lower 
its output by 20 dB 
whenever the telephone or 
the door is answered, etc. 

I hope to stay with a 
single-board computer for 
the simple scheduling and 
control functions, but I have 
not yet calculated my 
memory requirements. I'm 
considering an SD Systems 
Z80 starter kit with an addi- 



258 



March 1981 © BYTE Publications Inc 



Circle 171 on inquiry card. 



Why The People 
Who Know Use 

FMS-80 



FMS-80, a data base management system, is the most 
powerful DBM program available to the microcomputer 
industry. Written in assembly language, it offers 
these features: 

• Operates on CP/Mf MP/M" or CDOS" systems. 

• User Definable: Screen formatting with up to 255 
screens per data file, report generator, and menus capable 
of calling other CP/M programs or FMS-80 programs. 

• No restrictions to record size other than 
available RAM memory size. 

• Instantaneous data record inquiry 
on indexed data records. 

• Ca])able of selecting on any 
field or multiple fields with 
multiple selection criteria 
(fields do not have to be 
keyed). 

• Mathematical manipula- 
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(add, subtract, multiply 
and divide). 

• Capable of collect- 
ing information from 
multiple data files 
and generating a new 
data file or report. 

• All menu driven. 

• Callable of abstract- 
ing data from other pro- 
grams written in other 
languages. 

• Available now (off 
the shelf). 

All these capabilities are 
available with the added 
plus of ease of programming. 

See What Users of FMS-80 
Have to Say: 

Mike Ketcham, systems consult 
ant and programmer for 
Management Information 
Systems: "FMS-80 



allows me the flexibility of quickly creating programs 
for user applications. It is flexible, in that data can be 
entered in a form that the secretary recognizes and gen- 
erates reports that the manager requires. Also, the user- 
definable menus allow me to actually generate a menu 
from which the user can select, creating a true turnkey 
system!'Tom Niccoli, Partner, Computerland of Phoenix: 
FMS-80 is flexible enough to acquire data from an appli- 
cation program that was previously written 
ind allowed me to generate the reports 
that my customer needed. It closed the 
deal for me. Considering its capa- 
bility, FMS-80 is one of the most 
cost-effective application pro- 
grams available today." 

If you're continuously asked 
to do applications program- 
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the time to do it in Basic, 
consider FMS-80. For 
additional information 
on FMS-80, contact 
Systems Plus, 3975 
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Phone (415) 969-7047. 





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Mike Kotdiam. Management Information SysU.'tns, BulmonI, CA 



"TM nl Digital Research, Pacific Crave, CA 
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Circle 172 on inquiry card. 



BYTE March 1981 



259 



Circle 173 on inquiry card. 



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Ask BYTE, 



tional memory and I/O (in- 
put/output) board. Am I 
too optimistic? 

I plan to loosely couple 
the control computer to a 
more general-purpose com- 
puter, for advanced schedul- 
ing and control functions 
(perhaps including voice 
recognition). The general- 
purpose machine will be 
used as a programming ter- 
minal for work I do at 
home; I currently use a TI 
Silent 700. Whatever I get, it 
must have good graphics, 
because I want to use it as a 
Telidon terminal until the 
real thing gets to market. In- 
cidentally, why are high- 
speed modems so expensive? 

Putting intelligence into 
home applicances can make 
them more useful, as you so 
aptly demonstrate in your 
column. Putting that same 
intelligence behind a hand- 
held controller would offer 
still more advantages. I've 
had a lot of fun considering 
the human engineering as- 
pects of a single hand-held 
controller wielding so much 
power. 
Ian Smith 



1 appreciate your ac- 
tivities. I have been attempt- 
ing a similar effort during 



the past year and a half. 
The BUSY BOX was specifi- 
cally designed because ! was 
getting tired of expensive 
hard-wired AC control. I 
started out with a single- 
board computer, but it has 
evolved into a 26 K-byte 
mainframe with sixteen I/O 
ports and many of the inter- 
faces presented in my ar- 
ticles during the past year. 
It's quite possible to use a 
single-board computer, but 
you may find, as I did, that 
a larger unit accommodating 
a combination of assembly- 
language and BASIC pro- 
gramming is necessary. 
BASIC makes report genera- 
tion much easier. 

I too have been thinking 
of hand-held master con- 
trollers. I have a few designs 
and will probably have 
more articles on this subject 
in the near future. If you get 
something working in the 
meantime, let me know. 

High-speed modems must 
pack a lot of information in- 
to a limited bandwidth and 
recover this information, 
often in noisy environments. 
The high cost is a function 
of the increased circuit com- 
plexity necessary to ac- 
complish this feat. I wish 
you luck in your venture. 
. . . Steve ■ 



And then 

there were 

none. 



The list of already extinct animals 
grows . . . the great auk, theTexasgray 
wolf, the Badlands bighorn, the sea mink, 
the passenger pigeon . . . 

What happens if civilization 
continues to slowly choke out wildlife 
species by species? 

Man cannot live on a planet unfit for 
animals. 

Join an organization that's doing 
something about preserving our 
endangered species. Get involved. Write 
the National Wildlife Federation, 
Department 105, 1412 16th 
Street, NW. Washington, 
ggj^ DC 20036. 
" It's not too late. 




260 March 1981 © BYTE Publications Inc 



Circle 174 on inquiry card. 



Circle 175 on inquiry card. 




" MICROPOLIS- Ml 



THIS COULD BE THE START OF 
SOMETHING SMALL. 



At Micropolis, we make a big 
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Because we believe there 
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we do everything we can to take 
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When you ask us for help, we 
don't just slap a brochure in your 
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your system to market. 

The single fact is, nobody 
can help systems integrators with 



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For more information about 
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call Jim Molenda at extension 330. 
He'll be glad to tell you all about it. 

Because we're Micropolis. 

And we've got big ideas for 
small system integrators. 



MICROPOLIS 

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In Europe: Micropolis International 
(U.K.) 0734-860817 Telex 851847395 



A Simple Approach 
to Data Smoothing 



Fred Ruckdeschel and Janice A Krinsky 

c/o BYTE 

POB 372 

Hancock NH 03449 



Existing trends in data may not be 

visible because they are masked by 

statistical fluctuations. 



The storage and processing of data has become a major 
activity in modern society. Computers have created an 
increasing demand for data because of their highly 
organized storage and retrieval facilities. Computers 
have also provided a means for rapidly transforming data 
into a format that emphasizes particular aspects of the 
underlying information. Data and information as used in 
this context are not synonymous terms. The word data 
refers to sets of numbers. Information is the knowledge 
that may be derived from those numbers. 

Data appears in many forms. For example, a person in- 
terested in stocks may have a history of daily quotations 
for a particular company. A businessman may have a 
weekly sales record for each item in his inventory. A 
hospital administrator may have a record of emergency 
admittances. A scientist may have a table of results from 
a series of experimental measurements. All these types of 
data, when plotted against time (or another independent 
variable), may contain information regarding trends. 
However, existing trends in the data may not be visible 
because they are masked by statistical fluctuations, 













1978 


Month 








Sales Volume 


January 










3279 


February 










2421 


March 










4864 


April 










3629 


May 










3180 


June 










4744 


July 










6181 


August 










3653 


September 










3418 


October 










1722 


November 










1235 


December 










2408 


Table 1: 1978 sales data 


for a 


hypothetical 


company. The 


figures indicate that the 


produ 


ct being 


sold has 


an obvious 


seasonal appeal. 













which are often a component of any real-world measure- 
ment. 

The importance of somehow removing the "noise" (or 
statistical fluctuation) from the data may be seen by using 
a simple example. Consider the monthly sales-volume 
data for a new business or product as shown in table 1. 
The data clearly indicates that the sales generally peak in 
the summer, with a slump in late autumn. Plotting the 
data, as shown in figure 1, demonstrates the basic season- 
al nature of the sales volume. If this data were to be used 
to supply information regarding the number of units that 
should be ready for sale for July of the next year, several 
factors would have to be taken into account, the first of 
which is the "noise" in the data. 

As the sales are assumed to have started in January 
1978, there is no previous history that can be used to 
directly measure the noise by a monthly comparison. 
Thus the noise must be extracted using the data given. If 
there is no reason to expect sales to be statistically much 
different during the next year, we can use the smoothed 
results for 1978 to predict 1979. If the raw data value of 
6181 units were prepared for July 1979, there is a chance 
for that number to be too high, with a corresponding 
penalty to be paid (eg: bank interest) for maintaining the 
inventory. Thus, a more realistic estimate is required. 

Predicting Future Performance 

One approach to obtaining sales estimates is to assume 
a functional form for the average sales-volume behavior 
and perform a regression. One mathematical form which 
might be tried is: 



S(t) = A + B X sin{ 2ir(t + t )/12 } 



(1) 



where f=l represents January, f = 2 represents February, 
and so on. A regression using S(t) could be performed 
that minimizes the sum of the squares of the differences 
between the true values and the ones eventually cal- 
culated using S(t). The regressed coefficients would then 
be A, B, and f 0/ and the desired estimate for July 1979 is 
then S(7). 

There are two practical considerations that make this 
approach less than ideal for the average businessman. 
First, though the form of S(t) given above may be ap- 
propriate, it is simply a guess. Second, few businessmen 
have the knowledge, facilities, or inclination for doing 



262 March 1981 © BYTE Publications Inc 



DYNACOMP 

Quality software for^ : 



ATARI 

PET 

APPLE II Plus 



TRS-80 (Level II)* 
NORTH STAR 
CP/M 8" Disk 



GAMES, SIMULATIONS, EDUCATION and 
MISCELLANEOUS 

BR[DGt 2.0 (Available for all computers) Price: S17.VS Casse(te/S21.95 Diskelle 

An all-inclusive version of Ihis moll popular or card games. This program hoih Til DS and PLAYS eiihe: contract or duplicate bridge. 
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HEARTS 1.5 (Available for all computers) 

An cxcilmg and entertaining computer version of this popular card game. Hcatls 
lake any hearts or ihe queen of spades. Play against two compuler opponents w 



Price: $14. 95 Cuss* (te/S 18.95 Diskelle 

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armed with hard-to-beat playing strategies. 



STUD POKER (ATARI only) 

This is Ihe classic gambler's card game. The compuler deals Ihe card 1 
compuler does nol cheal and usually hels the odds. Howl 
lice program. This package will run on a IhK ATARI. ( 






Price: $11.95 CBSselle/$15.95IHskelle 

! a lime and you (and Ihe compuler) bei on what you sec. The 
bluffs! Also included is a five card dTOW poker belting prac- 



POKER PARTY (Available for all computers) Price: S17.95 Csssclle/SIl.M Diskelle 

POKER PARTY is a draw poker simulation based on the hook. POKER, by Oswald Jacoby. This is ihe mosi comprehensive version 
available for microcomputers. The parly consisls of yourself and sis other (compuler) players. Each of these players (you will gel to 
know Ihem) has a different personalis in Ihe form of a varying propensily io bluff or fold under pressure. Praclice vsilh POKI-R PAR- 
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Vjlliam Sound and Valdc/ Narrows. The program uses an extensive 256X2 5fi ele- 
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VALDEZ (Available for all computers) 



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ngram utilizes aerodynamic equation* and the 
jsing radials and compass headings. The more 



FLIGHT SIMULATOR (Available for all computers) 

advanced flyer can also perform loops, half-rolls and similar acrobatic man 

CRIBBAGE 2.0 (TRS-80 only) Price: 514.95 C*sselle/S18.9S Diskette 

this is a well -designed and nicely csccuied two-handed version of the classic card tgnic, ciihbugc li is ml excellent program for Ihe crib- 
bage player in search of a worthy opponent as well as Ihe beginner wishing lo learn Ihc game, in particular [he scoring and jargon. The 
standard cribbage score board is continually shown al the lop of the display (utilising the TRSnO's graphics capabilities!, with the cards 
shown underneath. The computer automatically scores ant] also announces the points using Ihe traditional phrases, 

CHESS MASTER (North Star and TRS-80 only) Price: SI9.95 Casselle/SU.95 Diskette 

This complete and very powerful program provides five levels of play. It includes castling, en passant caplures and the promotion of 
pawns. Additional Is, the hoard mas be preset before the start of play, permitting the examination of "bonk" plays. To maximize execu- 
tion speed, Ihe program is Written in assembly language (by SOFTWARE SPECIALISTS of California). Full graphics are employed in 



STARTREK 3.2 (Available for nil computers) 

Thii is Ihe classic Startrck simulation, bul wilh several ni 
warning while also ailackmg 



Price: S 9.95 Ciissttle/S13.95 Diskelle 



SPACE TILT (Apple only) 

Use the game paddles to lilt Ihe plan 



Price: S10.95 Cassellc/S 14.95 Diskette 

I screen to "roll" a ball into a hole in the screen. Sound simple? Sol when ihe hole gels 
<u to measure your skill against others in this habit-forming action game. 

GAMES PACK I (Available for all computers) Price: 59.95 Cassette /$ 13.95 Diskelle 

GAMES PACK 1 contains Ihc classic compuler games of BLACKJACK. LUNAR LANDER. CRAPS. HORSERACE, SWITCH and 
more. These games have been combined mlo one large program for ease in loading. They arc individually accessed by a convenient 

GAMPS PACK II (Available for all computers) 

GAMES PACK II includes Ihc games CRAZY EIGHTS, JOTTO. ACEY-DUCEY, 

PACK 1. all the games arc loaded as one program and are called from a menu. 

Why pay S7.95 or more per program when you can buy a DYNACOMP collection for jusl S9.957 

NOMINOES JIGSAW (TRS-80 only) Price: 516.95 Cassette /S20.95 Diskelle 

NOMINOES JIGSAW is an intriguing and sophisticated graphical nu«le. The jigsaw consists of a 9 by <i board partially filled with ran- 
domly chosen shapes (nominoes}, of which there are 60 types. By knowing [hat ihc shapes must be legally connected, and by guessing 
the shape al each location, all the nominoes may be eventually deduced. Scoring is based on the number of guesses required and ihc dif- 



MOVING MAZE (Apple only) 

MOVING MAZE employs Ihc games paddles to dirccl a puck fron 
(and randomly) built and is continually being modified. Ihe ob;C' 
Scoring is by an elapsed time indicator, and three levels of play a 



Price: 510.95 Cssselle/514.95 Diskelle 

o ihe other. However. Ihe maze is dynamically, 
la/c without touching (or being hit by) a wall. 



BLACK HOLE (Apple only) 

This is an exciting graphical simulation of the profile: 
enier and maintain, for a prescribed lime, an orbil clos 
thai ihe tidal stress destroys the probe. Control of thl 
acceleration. This program employs Hi-Res graphics 



Price: 514.95 Cas.selle/518.95 Diskelle 

involved in closely observing a black hole with a space probe. The objeel is lo 
o a small black bole. This is lo be achieved without coming so near ihe anomaly 
rafl is tealislically simulated using side iets for roiaiion and main thrusiers for 
id is educational as well as challenging. 



TEACHER'S PET I (Available for all computers) 

This is the first of DYNACOMP'* cducalional packages. Primar 
young student with counting practice, leiier-word recognition a 

CRYSTALS (ATARI only) 



Price: S 9.95 Cassciic/S 13.95 Diskette 

d for prc-school lo grade 3. TEACHER'S PE f provides the 



Price; S 9.95Casscllc/S13.95 Diskelle 



A unique algorithm randomly produces fascinating graphics displays accompanied wilh lories w 
t»o palierns are the same, and the combined ef leer of the sound arid graphics are mesmcrmn 
-lores to demonstrate the sound and color features of Ihc Alari. 



CRYSTALS h 



CRANSTON MANOR ADVENTURE (North Star only) 

Al last! A comprehensive Adseniure game for Ihc North Slar. CRANSTON MANOR ADVENTURE ta 
CRANSTON MANOR where sou allempl lo gather fabulous treasures. Lurking in Ihe manor arc wild animal 
give up the treasures without a fight, The number of rooms is grcalcr and the associated descriptions arc mud 
current popular scries ol Advcnlurc programs, WkiWJ ItliJ game Ihc lop in its class. Play can be stopped al 
stored on diskelle. Requires UK. 

NORTH STAR SOFTWARE EXCHANGE (NSSE) LIBRARY 

DYNACOMP now distributes the 2(1 ' volume NSSE library. Most of ihese diskettes offer an oulsianding vali 
Write for deiails regarding Ihe contents of this library and quantity (lour or morel purchases. 



Availability 



IJVS'Al OMP sol tware is supplied w 
programs will run within I6K progra 
TRS-80 (Level II) and Apple (Apples 



I complete documentation containing clear explanations at 
memory space (ATARI requires MK). Excepl where noted 

I I cassette and diskette as well as North Star sin fir Jen sin (double density ct 
cd on standard (IBM format} X" CP/M floppy disks for sysicms running 



■KTII.sr.-W. CP/M a 



BUSINESS and UTILITIES 

MAIL LIST II (Apple and North Star diskettes only) 

This many-fealured program no* includes full alphabetic and zip code sorting as well as file me 
defined code, client name or Zip Code. The printout formal allows the use of standard size addr< 
than 1 100 entries (single density Norlh Slar or Apple EOS 3.2; over 2200 with d< 

FORM LETTER SYSTEM (FLS) (Apple and North Star diskette only) 

FLS may be employed lo gencrale individually addressed form Icllers. The user creates Ihe address file and separately O 
(er. ELS will then print form letters using each address. FLS is completely compatible wilh MAIL LIST II. which 
manage your address Tiles. 



FLS and MAIL LIST 11 are available as 
TEXT EDITOR I (Letter Writer) 



d package lor 137.95. 



is quite capable of handling m 



Price: $14.95 Casselle/5 18.95 Diskelle 

widths and simple paragraph indexing. This text editor is idealls 
arger jobs. Available for all computers. 



PERSONAL FINANCE SYSTEM (ATARI only) price: 534.95 Diskette 

PFS is a single disk menu oriented system composed of 10 programs designed to organize and simplify your personal finances. Fealutcs 
include a 300 transaction capacity: fast access; 26 optional user codes; data retrieval by monih, code or payee; optional printing of 
reports; checkbook balancing; bar graph plotting and more. Also provides on Ihe diskelle is ATARI DOS 2. 



FINDIT (North Star only) 

This is a ihree-in-one program w 

cial (eg: plumbers) and Reference (eg: magazine articles, i 
niversary and appointment searches for Ihe personal reco 
are accessed by a single keyword or by cross-referencing 

UFILE (North Sl«r only) 

This handy program allows Norlh Star users to maintain i 
variably accumulates. DP1LE is easy lo set up and use. li 



Price: 519.95 

formation accessible by keywords of three types: Personal (eg; last name), Commer- 
d albums, etc). In addition lo keyword searches, there are birthday, an 
ind appointment searches for Ihe commercial records. Reference records 
or three keywords. 



Price: 519.95 



COMPARE (North Star only) 

COMPARE is a single disk utility sof 
bytes, Ihc lengths in terms of the num 



Price: 512.95 

e package which compares two BASIC programs and displays the file sizes of the programs in 
of slalement lines, and Ihc line numbers at which various lisied differences occur. COMPARE 
s software lo verify which are the more current, and to clearly identify the changes made dur- 



COMPRESS (North Slar only) 

COMPRESS is a single-disk ulility program whi. 
BASIC programs. The source Tile is processed . 
small amount of computer memory. File comp 

GRAFIX (TRS-80 only) 



py \. 



it IIS a 



I '.lien 



Price: 512.95 

from North Slat 
ipressed using only a 



Price: 512.95 Cawlle/S 16.95 Diskelle 

lireclly from [he keyboard, You "draw" your figure using Ihc program's ex- 
alically appended to your BASIC program as a string variable. Dtaw a "bap- 
using PRINT US! This is a very easy way to create and save graphics. 



TIDY (TRS-80 only) 

TIDY is an assembly language program w 
necessary spaces and REMark statements. 
signiTicanlly fasler. Once loaded, TIDY ret 
TIDY! 



Price: 510.95 Ousel le/S 14.95 Diskelle 

our BASIC programs. TIDY also removes un- 
:r of BASIC programs without having lo reload 



STATISTICS and ENGINEERING 

DATA SMOOTHER (Nol available for ATARI) 

This special data smoothing program may be used to rapidly derive useful in 

are equally spaced. The soft w ate fealutcs choice in degree and range of Til. as well as siiiiioiiii-d. hm .:»,I second dens alive calculation. 

Also included is automatic plotting of the input data and smoothed results. 

FOURIER ANALYZER (Available for all computers) Price: 514.95 Cas.wiie/518.95 Diskette 

Use (Ins program to examine ihe frequency specira or limited duration signals. The program features automatic scaling and plotting of 
the input dala and results. Practical applications include Ihc analysis of complicated patterns in such fields as cleclronics. communica- 

TEA (Transfer Function Analyzer) Price: 519.95 Ca.sselle/523.95 Diskelle 

examining their response to pulsed inputs. TFA is a major moditication ol FOL'RILR ANALY/I H and contains an engineering 
oriented decibel versus log-frequency plot as well as dala editing features. Whereas FOURIER ANALYZER is designed lor educational 
and scientific use, TFA is an engineering lool. Available lor all computers. 



HARMONIC ANALYZER (Available for all computers) 

HARMONIC ANALYZER was designed for the spectrum analysis of repetitive 
editing and storage 'retrieval as well as data and spectrum plotting. One particular 
equally spaced or in order. The original data is sorted and a cubic spline interpolate 

FOURIER ANALYZER. TFA and HARMONIC ANALYZER may be purchased 
ssetles) and Si6.9J (three diskettes). 

REGRESSION 1 (Available Tor all computers) 

REGRESSION I is a unique and exceptionally versatile one-dimensional least squan 
elude very high accuracy; an automatic degtec determination option; an eitensivi 
automatic dala and curve plotting: a slaiislical analysis leg: standard deviation, co 
lion, new fits may be tried without reentering the data. REGRESSION I is ccrtatnl; 
ware library. 



Price: 524.95 C«ssette/S28.95 Diskelle 

vcforms. Features include data file generation. 
irllqut facility is thai the input dala need not be 



Price: S19.95 Casse lie/ 523. 95 Diskelle 

polynomial" curve fitting program. Features in- 
crnal library of Tilling functions; data editing; 
ilinn coefficient, etc.) a id much more. In addi- 
program in any data analysis soft- 



Price: S19.95 Cassellc/SU.95 Diskelle 

ibly nonlinearly) in Ihe Titling function. The 

ie or more fiASIC slalement lines, Data and 

REGRESSION I lor polynomial fining, and PARAFIT lor those 



arly independent vnria'i 



Price: 519.95 Cassette 
523.95 Diskelle 

, Besides perform- 
ing functions. In addi- 



REGRESSION II (PARAFIT) (Available for all computers) 

PARA1TT is designed to handle those cases in which the parameters are imbedded 
user simply inserts Ihc functional form, including the parameters IA(1). All 
results may be manipulated and plotted as with REGRESSION 
complicated functions. 

MULTILINEAR REGRESSION (MLR) (Available for all computers) 

MLR is a professional software package for analyzing dala sets containing Iwo o 
ing the basic regression calculaiiori. this program also provides easy lo use data 
lion, the user mas interrogate I he solution by supplying values for the indepenc 
limited only by ihe available memory. 
REGRESSION I, II and MULTILINEAR REGRESSION may be purchased 



BASIC SCIENTIFIC SUBROUTINES, Volume I (Not available for ATARI) 

UYNACOME' is Ihc exclusive distributor for the software keyed lo the text BASIC Scientific Subroutines, Volume I by F. Ruckdeschc 
(see the BYTE/McGraw-Hill advertisement in BYTE magazine. January |ug|). These subroutines have been assembled according it 
chapter. Included with each collection is a menu program which selects and demonstrates each subroutine. 
Collection "I : Chapters 1 and ); Data and function plotting, complex variables 



Colli 



n Mi Chap 



Mai 



Collection Mi: Chapters 5 and 6: Random number generators, series ap; 
Price per collection: SI4.95 Casselie/SIH.S>5 Diskette 
All Ihree collections are available for S39.<J5 (three cassettes) and S-S9.9S (three 
Because Ihe texl is a vital part of the documentation. BASIC Scientific Subro 
519.95 plus 75* postage and handling. 

ROOTS (Available for all computers) 



lable from DYNAI 



Price 59.95 Cassctie/S13.95 Diskelle 



Ordering Information 



Add 11.50 to diskette price for H" floppy disk (IBM format soft sectored, CE'.'M. 
•TRS-80 diskettes are nol supplied wilh DOS or BASIC. 

Deducl 10% when ordering 3 or more programs. 



DYNACOMP, Inc. 

6 Rippingale Road 

Pittsford, New York 14534 

24 hour mail order phone: (716)586-7579 

Office phone (9AM-5PM EST): (716)442-8960 



Circle 176 on inquiry card. 



Listing 1: Listing of program for data smoothing. This program 
was written in North Star BASIC, version 6, release 4. To make 
the software portable to other machines, only a subset of the 
language was used. In most cases, only the statement delimiters, 
backslashes, need to be changed to colons, and certain commas 
changed to semicolons (in print statements) to get this program 
to operate in other B ASICs (in particular, Microsoft BASIC). 



1 REM 




2 REM 




3 REM DATA SMOOTHING PROGRAM 




4 REM 




5 REM BY F.R. RUCKDESCHEL 




6 REM 




7 REM 




B REM 




9 REM 




10 DIM B<5»3) ,C(B,91> ,D<70) » E(B) 




11 REM DIMENSION OF D,Y AND Yl MAY HAVE 


TO 


12 REM INCREASED FOR LARGE SETS. 




13 DIM U(8).U<8>12)iU(12) iY<70) iYK70) 




14 PRINT 




15 PRINT 




16 PRINT 'DATA SMOOTHER FOR EQUALLY 1 




17 PRINT "SPACED DATA SETS 1 




IB PRINT 




19 PRINT 




20 PRINT "INPUT THE NUMBER OF" 




21 PRINT "DATA POINTS IN SET: ", 




22 INPUT N4 




23 PRINT 




24 PRINT "HOU MANY POINTS ARE" 




25 PRINT "TO BE AVERAGED OVER! ", 




26 INPUT N3 




27 PRINT 




28 PRINT "WHAT IS THE DESIRED LEVEL" 




29 PRINT "OF FIT (1,2,3,4,5)! ", 




30 INPUT Nl 




31 PRINT 




32 PRINT "WHAT IS THE DESIRED" 




33 PRINT "DERIVATIVE (0,1,2,3)! ", 




34 INPUT N2 




35 REM CHECK FOR ERRORS 




36 REM DETERMINE TABLE 




37 GOSUB 169 




38 REM CHECK ERROR CODES 




39 GOSUB 193 




40 PRINT 




41 PRINT 




42 IF E=0 THEN GOTO 50 




43 PRINT "*** ERROR IN INPUT ***" 




44 PRINT " ERROR CODE",E 




45 PRINT 




46 PRINT "RESTART" 




47 PRINT 




48 GOTO 20 




49 REM IF THIS POINT PASSED, OK 




50 PRINT 




51 PRINT "INPUT DATA AS PROMPTED!" 




52 PRINT 




53 FOR K = l TO N4 




54 PRINT K>TAB(6)> 




55 INPUT Y(K) 




5 6 NEXT K 




57 REM PLOT ABS VALUE OF DATA 




58 PRINT 




59 PRINT 




60 FOR K=l TO N4 




61 D(K)=ABS( YCK ) ) 




62 NEXT K 




A3 REM GO TO PLOTTING SUBROUTINE 




64 GOSUB 472 




65 REM GOTO SUPERVISOR SUBROUTINE 








67 PRINT 




68 GOSUB 118 




69 REM RESULTS READY FOR DISPLAY 




70 PRINT 




71 PRINT 




72 PRINT "THE SMOOTHED DATA IS! " 




73 PRINT 




74 FOR K = l TO N4 




75 PRINT K,TAB(6> ,Y1(K) 





such a regression. Thus, a more reasonable method might 
be to simply "eyeball" a curve through the data (as done 
by the dashed lines in figure 1). Using the dashed curve, 
the businessman would plan on having about 4800 units 
ready in July, instead of 6181. 

The eyeballing method shown above has two clear 
deficiencies. The first obvious shortcoming is the assump- 
tion that the data of the next year, 1979, is a continuation 
of the data of the present year, 1978. This assumption is 
violated because the slopes of the curve at the January 
and December end points are not the same. However, 
this could be corrected graphically by a second freehand 
curve that would make sure that the tangent lines at 
January and December are parallel. 

The second and more important deficiency is that there 
is uncertainty whether the smoothed value obtained for 
July 1979 is statistically correct, coupled with a lack of 
knowledge as to what the expected error might be. For 
example, a "better" analysis might show that the estimate 
is 4900 units with a standard deviation of 700 units. 
Thus, if 4900 units were on hand, there would be a 50% 
chance that all the orders could be filled. If 5600 (4900 
plus one standard deviation) were available, the prob- 
ability would become roughly 83%. With this type of in- 
formation (that is, conclusions about data), the 
businessman can better plan his inventory. 

In the following sections, a very simple technique is 
presented for data smoothing. This technique is based on 
the use of tables that are applied to adjust the value of a 
given data point according to the weighted sum of the 
values of surrounding data points. The smoothing 
criterion used is that of least squares, although it is ap- 
plied in a manner not commonly taught in numerical 
analysis courses. As we will see, the method is amenable 
to pencil and paper calculations, but it is much more 
readily accomplished with a computer. A program to ac- 
complish this, given in listing 1, is written in a nearly 
universal dialect of BASIC. 

An important point is that the utility of the procedure 
is based on the assumption that the "noise" apparent in 
figure 1 is truly a random fluctuation independent of the 
signal (or month). In principle, it is possible for the 
month-to-month sales volume to be totally deterministic 

Text continued on page 276 



6000 


- 
















_ 


5000 
4000 


- 






/ x^* / 
1 s\ / 
Is 'v / 


-A 


K 






- 


3000 


- 




/'I 














2000 


- 


s 














- 


1000 


- 




1 


1 1 1 1 






i i 




- 



Listing 1 continued on page 266 



JFMAMJ JASOND 

MONTH IN 1978 

Figure 1: Chart of sample data used in this article. The data 
plotted in this chart, drawn in a solid line, represents the sales of 
a hypothetical company for the months January through 
December 1978. The broken line is a human-drawn estimate of 
the ideal numbers that the given data roughly represents. 



264 March 1981 © BYTE Publications Inc 




Are important letters and reports 
leaving your office with spelling errors? 



ELLGUARD 

can proofread 
10,000 words 
in one minute. 



SPELLGUARD is a revolutionary new computer program that finds 
spelling mistakes and typographical errors in documents prepared with 
CP/M 1 or CDOS 5 compatible word processors and text editors. 

In less than one minute, SPELLGUARD proofreads 20 pages of text 
(10,000 words) and identifies all misspelled or mis-typed words based on 
its 20,000-word dictionary. After proofreading, SPELLGUARD first 
provides an alphabetized list of the words identified as potential errors. 
The operator judges each word as correct or incorrect. Correct words may 
be added to the dictionary. SPELLGUARD automatically marks incor- 
rect words in the text with a special character. The operator can then use 
the word processor to easily find and correct them in the document. 

SPELLGUARD is Easy to Use 

• proofreading capabilities are mastered in a few minutes. 

• comprehensive user's manual contains step-by-step examples of all 
SPELLGUARD features. 

SPELLGUARD is Powerful 

• text files to 85 pages (CP/M 1 .4), and 2,800 pages (CP/M 2.0). 
includes a 20,000-word, expandable dictionary. 

• contains powerful commands to construct customized dictionaries for 
special areas, e.g., medicine, real estate, law, insurance, engineering. 

SPELLGUARD is Reliable 

• thoroughly tested in actual use with free one-year maintenance service. 

• 30-day money-back limited warranty. 

• includes computer program for software updates and maintenance. 

Minimum System Requirements: 8080/85. Z80 CPU with 32K memory: CP/M' 1.4 (dictionaries to 

256K bytes), CP/M' 2.0 or later (dictionaries to 4 MB), or CDOS; word processor or text editor 

compatible with SPELLGUARD (currently several excellent new CP/M word processors, and 

WordStar". WordMaster, Magic Wand :1 . Electric Pencil 1 , and ED). 

Trademarks: 'Digital Research (registered). -MicroPro lnt'1 Corp.. 'Small Business Applications. 

'Michael Shrayer Software. "'Cromemco. 

"Time estimates based on 4Mhz 8085 with 48K memory. CP/M 2.1 double density 8" floppy drive, 

10,000-word text file. 



The price of SPELLGUARD includes 
rapid turnaround and delivery by UPS or 
airmail. Sales will be made only if the 
purchasers' word processor is compatible 
with SPELLGUARD. Software license 
agreement is required. 

□ Send me a free, detailed description and 
latest diskette format availability. 

□ Send me SPELLGUARD at $295.00. 
(Manual and diskette(s). Formats: 8" 
CP/M single density Shugart compat- 
ible, and 5'A" Northstar double.) 

□ Send me copies of the 

SPELLGUARD manual at $20.00 each. 
(Airmail, credited toward purchase.) 

D Send COD (add $10.00 handling). 

California residents add 69c tax. 

Add $10.00 for foreign shipment. 

Check enclosed for $ . 

(Certified check, COD, and money order 
shipped immediately.) 



ORGANIZATION 



WORD PROCESSOR 



COMPUTER SYSTEM 



DISK FORMAT 



Checks pay 
Box 2797. 



ayable to ISA . I 
', Menlo Park, CA 94025. I 



INNOVATIVE SOFTWARE APPLICATIONS 

Box 2797, Menlo Park, California 94025 415-326-0805 



(Dealer inquiries invited.) 

STATE-OF-THE-ART 
SOFTWARE 



Circle 177 on inquiry card. 



BYTE March 1981 



265 



Circle 178 on inquiry card. 




i«r<\ system?, ma. 

No. P7 Zenith Data Systems Z89F Microcomputer with Z47 8" Dual Disk Drive 

ZENITH DATA SYSTEMS LIST OCR PRICE 

Z89-FA Microcomputer System $2,895 $2,495 

48KB, 5.25' Disk, HDOS 
Z89-GA Microcomputer System $2,595 $2,259 

48KB, HDOS (No Disk) 

Z19 CRT Terminal SPECIAL $ 950 $ 795 

Z87 Dual 5.25' Disk Unit (200 KB) $1,195 $1,095 

Z47-BA Dual 8" Disk Unit (2MB) NEW $3,695 $3,295 

CP/M® V.2.2 for Z89 $ 150 $ 140 

HDOS Operating System (with BASIC) $ 150 $ 140 

Microsoft BASIC V5. 1 for CP/M $ 175 $ 160 

Microsoft BASIC V5.1 for HDOS $ 150 $ 140 

Microsoft FORTRAN $ 195 $ 180 

Microsoft COBOL $ 395 $ 350 

Word Processing for Z89 $ 395 $ 375 

To Order: Send Check or Money Order to: PK Systems, Inc., 113 North 

Center, Bloomington, IL 61701 Allow two weeks for personal checks to clear. 

For COD Orders, add 5% for handling and service charge. Rush orders, add 

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Shipping: Freight collect, FOB Bloomington. We ship UPS, air freight, or 

motor freight. 

PK Systems is an Authorized Zenith Data Systems Dealer and Zenith Service 

Center. P^S3B i 

5(JC£J£EEiS3 C' M ' s a trademark of Digital Research 



MULTIPATH TREE 

KEY FILE SYSTEM 

RUNS ON UCSD* 

PASCAL 

Locate 1 Key Element in 32,000 + 
in Under 3 Disk Accesses 

Library procedures Allow You To: 

INSERT DELETE FIND NEXT RANGE 

Optional Procedures For: 

CREATE PRINT TREE 

One single density 8 inch disk (others available) 
contains 24 variations- 
use the one best suited to your application. 

Also available using this key system are high performance 
business, engineering, system and personal software 
packages. Write for more information and catalog. 

Diskette plus Documentation $90.00 

Please specify type of system and version operating system. 

KeeSoft, Suite 1351, 10 Milk St. Boston, MA 02108 



•TM Univ. Of Calif. 



Listing 1 continued: 

74 NEXT K 

77 PRINT 

78 GOSUB 535 

79 PRINT *TH 

80 PRINT 'BE 

81 PRINT "UN 

82 PRINT D 

83 PRINT 

84 GOSUB 535 

85 REM PLOT 

86 FOR K = l T 

87 D(K)--=ABS< 

88 NEXT K 

89 REM GO TO 

90 PRINT 

91 PRINT 

92 GOSUB 472 

93 PRINT 
9 4 PRINT 
95 PRINT 
9 4 END 

97 REM ***** 

98 REM DATA 

99 REM VISOR 

100 REM IT I 

101 REM B,C, 

102 REM HAVE 

103 REM DIME 

104 REM B( 

105 REM C< 
104 REM D( 

107 REM U( 

108 REM V( 

109 REM U( 

110 REM Y< 

111 REM Yl 

112 REM IT I 

113 REM THE 

114 REM AVAI 

115 REM N 

116 REM Y 

117 REM THE 

118 I=N1 

119 J=N2 

120 REM THE 

121 REM FIRS 

122 FOR K=l 
12 3 Y 1 ( K ) - 

124 NEXT K 

125 REM DETE 

126 GOSUB 16 

127 REM DETE 

128 GOSUB 19 

129 REM ERRO 

130 IF E>0 T 

131 REM 0BTA 

132 REM 

133 REM 

134 GOSUB 22 

135 REM SAVE 

136 REM NORM 

137 U=U(B ( I i 

138 A=(N3-1> 

139 V=V(B< If 

140 REM GET 

141 GOSUB 37 

142 REM CREA 

143 REM DATA 

144 GOSUB 41 

145 REM SMOO 

146 REM THE 

147 REM IS M 

148 FOR M^A + 

149 GOSUB 43 
15 Y 1 ( M ) = D 

151 NEXT M 

152 REM SHIF 

153 GOSUB 45 

154 REM RESU 

155 REM GET 

156 GOSUB 45 

157 REM RESU 

158 PRINT 



E STANDARD DEVIATION" 
TUEEN THE SMOOTHED AND" 
SMOOTHED DATA SETS IS". 



ABSOLUTE UALUE OF RESULTS 
N4 
Y 1 ( K > ) 

PLOTTING SUBROUTINE 



OOTHER SUPER- 

UBROUTINE 

ASSUMED THAT 

U.V.U.Y AND Yl 

LREADY BEEN 

IONED . 

3) 

91) 

+ 2 * N 3 + 2 ) 

12) 

) 

) 

4) 

ALSO ASSUMED THAT 

PUT DATA IS 

BLE- 

N2rN3iN4 

) 

OGRAM USES I AND J 



OUTPUT IS Y 1 ( K > 

T INITIALIZE Y1CK) 

TO N4 



RMINE THE TABLE 

9 

RMINE IF ERROR 

7 

R ON E>0 

HEN RETURN 

IN COEFFICIENTS 

U(I) >V(I> J) 

C(I.K) 

5 

THE SYMMETRY AND 
ALIZING FACTORS 
J) ) 
/2 

J) , 13-A) 
UEIGHTS. U(K) 
5 
TE AUGMENTED 

V E C T R . D ( K ) 
9 

TH THE DATA VECTOR IKK) 
DATA POSITION POINTER 

1 TO N4+A+1 
9 



T YKM) DOWN 

2 

LT IS YKM) 

STANDARD DEVIATION 

9 

LT IS D 



Listing 1 continued on page 268 



266 March 1981 © BYTE Publications Inc 



Circle 179 on inquiry card. 



MEMORY PRODUCTS FOR THE80'S 




16K Byte — Fully Static 



8/16 RAM 



Designed with the Future in Mind— 



Able to use the full 24-bit address bus of the IEEE 
S-100 Standard for a 16-megabyte address 
range. 

Fully static design eliminates system timing 
problems. Promotes reliable operation with a 
wider range of CPU cards and DMA devices. 

Easy to integrate into your system. Addressable 
on 4K boundaries. PHANTOM, extended ad- 
dressing, 16-bit operation may be switched off if 
desired. 



• Can act as either an 8-bit or 1 6-bit wide memory. 
Dynamic bus switching per the IEEE Standard. 

• Fast 200 nanosecond memory chips help you 
keep up with the ever-rising clock speeds of 
newer CPUs. 

• The 8/16 is the only memory board made which 
is designed to run at full speed with our 16-bit 
8Mhz. 8086 CPU card. And, it has plenty of 
speed to spare. 



From Seattle Computer, the Static Memory Experts 



Why static memory? First, compatibility. Most S-100 
products do not meet the IEEE Standard. Because of 
their critical timing requirements, dynamic memory 
boards must often be configured for a particular CPU — 
a situation that could make future upgrading difficult. 
Static memories are inherently more versatile. 

Second, speed. The access times of static and 



dynamic memories are not comparable numbers. Static 
memories get a substantial head start while dynamic 
memories wait for a "clock." The IEEE S-1 00 Standard 
guarantees this head start is at least 70 nanoseconds. 
The result: most of today's dynamic memory boards will 
not run at full speed with tomorrow's (or even today's) 
faster CPUs. The 8/16 will. 



The 8/16 memory card is fully assembled, tested, guaran- 
teed one full year. Suggested retail price: 1 -4, $395; 5-9, $345. 
Manual only — $3. Overseas purchasers add $15 per board 
for air shipment. 

Circle 180 on inquiry card. 



A 

y Seattle Computer Products, Inc. 

* -*-- * 1114 Industry Drive, Seattle, WA. 98188 

(206) 575-1830 



BYTE March 1981 



267 



Circle 181 on inquiry card. 





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178 REM E=l 

179 REM E=2 

180 REM E=3 

181 REM 

182 REM E=4 

183 REM E=5 

184 REM 

185 REM E=6 

186 REM E = 7 

187 REM E=8 



Listing 1 continued: 

1 J V Ktn V V *(t It *(t It * If * *|C 1^ It 3|t 3|t )(t Jft )(( J(t 3(C Jf( 

160 REM TABLE DECODE SUBROUTINE 

161 REM THERE ARE 8 TABLES OF 

162 REM COEFFICIENTS TO BE CHOSEN 

163 REM ACCORDING TO THE DEGREE OF 

164 REM FIT, I> AND THE DERIVATIVE 

165 REM LEVEL, J. THE DECODING 

166 REM ARRAY IS B < I , J ) . 

167 REM NEW TABLES 12 AND 13 

168 REM ARE MOVED TO 5 AND 3 

169B(1,0)=5\B(1,1)=3\B(1,2)=0\B<1,3)=0\B<2,0>=1\B(2,1)=3 
170B(2,2>=6\B<2,3>=0\B<3,0)=1\B(3,1>=4\B(3,2>=6\B<3,3)=8 
171B(4,0>=2\B(4,1)=4\B(4,2>=7\B(4,3)=8\B(5,0)=2\B<5,1>=0 
172B(5,2>=7\B<5,3)=0 

17 3E<1>=5\E<2)=7\E(3)=3\E(4)=5\E(5)=3\E<6)=5\E(7)=5\E(8>=5 

174 RETURN 

175 REM *********** ****** ** * 

176 REM ERROR CODING SUB. 

177 REM E=0 - NO ERROR 
TOO FEU POINTS 
TOO MANY POINTS 
DERIVATIVE > FIT 
LEVEL 

FIT TOO HIGH 
DERIVATIVE TOO 
HIGH 

TABLE NOT AVAIL. 
NOT ENOUGH DATA 
ILLEGAL VALUE 

188 REM N1=LEVEL OF FIT 

189 REM N2=0RDER OF DERIVATIVE 

190 REM N3=N0. OF DATA POINTS 

191 REM TO BE AVERAGED 

192 REM N4=T0TAL DATA SET SIZE 

193 E=0 

194 IF B(N1,N2>=0 THEN E=6 

195 IF NKO THEN E = 8 

196 IF N2>3 THEN E = 5 

197 IF N3<3 THEN E>1 

198 IF N3:;25 THEN E»2 

199 IF N3<E(B(N1,N2> ) THEN E- 1 

200 IF N2>N1. THEN E = 3 

201 IF N2<0 THEN E =0 

202 IF INT (N3/2) =N3/2 THEN E-B 

203 IF N3>N4 THEN E^7 
20-1 IF Nl>5 THEN E-A 

205 RETURN 

206 REM ******************* 

207 REM COEFFICIENT STORAGE SUB. 

208 REM THE WEIGHTS ARE STORED IN 

209 REM THE ARRAY C < I , Iw . THE IN- 

210 REM DEX, Ii REPRESENTS THE 

211 REM TABLE NUMBER (1 TO 8). 

212 REM THE INDEX, K, REPRESENTS 

213 REM THE ELEMENT IN TABLE I. 

214 REM THERE ARE UP TO 91 SUCH 

215 REM ELEMENTS. 

216 REM ALSO STORED ARE THE NORM- 

217 REM ALIZING FACTORS, V ( I , K > , 

218 REM WHERE K RANGES FROM 1 TO 

219 REM 13. IN ADDITION, THE 3 

220 REM SYMMETRY VALUES, U(I>, 

221 REM ARE ALSO INCLUDED. 

222 REM NOTE THAT TABLES 12 (NOW 5) 

223 REM AND 13 (NOW 3) ARE CALCULATED 

224 REM ELSEWHERE. 

225U(1 )-l\l.l(2)=l\U(3)=-:l \U(4)=-1\UC5) = 1\U(6) = 1\U(7) = 1\U(8)=-1 

226V(1,1)=5175\V(1,2)=805\V(J. ,3)=3059\V( 1,4) =2261 

2 2 7V (1 ,5>=323\V(1 , 6 ) = :l. 105W ( 1 ,7)-143\V< 1 , B ) =429\V ( 1 1 9 ) '=23 1 

228V(l,1.0)=21\V(l,ll)=35\V(2,l) = 3 001.5\V(2,2)-6555 

229V(2,3>=260015\V(2,4)=7429\V(2,5}=<U99\Vl2,6)=46189 

230V (2, 7>=2431\V(2,8)=429\V(2,9)=429\V(2, 101=231 

231V(4,l) = 1776060\V(4,2) = 197340\V(4,3i=3634092\V(4,4)=255B1.6 

232V(4,5)=23256\V(4,6)=334152\V(4,7) = 24024\V(4,8)=:;il4£) 

233V(4,9) = 11B8\V(4,10)=252\V(4,1. 1. ) = :I2 

234V(6,1. )=26910\V(6,2)=17710\V(6,3)=33649\V(6,4)=6783 

235V(6,5)=3876\V(6,6)=6188\V(6,7)=1001\V(6,8)=429\V(6,9)=4 62 

236V (6, 10)=42\V(6, 11) =7\V(7,1 1=4292 145\V(7, 21=2812095 

237V(7,3)=245157\V(7,4)=490314\V(7,5)=4 78686\V(7,6)=2 77134 

238V(7,7)=160446\V(7,B)=16731\V<7,9)=4719\V(7,10)=99\V(7,11)=3 

239V(8,1)=296010\V(B,2)"32890\V<8,3)=86526\V(8,4)=42636 

24 0V(8,51=3876\V(8,61=7 956\V(8,71=572\V(8,81=858\V<8,91=198 

241V(8,10)=6\V(8,11)=2 

242I-URK = 1T012\V(5,K1=27-2*K\V(3,.1.3-K1=K*<K+11*(2*Kt1 )/3\NEXTK 

Listing 1 continued on page 270 



268 March 1981 © BYTE Publications Inc 



Circle 182 on inquiry card. 



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A 



Listing 1 continued: 

243FDRK=1T0.12\V<7»K> = 12*VC7,K)\NEXTK 

244C<1.1)=467\C<1>2)=462\C<1.3)=447\C<1>4)=422\C<1>5)=387 

245C(1.6)=342\C<1.7)=287\CU»8)*'222\C<1»9)=147\C<1,10>=62 

246C<l>ll)=-33\C<l»i2)=-138\C<i»13)=~253\C<l>14)=79\C<l>15>=78 

247C<1,16)=75\C<1,17)=70\C<1,18)=63\C<1,19>=54\C<1,20>=43 

248C<l>2i)=30\C(l>22)=15\C(1.23)=~2\C<i»24)=-21\C<:l. .25)=~42 

249C<1,26>=329\CC1,27>=324\C<1,28)=309\C<1,29)=284\C(1,30>=249 

250C(l>31)=204\C(1.32)=149\C<1.33)=84\C(l»34)=9\CU»35>=-76 

251 C < 1.3 6) =-17 1\C( 1.37) =269\CC1. 38 )=264\C (1.39) =249 

252C(1.40)=224\C(1.41)=189\C(1.42)=144\C(1.43)=89\C(1.44)=24 

253C<1.45)=-51.\C<1>46)=-136\C<1.47)=43\C<1»48>=42\C(1>49)=39 

254C(1.5 0)=34\C(1.51)=27\C(1.52)=18\C(1.53)=7\C(1.54)=-6 

255C<1»55)=-21\CU.56)=167\C(1.57)=162\C(1.58)=147\C<1»59>=122 

256C<1.60)=87\C<1.61)=42\CU.62)=-i3\CC1.63)=-78\CCl»64)=25 

257C(l,65)=2 4\C<l,66)=21\C<l,67)=16\CU,68)=9\Ctl,69>=0 

25BC<1,70>=-11\C<1,71)=89\C(1,72)=84\C<1,73)=69\C(1,74)=44 

259C<1.75)=9\C<1.76)=-36\C<1.77) = 59\C<1.78)=>54\C<1»79)=39 

260C(1.80)=14\C(1.81)=-21\C<1»82)=7\C(1.B3)=6\C(1.84)=3 

261C(1,85)=-2\C(1,86)=17\C(1,87)=12\C<1,88)=-3\C<2,1)=4253 

262C(2.2)=4125\C<2,3)=3750\C(2.4)=3155\C(2,5)=2385\C(2,6) = 1503 

263C(2,7)=590\CC2,8)=-255\C<2,9)=-915\C<2,10)=-1255 

264C(2,11)=-1122\C<2.12)=-345\C<2»13)=1265\C(2»14)=1011 

265C(2.15)=975\C(2,16)=B70\C(2,17)=705\C(2,18)=495\C(2,19>=2 61 

266C(2,20)=30\C(2,21)=-165\C<2,2 2>=-2 85\C(2,23)=-285 

267C(2,24)=-114\C(2,25)=285\C(2,26)=4 4003\C<2,27)=42120 

26BC(2,28)=36660\C(2,29)=28190\C(2,30)=17655\C(2,31)=6378 

269C<2,32)=~3940\C(2,33)=-11220\C(2,34)=-13005\C<2,35)=- 6460 

270C(2,36)=11628\C(2,37>=1393\CC2,38)=1320\C(2,39)=1110 

271 C<2»40)=790\C(2»41)=405\C< 2,42 )=18\C<2,43)=-290 

272C(2,44)=-420\CC2,45)=-255\C(2,46>=340\C<2,47)=883 

273C<2,4B)=825\C(2,49)=660\C<2,50)=415\C<2,51)=135 

274C(2,52)=-117\C<2,53)=-260\C(2,54)=-195\C<2,55)=195 

275C(2,56)=11063\C(2,57)=10125\C(2,58)=7500\C(2,59>=3755 

276C<2,60)=-165\C(2,61)=-2937\C<2,62)=-2860\C<2,63)=2145 

2 77C<2,64)=677\C(2,65)=600\C(2,66)=390\C(2,67>=110 
278C(2,68)=-135\CC2,69)=-198\C(2,70)=110\C(2,71)=143 
279C(2,72)=120\C(2,73)=60\C(2,74)=-10\C(2,75)=-45\C(2,76>=18 
280C(2,77)=179\C<2,78)=135\C<2,79>=30\C<2,80)=-55\C(2,81)=15 
281C(2,82)=131\C<2,83>=75\C<2,84)=-30\C<2,85)=5 
282C(4,l)=0\C(4,2)=-8558\C<4,3)=-16649\C<4,4)=-23806 
283C<4,5)=-29562\C<4,6)=-33450\C<4,7)=-35003\C<4,8)=-33754 
284C(4,9)=-29236\C(4,10)=-20982\C(4,11)=-8525\C<4,12)=8602 
285C<4,13)=30866\C<4,14)=0\C<4,15)=-1222\C(4,16)=-2365 
286C<4.17>=-3350\C(4,18>=-409B\C(4,19>=-4530\C<4,20>=-4567 
287C(4,21)=-4130\C(4,22)=-3140\C<4,23)=-1518\C(4,24)=815 
28BC(4,25)=3938\C<4,26>=0\C<4,27)=-29592\C<4,28)=-56881 
289C(4,29)=-79564\C(4,30)=-95338\C<4,31)=-101900 
290C(4,32)=-96947\C<4,33)=-78176\C(4,34)=-43284\C<4,35)=10032 
291C(4,36)=84075\C(4,37)=0\C<4,38)=-2816\C<4,39)=-5363 
292C(4,40) = -7372\C(4,41)=-8574\C<4,42)=-8700\C(4,43)=--7481 
293C(4,44)=-4648\C(4,45)=6 8\C<4,46)=6936\C<4,47)=0 
294C(4,48)=-358\C<4,49)=-67 3\C<4,50)=-902\C<4,51)=-1002 
295C(4,52)=-930\C(4,5 3)=-643\C<4,54)=-98\C<4,55)=74B\C(4,56>=0 
296C < 4,57 )=-7506\C< 4,58 >=-13843\C< 4,59 )=-.1.7842\C( 4, 60) = -18334 
297C(4,61)=-14150\C(4,62)=--4121\C<4,63) = 12922\C(4,64)=0 

298C ( 4,65 ) =-832\C( 4,66)=- 1489 \C( 4,67 )=-1796\C(4 .68)=- 1578 

299C(4,69)=-660\C(4,70)=1133\C(4,71)=0\C(4,72)=-296 

300C(4,73)=-503\C(4,74)=-532\C(4,75)=-294\C(4,76)=300 

3 01C(4,77)=0\C( 4,78 )=-126\C< 4,79 )=-193\C( 4,80 > =-142\C ( 4 , 8 1 > =86 
302C(4,82)=0\C(4,83)=-58\C(4,84)=-67\C(4,85)=22\C<4,86)=0 
303C(4,87)=-8\C(4,88)=l\C(6,l)=-52\C(6,2)=-51\C(6,3)=-48 
304C<6,4)=-43\C(6,5)=-36\C(6,6)=-27\C<6,7)=-16\C(6,8)=-3 
305C(6,9)=12\C<6,10)=29\C(6,11)=48\C(6,12)=69\C(6,13)=92 
306C<6.14>=-44\C<6.15)=-43\C(6.16)=-40\C(6,17)=-35\C<6,18)=-28 
307C<6,19)=-19\C(6,20)=-8\C(6.21)=5\C(6,22>=20\C(6.23>=3 7 
308C(6,24) = 56\C(6,25)=77\C(6,26)=-110\C(6.. 27 ) =- 107\C < 6 , 28 ) =-98 
309C(6,29)=-83\C(6,30)=-62\C<6,31)=-35\C<6,32>=-2\C16,33>=37 
310C(6,34)=82\C<6,35)=133\C(6,36)=190\C<6,37)=-30\C(6,38)=-29 
311C:(6,39)=-26\C(6,40)=-21\C(6,41)=-14\C(6,42) = -5\C(6,43)-A 
312C<6,44)^19\C(6,45)=34\C(6,46)=51\C(6,47)=-24\C(6,48)=-23 
313C:(6,49) = -20\C(6,50)=-15\C(6,51)=-8\C(6,52) = 1\C(6,53)-12 
314C(6,54)=25\C(6,55)=40\C(6,56)=-56\C(6r57)=-53\C(6,58)=-44 
315C(6,59)=-29\C(6,60)=-8\C(6,61)=19\C(6,62)=52\C(6,63)=91 
316C(6,64)=-14\C(6,65)=-13\C(6,66)=-10\C<6,67)=-5\C(6,68)=2 
317C<6,69)=ll\C(6,70)=22\C(6,71)--10\C(6,72)=-9\C(6,73)=-6 
31BC(6.74)=-1\C(6,75)=6\C(6,76)=15\C(6,77)=-20\C<6,78)=-17 
319C(6.79) = -8\C(6,80) = 7\C(6.81)--2B\C(6,82)=-4\C(6,83)=-3 
320C(6,84)=0\C(6,85)=5\C(6,86)=-2\C(6,87)=-1\C(6,88)=2 
321C(7,1)=-4418 70\C(7,2)=-418011\C(7,3)=-348429\C(7,4)=-239109 
322C(7,5)=-100026\C(7,6)=54855\C(7,7)=207579\C(7,8)=336201 
323C(7,9)=414786\C<7,10)=413409\C(7,11)=298155\C(7,12)=31119 
324C(7,13)=-429594\C<7,14)=-373230\C(7,15)=-349401 
325C(7,16)=-280275\C(7,17)=-172935\C(7,18)=-39186 
326C:<7,19) = 104445\C(7,20)=236709\C(7,21)=331635\C<7, 22) =358530 

Listing 1 continued on page 272 



270 March 1981 © BYTE Publications Inc 




'■:•*■ ■ I %i? : -Jags™ #w£^TS 




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C1P: 03440, OSI C4P: 03401. PET: each (ape $29.95. 
03408. TRS 80 Level II Disk: 03409. Apple II Disk: 
03414. OSI C IP Disk: 03444. OSI C4P Disk: 
03484. C8P Disk: each S34.9S 



BLACKJACK MASTER: A Simulator Tutor 
Game (Wazaney) A serious game that performs 
complex simulations and evaluations of playing and 
belting strategies 05303. TRS 80 Level II tape. 
S24 95. 05308. TRS 80 Disk Version. $29 95 

REVERSAL (Spracklen) 

Winner of the software division of the Firsf Inter 

national Man Machine OTHELLO'" Tournament. 

this version of the 200-year old game Reversi .features 

27 levels of play and high resolution color graphics 

07004. APPLE II tape. $29.95: 07009. APPLE II Disk. 

S34.9S 

APPLESOFT UTILITY PROGRAMS (Gilder) 
Increase your BASIC programming speed and llexi 
bility Contains 9 useful subroutines: 1 . REM Writer 
2. PRINT Writer 3 POKE Writer 4. Hexadecimal 
Decimal Converter 5 Line Counter 6. Renumber 
7. Append 8. Byte Counter 9. Slow List Stop List 
03504. Apple II tape. S29.95 

ENERGY MISER (SuperSofl Associates) A 
complete healing cooling analysis program for your 
home or office that will calculate heat loss or gain 
due to poor insulation, leaky doors and windows, 
and more. 05601 . PET: 05603. TRS 80 Level II: 
05604, Apple //; each tape $24.95: 05609. Apple II 
Disk Version: 05613. Heathkit/Zenith Disk Version: 
S29.95 



6502 DISASSEMBLER (Slamm) 
Produce assembly language source files with labeled 
subroutines and references from programs already 
in memory. It is compatible with Hayden's ASSEM 
BLY LANGUAGE DEVELOPMENT SYSTEM. 
08609. APPLE II Disk. $34 95 

PSEUDODISK (Neuschatz) 

This money saving program simulates a disk memory 

system for Integer BASIC programs. It allows mulli 

pie programs in memory at the same time which 

can be run from a catalog 04804, APPLE II tape. 

$24.95 

L1NE& VARIABLE CROSS REFERENCE 
GENERATOR (Johnson) Provides a cross refer 
ence of line numbers and variable names. 07301 . 
PET tape. $16.95 

DISK CATALOGER (LeBar) 
Automatically maintainsa cross-reference listing 
of all your programs, their location by disk number, 
their function and use. Catalogs, lists and sorts 
programs 05203. TRS-80 Level II tape. $16.95: 
05208. TRS 80 Level II Disk. $21.95 

APPLE'" ASSEMBLY LANGUAGE DEVEL- 
OPMENT SYSTEM: An Assembler/Editor 
Formatter (Lutus) Write and modify your machine 
language programs quickly and easily 04609, Apple 
11 Disk Version. $39.95 

SUPER APPLE'" BASIC (Lutus) A structured 
BASIC that compiles into an optimized Applesoft 
or Integer BASIC program. 05409. Apple II Disk. 
$39.95 

MAILING LIST (Tru Data Software) Lists 
addresses, prints labels, allows for alterations and 
deletions, and has the capacity to make duplicate 
data file disks. Can only be used with version 1 .5. 
05713. Heath Disk, $49.95 



ORDERING INFORMATION 

Send me the software checked below. A check or money 
order is enclosed. 1 understand thai Hayden pays shipping 
and handling costs and that 1 can return any disk or tape within 
10 days if it is defeclive or I am dissatisfied with it for any 
reason Residents of NJ and CA must add sales tax. Offer 
good in US only. 

D 0340 1 □ 03414 □ 0450M 

D 03403 □ 03440 □ 04504 

G 03404 D 03444 □ 045 13 

D 03408 D 03484 □ 04509 

D 03409 G 03504 □ 04804 

G 03410 G 04501 G 0490Q 



Book Company, Inc. 

50 Essex Street, Rochelle Park, N J 07662 



n 


on inn 


D 


OZ404 


D 


01401 


D 


02501 


D 


01403 


D 


02503 


n 


01404 


n 


02601 


D 


01407 


D 


02701 


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01413 


D 


03304 



D 05105 
D 05108 
□ 05203 
D 05208 
D 05308 
D O540'J 



D 05603 
D 05604 
a 05609 
D 05613 
D 07004 
D 07301 



D 07809 
D 08609 
D 5681 8 



Name 

Add ress 

City/Stale/Zip 

Name of individual ordering must be filled in. 



B 3/81 



FINPLAN: A Financial Planning Program for 
Small Business (Montgomery) Allows you to enter 
data from a balance sheet into the program, to make 
assumptions about future growth of business, and 
to have the computer project results for up to a five 
year period based on those assumptions. And if 
you change any data, the program revises all result 
ing data automatically. The disk version can only 
be used with TRSDOS Version 2 3. 05103, TRS 80 
Leuel II tape, S69.95; 05 108. TRS 80 Level II Disk 
Version, S74.95 

DATA MANAGER: A Data Base ManagemenI 
System and Mailing List (Lutus) Store information 
on a floppy disk, and retrieve it quickly and easily 
by specific names, or by category. 04909, Apple 11 
Disk Version, $49.95 

MCAP: A Microcomputer Circuit Analysis 
Program (Savon) Performs a linear voltage, 
impedance, or transfer impedance analysis of an 
electronic circuit. 04501 . PET;04503, TRS-80 Level 
II; 04504. Apple II; each tape $24.95; 04513. 
Heathki f Zenith Disk, S29.95 

MICROCOMPUTER AIDED DESIGN OF 
ACTIVE FILTERS (Gilder) Eight programs that 
simplify the design of active filters and will calculate 
the component values needed for various bandpass, 
low-pass, and notch-type filters. 0J40J. PET; 01403, 
TRS-80 Level II; 01404. Apple 11; 01407. Heath; each 
tape S16.95; 01413. Healhkit Zenith Disk Version, 
S21.95 

DISK CERTIFIER AND COPIER (Jacc Inc.) 
A handy utility program that certifiesthe acceptability 
of blank diskettes and rejects those with flaws. It 
alsoincludesafast machine language disk copying 
program that will work on single and dual drive 
svs\ems.07809. APPLE II Disk. S19 95 

SONGS IN THE KEY OF APPLE (Lopatin) 
Allowsyouto see and hear your favorite tunes, pre 
programmed tunes or music you create (up to 200 
notes, including rests, per musical piece). 03304. 
Apple II tape. S10.95 

HOW TO BUILD A COMPUTER-CON- 
TROLLED ROBOT (Loofbourrow) Contains 5 
control programs that consist of: Joystick Control 
Program; Self Direction Program; Impact Sensor 
Control Routine; and more. 00100.KIM 1 tape.$14.95 
Should be used with text HOW TO BUILD A 
COMPUTER-CONTROLLED ROBOT, 5681 8. 
S9.75 



Apple is a trademark o I Apple Computer Company, It 

and is no/ alfilialpd with Harden Bonk Co"i/)unv. mi'. 



Call Toll Free, 

24 hours a day, 

(1-800-821-3777. ext. 302)* TO CHARGE 
YOUR ORDER TO Master Card or Visa. 
Minimum order is $ 10.00; customer pays 
postage and handling. 
From Missouri call (1 800 892-7655, ext. 302) 




50 Essex Street, Rochelle Park, NJ 07662 



Book Company, Inc. 



Circle 184 on inquiry card. 



BYTE March 1981 271 



Circle 185 on inquiry card. 



MTI stocks 'em all 
for faster delivery. 



No hidden charges. Prices include delivery. 

Ask about our"QED" discounts. 

VISA and MasterCard orders accepted. 

VIDEO TERMINALS 

VT100 DECscope $ 1695 

VT132 DECscope 2295 

ADM-3A (dumb terminal) • 

ADM-3A+ (dumb terminal) • 

ADM-31 (2 page bufferl • 

ADM-42 (8 page buffer avail.) • 

1410 (Hazeltine dumb terminal) 825 

1420 (dumb terminal) 895 

1421 (Consul 580 & ADM-3A comp. I.... 895 

1500 (dumb terminal) 1045 

1510 (buffered) _ 1145 

1520 (buffered printer portl 1395 

1552 (VT-52 compatible] 1350 

300 BAUD TELEPRINTERS 

LA34-DA DECwriter IV 1045 

LA34-AA DECwriter IV 1295 

Teletype 4310 1085 

Teletype 4320 1225 

Diablo 630 RO 2295 

Diablo 1640 RO 3085 

Diablo 1640 KSR 3285 

Diablo 1650 RO 3185 

Diablo 1650 KSR 3385 

Tl 743 (portable) 1190 

Tl 745 (portable/built-in coupler) 1585 

Tl 763 (portable/bubble memory) 2690 

Tl 765 (port/bubble mem/b-i coupler) . 2895 

600 BAUD TELEPRINTERS 

Tl 825 RO impact 1565 

Tl 825 KSR impact 1645 

Tl 825 RO Pkg 1750 

Tl 825 KSR Pkg 1895 

1200 BAUD TELEPRINTERS 
LA120AA DECwriter III (formspkg.) . 2410 

LA180 DECprinter I 2195 

Tl 783 (portable) 1745 

Tl 785 (port/built-in couplerl 2395 

Tl 787 (port/internal modem) 2845 

Tl 810 RO impact 1800 

Tl 810 RO Pkg 2047 

Tl 820 KSR impact 1895 

Tl 820 KSR Pkg 1995 

Tl 820 RO 1895 

Tl 820 RO Pkg 2047 

2400 BAUD 

Dataproducts M200 (2400 baud) 2595 

DATAPRODUCTS LINE PRINTERS 

B300 (300LPM band) 5535 

B600 (600LPM band) 6861 

2230 (300LPM drum) 7723 

2260 (600 LPM drum) 9614 

2290 (900LPM drum) 12655 

ACOUSTIC COUPLERS 

A/J A242-A (300 baud orig.) 242 

A/J 247 (300 baud orig.) 315 

A/J AD342 (300 baud orig./ans.) 395 

A/J 1234 (Vadic compatible) 895 

A/J 1245 (300/1200 Bell comp.) 695 

MODEMS 

GDC 103A3 (300 baud Bell) 395 

GDC 202S/T (1200 baud Bell) 565 

GDC 212-A (300/1200 baud Bell) 850 

A/J 1256 (Vadic compatible) 825 

CASSETTE STORAGE SYSTEMS 

Techtran816 (store/forward) .1050 

Techtran 817 (store/for/speed up) 1295 

Techtran818 (editing) 1795 

Techtran 822 (dual) 2295 

MFE 5000 (editing) 1495 

FLOPPY DISK SYSTEMS 

Techtran 950 (store/forward) 1395 

Techtran 951 (editing) 1995 

•Please call for quote. 



mti 



Applications Specialists & Distributors 
Great Neck. New York/Cleveland Ohio. 



N.Y.: 516/482-3500 & 212/895-7177 
800/645-801& Ohio: 216/464-6688 



Listing 1 

327C(7 

328C<7 

329C<7 

330C(7 

331C(7 

332C(7 

333C(7 

334C(7 

335C (7 

336C<7 

337C<7 

338C(7 

339C<7 

340C(7 

341C<7 

342C<7 

343C<7 

344C<7 

345C(8 

346C<8 

347C(8 

348C(8 

349C(8 

350C<8 

351C(8 

352C<8 

353C<8 

354C(8 

355C<8 

356C<8 

357CC8 

358C<8 

359C<8 

360C<8 

361C<8 

362C<8 

363 

364 

365 

366 

367 

368 

369 

370 

371 

372 

373 

374 

375 

376 

377 

378 

379 

380 

381 

382 

383 

384 

385 

386 

387 

388 

389 

390 

391 

392 

393 

394 

395 

396 

397 

398 

399 



continued: 

23)=281979\C(7,24)=61845\C(7,25)=-346731\C<7.26)=-42966 
27)=-39672\C<7r28)=-30183\C(7.29)=-15678\C<7,30)=1878 
31>=19734\C(7,32>=34353\C<7r33)=41412\C<7>34) =35802 
35)=11628VC<7.36>= -377 9 1 \ C < 7 • 37 > = - 1 1 68 20 

38>=-105864\C(7r39>=-74601\C<7>40> =-27846 \C<7. 41) =26376 
42>=76830\C<7i43)=109071\C<7»44>=105444\C<7,4 5)=45084 
46>=-96084\C(7,47)=-160740\C<7, 48) =-141873 
49) =-88749\C< 7, 50 >=-11799\C< 7,51 )=71592\C< 7.52) =137085 
53>=153387\C(7i 54) =82251\C(7i 55) =-121524 
56)=-137340\C(7/57)=-116577\C(7,58)=-59253 
59>=19737\C(7.60)=9556B\C<7i61 > =133485\C ( 7 r 62) =88803 
63)=-93093\C(7r64)=-124740\C<7>65>=-99528 
66>=-32043\C(7.67)=53262\C<7.68>=1156 32\C(7i69)=9 8010 
70)=-72963\C(7»71)=-22230\C(7>72)=-15912\C(7,73)=l:17 
74>=17082\C(7,75)=20358\C<7. 76) =-10530\C(7r77>=~ 12210 
78)=-6963\C(7,79)=4983\C(7,80) = 12 24 3\C(7,81)=--4158 
82)=-630\C(7,83)=-171\C(7r84)=603\C(7,85)=-117 
86>=-90\C(7.87)=48\C<7r88)=-3\C<8rl)=0\C<8r2>=77 
3)=149\C(8r4>=211\C<8r5>=258\C(8,6>=285\C<8,7)=287 
8)=259\C(8F9)=196\C(8rl0)=93\C<8rll)=-55\C(8,12)=-253 
13)=-506\C(8,14)=0\C(B,15)=13\C(8rl6)=25\C(8.17)=35 
18)=42\C(8rl9)=45\C(8.20)=43\C(8.21)=35\C(G.22)=20 
23)=-3\C(8.24)=-35\C<8,25)=-77\C(8i26)=-0\C<8.27)=54 
28)=103\C(8,29)=142\C(8,30)=166\C(8»31)=170\C(8r32)=149 
33)=98\C<B.34)=12\C(8,35)=-114\C(8t36)=-285\C(8,37)=0 
38)=44\C(8,39)=83\C(8r40)=112\C(8r41)=126\C(8r42)=120 
43)=89\C<8.44)=28\C(8f45)=--68\C<8.46)=-204\C<8.47) = 
48)=7\C(8.49) = 13\C(8,50) = 17\C<8»51) = 18\C(8,52)=-15 
53)=7\C(8,54)=-7\C(8.55)=-28\C(8.56)=0\C(8,57)="27 
58)=49\C<8.59)=61\C<8.60)=58\C<8.61)=35\C<8,62)=-13 
63)=-91\C(8»64)=0\C(8,65)=4\C(8r66)=7\C(8,67)=8 
68)=6\C(8i69)=0\C(8,70)=-ll\C(8r7 1)=0\C(8r72)=14 
73)=23\C(8.74)=22\C(8r75)=6\C(8r76)=-30\C(8.77)=0 
78)=9\C(8>79)=13\C(8,80)=7\C<8i81)=-14\C<8,82)=0 
83)=1\C(8,84)=1\C(8>85)=-1\C<8.86>=0\C(B.87)=2 
88)=-l 
RETURN 

WEIGHTS SUBROUTINE 
N3=N0. OF DATA POINTS 

TO BE AVERAGED OVER 
B(ItJ)=THE TABLE NUMBER 
THE TABLE IS STRUNG 
OUT STARTING WITH THE 
25 POINT SET WHICH, AS 
IT IS IS SYMMETRICAL* 
IS REDUCED TO 13 ELE- 
MENTS. 

G0SUB 397 

G0SUB 407 

RETURN 

RETURN 



B(I 
B(I: 

B(I 

B(I: 



J)=5 
J>=3 
J)=5 
J) = 3 



THEN 
THEN 
THEN 
THEN 



REM 

REM 

REM 

REM 

REM 

REM 

REM 

REM 

REM 

REM 

IF 

IF 

IF 

IF 

L=12 

K = l 

FOR K1=0 TO L 

U(K1)=C(B(I»J).K) 

K = K + 1 

NEXT Kl 

REM TABLE IS READ IN 

REM SEQUENCE UNTIL THE 

REM RIGHT SET IS FOUND. 

IF A=L THEN RETURN 

L = L-1 

GOTO 381 

TABLE 12 (5) SUBROUTINE 
THIS TABLE IS FOR THE 
LINEAR LEAST SQUARES 
SMOOTHING AND IS 
ONLY A MOVING AVERAGE. 
K=0 TO 12 



REM 

REM 

REM 

REM 

REM 

FOR 

U < K ) = 1 

NEXT K 

400 RETURN 

401 REM ******************** 

402 REM TABLE 13 (3) SUBROUTINE 

403 REM THIS TABLE IS FOR 

404 REM LINEAR LEAST SQUARES 

405 REM FIRST DERIVATIVE 

406 REM SMOOTHING. 

407 FOR K=0 TO 12 

408 U<K)=-K 

409 NEXT K 

410 RETURN 

411 REM ******************** 

412 REM DATA VECTOR SUB. 



Listing 1 continued on page 274 



272 March 1981 © BYTE Publications Inc 



KEYS TO 
PRODUCTIVITY 



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esc 1 



If you plan, make, use, or buy computer 
systems or services, you can't afford to miss 
the upcoming National Computer Confer- 
ence, McCormick Place, Chicago, May 4-7. 

The theme of this year's conference is 
"Keys to Productivity", how to use computers 
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Come see the latest in new equipment and 
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Take your pick of over 100 technical sessions 
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Enjoy the Personal Computing Festival, now 
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For Conference Information, call or write 
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For discount air fares, airline reserva- 
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Circle 186 on inquiry card. 



BYTE March 19B1 273 



Circle 187 on inquiry card. 




WORKING 
OVERTIME 



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Payroll, Word Processing, Accounting & 

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Check your Local Dealer or Contact: 

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We Will Try To Beat Any Advertised Price 

Automated Equipment Inc. 

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TOLL FREE ORDERING 

(714) 963-1414 (800) 854-7635 




o 






Listing 1 continued: 

413 REM THE INPUT DATAr Y ( K ) r 

414 REM ARE CONVERTED TO A 

415 REM DATA VECTOR WHICH IS 

416 REM AUGMENTED BY ZEROES ON 

417 REM BOTH THE LEFT AND 

418 REM RIGHT. 

419 FOR K = TO A 

420 D(K)=0 

421 IKK+N4+A+1 >=0 

422 NEXT K 

423 FOR K = l TO N4 

424 IKK + A) = Y(K) 

425 NEXT K 

426 RETUF.N 

427 REM ******************** 

428 REM CONVOLUTION SUBROUTINE 

429 REM THIS ROUTINE SMOOTHS THE 

430 REM DATA POINT M USING THE 

431 REM SURROUNDING N3 DATA POINTS. 

432 REM THE WEIGHTING FUNCTION IS 

433 REM U(I>, AND THE DATA IKK"). 

434 REM THE SYMMETRY IN WEIGHTING 

435 REM IS GIVEN IN U . 

436 REM THE RESULT IS D. 

437 REM .THE RESULT IS NORMALIZED 

438 REM USING V. 

439 D=0 

440 D="D + U(0)*D<M) 

441 FOR K-=l TO A 

442 D=H+U(K)*(U*D(M+K)+D(M-K) ) 

443 NEXT K 

444 D = D/V 

445 RETURN 

446 REM ******************** 

447 REM DATA SHIFT SUB. 

448 REM THE SHIFTED AND 

449 REM SMOOTHED DATA SET 

450 REM IS IKK). THE DESIRED 

451 REM SMOOTHED SET IS TICK). 

452 FOR K==l TO N4 

453 Y1(K)=-Y1(K + A) 

454 NEXT K 

455 RETURN 

456 REM ******************** 

457 REM STANDARD DEVIATION 

458 REM SUBROUTINE 

459 D*0 

460 FOR K=l TO N4 

461 D=D+(Y(K)-Y1(K))*(Y(K)-Y1(K)) 

462 NEXT K 

463 D = SQRT(D/(N4-I- .999999) ) 

464 REM IF YKK) IS A DERIVATIVE 

465 REM THEN CALCULATION IS NOT 

466 REM APPLICABLE. 

467 IF N2>0 THEN D=0 

468 RETURN 

469 REM ******************** 

470 REM PLOTTING SUBROUTINE 

471 REM SHIFT DATA TO NON-NEGATIVE 

472 PRINT 

473 PRINT 'INPUT DESIRED PLOT WIDTH. ", 

474 INPUT L 

475 REM FIND MAX. DATA VALUE 

476 C=0 

477 FOR K=l TO N4 

478 IF C<D(K) THEN C=D(K) 

479 NEXT K 

480 REM DETERMINE PRINTING SCALE VALUE 

481 A=L/C 

482 PRINT 

483 PRINT 

484 PRINT"***** DATA PLOT (SCALED) ****** 

485 PRINT 

486 PRINT 

487 PRINT 'MAXIMUM VALUE= ",C 

488 FRINT 

489 PRINT 

490 REM GO TO AXIS PRINT SUBROUTINE 

491 GOSUB 519 

492 FOR K=l TO N4 

493 REM INSERT LINE FEED FOR AUTO SPACING 

494 FOR P = l TO ( I NT ( . 6*L/N4 ) ) 

495 PRINT - t ■ tTAB(L) , ■ ! ■ 

496 NEXT P 

497 REM LOCATE DATUM POSITION 

498 E2 = A*D(K) Listing 2 continued on page 276 



274 March 1981 © BYTE Publications Inc 



Circle 188 on inquiry card. 









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Compatibility with 



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Each program 5195.00 from stock. Specif)' 
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Circle 263 on inquiry card. 



Circle 264 on inquiry card. 



Circle 265 on inquiry card. 



Listing 1 continued: 

499 REM FORMATTED PRINT 

500 IF E2>=1 THEN GOTO 503 

501 PRINT - * - , 

502 GOTO 506 

503 PRINT - ! - , 

504 PRINT TAEKE2) r "* - » 

505 IF INT(E2)=L THEN GOTO 507 

506 PRINT TAB(L> . - ! - , 

507 PRINT 

508 NEXT K" 

509 REM GO TO AXIS PRINT SUBROUTINE 

510 GOSUB 519 

511 PRINT 

512 GOSUB 535 

513 PRINT 

514 PRINT 

515 REM RETURN TO DATA SOURCE PROGRAM 

516 RETURN 

517 REM *###*###* 

518 REM AXIS PLOT 

519 FOR K=l TO L/5 

520 PRINT'I , 

521 NEXT K 

522 PRINT"I - f 

523 E4=(K-1)*5+1 

524 IF E4=L+1 THEN PRINT 

525 IF E4=L+1 THEN GOTO 532 

526 E4=E4+1 

527 IF E4>=L+1 THEN GOTO 530 
52B PRINT - -" t 

529 GOTO 526 

530 PRINT - : " 

531 REM RETURN TO MAIN PLOTTING PROGRAM 

532 RETURN 

534 REM PAUSE 

535 PRINT "CONTINUE" , 

536 INPUT R4$ 

537 PRINT 

538 RETURN 
READY 



Text continued from page 264: 

(eg: a government contract) so that, depending on the 
situation, the next year's sales might be either exactly the 
same or drastically different. Thus data smoothing must 
be performed using some common sense concerning how 
to evaluate the results. 

The Moving Average 

This section presents the basic table-oriented 
algorithm; the following section provides the mathe- 
matical derivation of the table values for the linear least- 
squares case. Although the mathematics may appear 
complicated, especially for the parabolic, cubic, and 
higher fits, you will find the actual application of the 
results very simple. 

The algorithm is conceptually identical to that of the 
moving average. In the calculation of the three-point 
moving average, the data point for the month of interest 
(using our example from table 1) is replaced by the 
average Value of that data point and its two surrounding 
neighbors: 



S(t) = 



Y(t-1) + Y(t) + Y(t + 1) 



(2) 



In this notation, S(t) is the smoothed value at position t 
and Y(t) is the actual datum for position f. If a five-point 
moving average were used, the corresponding equation 
would be: 



S(t) = Y(t-2) + Y(t-l) + Y(t) + Y(t + l) + Y(t + 2) 



TUT TXTTYP "R f^T Of^Tf "PT T 7Q™ PUT TIME AND REMOTE 

iflUn l^CIV^l^^f^ JV 1LUO CONTROL IN YOUR APPLE II 

The THUNDERCLOCK PLUS is two peripheral systems on one card for your APPLE II OR II PLUS. An accurate, reliable, 
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APPLE II is a trademark of APPLE COMPUTER, INC California residents add 6% sales tax 





276 March 1981 © BYTE Publications Inc 



Circle 189 on inquiry card. 



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RT-11 is a trademark of Digital Equipment Corp 
CP/M is a trademark of Digital Research. 



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Circle 272 on inquiry card. 





1978 




Th 


ree-Point 


Five-Point 


Month 


Sales Volume 


Smoothing 


Smoothing 


(November) 


(1235) 










(December) 


(2408) 










January 


3279 






2703 


2842 


February 


2421 






3521 


3321 


March 


4864 






3638 


3475 


April 


3629 






3891 


3768 


May 


3180 






3851 


4520 


June 


4744 






4702 


4277 


July 


6181 






4859 


4235 


August 


3653 






4417 


3944 


September 


3418 






2931 


3242 


October 


1722 






2125 


2487 


November 


1235 






1788 


2412 


December 


2408 






2307 


2213 


(January) 


(3279) 










(February) 


(2421) 










Standard Deviation: 






719 


994 


Table 2: 1978 sales with three-poi 


nt and five 


-point moving- 


average data 


smoothing. 


Note tha 


extrapolat 


ed figures must 


be given for 


November and D 


ecember 1977 and January and 


February 1979 in order 


for 


the 


smoothed 


versions to be 


calculated. 













6000 


- 






RAW 


DATA 




- 


5000 
1000 
3000 


- 


■''SV 


1>&J 

5 POINT AVERAGE—' 
a = 994 


\ /-THREE POINT AVERAGE 
~"\i cr = 719 


- 


2000 


- 








V~^ 


— — ' / 


- 


1000 


- 


1 1 





i 


1 1 


1 1 


- 



JFMAMJ JASOND 

MONTH IN 1978 

Figure 2: Computation of a smoothed set of data using the 
moving-average method. The chart shows the raw data (solid 
line), the smoothed version using a three-point average (the 
dashed line) and the smoothed version using a five-point 
average (the dotted line). The Greek letter a indicates the stan- 
dard deviations for the respective graphs. 



Note that the number of points included in the average is 
odd. This is required to keep the smoothed points from 
being shifted in phase. Contrast this with the average of 
the two data points for June and July — the smoothed 
value would have to be plotted halfway between the two 
months. 

The results of applying the three-point and five-point 
moving averages to the data shown in table 1 are given in 
table 2, and the results are plotted in figure 2. The 
assumption that the pattern will repeat is used to supply 
the extra data points required at either end of the data set. 

This particular example demonstrates several general 
features of moving-average data smoothing. First, from 
figure 2, it is apparent that the moving average tends to 
smooth out extreme fluctuations in the data. Using a five- 
point average instead of a three-point one has a greater 
effect on limiting the range of variation. However, using 
a five-point average does not guarantee that a locally 
smoother curve will result, although the tendency will 
exist. 



Note, for example, the region near May. The five-point 
average equally weights the values from the two-month 
periods on either side, which, in this case, contain two 
peaks (one in March and one in July). Thus, where there 
is a local minimum in the raw data, the five-point average 
gives a local maximum. This obvious weakness in the 
smoothing is due to the implied assumption that the five 
data points over which the averaging is performed should 
all be equally weighted; the July value is included with 
the May value with equal importance, even though the 
smoothed result is being calculated for May. As we will 
see later, nonuniform weighting may be used, partially 
avoiding this problem. 

The second feature to note is that the three-point and 
five-point moving averages naturally give different 
results. For the smoothed July value, the three-point 
method gives an average of 4859, with a standard devia- 
tion of 719, while the five-point method gives an average 
of 4235, with a standard deviation of 994. 

Which result is correct? The answer is probably 
neither. However, one result is likely to be more repre- 
sentative of the truth than the other. If reason exists for 
believing that correlation between monthly results ex- 
tends only as far as one month on either side of a given 
month, then the three-month average is likely to be bet- 
ter. (That is, if the sales for the June and August time 
periods are expected to be the same as those for July, with 
the only difference being the "noise," then it is reasonable 
to average these three months, or maybe more. This is 
the case for, say, a five-month average. However, if the 
May and September sales are expected to represent a sea- 
sonal response different from the response that caused the 
July sales, then the average should be limited to a span of 
only three points. Such might be the case if the data in 
table 1 represented the sales of a seasonal item such as 
lawn mowers. 

The conclusion is that the number of points used in the 
moving average (3, 5, 7, 9,...) should be dictated by some 
knowledge of the time frame associated with the underly- 
ing customer sales motivation (or, for physicists, the 
physics; for engineers, the forcing function). The span 
parameter in the moving-average and the weighted- 
averaging techniques to be discussed in the next section 
should generally be chosen based on some idea of the 
general trends that are the basis of the observed data. 
With this in mind, the moving-average calculation can 
then be used to refine the estimate in an intelligent man- 
ner. Only in this way can real information be derived 
from the data. 

Least-Squares Data Smoothing 

The simple moving-average calculation presented in 
the previous section is a special case of the general con- 
cept of weighted averages, which can be stated mathe- 
matically as follows: 



S(t)= £ w(i)Y(t+i)/ E w(i) 



w(-n)Y(t-n) + ...+w(0)Y(t) + ...+w(n)Y(t + n) 



(4) 



E w(i) 



For the moving-average case we have w(i) = 1 for all i. 



278 



March 1981 © BYTE Publications Inc 



Circle 190 on inquiry card. 



Circle 191 on inquiry card. 



IEEE-488 To TRS-80* INTERFACE 



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t sciEHTinc mmm munma « 




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BYTE March 1981 



279 





Num 


ber of Averaging Points 




Index/ 25 23 21 19 17 15 13 11 9 7 5 3 




12 1 






11 1 






10 1 






9 1 


1 1 


1 


8 1 


1 1 1 


1 


7 1 


1111 


N 

T 


6 1 
5 1 


11111 
111111 


E 
G 


4 1 

3 1 


1111111 
11111111 


E 
R 


2 1 

1 1 


111111111 
1111111111 


W 


1 

- 1 1 


1111111111 
1111111111 


E 


-2 1 


111111111 


1 


-3 1 


11111111 


G 

H 


-4 1 
-5 1 


1111111 
1111111 


T 


-6 1 


111111 


S 


-7 1 


11111 




-8 1 


1111 


W(i) 


-9 1 
-10 1 
-11 1 
- 12 1 

Normalizing 
factor, 


1 1 1 




N 25 2 


3 21 19 17 15 13 11 9 7 5 3 


Table 3: Weighting 


coefficient table for the moving-average 


method of data smo 


othing. This is a trivial case, but it clearly 


introduces the table 


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At this point, you should become familiar with the idea 
of tables of weighting coefficients, which are the w(i) 
terms in equation 4. Such a tabulation for moving 
averages is shown in table 3. Although this table is 
trivial, it demonstrates the concept of integer weighting 
coefficients as presented in an article by Savitzky and 
Golay. (See references.) In that article (and here as well), 
the weighting coefficients, w(i), are integers, and the nor- 
malization N is performed after the multiplication/addi- 
tion sequence: 



S(t) = 



1_ 
N 



£ w(i)Y(t+i) 



(5) 



For a given number of averaging points, the coefficients 
are easily found in the table, the summation performed, 
and the result then normalized (by dividing by, for the 
moving-average case, N = 2« + l, the sum of all the w(i)s 
from w(— n) to w(n)). 

For the moving average, it is very obvious how the en- 
tries in table 3 were obtained. As an illustrative example, 
we will now derive the table entries for a linear (as op- 
posed to parabolic, cubic, etc) least-squares smoothing. 

Consider a set of data where there are 2n+l elements 
having coordinates (X, , Y,). Generally, the method of 
linear least-squares fitting leads to a "best fit" line having 
the equation: 



Y(X) = mX + b 



(6) 



The "best fit" criterion is to find values for m and b 
such that the sum of squares, SS, is a minimum: 



SS= £ (Y(X-)-Y,-) 2 



(7) 



The case we are considering is a little special in the sense 
that we are examining least-squares fitting with only an 
odd number of data points. The index range is not the 
usual i = l to some positive value, but rather i=— n to 
i = n. 

The analytical solution to the desired parameters, m 
and b, may be found in any standard statistics text. For 
example, reference 2 presents the results in a particularly 
convenient form modified here: 



m- E (X- X)(Y- YV2 (X- X)' 
b=Y-mY 



(8) 
(9) 



In this notation, X and Y are simply the averages of X, 
and Y, : 



X = £ Xi/ln+l 



V = E Y./2W+1 



(10) 



(11) 



The weighting coefficients we are looking for are implicit- 
ly contained in the above equations. This may be seen as 
follows. 

We are interested in replacing the data point Y with a 
"better" one as determined by the least-squares smooth- 
ing. This smoothed value is simply: 



Y = mX + b = mX + Y -m X 



(12) 



280 



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BYTE March 1981 281 



































Number o 


Averaging Points 










Index / 


25 


23 


21 


19 


17 


15 


13 


11 


9 


7 


5 3 




12 


12 
























11 


11 


11 






















10 


10 


10 


10 




















9 


9 


9 


9 


9 
















1 


8 


8 


8 


8 


8 


8 














N 


7 


7 


7 


7 


7 


7 


7 












T 


6 


6 


6 


6 


6 


6 


6 


6 










E 


5 


5 


5 


5 


5 


5 


5 


5 


5 








G 


4 


4 


4 


4 


4 


4 


4 


4 


4 


4 






F 


3 


3 


3 


3 


3 


3 


3 


3 


3 


3 


3 




R 


? 


2 


2 


2 


2 


2 


2 


2 


2 


2 


2 


2 




1 


1 


1 


1 


1 


1 


1 


1 


1 


1 


1 


1 1 


W 






































E 


-1 


-1 


-1 


-1 


-1 


-1 


- 1 


- 1 


- 1 


-1 


-1 


-1-1 


1 


-2 


-2 


-2 


-2 


-2 


-2 


-2 


-2 


-2 


-2 


-2 


-2 


G 


-3 


-3 


-3 


-3 


-3 


-3 


-3 


-3 


-3 


-3 


-3 




H 


-4 


-4 


-4 


-4 


-4 


-4 


-4 


-4 


-4 


-4 






T 


-5 


-5 


-5 


-5 


-5 


-5 


-5 


-5 


-5 








S 


-6 


-6 


-6 


-6 


-6 


-6 


-6 


-6 












-7 


-7 


-7 


-7 


-7 


-7 


-7 














-8 


-8 


-8 


-8 


-8 


-8 
















-9 


-9 


-9 


-9 


-9 


















-10 


- 10 


-10 


-10 




















-11 


-11 


-11 






















-12 


-12 






















Normalizing 






















factor, 
























N 




1300 


1012 


//O 


b/0 


408 


280 


182 


110 


6U 


28 


10 2 


Table 4: 


Weig h ting-co efficient 


table for linear, 


easf- 


squares, first- 


derivative data 


smoo 


thing 


. The symmetry arour 


rf i = 


-0 allows this 


table to 


be cut 


in half when used ir 


a computer program. 







f RUN J 








DIMENSION ARRAYS 










INPUT 

NO. OF ELEMENTS IN SET 
AVERAGING RANGE 
LEVEL TO FIT 
DERIVATIVE ORDER 












DETERMINE TABLE 
TO BE USED 










CHECK FOR INPUT 
ERRORS 




YES /frror\ 



Since the data points are equally spaced, it does no 
harm to redefine the X, values. In _p_articular, choose 
Xi = i. In that case, X o = and X = 0, giving the 
smoothed value: 



Y= Y = £ Y,/2n+l = 



2n + l 



EX 



(13) 



That is, the smoothed value obtained by the linear least- 
squares criterion is just the moving average! Thus table 3 
gives the weighting coefficients for linear, least-squares 
data smoothing. 

The analysis can be taken yet one more step. If we 
want the first derivative at X o = of the function fitted to 
the 2n + l points centered at X 0l we have simply: 



INPUT DATA SET 



PLOT DATA 



SMOOTH DATA SET 



DISPLAY 
SMOOTHED DATA SET 

STANDARD DEVIATION 
(IF APPLICABLE) 



PLOT SMOOTHED DATA 



f END J 



TABLE 
SUBROUTINE 



ERROR CODE 
SUBROUTINE 



PLOTTING 
SUBROUTINE 



SUPERVISOR 
SUBROUTINE 



PLOTTING 
SUBROUTINE 



dY 
dX 



(14) 



X = X 



Recalling that X =0 and noting that EX, Y is propor- 
tional to X Y , we get: 



dY 
dX 



X = X 



L X,V L X*, 



(15) 



Thus, the nonnormalized integer weighting coefficients 
for linear, least-squares, first-derivative data smoothing 
are: 

W(i) = 

with 



( — n < i < n ) 

n(n + l)(2n + l) 



N= £ « 2 = 



(16) 
(17) 



The last two equations were used to generate table 4. 

Two important characteristic features are apparent 
from table 4. The first is that the normalizing factor, N, is 



Figure 3: Flowchart for the least-squares data-smoothing pro- 
gram given in listing 1. See figure 4 for the supervisor subroutine 
flowchart. 

not simply a sum of the weighting factors in the cor- 
responding column. That is true only for the moving 
average. Second, the table is symmetrical about the i = 
row. The weighting tables are exactly symmetrical or in- 
versely symmetrical, thus making nearly half the entries 
redundant. This property may be used to save program 
space. 

Implementing the Algorithm 

The algorithm represented by equation (5) may easily 
be implemented as a computer program that applies the 
appropriate table depending on the prompted inputs. The 
flowchart for such a program is shown in figure 3. 

The program is laid out in modular (ie: subroutine) 
form. As shown in figure 3, the basic program flow is to 
input the smoothing parameters, check for errors in those 
parameters, and then input the data. The input data is 



282 



March 1981 © BYTE Publications Inc 



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BYTE March 1981 



283 



then plotted, and control is subsequently passed to a 
generalized supervisor (or executive) program that per- 
forms the desired smoothing by calling in several other 
subroutines. (See figure 4.) The smoothed results are 
returned to the main program and are printed out along 
with the standard deviation between the original and 
smoothed data. In the case of derivative smoothing, 
which will be discussed later, the concept of standard 
deviation is not applicable, and is printed. After the 
numerical display, the smoothed results are plotted. 

The plotting routine properly deals with only non- 
negative data. This restriction helps keep the program 
short and simple. If negative values are encountered, 
only the absolute values are plotted. This generally does 
not cause much confusion because the values themselves 
are also printed. The plot is only a convenience item. 

The supervisor subroutine is interesting because it can 
be called by some other data-gathering program instead 
of the one outlined in figure 3. It requires the variables 
given in table 5a as input and returns the values given in 
table 5b. 

Before entering the supervisor, the arrays must have 
already been dimensioned. The reason for this require- 
ment is that in many BASIC interpreters an array cannot 
be dimensioned more than once. Since the supervisor 
subroutine may be called more than once, it therefore 
cannot contain DIM (dimension) statements. 

The complete program is shown in listing 1. As can be 
seen from the listing, the subroutines indicated in figures 
3 and 4 are clearly identified by liberal use of REM 
(remark) statements. 



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(5a) 



(5b) 



N1: The level of fit (0,1,2,3,4,5). 

N2: The order of the derivative (0,1,2,3). 

N3: The number of points to be smoothed over 

(3,5,7,9,. ..25). 
N4: The number of data points. 
Y(K): The data array. 



E: The error code if an improper input was given. 
Y1(K): The smoothed data (or derivative). 
D: The standard deviation (if applicable). 



Table 5: Variables used in the supervisor subroutine that ap- 
pears in the flowchart in figure 4. This subroutine is given in 
lines 98 thru 158 of listing 1. 



(main N 
PROGRAM ) 



INITIALIZE 
THE OUTPUT 
VECTOR, Yl (K) 



DETERMINE TABLE 
TO BE USED 



CHECK FOR ERRORS 



f RETURN \> 




OBTAIN 
COEFFICIENTS 



U = SYMMETRY VALUE 
V= NORMALIZATION 



GET WEIGHTING 
COEFFICIENTS 



CREATE AUGMENTED 
DATA VECTOR, D (K) 



SMOOTH D(K) 



EXTRACT Y1(K) 
FROM D(K) 



OBTAIN STANDARD 
DEVIATION 



f RETURN ) 



TABLE 
SUBROUTINE 



ERROR CODE 
SUBROUTINE 



COEFFICIENT 
SUBROUTINE 



WEIGHTS 
SUBROUTINE 



DATA VECTOR 
SUBROUTINE 



CONVOLUTION 
SUBROUTINE 



SHIFTING 
SUBROUTINE 



STANDARD DEVIATION 
SUBROUTINE 



Figure 4: Flowchart for the supervisor subroutine. The super- 
visor calls several other subroutines in order to perform the task 
of data smoothing. Note that the calling program, shown in 
figure 3, can be entirely replaced by a program that obtains the 
appropriate inputs and then calls this subroutine. 



284 March 1981 © BYTE Publications Inc 



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A 


M 


B(I,J) 


N1 


C(I.J) 


N2 


D 


N3 


D(l) 


N4 


E 


O 


E(D 


P 


E2 


R4$ 


E4 


U 


I 


U(l) 


J 


V 


K 


V(I.J) 


K1 


W(l) 


L 


Y(l) 




Y1(l) 


Table 6: A table of variables used 


in the subroutines of listing 


1 . This table is used to prevent du 


plication of variable names 


when generating a new main 


program that uses the 


subroutines of listing 1. 







Derivative 








1 


2 


3 


1 


Yes Yes 


No 


No 


Level 2 


Yes Yes 


Yes 


No 


of 3 


Yes Yes 


Yes 


Yes 


Fit 4 


Yes Yes 


Yes 


Yes 


5 


Yes No 


Yes 


No 


Table 7: Table of perm 


itted data-smoothing operations with 


the program shown in 


listing 1. The derivative/level-of-fit 


combinations omitted 


were done to 


'<eep the 


program at a 


reasonable length. 









The smoothing parameters are stored as explicit ar- 
rays. It would have been more efficient to store this infor- 
mation in BASIC data statements. However, the super- 
visor (and the routines it calls) is meant to be a sub- 
routine, and it is not good programming to use data state- 
ments in subroutines that may be called often. For exam- 
ple, if the main program and the subroutine both have 
data stored that way, how does the subroutine read the 
appropriate data and restore the data pointer to its pro- 
per location after repeated calls? The way the program 
shown in listing 1 is written, the main program (state- 
ments 1 thru 96) can be replaced by a user program with- 
out any change in the subroutines. If you want to replace 
the main program, keep in mind that the subroutines 
have variables that should not also be employed in the 
calling program without some caution. The subroutine 
variables list is shown in table 6. 

Using the Program 

As presented, the program may be used to smooth data 
over the range of fits and derivatives shown in table 7. As 
an example of how the program operates, we will now 
apply it to the sales-volume example discussed earlier. 

Listing 2 shows a sample run in which a parabolic (ie: 
second level) fit was applied using a five-point average. 
Note that sixteen data points are necessary to do this, 
since we require an additional two points on either side of 
the point of interest. (These points can be deleted later.) 
The user inputs are underlined. If a "fatal" error in the 
parameter input sequence had been made, the error 

Text continued on page 290 



286 



March 1981 © BYTE Publications Inc 



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Circle 208 on inquiry card. 



Listing 2: Sample run of data smoothing program, using data from table 1. In this listing, user input is underlined. 



RUN 



DATA SMOOTHER FOR EC1UALLY 
SPACED DATA SETS 



INPUT THE NUMBER OF 
DATA POINTS IN SET: 716 



HOU MANY POINTS ARE 

TO DE AVERAGED OVER! ?J 



WHAT IS THE DESIRED LEVEL 
OF FIT (1,2.3.4.5): 72 



UHAT IS THE DESIRED 
DERIVATIVE (0,1.2.3): TO 



INPUT DATA AS PROMPTED! 



1 


71235 


n 


72408 


3 


73279 


4 


7 2 4 21 


5 


74864 


6 


73629 


7 


73180 


8 


74744 


9 


76181 


10 


73653 


11 


73418 


12 


71722 


13 


71235 


14 


72408 


15 


73279 


16 


72421 



INPUT DESIRED PLOT UIDTH! 750 



***** DATA PLOT (SCALED) ***** 



MAXIMUM VALUE= 



CALCULATING, 




THE SMOOTHED DATA IS! 



CONTINUE?^ 

288 March 1981 © BYTE Publications Inc 



1 


1144 


4 


2 


2509 


7429 


3 


2725 


5429 


4 


3450 


3429 


5 


3883 


1714 


6 


3906 


4571 


7 


3468 


6 


8 


4889 


54 2 9 


9 


5 315 


6286 


10 


451 1 


1714 


11 


2867 


3714 


12 


1912 


D 


13 


14 41 


8286 


14 


2362 


1429 


15 


314 2 


,4571 


16 


2093 


,7429 


C0NTINUE7Y 





THE STANDARD DEVIATION 
BETWEEN THE SMOOTHED AND 
UNSMOOTHED DATA SETS IS 589.8642 

C0NTINUE7Y 



INPUT DESIRED PLOT UIDTH! 750 



***** DATA PLOT (SCALED) ***** 



MAXIMUM VALUED 5315.6286 




CONTINUE? 



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BYTE March 1961 289 



Error 

Code Explanation 

No Error. 

1 Number of data points to be averaged over is too 

small. 

2 Number of data points to be averaged over is too 

large. 

3 The order of the derivative is greater than the level 

of the fit, which gives a trivial (0) result. 

4 The level of fit attempted is too high. 

5 The order of the derivative attempted is too high. 

6 The particular table required is not available in the 

program. 

7 There is not enough data to do the smoothing re- 

quested. 

8 An illegal or otherwise out-of-range parameter was 

given. 

Table 8: Table of error codes returned by a call to the super- 
visor subroutine. 



6000 


- 


- 


5000 




'"N. 


4000 


. v/ 


\ 


3000 


- yT 


\ 


2000 


- 


N. / - 


1000 


i i i i i i 






A M J J A 

MONTH IN 1978 



Figure 5: Chart of smoothed sample data using five-point 
parabolic smoothing. This chart is identical to the one plotted in 
listing 2. 



Text continued from page 286: 

would have been indicated according to the code in table 
8. 

As shown in listing 2, the program prompts for all the 
inputs. The user can then specify the plotting width for 
the terminal being used. Note that only absolute values 
are plotted. The program then performs the smoothing 
and calculates the standard deviation (when applicable). 



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Finally, the routine plots the smoothed data. 

The smoothed data for the sales-volume example has 
been replotted as shown in figure 5. Observe that the first 
two and last two of the sixteen input values have been 
discarded. If a seven-point average had been used, three 
points on either side of the desired results would have 
been dropped. Comparing figure 5 with figure 2, we see 
that the five-point parabolic smoothing looks much more 
"reasonable" than the three-point and 
five-point linear smoothing. The peak 
in July is apparent, as well as the dips 
in May and November. Recalling that 
the nominal purpose of the example 
was to better predict the July sales 
volume, we find the value to be 5316 
units, with a standard deviation of 
590. We expect that the standard 
deviation will be lower for the 
parabolic fit than for the correspond- 
ing linear fit, and it is. 

Discarding points at the ends of the 
smoothed data set is necessary. The 
smoothing at each position uses data 
on either side. At the extremes of the 
data set there is missing information. 
The program supplies values (eg: 0) 
for this missing data. In general, if the 
number of data points averaged over 
is N3, then the number of data points 
that should be discarded at either end 
of the data list is (N3-l)/2. 




MFJ 



Square-Wave Example 

We will now look at the results of 
smoothing a very discontinuous func- 
tion, the square wave. The purpose is 
to show the comparative effects of the 
various levels of fit on "smoothing" 
an abrupt transition. 



290 March 1981 © BYTE Publications Inc 



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BYTE March 1981 



291 



Using a computer, the mechanics of 

data smoothing can be made fairly 

simple. 



To electrical engineers, the multipoint averaging tech- 
nique presented in this discussion is the equivalent of 
nonrecursive digital filtering. The way in which the cal- 
culation is applied is identical to convolution. According 
to one of the important theorems of Fourier transform 
theory, performing a discrete convolution on a "signal" 
(the data) is the same as frequency filtering. The shape of 
the frequency filter is simply the discrete Fourier trans- 
form of the weighting function. 

Thus, every table of weighting coefficients can be con- 
verted to a corresponding set of filter coefficients. Usual- 
ly, in electrical engineering one chooses the frequency 
filter response and then finds the convolution (ie: 
weighting) coefficients. In our case, we chose our coeffi- 
cients according to a least-squares curve-fitting criterion 
first. However, the idea of frequency filtering is still 
valid. 

The square wave is built of many spatial-frequency 
components. Filtering out some of the high-frequency 
components results in a less-than-abrupt square-wave 
transition. Figure 6a on page 294 shows the square-wave 
input data that was provided as an example to the pro- 
gram. The square wave is 1 unit high and 18 units wide. 
For clarity, lines have been drawn between the points 
plotted by the computer. 




Figure 6b shows the effect of applying a linear (first 
level fit, zeroeth-order derivative) smoothing using nine 
averaging points. The effect is simple. Applying a para- 
bolic fit leads to a more curious form. (See figure 6c.) The 
dashed parts of the "curve" indicate negative values. The 
overshoot effect is called ringing. 

Going one step further and applying a quartic (fourth- 
order polynomial) smoothing, we get figure 6d. Note that 
the ringing has increased, but the standard deviation be- 
tween the square wave and the quartic smooth version 
has decreased relative to the parabolic or linear case. 
There is more ringing but a better fit. The overshoot ef- 
fect is related to the Gibbs phenomenon, which is a 
nonuniform convergence problem in Fourier transform 
theory. 

The square wave may also be used to demonstrate 
derivative smoothing. (See figures 7a and 7b on page 
298.) It might be argued that these curves are not very 
smooth: however, remember that the unsmoothed 
derivative is an infinite spike! 

Figure 7a calls attention to an important point regard- 
ing derivatives. From figure 6b, we might have expected 
the linear smoothing of the first derivative to be just a 
step from to 1/9 and back to again, since the linearly 
smoothed function has a constant slope ramp on one 
side. However, the result shown in figure 7a resembles a 
parabola. The reason for the difference is that the 
derivative is not derived from the smoothed data. Rather, 
at each data point the derivative of the curve fitted over 
the nine-point interval surrounding that position is used. 
This is not the same as the slope between neighboring 
smoothed data points, a very important conceptual dif- 
ference. 

As you might expect, the situation for the second and 
third derivatives is even more complicated. Examination 
of those forms is left to you. 

Conclusion 

As indicated earlier, the mechanics of data smoothing 
can be made fairly simple given a computer that can ex- 
ecute the program provided. Running the program is 
easy. Choosing the appropriate fitting parameters and 
applying the results is much more difficult. The two main 
choices for fitting are the averaging range and the level of 
fit. The averaging range should be chosen based on an 
idea of the true correlation between the data points. If 
changes over a range of N3 are not expected, then an 
averaging range of that size is warranted. 

Choosing the level of fit is more difficult. In the sales- 
volume example, the parabolic fit appeared better than 
the corresponding linear fit. However, that is a subjective 
judgment based largely on the feeling that the peak and 
two major dips observed in the data should appear in the 
smoothed curve. There is still no replacement for com- 
mon senselH 



REFERENCES 

Savitzky A, and M JE Golay. "Smoothing and Differentiation of 

Data by Simplified Least Squares Procedures." Analytical 

Chemistry, Volume 36, Number 8, July 1964. 

Wesolowsky, G 0. Multiple Regression and Analysis of Variance. 

New York: Wiley Interscience, 1976. 

Weast, R C and S M Selby. Handbook of Tables for Mathematics. 

Third Edition. Cleveland OH: Chemical Rubber Company, 1967. 



292 March 1981 © BYTE Publications Inc 



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Circle 218 on inquiry card. 



BYTE March 1981 



293 



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Figure 6: Smoothing a square wave. The test square wave in figure 6a was smoothed in figures 6b thru 6d using a nine-point 
average. Figure 6b shows a linear smoothing. Figure 6c shows the results of a parabolic smoothing with a cubic smoothing giving the 
same results. Figure 6d shows the results of a quartic and quintic smoothing. In all figures, dashed lines denote negative values plot- 
ted here as positive. These figures and those of figure 7 were generated using the program given in listing 1. 



294 March 1981 © BYTE Publications Inc 



Circle 219 on Inquiry card. 



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Circle 221 on inquiry card. 



BYTE March 1981 



295 



(6c) 



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296 March 1981 © BYTE Publications Inc 



Circle 222 on Inquiry card. 



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Circle 224 on Inquiry card. 



BYTE March 1981 



297 



(7a) 



L-1 

111 

_l 



LL 
<E 

r- 

<L 



N 



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(7b) 




Figure 7: Least-squares smoothed (nine-point) first derivatives of the square wave shown in figure 6a. Figure 7a shows the result for 
a linear and a parabolic first-derivative smoothing. (Both are the same.) Figure 7b shows the result for a cubic and quartic first- 
derivative smoothing. 



298 March 19B1 © BYTE Publications lnc 



Circle 159 on inquiry card. 



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BYTE March 1981 



299 



The New Literacy: 

Programming Languages as Languages 



"To be a good programmer today is as much a privilege 
as it was to be a literate man in the sixteenth century." 

Andrei Ershov, USSR Academy of Sciences, Novosibirsk University 



Many people would declare that 
Ershov is making an incongruous 
comparison: he compares the ability 
to read, a universally desirable trait, 
with the ability to program a com- 
puter, which fewer people deem to be 
a desirable trait. Stranger still, he 
compares reading, which is linked 
with the appreciation of literature 
and with the artistic use of language, 
to programming. Programming is the 
recording of arcane codes that make a 
computer perform some data manip- 
ulation. Such coding seems uncon- 
nected with art and language, yet he 
implies that it is. Consonant with this 
view, program-coding systems are 
called languages, but most people 
would find it difficult to specify any 
way in which a computer program- 
ming system merits the label 
language. 

Some people are, in fact, hostile to 
the very idea that programming and 
programming languages have any- 
thing at all to do with creativity and 
language. Sometimes these people are 
confused between the computer and 
its human programmer, attributing 
programming to the computer rather 
than to human beings. 

Programming languages are in fact 
languages in a meaningful sense of 
that word: they exhibit some of the 
complexity of form and function that 
natural languages do. Computer pro- 
gramming languages are much more 
than mere coding systems. 

It is important that programming 
languages be recognized by lay peo- 
ple as languages. The ability to pro- 



Jon Handel 

3 Gilmore Ct 

Scarsdale NY 10583 



gram computers, or at least to 
understand programming and com- 
puters in a general way, is important 
today, just as literacy was important 
in the sixteenth century. Those who 
lack the new literacy — computer 
literacy — will find increasing difficul- 
ty in participating effectively in 
political, professional, and business 
life. If you don't know what a com- 
puter can do, how can you decide 
whether we should sell them to the 
Soviets — or whether you should buy 
one to help around the house? 

What a computer can do is greatly 
determined by its software — that is, 
by the programs it executes. The soft- 
ware is expressed in some program- 
ming language, and this is the subject 
to which we now turn. 

To explore the nature of pro- 
gramming languages and examine the 
characteristics of natural language ex- 
hibited by programming languages, 
the term language must first be de- 
fined. A reasonable definition is that 
language consists of a set of symbols, 
sounds, and/or gestures, and a set of 
rules according to which these 
elements may be systematically com- 
bined to communicate an indefinite 
number and variety of thoughts and 
ideas. Usually, these symbols are 
combined into subunits called words. 



and these words are then combined 
into sentences. 

Notice that the communication ef- 
fected by a language need not be be- 
tween people; it may also involve 
machines. A computer programming 
language is a language which is most 
often used for communication with 
computing machinery. The instru- 
ment of communication is a computer 
program, which is a detailed, step-by- 
step set of directions for the computer 
to follow. The purpose of a particular 
program can be practically anything 
from printing mathematical tables to 
controlling oil refineries. 

Three computer programs in com- 
mon languages will be examined. 
Following this is an examination of 
the communicative function of pro- 
gramming languages and the gram- 
mar of programming languages. The 
examples presented will show that 
programming languages are much 
more than mere coding systems. They 
exhibit structural patterns and con- 
cepts that are both complex and in 
some ways parallel to patterns and 
concepts of natural languages. 

(The several computer languages 
discussed in this article represent only 
a small fraction of the existing 
languages. Jean Sammet of IBM com- 
piled a list of 167 major languages, 
noting the existence of numerous 
dialects of some of these (Com- 
munications of the ACM, December 
1976, page 655). In an earlier roster 
(Communications of the ACM, July 
1972, page 601), Sammet presented a 
chronological chart of languages ar- 



300 March 1981 © BITE Publications Inc 



ranged by application area (eg: scien- 
tific computation, business data pro- 
cessing, experimental, etc). There are 
dotted, dashed, single, and double 
lines on the chart representing evolu- 
tionary changes from one language to 
another, as well as circles, squares, 
triangles, and three different type 
styles. The whole effect is that of a 
collapsed and tangled spiderweb. 
This complexity reflects the diversity 
of programming languages in use to- 
day.) 

My sample programs deal with 
a specific problem. Imagine a com- 
puter user who wishes to calculate the 
reciprocals of some numbers. The 
user is sitting at a computer terminal 
and will use it to type in the numbers 
to the computer and receive the print- 
out of the reciprocals. The programs 
illustrated will allow her or him to 
input a number X and have the com- 
puter print out the reciprocal of the 
number X, which is 1 divided by X. If 
the number X is 0, instead of printing 
the result of its computation, the pro- 
gram will print the message 
"Reciprocal of does not exist." 

BASIC Program 

Listing 1 shows the reciprocal pro- 
gram coded in the BASIC language. 
When this program is typed into the 
computer as shown, and the com- 
mand RUN is typed, the computer 
begins executing the program in the 
order of increasing line numbers. Line 
10 instructs the machine to print the 
message in quotation marks exactly 
as it is written. The message reminds 
the user of what he will be expected 
to do. Line 20 causes the machine to 
print a question mark at the terminal 
and wait for the user to type in a 
number. Since the statement iden- 
tifies the input as X, whatever 
number the user types will be placed 
in the variable X. The program can 
then use the number by referring to 
X. 

In line 30, the program tests to see 
if X is equal to 0. If so, the computer 
does not execute the next statement in 
numerical order (line 40), but 
transfers control to line 70, as 
directed by the IF-THEN statement, 
and continues from there. Line 70 
causes the printout of the message in- 
dicating that the reciprocal of does 
not exist. Line 80, which is executed 
next, tells the computer that the pro- 
gram is over. The computer stops ex- 
ecuting the program, and the user 



may restart it and enter a new 
number, or run a different program 
altogether. 

If X does not equal 0, then the pro- 
gram continues from line 30 on to line 
40. Line 40 performs a computation 
of the reciprocal of X. This value is 
placed in the variable Y. Subsequent 
references to Y will use this computed 
value. 

Continuing with the sequence, line 
50 prints the numerical value of Y. If 
the number typed in were 2, then Y 



It should be realized 
that even though pro- 
gramming languages 

are used for com- 
munication In many 

ways, they do not 
serve the same com- 
municative functions 
as natural languages. 

Programming lan- 
guages are used for 
communicating tech- 
nical procedures In a 
precise fashion. 



would be printed as 0.5. Finally, line 
60 causes the computer to stop ex- 
ecuting the program. This line has 
essentially the same effect as the END 
statement in line 80. 

ALGOL Program 

Listing 2 shows the reciprocal pro- 
gram written in ALGOL 60. ALGOL 
60 was created and formally defined 
in a report of an international com- 
mittee which appeared in 1960. 
ALGOL 60 is important because its 
syntax wa s described using a formal 
notation. (See "An Introduction to 
BNF" by W D Maurer, BYTE, 
January 1979, page 116.) A different 
version of the language, ALGOL 68, 
appeared eight years later. 

When execution begins, the first 
line of the program in listing 2 serves 
two distinct functions. The word 
BEGIN indicates the beginning of a 
program, and the phrase REAL X,Y 
declares that variables named X and 
Y will be used in the program. These 
two variables are to represent real 
numbers (ie: numbers that can have a 



decimal point and a decimal fraction 
part, for example, 0.5, 6.2, or 4). 

On the next two lines, the PRINT 
and INPUT directives work in a 
similar manner to those in the BASIC 
program, although the syntax is 
slightly different. 

The IF-THEN-ELSE structure on 
the succeeding lines is different from 
the IF-THEN encountered in 
BASIC. The intent is the same, but 
the structure is more complex. In the 
ALGOL program, if X is equal to 0, 
the clause following THEN is ex- 
ecuted [PRINT ("RECIPROCAL OF 
DOES NOT EXIST")]; otherwise, 
the compound statement following 
ELSE is executed. This compound 
statement is composed of the two 
statements Y:=l/X, which assigns 
the value of the reciprocal of X to Y, 
and PRINT(Y), which prints out the 
value of Y. These two statements 
are bracketed by the pair of words 
BEGIN and END. This bracketing 
allows the two statements to be 
treated syntactically as a single 
statement group. If X does not equal 
0, it is this compound statement that 
is executed. 

Finally, we encounter the second 
END statement, which is paired 
with the BEGIN at the beginning of 
the program. This indicates the end 
of the program; execution of the 
program terminates. 

Notice that, in contrast to the 
BASIC program, the physical lay- 
out of the ALGOL program displays 
its logical structure. The indentation 
shows the functional grouping of in- 
dividual statements. This indenta- 
tion, and the associated BEGIN- 
END delimiters, are used to clarify 
the structure of ALGOL programs. 
[Editor's note: Indentation is also 
used to clarify structure in other 
languages, such as Pascal. . . . 
RSS] 

Despite the differences between 
ALGOL and BASIC, one common 
characteristic of the two languages 
is that they are both similar to 
English and conventional algebra in 
the notation and verbs (eg: PRINT 
and INPUT) that they use. This 
similarity is not a characteristic of 
the language used for the third ver- 
sion of the reciprocal program, 
which makes extensive use of Greek 
letters and special symbols. 

APL Program 

The language of the third 



March 1981 © BYTE Publications Inc 



301 



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Listing 1: Reciprocal-determining program written in the BASIC language. 

10 PRINT "INPUT NUMBER FOR RECIPROCAL"; 

20 INPUT X 

30 IF X = THEN GOTO 70 

40 LETY=1/X 

50 PRINT Y 

60 STOP 

70 PRINT "RECIPROCAL OF DOES NOT EXIST." 

80 END 



Listing 2: Reciprocal program written in ALGOL. 

BEGIN REAL X,Y; 

PRINT ("INPUT NUMBER FOR RECIPROCAL"); 

INPUT (X); 

IF X = THEN 

PRINT ("RECIPROCAL OF DOES NOT EXIST.") 
ELSE 

BEGIN 

Y:=l/X; 

PRINT (Y) 

END 
END 



Listing 3: Reciprocal program written as an APL function. 

V RECIPROCAL 

(1) ' INPUT NUMBER FOR RECIPROCAL' 

(2) - (0 = X-D)/5 

(3) □ -Y~-r-X 

(4) - 

(5) ' RECIPROCAL OF DOES NOT EXIST.' 
V 



reciprocal program is APL (A Pro- 
gramming Language), which was 
created by Dr Kenneth Iverson. The 
keys to its power are conciseness of 
notation and ability to deal with 
tables of data (arrays) as easily a s 
with a single number. This con- 
ciseness can, however, make even a 
simple program difficult to read for 
the uninitiated. 

Listing 3 shows our reciprocal 
routine written in APL. The first line, 
which is unnumbered, denotes the 
beginning of an APL function to be 
named RECIPROCAL. (Programs are 
called functions in APL. Once a func- 
tion is entered into the computer, it is 
executed by typing its name, 
RECIPROCAL.) Execution proceeds 
starting with line 1. 

Line 1 simply causes the computer 
to print the text that is within the 
single quotation marks. 

Line 2 illustrates some of the com- 
plexity of the APL language. This line 



does two separate things. The 
characters X— □ cause input from 
the computer terminal to be placed in 
the variable X for subsequent use. 
These three characters do the same 
thing as the seven characters INPUT 
X (counting the space) do in BASIC. 

Continuing on line 2, once X has 
been assigned the numeric value input 
from the terminal, the expression 
= X compares the value, now in X, 
against 0. If X is equal to 0, the ex- 
pression produces the logical value 1; 
if X is not equal to 0, the expression 
produces the logical value 0. 

This logical result of either or 1 is 
still within the parentheses of line 2. 
The combination of this value (0 or 1) 
and the /5 to the right of the paren- 
theses produces either a null vector or 
the value 5. 

The arrow -* at the left of line 2 is 
followed by the expression in paren- 
theses, whose value is either the null 
vector or 5. The arrow is known as 



302 March 1981 © BYTE Publications Inc 



the branch arrow; to branch is to 
change the order of execution of pro- 
gram statements. The branch arrow 
does this as the GOTO statement 
does in BASIC. If the value following 
the arrow is 5, indicating that X is 
equal to 0, the arrow causes a branch 
to line 5. If the value is the null vec- 
tor, indicating that X is not equal to 
0, no branch at all is taken and execu- 
tion proceeds to line 3 of the function. 
In summary, line 2 performs the 
functions of the following two lines 
from the BASIC version of the pro- 
gram: 

20 INPUT X 

30 IF X = THEN GOTO 70 

Line 3, which should be read from 
right to left, calculates the reciprocal 
of X (written in APL as -*-X), places 
this value in the variable Y, and then 
prints Y. This line functions as do the 
lines: 

40 LET Y = l/X 
50 PRINT Y 

in the BASIC program. 

Line 4 seems to direct a branch to 
line 0. Actually, — is an idiom that 
means branch out of the function en- 
tirely — in other words, stop the pro- 
gram. 

Finally, line 5, which is only 
executed if X was found equal to in 
line 2, directs the computer to print 
the text in quotation marks. After line 
5 is executed, the computer encoun- 
ters the V symbol, which denotes the 
end of the program. 

Uses of Programming Languages 

Programming languages, like all 
languages, are used for communica- 
tion in a variety of ways. Two broad 
classifications are communication 
between people and machines, and 
communication between people and 
people. 

The way in which people use pro- 
gramming languages to communicate 
their desires to computers is self- 
evident. If the user desires computa- 
tion of reciprocals, a program is writ- 
ten for this computation in a language 
understood by the particular com- 
puter at the programmer's disposal. It 
should then be entered into the 
machine. The aspect of communica- 
tion is the same for more difficult 
tasks. 

Programming languages are also 



used for communication between 
people. For example, since many pro- 
gramming projects involve more than 
one person, those involved must 
communicate. Naturally, much of 
this communication requires trans- 
mission of segments of the program 
being worked on. 

Another example of this type of 
communication is the publication in 
professional journals of algorithms 
expressed by programs. One of the 
most popular languages for such 
communication is ALGOL 60. The 
ALGOL 60 report, by defining a 
publication language differing slight- 
ly from the hardware representation, 
explicitly recognizes the two facets of 
programming language communica- 
tion. 

It should be realized that even 
though programming languages are 
used for communication in many 
ways, they do not serve the same 
communicative function as natural 
languages. Programming languages 
are used for communicating technical 
procedures in a precise fashion. 
Natural languages are not very well 
adapted to this type of communica- 
tion. Indeed, natural languages, when 
used for communication of detailed 
instructions, are often augmented 
with charts, diagrams, pictures, and 
mathematical expressions. 

Grammar and Syntax 

The noun of a programming lan- 
guage is the variable, which is con- 
ceptually an object or storage cell 
capable of holding information. The 
primal variable, seen in the reciprocal 
programs, can hold only one number. 
There are two distinct directions in 
which this concept of variable may be 
extended: by allowing different types 
of data to be stored in the variable, or 
by allowing different amounts of data 
to be stored. 

In most languages, if different 
types of data are to be stored in dif- 
ferent variables, the variables them- 
selves must possess the attribute of 
data type. This attribute is an iden- 
tification that a particular variable 
can be used to store a particular type 
of data. Consider some of the data 
types offered by ALGOL 68 as shown 
in table 1. For example, to declare in 
an ALGOL 68 program that I and 
"class size" (a single variable; lower- 
case and spaces are okay) are to be 
variables capable of storing an in- 
teger; COST, to be capable of storing 



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March 1981 © BYTE Publications Inc 303 



a real number, and NAME, to be 
capable of storing a character string 
(such as "John Smith"); the program- 
mer would use the following 
statements: 

INT I, class size; 
REAL COST; 
STRING NAME; 

The structure of these declarations is: 

predicate-adjective subject 

with an omitted linking verb. This 
structure is similar to the English 
structure: 

subject is predicate-adjective 

Data types are attributes of variables 
and are specified in the same way as 
an attribute of a noun in English. 
(The parallel is even stronger in Rus- 
sian, since that language usually 
omits the linking verb in the present 
tense.) The names of the data types 
(INT, REAL, CHAR, STRING, and 
others) are adjectives in the grammar 
of ALGOL 68. 

In addition to the four data types 
outlined above, ALGOL 68 offers a 
number of other data types, each of 



which is an extension of the concept 
of data type in a distinct direction. 
One class of data type that is of a par- 
ticular interest is reference-to modes. 
(Mode means data type.) 

Such modes can be viewed simply 
as the recognition of the difference 
between nouns and pronouns. A 
noun, in English, is a symbol for 
some person, place, or thing. A pro- 
noun is a reference to a particular 
noun, termed the referent of the pro- 
noun. With this distinction in mind, 
consider the following sequence of 
ALGOL 68 statements: 

BEGIN 
INT I,J; 
I:=2; 
J: =1+3; 

END 

This seems simple enough, but con- 
sider carefully the statement J: = I + 3 . 
What is being added here? The 3, cer- 
tainly, is being used as it stands, but 
the I really is not. The I refers to a 
number (2 in this case) and it is ac- 
tually this number that figures in the 
addition, 2 + 3. The constants 2 and 3 
in this program are the nouns and the 
variables I and J are pronouns. 



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The declaration INT I, J is a short- 
hand: it does not signify that I and J 
are themselves of type INT, but that 
they are to refer to objects (ie: 
numbers) of type INT. The variables 
themselves are of mode (type) REF 
INT, meaning reference to integer. 
REF REAL, REF CHAR, REF 
STRING, etc are all possible. These 
different types of reference-to modes 
are analogous to pronouns of dif- 
ferent genders and cases in human 
languages. 

The distinction between variables 
and the values to which they point 
may strike you as pointless. Indeed, 
some languages — BASIC, APL — ig- 
nore the distinction. Others — 
ALGOL 68, Pascal— don't. Like 
genders and cases in Russian, pointer 
variables (a more common term than 
reference-to) can be a pain to learn, 
but once learned, a subtle and useful 
tool. 

The concept of variable type or 
mode is only one way in which the 
concept of variable may be extended. 
Another extension is to remove the 
restriction that a variable hold only 
one item. Such variables must have 
some internal organization or struc- 
ture to allow access to subsets of the 
stored data. One type of structured 
variable is the array. 

In an array, all data items are of the 
same type (eg: all integers) and are ar- 
ranged in a regular rectangular pat- 
tern. A one-dimensional array is 
called a vector or list; an example is: 

95 78 99 

This three-element vector could 
represent the final examination 
grades of three students; the first 
scored a 95, the second a 78, and the 
third a 99. Though all elements of the 
vector are integers, the programmer 
can just as easily work with a vector 
of real numbers, of characters, or of 
any particular type. To create this 
vector of integers for use in an 
ALGOL 68 program, use the fol- 
lowing statements: 

[1:3] INT GRADES; 
GRADES: = (95, 78,99); 

The first statement declares GRADES 
to be a vector of integers, the 
elements of which are numbered from 
1 to 3. The second statement assigns 
to GRADES the three grades 95, 78, 
and 99. It is clear that a vector is 
called a one-dimensional array 



304 



March 1981 © BYTE Publications Inc 



because it is an array of numbers that 
extends in one direction only 
(mathematically, along one dimen- 
sion). 

An example of a two-dimensional 
array, or matrix, is: 

96 95 98 95 
67 83 72 78 

97 95 99 99 

Each row could correspond to the test 
grades of a particular student; thus, 
student number 1 scored a 96 on the 
first test, a 95 on the second, a 98 on 
the third, and a 95 on the final exam. 
A matrix is called a two-dimensional 
array because it extends along two 
directions, horizontal and vertical. 

Higher-dimensional arrays are also 
possible, though clumsy to represent 
on the printed page. It is even possi- 
ble in ALGOL 68 to have arrays of ar- 
rays, arrays of arrays of arrays, and 
so forth. 

The concept of array is analogous 
to that of plurals in natural 
languages. At one stroke, a sentence 
such as Cheshire cats always grin 
makes a statement about all members 
of the set of Cheshire cats. Similarly, 
the expression Y: = GRADES — 5 sub- 
tracts 5 from all elements of GRADES 
at once, setting Y equal to (90,73,94). 

There is also a parallel between ar- 
ray subscripting and prepositional 
phrases. Consider again the vector 
GRADES. To access the first element 
of GRADES by itself, the subscripts 
to the elements in GRADES must be 
assigned. In ALGOL 68, this is writ- 
ten GRADES [1J. 

GRADES [1] is the single number 
95; it may be printed or used in 
calculations just like a single variable. 
The construction [1] may be viewed 
as a prepositional phrase, the 
brackets being the preposition, and 
the 1, its object. The preposition [ ] 
shows the relationship between the 
two nouns GRADES and 1. In- 
terestingly, the way GRADES [1] is 
read aloud reflects this structure: 
"GRADES sub [meaning subscripted 
by] one." 

Just as a noun cannot communicate 
much without verbs, a variable is 
useless without the verbs of program- 
ming languages, operators and func- 
tions. Operators are the symbols used 
in mathematics and programming 
languages to represent arithmetic and 
other operations. Thus, +, — , and * 
(multiplication) are all operators. In 
conventional notation, operators are 



placed between their operands (X + Y) 
if there are two, or in front of them 
(—X) if there is one. 

Functions, on the other hand, 
precede and enclose their operands. 
For example, the function SQRT(X) 
in FORTRAN computes the square 
root of X. A function can have more 
than one operand. An example of this 
is the function MAX(X1, X2, X3, 
. . .), which selects the largest of its 
indefinitely many operands. The 
distinction between functions and 
operators is fundamentally one of 
notation; operators will be used in the 
examples presented here. 

Operators change their actions 
depending on the data types of their 
operands. For instance, there are dif- 
ferences in the accuracy of addition of 
real operands and of integer 
operands, while addition of string 
operands is actually concatenation 
(eg: "John" + " Smith" yields "John 
Smith"). In general, ALGOL 68 ac- 
tually allows total redefinition of 
operators based on the data types of 
their operands. 

Operators can also change their ac- 
tions depending on the structure of 
their operands. To use an operator 
with arrays and inhomogeneous 
structures, ALGOL 68 requires prior 
definition of the operator's actions, 
which allows a great deal of flexibili- 
ty. In contrast to ALGOL 68, the APL 
language provides definitions such as 
"the addition of two arrays is the ad- 
dition of their corresponding ele- 
ments"; the programmer cannot 
redefine operators in APL. The PL/I 
language has a different solution; to 
add correspondingly named elements 
in two inhomogeneously structured 
variables, A and B, one uses: 

C=A + B,BYNAME; 

The keyword BY NAME functions as 
an adverb, modifying the + 
operator. 

APL, in addition to functions (such 
as + and — , which most languages call 
operators) which act as simple verbs, 
also has operators, which act as aux- 
iliary verbs. These operators (again, 
note the special meaning in APL) 
modify the results of regular func- 
tions in a systematic way. For exam- 
ple, + is the familiar addition func- 
tion. Applied to two vectors, it yields 
the sum of corresponding elements 
(eg: 3 4 5 + 689 produces 9 12 14). 
The reduction operator, /, is an aux- 
iliary verb. Juxtaposed, as +/, these 



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March 1981 © BYTE Publications Inc 305 



two form a new function, "plus- 
reduction," that operates on a single 
vector and produces the sum of its 
elements (eg: + /3 4 5 yields 12). The 
+ / function reduces its operand to a 
single number by addition. 

These complex verbs, nouns, adjec- 
tives, adverbs, pronouns, and 
prepositions all fit into equally com- 
plex syntactic structures. As with 
English, there is a range of syntactic 
complexity; some languages, such as 
BASIC, have a very simple set of syn- 
tactic patterns. Other languages en- 
compass some very complex and 
powerful syntactic structures. 

Probably the simplest syntactic 
form is that of many BASIC state- 
ments, which may be characterized 



imperative-verb object 

Examples of this form are PRINT X, 
INPUT Y, and GOTO 200. The ob- 
ject may also be a verbal phrase, as in 
PRINT X+ Y, in which the verb in the 
verbal is the + operator. 

A few forms of greater complexity 
are found in BASIC. One of these is 
the IF-THEN statement, an example 
of which is: 



INT integer 

REAL rational number [it may have a fractional component] 

CHAR character [a single character only] 

STRING string of characters [text string] 

Table 1: Data types which may be assigned to variables in the ALGOL 68 
language. 



IF X = 3 THEN PRINT 
"X IS EQUAL TO 3." 

This is a more complex form than the 
first for two reasons. First, it uses a 
conjunction-conjunctive adjective 
pair, IF and THEN; second, the 
phrase following THEN can be any 
BASIC statement. This makes the IF- 
THEN statement, in the terminology 
of English grammar, a complex 
sentence. 

Syntactic patterns much more com- 
plex than these are found in ALGOL 
60 and 68. An example from ALGOL 
60 is the statement: 



X: = 



= 2 + (IF Y = 
ELSE 6) 



1 THEN 3 



This statement assigns to X the value 
5 (2 + 3) if Y is equal to 1, and the 
value 8 (2 + 6) if Y is not equal to 1. 
An IF-THEN-ELSE clause may be 



used wherever a noun (ie: numerical 
or character value) is required by the 
syntax of ALGOL 60. This freedom is 
restrictive compared to the rules of 
ALGOL 68; there, not only IF-THEN- 
ELSE statements can be used as 
clauses in place of nouns, but any 
valid statement can be so used. 

Statements and phrases may be 
combined in ways such as: 

k: = (INTi; read(i); i + 1) 

This statement declares the variable i 
to be of type INT, accepts a value for 
i as input from some device (possibly 
a computer terminal), calculates the 
value of i + 1, and finally assigns this 
value to the variable k. One of the 
most impressive aspects of ALGOL 
68 is that the labyrinthine syntax of 
the entire language is rigorously 
defined using a formal notation. 



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As has been implicit in the above 
discussion, the meaning of a state- 
ment (English or programming 
language) is often determined by the 
meaning of the individual words 
(such as grin or PRINT) and the syn- 
tactic operations which combine 
them. This is made light of by Lewis 
Carroll in his poem "Jabberwocky," 
which begins: 

'Twas brillig, and the slithy toves 

Did gyre and gimble in the wabe: 

All mimsy were the borogoves, 

And the mome raths outgrabe. 

This verse is amusing because we 
understand the syntax, while the 
words, though suggestive, are mean- 
ingless. 

In the realm of more standard 
language, there are constructions 
whose meaning is not simply a com- 
position of individual word mean- 
ings. Such expressions are called 
idioms. A sentence like The FBI kept 
tabs on Bill's unicorn has nothing to 
do with actually sticking plastic tabs 
on a unicorn. And thinking about 
The cat got his tongue in such literal 
terms would lead to an anxiety at- 
tack. 

In programming languages, too, 
there are idioms. In APL, there are 
the constructions — , — 0, and —(null 
vector), all of which are idioms for 
special types of program branching. 
In ALGOL 68, there are operators 
such as +=: (plus and becomes). 
A+ = :l is equivalent to A = :A + 1, 
and instructs the computer to take the 
value of A, add 1 to it, and store the 
result back into A. These are truly 
idioms, as their meanings cannot be 
derived directly from the meanings of 
their individual elements. 

Good examples of expletives may 
be found in both ALGOL 68 and 
FORTRAN. In ALGOL 68, the SKIP 
statement is an expletive; it does 
nothing and is explicitly undefined. 
A similar example in FORTRAN is 
the CONTINUE statement, the execu- 
tion of which also has no effect. In 
practice, CONTINUE is used in only 
one particular context, while SKIP is 
used in many different contexts. 

While idioms, expletives, and syn- 
tax in general reveal the similarity 
between programming languages and 
natural languages on the level of the 
word and the sentence, there are also 
similarities on the level of the 
paragraph and the document. The 
paragraph in ALGOL 60 is the block, 



which is a sequence of statements 
beginning with BEGIN and variable 
declarations (REAL, INTEGER, etc), 
and ending with END. This is similar 
to a paragraph of English in several 
ways. It has a clearly marked begin- 
ning and end. It is required to state at 
the beginning the objects (variables) it 
will be working with, just as a good 
paragraph should declare its subject 
at the beginning. Finally, a good 
block deals with only one phase of 
the problem being solved by the pro- 
gram, just as a paragraph should deal 
with only one aspect of the idea being 
discussed. 

The analogy between program- 
ming languages and natural lan- 
guages at the level of whole 
documents is seen by comparing com- 
puter programs with books. Both 
usually have titles; some program- 
ming languages — APL and 
Pascal — actually require them. Many 
books have a dust-jacket blurb or 
preface to make the book easier to 
read and use. Good computer pro- 
grams have comments written into 
the code for the same purpose. 

You may be surprised to find 
paragraphs, idioms, expletives, and 
so forth in programming languages, if 
you have thought of them only as 
characteristics of natural language. 
Throughout this discussion, how- 
ever, we have seen how closely pro- 
gramming languages parallel natural 
languages. Therefore, the existence of 
idioms and similar attributes in pro- 
gramming languages is a nearly 
predictable situation. 

Importance of Similarity 

Granting that programming lan- 
guages are languages in the same 
sense as English or Mandarin, the 
question that follows is: does this 
make any difference to working pro- 
grammers? Yes, it makes a great deal 
of difference, for it leads to the con- 
cept of programming style, with 
associated benefits. 

The concept of programming style 
follows naturally. Just as English is a 
tool for which there are different uses 
and styles, so too are programming 
languages tools for which there are 
different uses and styles. Further, just 
as in English there are some writing 
styles that are superbly clear and effi- 
cient, while others are not, there are 
some programming styles that are 
more desirable than others. Aesthetic 
considerations indicate that a 



desirable style is a clear and concise 
one. But why should this interest the 
working programmer, who is just in- 
terested in doing a job, not in creating 
a work of art? 

Too many programs are written to- 
day without consideration for later 
revisions that may be necessary. It is 
as though these programs will never 
be read or changed. The inevitable 
result of such a programming practice 
is programs that do need to be 
patched, altered, and debugged to 
make them work, and programs that 
are so incomprehensible that they can 
be changed to meet future re- 
quirements only with great difficulty. 
Worse, the result may be a program 
that works 99 times out of 100. On 
that hundredth time, the program 
may fail and produce incorrect results 
that are accepted as true. Or perhaps 
it will be obvious, as bank accounts 
are jumbled, an oil refinery burns, or 
a spacecraft explodes upon launch, 
that something is indeed amiss with 
the computer programs in use. 

Working programs, programs that 
can be confidently (and even 
mathematically) labeled correct, are 
serious business in a society in which 
computers are performing more and 
more functions of ever greater impor- 
tance. For this and other reasons 
related to the costs of debugging a 
poorly written program, structured 
programming (which advocates a 
clear and systematic approach to 
programming) has become popular. 

Many programmers still do not 
write programs that work correctly 
the first time. There is still much to be 
done before good programming is 
nearly universal. However, better 
programming languages are being 
developed, more programmers are 
developing a clear and functional 
programming style, and more pro- 
grams work the first time. ■ 

References 

1. Ershov, A P. "Aesthetics and the Human 
Factor in Programming." Communica- 
tions of the ACM, July 1972, pages 501 
thru 505. 

2. Kernighan, B W and P J Plauger. The 
Elements ot Programming Style. New 
York: McGraw-Hill, 1974. 

3. Ledgard, H F. Programming Proverbs. 
Rochelle Park NJ: Hayden Book Co, 
1975. 

4. Naur, P (editor). "Revised Report on the 
Algorithmic Language ALGOL 60." 
Communications of the ACM, January 
1963, pages 1 thru 17. 



March 1981 © BYTE Publications lnc 307 



Event Queue 



March 1981 



March 

Fairchild Education Center 
Courses, South San Jose 
CA. Bit-slice techniques, the 
3870 microprocessor, and 
programming in Pascal are 
the courses offered by Fair- 
child during March. For 
details, contact Dr Dennis 
Lunder, Fairchild Education 
Center, M/S 43-4022, 133 



Bernal Rd, South San Jose 
CA 95119, (408) 224-7095. 

March-April 

Courses from George 
Washington University, 
Washington DC. George 
Washington University has 
schedules and descriptions of 
many courses in computers 
and communications. For 
your copy, contact the 
Director, Continuing 
Engineering Education, 



George Washington Univer- 
sity, Washington DC 20052, 
(800) 424-9773; in 
Washington DC (202) 
676-6106. 

March-September 

Seminars from WPI, 

Worcester Polytechnic In- 
stitute, Worcester MA. A 
series of 2-day seminars 
covering data communica- 
tions, microprocessors, and 
other topics of interest to 



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data-processing professionals 
is offered by WPI. For a 
detailed brochure, write to 
the Office of Continuing 
Education, Worcester 
Polytechnic Institute, 
Worcester MA 01609, (617) 
753-1411, attn: Ms Ginny 
Bazarian. 



March-November 

Advanced Data Processing 
Workshops, Deltak Inc, 
various cities throughout the 
US and Canada. These 
5-day workshops are aimed 
at data-processing training 
managers responsible for the 
management and administra- 
tion of data-processing train- 
ing and involved in plan- 
ning, monitoring, eval- 
uating, and reporting to up- 
per management on the 
status of the training. For a 
schedule of dates and loca- 
tions, contact Deltak Inc, 
1220 Kensington Rd, Oak 
Brook IL 60521, (312) 
920-0700. 

March 8-11 

TI-MIX 1981, Marriott 
Hotel, New Orleans LA. 
This is a conference for 
Texas Instruments equip- 
ment users. Thirty-six ses- 
sions consisting of individual 
presentations, panel discus- 
sions, and workshops are 
planned. Two exhibit rooms 
featuring the latest computer 
equipment from Texas In- 
struments will be open. 
Contact TI-MIX, M/S 2200, 
POB 2909, Austin TX 
78769, (512) 250-7151. 

March 11-13 

Business- and Personal- 
Computer Sales and Exposi- 
tion and New York Business 
Show, Madison Square 
Garden, New York NY. For 
details, contact Produx 2000 
Inc, POB 2000, Bala- 
Cynwyd PA 19004, (215) 
457-2300. 

March 14 

The Fourth Annual PACS 
Computer Games Festival, 

LaSalle College Ballroom, 
Philadelphia PA. This event 
is sponsored by PACS 



308 



March 1981 © BYTE Publications Inc 



(Philadelphia Area Com- 
puter Society) and the 
LaSalle College Physics 
Department. Presentations 
on computer-aided learning 
will be featured. Contact 
Stephen A Longo, Physics 
Department, LaSalle Col- 
lege, Philadelphia PA 19141, 
(215) 951-1255. 

March 17-20 

The Fourteenth Annual 
Simulation Symposium, 

Tampa FL. Papers describing 
digital discrete simulation 
and other techniques will be 
read. This symposium is a 
forum for the exchange of 
ideas and techniques in com- 
puter simulation. Contact 
Annual Simulation Sym- 
posium, POB 22621, Tampa 
FL 33622. 

March 20 

Digital Computer Associa- 
tion Annual Meeting, 

Pacifica Hotel, 6161 Cen- 
tinela Blvd, Culver City CA. 
Cocktails, dinner, and the 
annual meeting are the 
features of this gathering. 
For more information, con- 
tact Mary Rich, 731 
Bayonne St, El Segundo CA 
90245. 

March 23-25 

Office Automation Con- 
ference, Albert Thomas 
Convention Center, 
Houston TX. This con- 
ference presents seminars on 
the concepts and the 
methods behind the latest 
office technologies and an 
exhibition of office equip- 
ment. Contact Office 
Automation Conference, 
POB 9659, Arlington VA 
22209, (703) 558-3617. 

March 24-27 

Printemps Informatique, 

Palais des Congres, Paris, 
France. This is an electronic 
data-processing exhibition 
for computer OEMs 
(original equipment 
manufacturers). Additional 
information is available 
from Kallman Associates, 30 
Journal Sq, Jersey City NJ 
07306, (201) 653-3304. 

March 24-26 

The Southwest Semiconduc- 
tor Exposition, Phoenix 



Civic Plaza Convention 
Center, Phoenix AZ. More 
than 140 equipment and 
materials makers will exhibit 
semiconductor, hybrid, and 
printed-circuit board pro- 
duction, processing, and test 
equipment. Contact 
Cartlidge & Associates Inc, 
491 Macara Ave, Suite 1014, 
Sunnyvale CA 94086, (408) 
245-6870. 

March 31-April 2 

Cincinnati Business Show, 

Cincinnati Convention- 



Exposition Center, Cincin- 
nati OH. Office equipment 
and services, including 
automated systems, com- 
munications, computers, 
telephone systems, word 
processing, data processing, 
printing equipment, and 
other office supplies, will be 
featured. A program of 
business seminars is also 
scheduled. Contact Ray G 
Nemo, 5679 Creek Rd, Cin- 
cinnati OH 45242, (513) 
531-5959. 



April 1981 



April 1-2 

Communications in the 
Twenty-First Century, Philip 
Morris Operations Center, 
Richmond VA. This con- 
ference focuses on tech- 
nological advances and their 
economic, political, social, 
and psychological implica- 
tions. Elie Abel, Professor of 
Communications at Stanford 
University and Lord Briggs, 
provost of Worcester Col- 



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IBM 3101 CRT Model 10 $1,195. 

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Selectric-like. detached keyboard. 9x16 
dot matrix. Maintenance contract from 
IBM only $70 per year 

ITHACA INTERSYSTEMS 

Full S-100 IF.EE Compatibility! Full 24 
address bits. DMA disk controller. SYS- 
TEM 2A includes 20 slot mainframe 
with front panel, 64K Dynamic RAM. 
Z80 CPU. 4 MHZ, extended addressing 
capability. 4 parallel, 2 serial I/O floppy 
controller. Our discounted price $3,415. 

MARINCHIP SYSTEMS M9900 
Elegant 16 bit CPU. 5-100 compatible, 
rnulti user, multi processor operating 

. system. BASIC. FORTH, META, PAS- 
CAL, Word processor, text editor. 
CPU kit and software package . $ 550. 

Assembled $ 700. 

Complete system, 64KB, 

twodrives $5,400. 

MICROANGELO $2,280. 

High resolution graphics system. 15", 
22MHZ, green phospher screen, 72 key 
keyboard; includes complete cabling 
and software. From SCION. 
S-100 Graphics card $ 960. 



GRAPHICS SOFTWARE 

On line, real time, for the M9900 to 
drive the Microangelo. For use in design 
of PC board masks, 1C masks and other 
applications. 

CORVUS HARD DRIVES 

We are the S-100 CORVUS dealer in the 
New York area. Demonstrations by ap- 
pointment. 
MODEL 11, Hard Disk System. 54,820. 

Mirror Backup System $ 715. 

Host Multiplexer S 675. 

MULTI-BUS 

Z-8000 CPU and supporting boards. 
From Central Data Corp. Complete sys- 
tems starting at $6,500. 

UPGRADE DEC LA 35/36 ... $750. 
Increases baud rate to 1200. Micropro- 
cessor controlled. Many options avail- 
able. Enthusiastic user response. Long- 
term reliability. From DataSouth. 

COMPUTER TO COMPUTER 
COMMUNICATIONS 

Enables communications from a micro 
to a terminal or to another micro, mini 
or maxi computer. Modes of operation: 
TERMINAL (your system acts like an in- 
telligent terminal), FILE-TO-FILE. LO- 
CAL (Disk commands), Full/Half 
Duplex on 8" or 5" disks. COM to COM 
mode does full CRC 16 error check and 
retransmits block on error. 
Object Code $75. Source Code S250. 

THE MAX BOX 

8" Dual Drive Cabinet complete with 
power supply and fan. Will hold 
Qumes, Shugarts or Siemens. Excellent 
design and engineering - $400. 

CAT from NOVATION 

Originate/Answerback $175. 

CAT-D : $185. 

Connects directly to telephone line with 
a plug-in jack. Eliminates need for 
acoustic coupler. 



WE OFFER A FULL RANGE OF EXPERT CONSULTING SERVICES 
COVERING ALL AREAS OF COMPUTER APPLICATIONS AND SYSTEMS 



JOHN D. OWENS 

Associates, Inc. 
SEE OUR AD ON FACING PAGE 



March 1981 © BYTE Publications Inc 309 



Circle 229 on Inquiry card. 



r 



DISK DRIVES 



8' 



Shugart 801R 

Sgi/Sided Dbi/Den 



$395.00 



Qume Dalatrak 8" dbl sided, dbl density 
QME-8DS (851R) compatible... $625.00 
Pkg of two $1150.00 



5 1 / 4 " 



MPI-B51 MPI B-51 $250.00 

Sgl Sided Sgi/Dbl Den 

Exact Replacement for SA-400 

MPI-B52 MPI B-52 $350.00 

Dbl Sided, Dbl Den 

MPI-B91 MPI B-91 $375.00 

Sgl Sided, Dbl Den, 77 tracks 

Shugart SA400 SMU-SA400 $250.00 

Sgl Sided, Dbi/Den 



QT DISK PACKAGES 

DDC-88-1 Dbl Den Controller, A&T, two 8" dbl den drives (801 R) CP/M® 
2.2 cabinet, power supply & cables SPECIAL $1395.00 

DDC-88-2 Two 801 R disk drives with cabinet, power supply, fan & 

cables $1100.00 

DDC-88-22 Two DT-8 Qume drives with cabinet, power supply, fan 

& cables $1500.00 

DDC-88-3 Cabinet with power supply, fan & cables $250.00 

DDC-88-4 Cabinet only $75.00 




COMPUTER 
SYSTEMS 
IMC. 
15620 South Inglewood Ave. 
Lawndale, California 90260 
(213) 970-0952 



WE ACCEPT M/C, VISA, AM EXP 
PLACE ORDERS TOLL FREE 

1-800-421-5150 

(CONTINENTAL U.S. ONLY) 

(EXCEPT CALIFORNIA) 

CP/M Is a trademark of Digital Research 



FINDING SOLUTIONS 

AND BEING COMPETITIVE 

IS OUR BUSINESS. 

Having problems and looking for a 

computer to help solve them? 

Are you finding computer dealers 

come in one of two ways? Either 

Full system support with Full price 

or Take it or Leave it with Low 

price. At Omega we don't believe 

that you should have to make a 

choice. Yes, we're in business to sell 

products but also, to solve your 

problems. Our prices will be the 

lowest possible. Our support and 

product quality will be second to none. Check out our Mail Order prices in this 

ad (our retail prices will be higher). See if you don't agree with our first claim. 

For our second claim, call us with your data processing needs and problems. 

Better yet, come in and see us. Finding solutions and being competitive is our 

business. We never forget either of them. 




'apple computer 

' Authorized Dealer 



APPLE III SCALL 

APPLE II "PLUS" 48K $ 1 169.95 

HEWLET PACKARD 85 or 63 $ CALL 

APPLE II ACCESSORIES: 

Disk II with controller $ 535.00 

Disk II 2nd drive 455.00 

Graphics Tablet 665.00 

Language System with PASCAL 395 00 

Silentype Printer W/Int 526.00 

Integer Firmware Card 152.00 

Microsoft Z-80 Softcard 259.00 

Videx videoterm 80 col Card 279.00 

Sanyo 12" Green Monitor 269.00 



Supplies: 

Scotch Diskettes - Best of Quality! 
price per box of (10) 

744-0, 10. 32 $ 27.00 

740-0 SS/SD Sector 31.00 

741-0 SS/DD Sector 37.00 

743-0 DS/DD No Format 44.00 

New Products: 

Videx L/C Adapter 1 10.00 

Microsoft 16K RAM Card 169.00 

D.C. Hayes Micromodem II 315.00 

Novation DCAT Modem 195.00 

EPSON MX-80 CALL 



Mail Order Terms of Sales: Price based on prepaid orders. NO COD'S. Visa or Master Charge orders add 3% to purchase 

Krice. Allow 14 working days for personal and company checks to clear. Order under $100.00 add $3.00 for shipping and 
andling. All orders (unless specified in ad) within Continential U.S. shipped U.P.S. no charge. APO or out of Continential 
U.S. write or call for shipping charges. All prices subject to change and all offers subject to withdrawl without notice. CA 
residents add 6% sales tax. 

OMEGA MIQFO 3CMPUTEFS 



The Problem Solving Company 



3447 Torrance Boulevard • Torrance, California 90503 • (2131 370-9456 



lege, Oxford, England, are 
keynote speakers. For infor- 
mation, contact the Manager 
of Media Relations, Philip 
Morris Inc, 100 Park Ave, 
New York NY 10017. 

April 1-3 

Assuring Quality in Elec- 
tronic Data Processing Ap- 
plications, McCormick Inn 
Hotel, Chicago IL. The ob- 
jective of this conference is 
to explain the methods, 
tools, and techniques that 
are valuable in improving 
the quality of computerized 
applications. Tutorials cover 
the areas of quality assur- 
ance; managing structured 
design; and designing, im- 
plementing, and enforcing 
application standards. Con- 
tact DPMA Quality Assur- 
ance Conference, 12611 
Davan Dr, Silver Spring 
MD 20904, (301) 622-0066. 

April 3-5 

The Sixth West Coast Com- 
puter Faire, Civic 
Auditorium, San Francisco 
CA. The Faire, a major 
personal-computing event, 
has continually attracted 
larger and larger numbers of 
exhibitors and attendees. A 
full program of talks plus a 
large display of hardware 
and software are featured. 
For more information, con- 
tact Computer Faire, 333 
Swett Rd, Woodside CA 
94062, (415) 851-7075. 



April 6-10 

Tutorial Week — East, Or- 
lando Marriott Inn, Orlando 
FL. Tutorials on VLSI (very 
large-scale integration) and 
microprocessors and 
graphics, software-en- 
gineering methodology and 
testing, and distributed com- 
puting and networks will be 
presented. For IEEE 
members, the cost is $400; 
for nonmembers, the cost is 
$475. Contact Tutorial 
Week— East, POB 639, 
Silver Spring MD 20901, 
(301) 439-7007. 

April 7-8 

Top Secrets '81, Pointe 
Resort, Phoenix AZ. 
Honeywell's annual com- 
puter security and privacy 
conference. Many author- 



310 March 1981 © BYTE Publications Inc 



Circle 230 on inquiry card. 



ities in the field of data 
security will discuss the 
business and legal impact of 
the latest incidents in com- 
puter crime and abuse. The 
conference fee is $500. Con- 
tact the Security Symposium 
Registrar, Honeywell Infor- 
mation Systems, M/S 
T-99-4, POB 6000, Phoenix 
AZ 85005, (800) 528-5343. 

April 7-9 

Computerized Office Equip- 
ment Expo, O'Hare Exposi- 
tion Center, Rosemont IL. 
More than 200 exhibitors 
will feature their office 
equipment at this show. 
Executives and ad- 
ministrators from wholesale, 
retail, commercial, financial, 
and industrial establishments 
are invited, along with the 
general public. Contact In- 
dustrial & Scientific Con- 
ference Management Inc, 
222 W Adams St, Chicago 
IL 60606, (312) 263-4866. 

April 7-9 

Electro/81, New York 
Coliseum and Sheraton Cen- 
tre Hotel, New York NY. 
Electro/81 will feature com- 
puters and computer-related 
equipment, plus seminars on 
components, devices, and 
materials; computer com- 
munications; memories; of- 
fice automation; speech; and 
more. Contact Electronic 
Conventions Inc, 999 N 
Sepulveda Blvd, Suite 410, 
El Segundo CA 90245, (800) 
421-6816; in California (213) 
772-2965. 

April 13-16 

The Fifteenth International 
Symposium on Minicom- 
puters and Microcomputers, 
MIMI '81, Sheraton Hotel, 
Mexico City, Mexico. The 
scope of this symposium 
covers hardware, software, 
distributed processor ar- 
chitecture, computer net- 
works, telecommunications, 
real-time applications, 
education, and more. Con- 
tact Ing. Jorge Gil, 
Academic Secretary, MIMI 
Symposium, IIMAS-UNAM, 
Apartado Postal 20-726, 
Mexico 20 D F, Mexico. 

April 26-30 

Saudibusiness '81, Riyadh, 
Saudi Arabia. This show has 



System Log 



3-/Q £/n. - IW^&^ /)tHu+u j 






£/KUot sf£JL/<SUUo( euut 



A+f&&*H ^tttek 0* ^&*u^ 




DIAGNOSTICS \\ 

Diagnostics II is SuperSoft's expanded Diagnostic package. 

Diagnostic II builds upon the highly acclaimed Diagnostics I. It will test 
each of the five areas of your system: 

Memory Terminal Printer CPU Disk 

Every test is expanded. 

Every test is "submit"-able. A "submit" file is included in the package which 
"chains" together the programs in Diagnostics II, achieving an effective 
acceptance test. All output can be directed to a log file for unattended operation, 
for example over night testing. Terminal test is now generalized for most crt 
terminals. A quick-test has been added for quick verification of the working 
of the system. 

The memory test is the best one we have encountered. It has new features, 
including: 

• default to the size of the CP/M Transient Program Area (TPA) 

• printout of a graphic memory map • burn in test 

• bank selection option • memory speed test 
Diagnostics-ll still includes the only CPU test for 8080/8085/Z80. 

A Spinwriter/Diablo/Qume test has been added, which tests for the positioning 
and control features of the Spinwriter/Diablo/Qume as well as its ASCII 
printing features. (Serial Interface only) 

And, as with all SuperSoft products, a complete online HELP 
system and user manual is included. 

Price: $100.00 (manual only): $15.00 

Requires: 32K CP/M 

CP/M Formats'. 8" soft sectored, 5" Northstar, 5" Micropolis 
Mod II, Vector MZ, Superbrain DD/QD 



All Orders and General Information: 

SUPERSOFT ASSOCIATES 

P.O. BOX 1628 

CHAMPAIGN, IL 61820 

(217) 359-2112 

Technical Hot Line: (217) 359-2691 

(answered only when technician is available) 

CP/M REGISTEREDTRADEMARKDIGTAL RESEARCH 



SuperSoft 



First in Software Technology 



March 1981 © BYTE Publications Inc 311 





#1 1 SOFTWARE 

•* new items/new prices. 

FANTASTIC PRICE PROTECTION POLICY 

We'll match any advertised price on any item that we carry. 
And if you find a lower price on what you bought within 
30 days of buying it, just show us the ad and we'll refund 
the difference. 

It's that simple. 

Combine our price protection with the availability of full 
professional support and our automatic update service and 
youhavethe Ultimate Software Plan. 

It's a convenient, uncomplicated, logical way to get 
your software. 

CP/M users:specify disk systems and formats. Most formats available 



£373. 

$ 59/S20 
$ 59/$20 
$ 59/$20 
$118/$57 



$149/$25 
$169/$25 



CP/M> 

OSBORNE «I 
General Ledger**. . . 
Acct Rec/Acct Paytt 

Payroll w/Cost# 

Buy 2 get 1 free ... 

All 3S.CBASIC-2 $199/$ 71 

DIGITAL RESEARCH 
CP/M 2.2 Northstar 

s CP/M 22 Micropolis 

*- CP/M 2 2 Durango 

F-85 $169/$ 25 

CP/M 2.2 Cromemco $189/$25 

CP/M (otherversions) Call 

PL/l-80 $459/$35 

Mac * 85/$ 15 

Sid $ 65/$15 

Z-Sid S 95/$15 

Tex $ 70/$ 15 

DeSpool $ 50/$10 

MICROSOFT 

Basic-80 $294/$30 

Basic Compiler $334/$30 

Fortran-80 $384/$30 

Cobol-80 $574/$30 

Macro-80 $144/$20 

Edit-80 $ 84/$20 

MuSimp/MuMath. ... $224/$25 

MuLisp-80 $174/$20 

MICRO DATA DASE SYSTEMS 
HOBS $250/$40 

^ MDBS $795/$40 

Other. Call 

S.O.F.T.W.A.R.E. 

MicroTax'}. 

Federal individual $749/$50 

Federal corporate $249/525 

State individual $249/525 

TCSt 

x- General Ledger $ 79/$25 

S Acct Receivable. ....$ 79/$25 

S Acct Payable. $ 79/$25 

s Payroll $ 79/$25 

$269/$99 



THIS MONTH S SPECIAL: 
T.I.M. DBMS JUST $299. 

Terrific for inventory, mailings, 
financial, you-name-it! Menu- 
driven. auto»sort, 32000 records 
per file, any number of files, and 
dynamite documentation! 



• WordStar/Mail-Merge $434/$85 

x" DataStar $279/$60 

*• Word-Master $119/540 

^ SuperSort I 5199/540 

v* SuperSort II S169/S40 

^ SuperSort III S119/S40 

PEACHTREE'W 

General Ledger $399/540 

Acct Receivable 5399/540 

Acct Payable $399/$40 

Payroll $399/$40 

Inventory $399/$40 

Property Mgt $799/540 

C.PA Client Write-up. $799/540 
Mailing Address ... S349/S40 
STRUCTURED SYSTEMS 

GLorARorAP# $747/$25 

Payroll* $747/$ 25 

Inventory Control* . . .$447/$40 

Analyst* $197/$20 

Letteright# $167/520 

NAD# $ 87/520 

QSORT $ 87/$20 

GRAHAM-DORIANH 

General Ledger* $693/$40 

Acct Receivable* ... . $693/$40 

Acct Payable* $693/540 

Job Costing* $693/540 

Payroll* $493/$40 

Inventory* .$493/$40 

Cash Register* $493/$40 

Apartment Mgt* $493/540 

MICRO-AP 

Selector III-C2* $269/$20 

Selector IV* $469/535 

x- S-Basic $269/525 

WHITESMITHS 

"C" Compiler* $600/530 

Pascal (incl "C") • $750/545 

EIDOS SYSTEMS 

Kiss $299/$25 

K-Basic. $529/550 

ORGANIC SOFTWARE 

TextWriter III $111/$20 

DateBook $269/$25 

SoHo Group 

^ MatchMaker . 

^ Worksheet. 

"OTHER GOODIES" 

Tiny C" $ 89/$50 

x" Tiny C" Compiler $229/550 

CBASIC-2 $ 89/$15 

Pascal/Z. $369/$30 



s All 4 

SUPERSOFT 

Forth (8080 or Z80) $129/$25 

Diagnostic I $ 49/$20 

Other disk software ... less 10% 

SOFTWARE WORKS 

Adapt $ 69/ na 

Ratfor $ 86/ na 

COMPUTER PATHWAYS 

Pearl (level 1)* $ 99/$25 

s Pearl (level 2)# $299/540 

i^ Pearl (level 3)* . , . 5549/565 

COMPLETE BUSINESS 

SYSTEMS} 

^Creator $269/525 

• Reporter $169/$20 

v* Both $399/$45 

MICROPRO 
x- WordStar $324/$60 

Mail/Merge $114/525 

* — Special Bonus with »rder J — Requires microsoft BASIC H- Supplied in source code #-Requires CBASIC-2 & — Mfgs Traderr 

ORDERS ONLY-CALL TOLL FREE VISA- MASTERCHARGE 

1-800-854-2003 ext. 823 • Calif. 1-800-522-1500 ext. 823 

add $10 plus additional postage • Add $2 50 postage and handling per each item 



$ 97/$20 
$177/$20 



Pascal/UCSD . $299/$30 

Pascal/MT+ $224/$30 

Pascal/M $149/$20 

NevadaCobol $129/525 

x- Raid $229/$25 

x- MAGSAM III $129/$25 

x- MAGSAM IV $259/$25 

x- BSTAM $129/$ 10 

FMS-80 $649/545 

dBASE II DBMS $629/$50 

Condor DBMS . . $599/$30 

Vulcan DBMS $469/530 

T.I.M. DBMS*. $329/$35 

CBS $369/$45 

Whatsit? $149/$25 

x- Ultra-Sort II $159/525 

x- MicroStat $224/$15 

String/80 $ 84/$20 

x- Vedit. S 99/$ 15 

Postmaster $ 149/$20 

WordSearch $179/$25 

SpellGuard $269/525 

Spell Binder $349/$45 

x- VTS/80 $489/$65 

Magic Wand $299/$45 

Electric Pencil II less 15% 

CPAids iess 12% 

APPLE II- 

MICROSOFT 

Softcard (CP/M) $292 

Cobol 5574 

PERSONAL SOFTWARE 

Visicalc- 5122 

CCA Data Mgr . . . $ 84 

Desktop/Plan $ 84 

x* Zork. $ 34 

PEACHTREEMlt 

General Ledger $224/$40 

Acct Receivable $224/$40 

Acct Payable $224/$40 

Payroll. $224/$40 

Inventory $224/$40 

MUSE 

Super-Text II $127 

Other disk software. . less 10% 
STC (Software Tech.) 
x- Prof Time 8. Billing $279 
Other less 15% 

OTHER GOODIES" 

x* Data Factory $129 

Whatsit? - $129 

x- Creator $229 

x* LedgerPlus 

(GL A/R & A/P) $549 

TRS-SO- MODEL II 

CP/M 2.2 (P8.T) $159/535 

Electric Pencil II less 15% 

NORTHSTAR 

x- NorthWord. 5299 

x» Mail Manager $239 

x- Info Manager $369 

x* General Ledger $749 

x* Acct Receivable $449 

x- Acct Payable .$449 



Overseas 

residents add 6% sales tax • Allow 2 weeks on checks. CO D ok 

All items subject to availability 



California 
Prices subject to change without notice 



THE DISCOUNT SOFTWARE GROUP 

1610 Argyle Ave., Bldg. 102 • Los Angeles, C A 90028 • (213)666-7677 



been designed for the fast- 
growing Saudi Arabian 
business community. 
Pavilions by the United 
States, the United Kingdom, 
West Germany, France, 
Italy, and approximately fif- 
teen other countries will be 
featured. For more informa- 
tion, contact Donald Ryan, 
Project Manager, Rm 3200, 
US Department of Com- 
merce, Washington DC 
20230, (202) 377-4652. 



May 1981 



May Z 

National Computer 
Problem-Solving Contest for 
Junior and Senior High 
School Students, throughout 
the US. Small teams of 
junior and senior high 
school students will compete 
for two hours on computer 
systems to solve five pro- 
gramming problems. Win- 
ners will be judged on 
whether their programs run 
properly using the test data 
supplied in the problem, are 
easy to read, logical, im- 
aginative, and creative. 

To receive a copy of the 
1981 contest problems, local 
school directors should con- 
tact the University of Wis- 
consin — Parkside by April 4. 
Directors must agree to keep 
the problems confidential 
until the day of the contest. 
After that, any organization 
can use the problems to con- 
duct their own contest. 
Local contest winners can 
enter the national and inter- 
national contest. A national 
and worldwide ranking will 
be determined by a team of 
judges from the University 
of Wisconsin — Parkside. All 
interested schools or 
organizations can share the 
1981 contest problems. 

For additional informa- 
tion, write Dr Donald T 
Piele, Associate Professor of 
Mathematics, University of 
Wisconsin — Parkside, 
Kenosha WI 53141. 

May 4-7 

National Computer Con- 
ference, McCormick PI, 
Chicago IL. Approximately 
90,000 people are expected 



312 March 1981 © BYTE Publications Inc 



Circle 231 on inquiry card. 



to attend the National Com- 
puter Conference (NCC) this 
year. The use of robots and 
artificial intelligence will be 
among the program sessions 
at the Personal-Computing 
Festival during the NCC. 
For the first time, personal- 
computing exhibits will join 
the rest of the conference in 
the main exhibit area. Over 
thirty technical sessions will 
be held. All major com- 
panies will be represented. 
Contact the American 
Federation of Information 
Processing Societies Inc, 
POB 9658, 1815 N Lynn St, 
Arlington VA 22209, (703) 
558-3617. 

May 11-13 

The Thirty-First Electronic 
Components Conference, 

Colony Square Hotel, 
Atlanta GA. Papers on 
semiconductor-processing 
technology, optoelectronic 
devices, manufacturing 
technology, materials, hy- 
brid microcircuits, discrete 
components, interconnec- 
tions, reliability, and con- 
nectors will be read. Contact 
T G Grau, Bell Laboratories, 
Whippany Rd, Rm 3B-312, 
Whippany NJ 07981; or 
Electronics Industries 
Association, 2001 Eye St 
NW, Washington DC 20006. 

May 14-16 

The Tenth ASIS Mid-Year 
Meeting, Fort Lewis College, 
Durango CO. The American 
Society for Information 
Science's (ASIS) theme for 
this meeting is "Using Infor- 
mation." Among the topics 
to be addressed are user 
studies, decision making, 
organizational change, 
government, education, 
management, access to in- 
formation, and designing in- 
formation systems for use. 
For information, contact 
ASIS, 1010 16th St NW, 
Washington DC 20036, (202) 
659-3644. 

May 17-20 

Expo '81, Loew's Anatole 
Hotel, Dallas TX. Expo '81 
is a combination of exhibits 
and technical sessions. The 
exhibits cover everything 
from graphics systems to in- 
dustrial computer-control 
systems. The technical ses- 



CPU's & 

SUPPORT 

CHIPS 



aoaoA 

8085A 

AMD 2901 

8205 

8212 

8216 

B226 

8228 

8251 

8259 

8257IAM9517I - 

Z80A SID - 17.95 

8275 - 16.95 

FD1791 -3-1.95 



RAM'S 



4116 3 

41162 

21L023 

2102-4 

MK4027-3 

MK4096 II 

TMS404S-25- 

MS40SONL 

2101 1 

21 078)5280 

MM5270 

MK4008P 



ROM's 



«001 - 25 



4027 

Jti?H 
3 029 
4030 
4034 
■JO::") 



- .45 4053 



4072 

10)6 

tan 



4516 - 
4518 - 
4520 - 
4553 
74 CM 
74C02 
74C04 

74CDH 



74C20 - 
74C32 - 
74C73 



.25 74C76 - 

75 74CB3 - 

175 74CB5 - ' 

95 74C86 - 

75 74C9Q 

75 74C93 - 

1 95 74C151 - 

1.95 74C157 - I 



74C163 
71CI65 
74C173 - 



UART's 

AY5 1013 - 3.75 

TFH602II - 3.95 

AY3-8500 - 1.95 

PT14S2B -3 25 

INTERFACE 
& DRIVERS 

14BS - 90 

1489 - 1.25 

B130 - 2.50 

8131 - 2.50 

6830 - 2.50 

6833 - 2.50 

6834 - 2.00 
8B37 - 2.00 
8B3S - 2.00 
8T380 - 2.00 



2516 

253? 

6223 

82523 

82S112 

825115 

82S123 

825126 

825129 

82S130 

82S131 

AM9218C 



- 29 95 

- 3.95 

- 2.95 



-2.95 

- 3.25 

- 3.45 

- 3.95 



SHIFT 
REGISTERS 



MM1402 
MM1403 
MM1404 
MM5013 
MM50I6 
MM505S 
MM5056 
MM5057 
MM5D58 
MM5060 



PRINTED CIRCUIT BOARD 

4" x 6" DOUBLE SIDED 



LEADER 
OSCILLOSCOPES 

WE CARRY A FULL LINE OF HIGH 

QUALITY, LOW PRICED 

OSCILLOSCOPES WITH A TWO YEAR 

WARRANTY. COMPARE PRICE 

& FEATURES. 

LB0517 50 MHz D.T. CAL 

DELAY $1950.00 



SO- 302 

BO-308S 

3-310A 

J507A 

3 508A 
-J 5 V. 
3 513 



OSCILLOSCOPES 
10 MHi.D.T.,3" Compact 
20 MHz, D.T . 3" PO'iaule 

4MHI.S.T. Rocui Sweti 
20MHi. ST.. 5" 
20 MHi. D T.,5- 
10 MHt, ST.. 5" . 
10 MHj, S T. ImV Sens. 
IOMHi, O T.. lmVSens. 




1 790 00 
950.00 
275.00 



495 00 
. 645 00 
1.530 00 
1,100 00 



SPECIALS GOOD THRU MARCH 1981 



8" DISKETTES HARD SECTOR 
$1.75,10/516.00 



74S00 
74S02 
74S04 
74S05 
74S08 
74S11 
74S15 
74S20 



74S30 
74S32 
74S80 

74S80 
74S112 
74S133 
74S140 
74S153 



.40 74S151 

.40 74S157 

.60 74S158 

.90 74S174 

.85 74S257 

.40 74S25B 

.00 74S374 



7 WATT LD 65 LASER 
DIODE IR $8.95 



25 wan Infra Red Pulse ISG 2006 equiv.) 



Laser Diode (Spec sheet included) 



S24.95 



2N3S20 P FET $ .45 

2N 5457 N FET $ .45 

2N2646 UJT S .45 

ER 900 TRIGGER DIODES 4/51.00 

2N 6028 PROG. UJT 5 .65 

TTL REED RELAY - SPST5V20ma $1.00 

CLOCK CHIPS 

MM5387AA 55.95 

MM5314 64.75 

MM5316.. $4.95 

TANTALUM CAPACITORS 

.22UF35V 5/51.00 10UF 10U " s - 40 

.47UF 35 V 5/51.00 22UF 10V -5 .30 

.68UF35V 5/51.00 15U F 16V 3/S1.00 

1UF35V 5/51.00 30UF 6V 5/S1 00 

2.2UF20V 551.00 33UF 20 V 5 .60 

3.3UF20V 4/51.00 100 UF15V $ .70 

4.7UF15V 5/51.00 " " * „ 

6.8UF35V 3/51.00 150UF15V $ - 95 

SAIMKEN 

AUDIO POWER AMPS 

SM010G10WATTS .. $ 7.50 
Si 1020 G 20 WATTS .. $11.00 
Si 1050 G 50 WATTS .. $25.00 
Si 1030 G 30 WATTS. . $13.50 



200 PRV 1A LASCR .95 



RS232 

CONNECTORS 

DB25Pmale $3.25 

DB25S female ... $4.25 
HOODS $1.50 



CRYSTALS $3.45 ea. 

2.000MH* 6.144MHz 

3.000MHz 
ID.OOOMHj 
18.000 MHi 
18.432 MHz 
20.000 MHi 



RIBBON CABLE 

FLATICOLOR CODED) 

#30WIRE 

16cond. - ,40/per lool 
40cond. - .75/peifoot 
50cond. - .90/per fool 



MINIATURE MULTI-TURN TRIM POTS 
100.5K, 10K, 20K.250K. ... S.75 each . 



NO. 30 WIRE WRAP WIRE SINGLE STRAND 

100' 51.40 



.LCO MINIATURE TOGGLE SWITCHES 

MTA 106 SPOT SI. 05 

MTA206DPDT S1.70 

MTA206P-DPDTCENTROFF 91.85 

MSD206PDPDT CENTER OFF LEVER SWITCH SI 85 



SCR's 





1.5A 


6A 


35A 


110A 


100 


.45 


.60 


1.40 




?m 


.70 


an 


1.90 


9.00 


400 


1.20 


1.40 


2.60 


12.00 


600 




1.80 


3.60 


15.00 



TRIAC's 



PRV 

100 


1A 

.45 


10A 

.80 


2SA 

1.55 


200 


,!14 


1 .HO 


2.10 


400 
600 


1.30 
2.00 


1.90 
2.75 


3.10 
4.30 



FP 100 PHOTO TRANS $ .50 

RED, YELLOW OR GEEN LARGE LED's. .2" 6/S1 .00 

RED/GREEN BIPOLAR LED's. S .55 

MLED92 R LED S .75 

MRD14B PHOTO DARL. XTOR 5 .75 

TIL-118 0PTO-ISOLATOR. S .75 

IL-50PTO ISOLATOR S .80 

1 WATT ZENERS: 3.3.4.7.5.1, 5.6.6.8.8.2,9.1. 10. 

12, 15. 18, or 22V 6IS1.00 



SFC 3301 - 50 PRV 30A 
FAST RECOVERY DIODE (35ns) . 



$2.25 



SILICON POWER RECTIFIERS 



PRV 


1A 


3A 


12A 


50A 


125A 


240A 


100 


.06 


.14 


.35 


.90 


.3.70 


5.00 


200 


.07 


.20 


.40 


1.30 


4.25 


6.50 


400 


.09 


.25 


.65 


1.50 


6.50 


9.60 


600 


.11 


.30 


.80 


2.00 


8.50 


12.50 


SOO 


15 


.35 


1.00 


2.50 


10.50 


16.50 



~45 T25 3^00 12.50 20.00 



IN4148IIN914). 15/$1.00 

.lor .01 u(25V ceramic disc, capts. 16/51. 00, 100/55.00 



LED READOUTS 



FCS 8024 -4 digit 
C.C. 8" display 
FND503C.C..5" 
FND 510 C.A. .5" 
DL-704-.3" C.C. 
FND 359 L.A. 
DL-707C.A. .3" 
DL 747 C.A. .6" 
HP3400 .8" CA 
HP3405 .8" CC 



$5.95 
S .85 
S .85 
S .85 
S .60 
$ .75 
$1.50 
$1.95 
$1.95 



f -ill iMiilM -■■ 
TRANSISTOR SPECIALS 

2N1303PNPGETO5 . ... 

2N1307PNPGCTOS 

2N404APNPGMO-5 .. -. 3'S1.00 

HEPG6014 - PNPGETO 3 ... S .85 

TIP121 - NPNSiSWITCHING ., ..» 35 

2N6233 NPN SWITCHING POWER. S1.95 

MRF-8004 aCBRFTBANSISTQRNPN. .9 .75 

2N3772 NPN SiTO-3. .. SI 00 

2N49Q8 PNPSiTO-3. .... 51.00 

2N50B6PNPSiTO92 . . 4fS1.00 

2N3137NPNSiRF. . . -S .55 

2N3919NPN S.T03RF .. .91.50 

2N1420NPN Si TO 5 3:91.00 

2N3767NPN SiTO-66 S .70 

2N2222NPN SiTO 18 .SiSLOO 

2N2907 NPN SiTO IB . . .... 4/S1.00 

2N305SNPNSiTO3... . .. .5.60 

2N3904 NPN Si TO 92 . . . 6/91.00 

2N3906PNPSiTO92 .. 6JS1.00 

2N5236NPNSiTO220 . 
2N6109PNPS. TO 220. 
T1P31BNPNSiTO 220 
TIP32BPNPS. TO 220 
TlP34PNPSi 



7ALS113 - 45 

74LSI1A - 55 

741.S123 - 75 

74LSI25 - 90 

7ALSI26 - .90 

74LS132 - 60 

74LS136 - 80 

74LS138 - 75 



741S240- 160 
74LS24I - 1.60 
741.S212 - 1 60 
74LS2M- 160 
74LS244 - 1 60 
74LS245 -2 35 
74I.S251 - 1.29 
74LS2S3- 1 00 
74LS2S? - .90 
74LS25B- 90 
74LS259 - 1 50 
741.S266 - 70 
74LS273- 125 
74LS279 - .70 

74t_S290 - ea 

74LS293 - .80 
74LS365 - B0 
74LS366 - 
74LS367- 
74LS368- 
74LS3J3 - 
74LS375 - 
74LS377- 1. 
74LS3&6- 
74LS333- 1 



LINEAR CIRCUITS 




3 - 59 
i07 - 30 
308-75 



LM553 - 2.25 



LF355 
LI356 

LM3I1 
LM318 


1 25 

- 1.35 

- 1 $0 

- .75 

- I.J0 


LM3177 




LM337 




323H5V3A 


79HGKC 5Vai5A 



REGULATORS 



LM1310 - 1.95 
LM1B0B - 1.75 
LMI810 - 220 
LMI889 - 1.95 
CA758 - I 75 
CA301B- 1.95 
CA3MB - 85 
CA307B - 1.50 
C A 3080 - .95 
CA3086 - .35 
CA30M - 2.25 
NEW0L - 2.50 
8038CC - 390 
M5596A - 1.50 



LM305G 
3«0K 12.1 
340T 5, 6. 



112 . 12V3A 53 95 



POSTAGE ADO 10% FOR ORDERS UNDER 520.00 
RATES ADD 5% FOR ORDERS BETWEEN $20.00 AND $50.00 

ADD 3% FOR ORDERS ABOVE $50.00 



TERMS: FOB CAMBRIDGE. MASS. SEND CHECK 
OR MONEY ORDER. MINIMUM TELEPHONE, 
C.O.D. PURCHASE ORDER OR CHARGE $2000 
MINIMUM MAIL ORDER 55.00. 



SEND 5.25 FOR OUR CATALOG 
FEATURING TRANSISTORS & 
RECTIFIERS. 145 HAMPSHIRE 
ST.. CAMBRIDGE. MASS. 02139 



SOLID STATE SALES 

P.O.BOX74B 

SOMERVILLE, MASS. 02143 



g TEL. (617)547-7053 

WE SHIP OVER 95 c /</ 
OF OUR ORDERS THE 
DAY WE RECEIVE THEM 

TOLL FREE 1-800-343-5230 



Circle 232 on Inquiry card. 



March 1981 © BYTE Publications Inc 313 



CALL TOLL FREE 



800-538-5000 

CALL US FOR VOLUME QUOTES. ALL MERCHANDISE 100% GUARANTEED. 
WE WILL BEAT ANY COMPETITORS PRICES. GIVE US A CALL AND WE'LL PROVE IT. 





NEC UPD416C-2 [2716-SINGLE SUPPLY " 




4116-200NS m95EA 




8/9.95ea 




8/29.95 100/3.45ea J^2708 6.25ea 


8/5.95ea 




21 14L-3 4K STATIC ¥ 21 L02 L «^ er 


1.29ea 




LOW POWER 300 NS 








8/29.95 100/3.49ea I 2102 


450NS 


.99ea 




LS SERIES LOOK AT THIS LS PRICING! 




74LS00 .32 74LS73 .44 74LS156 .95 


74LS251 


1.32 




74LS01 .28 74LS74 .48 74LS157 .79 


74LS253 


.89 




74LS02 .38 74LS75 .58 74LS158 .82 


74LS257 


.89 




74LS03 .32 74LS76 .50 74LS160 .94 


74LS258 


.89 




74LS04 .35 74LS78 .59 74LS161 .99 


74LS259 


2.89 




74LS05 .28 74LS83 .90 74LS162 .99 


74LS260 


.68 




74LS08 .38 74LS85 1.23 74LS163 .99 


74LS266 


.68 




74LS09 .38 74LS86 .45 74LS164 .99 


74LS273 


1.69 I 




74LS10 .32 74LS90 .70 74LS165 .99 


74LS275 


3.39 




74LS11 .29 74LS92 .82 74LS166 2.40 


74LS279 


.59 




74LS12 .29 74LS93 .71 74LS168 1.79 


74LS283 


1.03 




74LS13 .38 74LS95 1.11 74LS169 1.79 


74LS290 


1.25 




74LS14 .99 74LS96 .86 74LS170 1.89 


74LS293 


1.89 




74LS15 .35 74LS107 .43 74LS173 .82 


74LS295 


1.09 




74LS20 .26 74LS109 .49 74LS174 1.19 


74LS298 


1.24 




74LS21 .30 74LS112 .48 74LS175 1.09 


74LS352 


1.59 




74LS22 .34 74LS113 .48 74LS1B1 2.19 


74LS353 


1.59 




74LS26 .40 74LS114 .55 74LS190 1.15 


74LS363 


1.39 !, 




74LS27 .35 74LS122 .55 74LS191 1.31 


74LS365 


.99 I: 




74LS28 .39 74LS123 .99 74LS192 .88 


74LS366 


.99 




74LS30 .35 74LS125 .99 74LS193 .98 


74LS367 


.99 




74LS32 .39 74LS126 .88 74LS194 1.80 


74LS368 


.99 




74LS33 .54 74LS132 .69 74LS195 1.39 


74LS373 


1.85 




74LS37 .78 74LS136 .58 74LS196 .82 


74LS374 


1.81 




74LS38 .39 74LS138 .79 74LS197 .82 


74LS377 


1.48 




74LS40 .25 74LS139 .79 74LS221 1.28 


74LS385 


1.90 




74LS42 .79 74LS145 1.19 74LS240 1.89 


74LS386 


.65 




74LS47 .78 74LS148 1.39 74LS241 1.89 


74LS390 


1.90 




74LS48 .78 74LS151 .79 74LS242 1.89 


74LS393 


1.90 




74LS51 .35 74LS153 .79 74LS243 1.89 


74LS395 


1.69 




74LS54 .35 74LS154 2.39 74LS244 1.79 


74LS670 


2.20 




74LS55 .32 74LS155 1.19 74LS245 2.89 










, 




8080 SUPPORT | 


M1SC 


EPROMS 








Ay5-1013 4.99 


MM5203AQ 1us 


256x8 13.95 




8212 2.75 


8T97 1 .69 


MM5204AQ 750ns 


512x8 14.95 




8214 5.25 


1488 1.39 


1702A 1us 


256x8 4.95 




8216 2.75 


1489 1.39 


2708 450ns 


1Kx8 5.95 




8224 2.95 


8202 34.95 


2716 450ns 


2Kx8 10.95 




8226 3.49 
8228 4.95 
8238 5.50 


3242 16.95 


2732 450ns 


4K X 8 29.95 


PROMS 








8251 6.95 ! 










8253 12.95 ; 


74S18B (82S23) OC 


32 X 


8 4.75 




8255 6.50 


74S2B7 (82S129) TS 


256 X 4 4.75 i 




8257 16.95 


74S288 (82S123) TS 


32 X 


8 4.75 




8259 14.95 


74S387 (82S126) OC 


256x4 5.75 




8275 49.95 


74S471 TS 


256 X 


8 18.75 




8279 15.95 


74S472 (82S147) TS 


512x 


8 18.75 






74S474 (82S141) TS 


512 X 


8 19.95 






74S570 (82S130) OC 


512x4 7.80 




CPU's 


74S571 (82S131) TS 


512x4 7.80 


Z-80 9-95 


DIP SWITCHES 


LINEAR 




Z-B0A 12.95 








8080A 3.95 4 Position .99 7 Position 1.09 


LM30IV 


.34 LM567V1.29 




8085A 12.95 I 5 Position 1.02 8 Position 1.14 


LM309K1.49 LM723 .49 




26 


50 12.95 6 Position 1.06 


LM311V .64 LM741V .29 
LM317T 2.29 LM747 .79 






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IC SOCKETS 


LM323K4.95 LM1310 1.90 
LM324 tn ' **•**'** 1 En 




43"LED DISPLAY ■ 7812T 89 7912T " 

.'iJ LCU UIOrLHT 7815T 99 79 15T , 19 


8 PIN 10/1.29 
14 PIN 10/1.49 
16 PIN 10/1.69 


LM339 
LM377 


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.99 LM1458 .69 

2.29 LM1488 1.39 




BEAUTIFUL RED ! ™24T -99 ?924T 1.19 

7 SEGMENT DISPLAY 1 7805K 1 - 39 7905K 1 " 9 
i acumcNi uiorLMT« 7812K 1 39 7912 k 1.49 


18 PIN 10/1.99 
20 PIN 10/2.89 
22 PIN 10/2.99 


LM380 

LM555V 

LM556 


1.29 LM1489 1.39 
.39 LM1800 1.99 
.69 LM 1889 2.49 




HP 5082-7760 ! 78L05 .69 79L05 .79 


24 PIN 10/2.99 


LM565 


.99 LM3900 .59 




.79 100/.65EA1 78L12 .69 79L12 .79 


28 PIN 10/3.99 


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^ ^^L. 78L15 .69 79L15 ..79 


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IR MICRODEVICES, INC. 


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sions range from tool 
design, design engineering, 
and robotics to numerical 
control. For more informa- 
tion, contact the Numerical 
Control Society, 519 Zenith 
Dr, Glenview IL 60025, 
(312) 297-5010. 

May 26-29 

The Second Annual Korea 
International Office Manage- 
ment Exhibition and Con- 
ference, Korea Exhibition 
Center, Seoul, Korea. 
American, British, Japanese, 
and Korean exhibitors will 
attend this conference. Ex- 
hibits include computers, 
facsimile systems, copiers, 
duplicators, micrographics, 
and other office equipment 
and products. Write to 
Clapp & Poliak, Interna- 
tional, 7315 Wisconsin Ave, 
Washington DC 20014, (301) 
657-3090. ■ 



BYTE's Bits 



Missing References 
In Circuit Cellar 

Three references were 
inadvertently omitted from 
Steve Ciarcia's Circuit Cellar 
article "Electromagnetic 
Interference" (January 1981 
BYTE, page 48). The follow- 
ing books provide additional 
reading material for those 
interested in the topic: 

1. Ott, Henry W. Noise 
Reduction Techniques in 
Electronic Systems. New 
York: John Wiley & 
Sons, 1976. 

2. Jones, R W. Electric Con- 
trol Systems. New York: 
John Wiley & Sons, 1953. 

3. Shadowitz, Albert. Elec- 
tromagnetic Field. New 
York: McGraw-Hill Book 
Company, 1974. 

Noise Reduction Tech- 
niques in Electronic Systems 
was reviewed by J N Demas 
in the September 1980 
BYTE, page 311. ■ 



314 



March 1981 © BYTE Publications Inc 



Circle 233 on Inquiry card. 



Clubs and Newsletters 



Atari Club 
Newsletter 



Each month the Atari 
Computer Enthusiasts News 
contains news, hints, and 
assistance for Atari owners 
and users. Most of the infor- 
mation is supplied by club 
members, but articles from 
all interested Atari users are 
welcomed. Contact the 
Atari Computer Enthusiasts, 
3662 Vine Maple Dr, Eugene 
OR 97405. 



TSUNAMI 



The Sorcerer Users 
Newsletter Around Michigan 
(TSUNAMI) is a free, bi- 
monthly newsletter for 
Exidy Sorcerer owners. The 
editorial focus is on ad- 
vanced applications in a 
variety of languages. Recent 
issues have featured a 
7-generation per second Life 
program and a Paper Tiger 
screen-printer program. 
Contact Joseph R Power, 
124 Cedar St #5, East 
Lansing MI 48823, (517) 
337-1049. 



MENTAT 



MENTAT is a brand-new 
publication probing profes- 
sional and recreational uses 
of computers, plus fantasy 
and role-playing designs, 
games, and simulations. 
MENTAT is an Amateur 
Press Association member. 
If you are interested in con- 
tributing, send a self- 
addressed, stamped envelope 
to Bill Seligman, 667 Rugby 
Rd, Brooklyn NY 11230. 



CPT Users 
Group Formed 

An independent group for 
CPT word-processing system 
users has been formed. A 
quarterly newsletter cover- 
ing word- and data-process- 
ing techniques and applica- 
tions is published. The 
newsletter features a pro- 



gramming and problem 
clearinghouse, application 
notes, program reviews, a 
directory of software and 
support packages, and 
general-interest items. The 
group is not affiliated with 
the CPT Corporation. Con- 
tact Larry Matthews, c/o 
APB Inc, 919 Lindy Ct, 
Dayton OH 45415, (513) 
890-9593. 



Boston 
Computer Update 

The Boston Computer Up- 
date is a bimonthly publica- 
tion from the Boston Com- 
puter Society. It is free 
when you join the society; 
membership fees are $15 per 
year. Articles, news reports, 
and story ideas are wel- 
comed. Members can place 



free classified ads for non- 
commercial items. For fur- 
ther details, contact the 
society at 3 Center Plz, 
Boston MA 02108, (617) 
227-9178. ■ 



YOU THINK YOU'VE SEEN WORD 
PROCESSING SOFTWARE? 



The 



MAGfc WAND "v 



Word Processing 



System offers you the best features of any system 

in the miCrO market Version 1.1 is now available 



FEATURES INCLUDE: 
Full-screen text editor 

Simple, control key operation 
Edit programs as well as text 

Assemble, compile or run programs 

without modification 
Files larger than memory 

Files up to 256K 
Library files 

Merge part or all of one file with 

another 
Spool printing 

Print a file while editing another 
Easy page formatting 

Simple commands set margins, page 

length, etc. 
Override commands at run-time 

Give any command from the key- 
board as well as in file 
Variable pitch control 

Change pitch in mid-line, even 

mid-word 
Up to 1 28 user-defined variables 

String, numeric or dollar format 
Form letter generation from external 
data files 

Compatible with both sequential and 

fixed-record files 
Conditional commands 

Any command may be conditional 
Print to disk and/or printer 

Save all or part of output on disk 
Switch from specialty printer to CP/M 
list device 

Print the same file on either specialty 

or standard printer 



EASE OF OPERATION 

With all its power, the MAGIC WAND is 
remarkably easy to use. This is no acci- 
dent. The command structure is designed 
to be flexible and logical so that you can 
perform basic functions with a minimum of 
commands. 

We have included in the manual a step- 
by-step instructional program, for the per- 
son who has never used a word-proces- 
sor before. The trainee uses sample files 
from the system disk and compares his 
work to simulated screens and printouts. 

In addition to the lessons, the manual 
has a complete documentation of the 
command structure, special notesfor pro- 
grammers, an introduction to CP/M for 
non-programmers and a glossary. The 
manual is typeset, rather than typewritten, 
for greater legibility. 

We have written the manual in non- 
technical English, because we want you 
to read it. We don't overload you with a 
bunch of jargon that could confuse even a 
PhD in Computer Sciences. 

We send out newsletters so that users 
of the MAGIC WAND can learn special 
applications of the print commands. For 
example, we might show you how to cre- 
ate a mailing list or set up an index for 
a file. 

In short, we've done everything we can 
to make thingseasy for you. Because the 
best software in the world is just a bunch 
of code if you can't use it. 



For more information , call or write: 

srcioW business applications, inc. 



3220 Louisiana • Suite 205 



Houston, Texas 77006 

CP'W,..., 



713-528-5158 

giSWied ir.iciem.uk ot Digiui Res, 



Circle 234 on inquiry card. 



March 1981 © BYTE Publications Inc 315 



BYTE's Bits 




Photo 1: Personal computers can give the handicapped access to everyday activities. Here, a Johns 
Hopkins engineer demonstrates typing on a computer-aid electronic keyboard activated by a chin 
controller. The Johns Hopkins National Search for Applications of Personal Computing to Aid the 
Handicapped hopes to uncover similar applications. 



All Printer 
Interface Cables $35.00 

(Call for all cable needs) 



RS232 CABLES 

Male to Male 9' long $24.00 

Male to Male 18' long $29.00 

Male to Female 9' long $29.00 

Male to Female 18' long $34.00 

Female to Female 9' long $34.00 

Female to Female 18' long $39.00 

Male to Open 9' long $18.00 

Male to Open 18' long $23.00 

Female to Open 9' long $24.00 

Female to Open 18' long $29.00 
26 Pin Card-edge Connector 

to DB25S 18" long $19.00 
26 Socket Type Connector 

to DB25S 4' long $19.00 

Power Cable Kit for Disk Drives 
comes with AC & DC plug 
and wire $10.00 

Call for prices on all types of connectors 



DISK DRIVE SIGNAL CABLES 

Single 5%" Drive Cable $24.00 

Dual 5W' Drive Cable $29.00 

Quad bVt" Drive Cable $34.00 

Single 8" Drive Cable $24.00 

Dual 8" Drive Cable $32.00 

Quad 8" Drive Cable $40.00 

Please state type connector: 
card-edge or socket. 



4116 (200 ns) - 


- 8/$30.00 


2708 — 


$6.00 


2716 (5V) — 


$9.00 


2732 — 


$25.00 


2114L3 — 


8/$28.00 



LAX COMPUTER PRODUCTS 

4728 Manhattan Beach Blvd. 
Lawndale, CA 90260 
(213) 542-4505 



WE ACCEPT VISA, 

MASTER CHARGE AND 

AMERICAN EXPRESS 



National Search to 
Aid the Handicapped 
Through Personal 
Computers 

Johns Hopkins University 
has announced a national 
search for ideas and inven- 
tions using personal com- 
puters and related tech- 
nology to assist the handi- 
capped. The National 
Science Foundation and the 
Radio Shack Division of the 
Tandy Corporation are 
cosponsoring the search. 

The competition seeks 
ideas, devices, methods, and 
computer programs to help 
handicapped people over- 
come learning disabilities, 
employment difficulties, and 
barriers that prevent adapt- 
ing to home and community 
settings. Categories that can 
be addressed include com- 
puter-based aids for the 
blind, deaf, and mentally 
retarded; for individuals 
with learning disabilities, 
neurological or neuromus- 
cular conditions; and the or- 
thopedically handicapped. 
One hundred awards will be 
made, including a $10,000 
grand prize, and other prizes 
consisting of computer 
equipment and cash. Pro- 
ceedings describing the win- 
ning entries will be pub- 
lished at the end of the con- 
test. All participants will re- 
tain commercial rights to 
their entries. 

Entries are being sought 
from computer specialists, 
high school and college 
students, and from all in- 
terested people. Orientation 
meetings are being scheduled 
at rehabilitation centers 
throughout the US to bring 
together potential inventors, 
handicapped individuals, 
and professionals in the 
habilitation /rehabilitation 
fields. 

Contestants must prepare 
and submit their entries by 
June 30, 1981. To obtain ad- 
ditional information and a 
contest application, BYTE 
urges you to write to Per- 
sonal Computing to Aid the 
Handicapped, Johns 
Hopkins University, POB 
670, Laurel MD 20810, (301) 
953-7100. ■ 



316 



March 1981 © BYTE Publications Inc 



Circle 235 on Inquiry card. 



Computer Music: 
A Design Tutorial 



The computational power 
necessary to synthesize high-quality, 
polyphonic computer music in real 
time exceeds the resources of the cur- 
rently available microprocessors. 
Despite this discouraging observa- 
tion, I decided early in the fall of 1978 
to design a microprocessor-based 
music synthesizer. My goal was to 
discover just how successful I would 
be with a minimum system con- 
structed from readily available parts. 
My self-imposed design constraints 
included an avoidance of special-pur- 
pose hardwired logic and an inten- 
tion to stick with a byte-oriented ar- 
chitecture. 

I hesitate to call the results of my 
efforts a music synthesizer. A more 
honest description might be a 
program-controlled, digital tone 
generator. Specifically, the design 
generates a predetermined sequence 
of sinusoidal waveforms in the man- 
ner of a player piano. A binary 
musical score or command program 
specifies the pitch and duration of 
each note. Each instruction in the 
command program selects between 
approximately 30,000 possible 
pitches from 0.1 Hz to 3 kHz, and 
selects between 255 possible dura- 



About the Author 

Tom Orlofsky is an employee of Bell 
Telephone Laboratories Inc. He works in 
systems engineering. His hobbies, in addition 
to application of home computers to music, in- 
clude tennis, hiking, and skiing. 



Thomas P Orlofsky 

8 Victoria Dr 
Eatontown NJ 07724 



tions from 10 ms to 2.55 seconds. 
This relatively fine time and frequen- 
cy resolution permits quite 
sophisticated melodic articulations 
such as the slur, glissando, and 
vibrato. While the design provides 
memory for 341 notes or rests, this 
limitation is by no means essential. 

I will begin by discussing the 
frequency-synthesis method before 
diving into a more detailed descrip- 
tion of the implementation in both 
hardware and software. Along the 
way, you will become familiar with 
the engineering trade-offs inherent in 
the design of a digital sound system. 
At the conclusion, some possible 
improvements and points of depar- 
ture for your own experiments will be 
discussed. 

Frequency-Synthesis Method 

Frequency synthesis is the process 
of generating an output frequency 
bearing a mathematical relationship 
to some reference frequency. Digital 
synthesis differs from analog syn- 
thesis in that the waveform is con- 
structed from a mathematical process 
rather than from modification of the 
energy storage of a physical system. 
Since the digital method is mathe- 



matical, the quality of the output 
signal is theoretically unlimited. In 
practice, however, the transforma- 
tion from samples to smoothly chang- 
ing voltages introduces noise that is 
independent of the precision of the 
mathematical calculation. 

Figure 1 illustrates the method of 
digital-frequency synthesis used in 
the design. A complete sine wave is 
divided into 256 segments. The 
average amplitude of each segment is 
measured with 8-bit precision. These 
measurements, or samples, are stored 
in consecutive memory locations. 
Each sample specifies the amplitude 
of the waveform at a particular phase 
angle. Consequently, the address of a 
sample is equivalent to its phase. One 
way to vary the frequency of the con- 
structed waveform is by varying the 
rate at which the samples are selected. 
However, a more practical procedure 
maintains a constant sampling rate 
and varies the phase increment be- 
tween the samples. A larger phase in- 
crement has the effect of skipping 
some of the samples during a pass 
through the memory. 

Observe that the phase of the cur- 
rent sample being selected is formed 
from the sum of the phase increment 
and the phase of the previous sample. 
Only the nine most significant bits of 
the phase register actually contribute 
to the address of the current sample. 
The addition of the phase and phase 
increment is performed modulo 2 16 , 
and the overflow is equivalent to a 



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March 1981 © BYTE Publications Inc 317 



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MEMORY 



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k = 0,l,..,255 



DATA 

n 



D 



SAMPLES TO 

DIGITAL-TO-ANALOG 

CONVERTER 



Figure 1: Conceptual block diagram of the frequency-synthesis method. This scheme 
will produce one of 32,768 unique frequencies. 



phase shift of — 2ir. 

As an illustrative exercise, assume 
a phase increment of 256, and that the 
addition is performed at a rate of 
6.5536 kHz. Under these circum- 
stances, the resultant set of addresses 
will select every sample once per 
cycle and produce a constructed 
waveform of frequency equal to 
(6.5536 kHz / 256) or 25.6 Hz. Now 
assume a phase increment of 257. In 
each cycle through the memory, one 
sample is skipped. However, one par- 
ticular sample is skipped only once in 
257 cycles. This shows that the 
second phase increment increases the 
frequency of the constructed wave- 
form in such a way that the second 
waveform will complete 257 cycles in 
the time that the first completed 256 
cycles. The new frequency is (6.5536 
kHz X 257) / (256 X 256) or 25.7 Hz. 
This particular choice of sampling 
rate and register size provides a con- 



venient frequency resolution of 0.1 
Hz. 

It is crucial to observe that the 
sampling rate is fixed and that the 
amplitude envelope of the selected 
samples determines the frequency of 
the constructed waveform. In other 
words, the average period of the con- 
structed waveform is not constrained 
to be an integer multiple of the 
sampling period. This result of 
sampling theory follows from the 
elegant properties of sine waves in the 
frequency domain. Sampling theory 
also shows that perfect construction 
of the sine wave is theoretically possi- 
ble with as few as two samples per cy- 
cle. 

Critical Design Considerations 

At this point, we judge that the 
sampling rate is by far the most 
critical design parameter. Increasing 

Text continued on page 320 



318 March 1981 © BYTE Publications lnc 










Photo 1: The author's microprocessor computer music system implemented in a breadboard prototype suitcase. A 2Vi-inch speaker 
(lower left) provides audio output for demonstrations. Best results were obtained by patching into the power amplifier of a high- 
fidelity receiver. 



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Text continued from page 318: 

the sampling rate increases the audio 
bandwidth, but the sampling rate is 
limited by the rate at which the 
microprocessor system can deliver 
samples to the output port. 

The method of waveform construc- 
tion adds considerations to the issue 
of the sampling rate beyond those 
already mentioned. A digital-to- 
analog (D/A) converter transforms 
the samples into discrete voltage 
levels producing a sine wave with a 
staircase appearance. A low-pass 
filter smooths over the discontinuities 
by removing the so-called sampling 
harmonics. Unfortunately, a practical 
filter passes some of the sampling har- 
monics due to finite attenuation of 
frequency components in the rejec- 
tion band. Therefore, the design must 
sacrifice some of the theoretical band- 
width of the synthesizer to achieve 
tones that are relatively free of audi- 
ble distortion. The magnitude of the 
sacrifice is, of course, a function of 
your sensitivity to harmonic distor- 
tion. If you are to judge harmonic 
distortion by the advertised specifica- 
tions of high-fidelity audio equip- 
ment, it is quite undesirable. 

My choice of sampling at a rate of 
6.5536 kHz represents- a compromise. 
On one hand, the 150 microseconds 
or so of calculation time allows the 
microprocessor to execute a non- 
trivial program, yet the audio band- 
width encompasses the range of the 
fundamental frequency of most 
musical instruments. However, on 
the other hand, much of the band- 
width contains audible harmonic 
distortion. 

Another important design con- 
sideration concerns the necessary 
precision and quantity of the stored 
samples. The difference between the 
stored value of a sample and the ac- 
tual value of the sine function 
evaluated at the same phase in- 
troduces an error into the constructed 
waveform. This disturbance is known 
as quantization noise. The quantiza- 
tion noise associated with 256 8-bit 
samples has an average power that is 
about one percent of the average 
power of the sine wave. Therefore, in 
this particular design, the noise due to 
quantization is quite inaudible in 
comparison with the sampling har- 
monics that sneak through the filter. 

Finally, the design must exhibit suf- 
ficient resolution between frequen- 
cies. You may have noticed in the il- 



320 March 1981 © BYTE Publications Inc 



Circle 238 on inquiry card. 



lustrative example that the length of 
the phase accumulator determined 
the smallest possible frequency incre- 
ment. Resolution of 0.1 Hz provides 
the potential of arbitrary tuning. Two 
tones 0.1 Hz apart in frequency 
played simultaneously beat together 
once every 10 seconds. Such mistun- 
ing is imperceptible under normal 
conditions. Another aspect is the 
granularity of pitch changes during a 
glissando. While 0.1 Hz might be suf- 
ficient for the casual listener, the 
granularity is audible under close 
scrutiny. Unfortunately, increased 
resolution for fixed-register length is 
purchased with decreased audio 
bandwidth, and the bandwidth can- 
not be spared. 

Hardware 

Now that the problems facing the 
designer are in perspective, the hard- 
ware design will be described so that 
you may digest the schematic 
diagram. Figure 2 provides an over- 
view of the system implementation; 
figure 3 is the schematic diagram. The 
hardware is functionally divided be- 
tween the microprocessor system and 
the analog signal conditioning. In ad- 
dition to the Z80 processor, the 
microprocessor system includes 2 K 
bytes of erasable programmable 
read-only memory (EPROM) and 
two input/output (I/O) devices. An 
8212 8-bit I/O port, hardwired into a 
simple output latch, serves as an 
interface to the D/A converter. A 
Z80 counter-timer circuit provides in- 
terval timing. The system includes no 
general-purpose programmable 
memory. The processor and counter- 
timer circuit serve as depositories for 
all dynamic information. A simple 
crystal oscillator generates the system 
clock signal, and a momentary push 
button allows the system to be reset. 
Sufficient device-select logic insures 
that two devices cannot be simulta- 
neously enabled, regardless of the 
state of the machine. Finally, the sys- 
tem requires well-regulated external 
power supplies of +5, +12, and 
-12 V. 

Although the 6 kHz sampling rate 
is quite demanding from the com- 
putational point of view, the rate is 
quite modest with respect to state-of- 
the-art conversion speeds. An inex- 
pensive D/A converter such as the 
MC1408 proves to be quite sufficient. 
The active low-pass filter is a second- 
order Butterworth-type with a cutoff 



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March 1981 © BYTE Publications Inc 321 



Circle 240 on inquiry card. 



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at approximately 3 kHz. If you are 
interested in maximum tone purity, 
use a higher-order filter design. The 
filter output appropriately buffered 
and attenuated can be patched into 
the power amplifier section of a 
typical home audio system. As usual, 
precautions should be taken to insure 
signal compatibility. You might want 
to use a blocking capacitor to trap the 
DC voltage present in the output dur- 
ing rests. 

Software 

Now with the hardware out of the 



way, I can get down to the heart of 
system design, the software. The soft- 
ware is functionally divided between 
the system program and the com- 
mand program. You can view the 
system program as a special-purpose 
operating system that not only per- 
forms the frequency synthesis, but 
also interprets the command pro- 
gram. The command program is 
essentially a musical score in a form 
understandable by the system pro- 
gram. Since the command program 
resides in its own memory device, 

Text continued on page 324 



Number 


Type 


+ 5V 


GND 


-12 V 


+ 12 V 


IC1 


Z80-CPU 


11 


29 






IC2 


Z80-CTC 


24 


5 






IC3 


2708 


24 


12 




19 


IC4 


2708 


24 


12 




19 


IC5 


8212 


24 


12 






IC6 


74LS32 


14 


7 






IC7 


74LS74 


14 


7 






IC8 


74LS04 


14 


7 






IC9 


74LS04 


14 


7 






IC10 


MC1408 


13 


2 


3 




IC11 


741 






4 


7 


IC12 


741 






4 


7 


IC13 


741 






4 


7 




Power Wiring Table for Figure 3 







FROM 
PUS 



HBUTTON ' 



RESET 



ZILOG Z80 

CENTRAL PROCESSING UNIT 



<*> T> 



SYSTEM CLOCK 



INTERRUPT 



8 BIT 

OUTPUT 

LATCH 



c 



>n c 



ni 



$ 



ADDRESS BUS 







ZILOG Z80 

COUNTER 

TIMER 

CIRCUIT 



L2. 



^2. 



2K BYTES 
ERASABLE 
PROGRAMMABLE 
READ-ONLY MEMORY 



DIGITAL TO 

ANALOG 

CONVERTER 



+ 2 



CRYSTAL 
OSCILLATOR 
3.2768 MHz 



LOW 
PASS 
FILTER 



POWER 

AMPLIFIER 

(EXTERNAL) 



<l^ ^r 



Figure 2: Functional overview of the hardware organization and signal flow. 



322 March 1981 © BYTE Publications Inc 




2 < 



r^ 



S " ll 

o o u 

_J Q u. 



-m — ♦— ^ 



t^- 



^ « ■CJ A. O ;* => O ' 

So_S^, 1 ,, Lfc -. 



:n 



Q Q Q Q Q Q Q 



QQOOOQOQ <<<< 



ra 




OOOOOOOQ <<«<<<<*t<< 



oqqq qqqqoIq 



II ° u - 
> > > 



♦— wv > t> 




Figure 3: Schematic diagram for the microprocessor-controlled music system. The design is self-contained except for power and the 
final audio-output stage. Efficient use of registers within the primary microprocessor eliminates the need for general-purpose 
memory. 



March 1981 © BYTE Publications lnc 323 



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No. 32 



ESSEX PUBLISHING CO. oept 2 ^sg- 

285 Bloomfield Avenue • Caldwell, N.J 07006 I- 

Order books by number. Send check, money order (U.S $), VISA or Master Charge ». Publisher pays 4th 
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Hexadecimal Contents 
Address 

System 
0000 Program 


Device 
IC4 


03FF Command 
0400 Program 


IC3 


07FF 

08FF 


Nonexistent 


FFFF 




Table 1: Memory map for 
of listings 1 and 2. 


the software 



Text continued from page 322: 

you can play a new song by simply 
substituting one memory chip for 
another. 

Figure 4 provides the algorithmic 
flow of the system program. Upon 
reset, the system program initializes 
registers within the Z80 processor and 
counter-timer circuit, reads the first 
command, calculates the first sample, 
and halts. The remainder of the pro- 
gram, contained entirely within one 
interrupt-service routine, executes 
once per sampling period in response 
to interrupt requests from the 
counter-timer circuit. As the samples 
are generated, the counter-timer cir- 
cuit clicks them off in a down 
counter. The processor polls the 
down counter during every sampling 
period and branches to the new-tone 
procedure when the counter reaches 
zero. The new-tone procedure fetches 
the next command and updates the 
registers accordingly. When the new- 
tone procedure reaches an end of file, 
it performs an unconditional branch 
to the beginning of the command pro- 
gram. 

Three bytes make up a command. 
The system program loads the first 
byte, the note duration, into the 
down counter within the counter- 
timer circuit. Bytes 2 and 3 contain 
the pitch information or phase incre- 
ment. Observe that a phase increment 
with a value of zero results in a 
stream of constant samples, a DC 
signal or rest. 



324 March 1981 © BYTE Publications Inc 



Circle 241 on inquiry card. 



Hexadecimal 
Address 


Device 


00 


Counter-Timer 




Circuit (CTC) 


03 

04 






Nonexistent 


7F 
80 
81 


8212 Latch 




Nonexistent 


f'f 




Table 2: I/O port 
of figure 3. 


map of the hardware 



In general, the system program 
completes the sample calculation with 
time to spare. However, during the 
command fetch, the processor delays 
acknowledgment of the next sample 
interrupt for a fraction of the 
sampling period. Basically, the pro- 
cessor steals some extra time for 
housekeeping. Fortunately, the 
postponement of one sample among 
thousands is inaudible. If you are 
familiar with the Z80, then you 
should have minimal difficulty in 
deciphering the details of the system 
program provided in listing 1. 

The command program example 
shown in listing 2 performs the 
measure of music pictured in figure 5. 
A macroassembler facilitates genera- 
tion of the command program. User- 
defined symbols for notes of the 
equally tempered scale (see text box) 
and common note durations elimin- 
ate the need to edit numbers. A note 
macroinstruction, which defines the 
data structure, reduces each com- 
mand to a single line of code. The 
programmer can generate the com- 
mand program quite efficiently by 
defining nested macroinstructions 
that specify repeated rhythms or arti- 
culations. Nevertheless, the process is 
quite tedious.. 

You may wonder why it is nec- 
essary to use sixteen bits to 
distinguish between twenty-four or so 
pitch symbols. The answer is that it is 
not strictly necessary, but. immense 
tonal flexibility can be gained. First of 
all, you can specify the sliding-note 
effects mentioned earlier. Second, 
you are not locked into the equally 

Text continued on page 331 



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Freight Air and Express delivery is available. 



Circle 242 on inquiry card. 



March 1981 © BYTE Publications Inc 325 



Circle 243 on inquiry card. 




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There is no handling charge. 



( START J 



INITIALIZE POINTERS 
WITHIN PROCESSOR AND 
COUNTER TIMER CIRCUIT(CTC) 



SET UP FIRST NOTE 
FROM COMMAND PROGRAM 



& 





OUTPUT SAMPLE TO 
DIGITAL TO ANALOG 
CONVERTER 



POLL TIMER (CTC) FOR 
CURRENT COUNT 



HAS CURRENT 
NOTE FINISHED r— 
PLAYING 



J 




CALCULATE NEXT SAMPLE 



YES 



SET UP NEXT NOTE 
FROM COMMAND PROGRAM 



I 1 

I IS MELODY |_ 
I FINISHED | 

I J 




RESET COMMAND PROGRAM 
COUNTER (DEVICE NOW 
READY TO REPLAY TUNE) 



YES 



PROGRAM COUNTER TIMER 
CIRCUIT WITH NEW 
DURATION 



LOAD PHASE INCREMENT 
REGISTER WITH NEW 
INCREMENT 



ADVANCE COMMAND 
PROGRAM COUNTER 



CALCULATE NEXT SAMPLE 



Figure 4: Flowchart of the system program. The system program, executed in real time, 
performs the frequency synthesis and interprets the binary musical score contained in 
the command program. 



326 



March 1981 © BITE Publications Inc 



Listing 1: The system program written in Z80 assembly language. See comment lines for 
details. 



(0003) 
(0002) 
(0000) 
(0000) 
(0080) 



0000 
0000 
0003 
0007 
0009 
000B 
000D 
OOOF 
001 1 
0014 



210000 

DD2 10004 

3E01 

ED47 

3E00 

D300 

ED5E 

310002 

3E57 



0002 
0003 
0004 
0005 
0006 
0007 
0008 
0009 
0010 
001 1 
0012 
0013 
0014 
0015 
0016 
0017 
0018 
0019 
0020 
0021 
0022 
0023 
0024 
0025 
0026 
0027 
0028 
0029 
0030 
0031 
0032 
0033 
0034 
0035 
0036 
0037 
0038 
0039 
004 1 
0042 
0043 
0044 
0045 
0046 
0047 
0048 
0049 
0050 
0051 
0052 
0053 
0054 
0Q55 
0056 
0057 
0058 
0059 
0060 
0061 
0062 
0063 
0064 
0065 
0066 
0067 
0068 
0070 
0071 
0072 
0073 
0074 
0075 
0076 
0077 
0078 
0079 
0080 
0081 
0082 
0083 
0084 



**************************************************** 



TONE SYNTHESIZER 
SYSTEM PROGRAM 



THI 
CESSOR SYS 
2K PROM, 8 
AND ANALOG 
RESIDES t 
SINUSOIDAL 
AND DURATI 
THE COMMAN 
OF MEMORY. 
TIONS PROV 

INT 
THE SYSTEM 
ARE USED T 
POLLS CH3 



PROG 

TEM CO 

212 US 

SIGNA 

N THE 

SAMPL 
ON OF 
D PROG 

THE 

IDED B 

ERRUPT 

PROG 

TIME 

FOR A 



RAM IS WRITTEN 
NSISTING OF A Z 
ED AS AN OUTPUT 
L CONDITIONING. 
FIRST IK OF MEM 
ES AT APPROX. 6 
EACH SINUSIOD 
RAM WHICH RESID 
SYSTEM PROGRAM 
Y THE COMMAND P 
S FROM CHANNEL 
RAM. CHANNELS 

TONE DURATION. 

TIME OUT CONDI 



FOR 
80-CP 

LATC 

THI 

ORY G 

KHZ. 
R TON 
ES IN 
EXECU 
ROGRA 
OF 
2 & 3 

THE 
TION. 



WRITTEN BY 
TOM ORLOFSKY 
12-8-78 

A Z80 MICRPRO- 

U, Z80-CTC, 

H, 8 BIT DAC, 

S PROGRAM WHICH 

ENERATES 

THE PITCH 
E IS SELECTED BY 

THE SECOND IK 
TES THE INSTRUC- 
M SEQUENTIALLY. 
THE CTC DRIVE 

OF THE CTC 
SYSTEM PROGRAM 



REGISTER USE: 
HL: 
BC: 
DE: 
I X: 
AF' : 
A : 

CTC CHANNEL V 
CHO: 

CH2: 
CH3: 



LIST 



CONTAINS THE PHASE 
CONTAINS THE PHASE INCREMENT 
CONTAINS THE SAMPLE ADDRESS 
COMMAND PROGRAM COUNTER 

CONTAINS THE CONTROL CODE FOR CTC CH3 
CONTAINS THE NEXT SAMPLE WHEN THE CPU 
IS HALTED 
E: 
DETERMINES THE SAMPLING PERIOD 
(250 T CYCLES) 

DEVIDE 3Y TEMPO SCALING FACTOR 
TIMES NOTE DURATION (CLOCKED BY CH2) 



NOGEN 



SUPPRESS PRINTING OF 
MACRO-EXPANSIONS 
**************************************************** 

SYMBOL DEFINITION 

**************************************************** 
CH3 . EQU 03H ;ADDRESS OF CTC CH3 
CH2 EQU 02H ;ADDRESS OF CTC CH2 
CHO EQU OOH ;ADDRESS OF CTC CHO 
BASE EQU OH ; D I S PLACEMENT FOR IX REG ADD 
DAC EQU 80H ;ADDRESS OF DAC BUFFERED 
BY 8212 

**************************************************** 

MACRO DEFINITION 
THE MACRO FACILITATES EDITING THE SAMPLES 

**************************************************** 

DATA: MACRO II A, Hi , IIC , #D , #E , II? , IIG , IIH 

DB «A 

DB lit, 

DB He 

DB HO 

DB II? 

DB f F 

DB IIG 

DB IIH 
MEND 
**************************************************** 

INITIALIZATION PROCEDURE 

**************************************************** 

ORG OH 

NIT: LD ML , OH ; I N IT PHASE REGISTER 

LD IX, 40011 ;INIT COMMAND PROGRAM COUNTER 

LD A, 1H ;INIT INTERRUPT REGISTER 

LD I, A 

LD A, OH ;LOAD CTC INTERRUPT VECTOR 

OUT CHO, A 

IM2 ;INTERRUPT MODE 2 

LD SP.020OH ;INIT SP TO FAKE STAK 

LD A.57H ;INIT CTC CHANNEL 3 



Listing 1 continued on page 328 



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March 1981 © BYTE Publications Inc 327 



Circle 244 on inquiry card. 



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Telephone (415) 592-2740 



Listing 1 continued: 







0085 




***C0NTR0L WORD DESCRIPTION*** 






0086 




BIT 7=0 


INTERRUPT DISABLE 






0087 




6 = 1 


COUNTER MODE 






0088 




5 = 


DON'T CARE 






0089 




4 = 1 


TRIGGER ON RISING EDGE 






0090 




3 = 


DON'T CARE 






0091 




2 = 1 


TIME CONSTANT FOLLOWS 






0092 




1 = 1 


RESET CHANNEL 






0093 




= 1 


CONTROL CHANNEL WRITE 


0016 


08 


0094 


EX 


AF, AF' 


SAVE CONTROL WORD 


0017 


DD7E00 


0095 


LD 


A, (IX+BASE) ;FETCH FIRST DURATION 


001A 


08 


0096 


EX 


AF.AF' 


GET CONTROL WORD 


00 IB 


D30 3 


0097 


OUT 


CH3.A 


OUTPUT CONTROL WORD 


001D 


08 


0098 


EX 


AF.AF' 


SAVE CONTROL WORD 


001E 


D303 


0099 


OUT 


CH3.A 


OUTPUT TIME CONSTANT 


0020 


3E57 


0100 


LD 


A, 57H 


INIT CTC CH2 SAME 






0101 




EXCEPT FOR TIME CONSTANT 


0022 


D302 


102 


OUT 


CH2, A 


OUTPUT CONTROL WORD 


0024 


3E40 


0103 


LD 


A.64D 


TEMPO SCALING FACTOR 


0026 


D302 


0104 


OUT 


CH2, A 


OUTPUT TIME CONSTANT 


0028 


DD23 


105 


INC 


IX 


INCREMENT COMMAND PC 


002A 


DD4E00 


0106 


LD 


C, (IX+BASE); INIT PHASE INC REG 


002D 


DD23 


0107 


INC 


IX 


INCREMENT COMMAND PC 


002F 


DD4600 


0108 


LD 


B, (IX+BASE) ;MOST SIGNIFICANT BYTE 


0032 


DD23 


0109 


INC 


IX 


INCREMENT COMMAND PC 


0034 


110002 


0110 


LD 


DE, 200H 


INIT SAMPLE ADDRESS REG 


0037 


3ED7 


0111 


LD 


A.OD7H 


INIT CTC CHO SAME AS CH3 


0039 


D300 


0112 


OUT 


CHO, A 


EXCEPT ENABLE INTERRUPTS 


003B 


3E7D 


0113 


LD 


A, 125D 


AND DIFFERENT TIME CONSTANT 


003D 


D300 


01 14 


OUT 


CHO, A 


OUTPUT TIME CONSTANT 


003F 


1A 


0115 


LD 


A, (DE) 


LOAD A WITH FIRST SAMPLE 


0040 


FB 


116 


EI 




ENABLE INTERRUPTS 


0041 


76 


0117 HOLD: HALT 




WAIT HERE FOR ALL INTERRUPTS 






0119 


**************************************************** 






0120 












012 1 




INTERRUPT SERVICE ROUTINE 






0122 












0123 


**************************************************** 


0042 




0124 


ORG 


lOOH 




0100 


0201 


0125 


DK 


INTRPT 


ADDRESS FOR INDIRECT JUMP 






01 26 




TO INTERRUPT SERVICE ROUTINE 






0127 




THE INTERRUPT VECTOR PRO- 






0128 




VIDED BY THE CTC POINTS HERE 


0102 


D380 


0129 INTRPT: OUT 


DAC , A 


OUTPUT SAMPLE TO DAC 


104 


09 


0130 


ADD 


HL.BC 


INCREMENT PHASE REK 






0131 




ROUND OFF UPPER 9 BITS OF 






0132 




PHASE REG TO 8 BITS AND 






0133 




USE THESE AS LOWER 8 BITS 






01 34 




OF SAMPLE ADDRESS 


105 


5C 


0135 


LD 


E,H 




106 


CB7D 


0136 


BIT 


7 ,L 


IF 1 THEN ROUND UP 


108 


CA0C01 


0137 


JP 


Z.NEXT 


IF THEN ROUND DOWN 


010B 


1C 


0138 


INC 


E 


ROUND UP 


010C 


DB03 


139 t 


EXT: IN 


A.CH3 


POLL CTC CHANNEL 3 


10E 


D601 


0140 


SUB 


A, 1H 


TEST FOR VALUE 1 


0110 


CA1701 


014 1 


JP 


Z.NEW 


1 MEANS CHANGE TO NEXT TONE 


0113 


1A 


142 


LD 


A, (DE) 


CONTINUE PRESENT TONE 






0143 




LOAD A WITH NEXT SAMPLE 


1 14 


FB 


0144 


EI 




ENABLE INTERRUPTS 


0115 


ED4D 


0145 


RETI 




RETURN FROM INTERRUPT 






0146 


************** *n EXT TON 


PROCEDURE* ******* ************ 


0117 


DD7E00 


0147 1 


IEW: LD 


A, (IX+BA! 


E) ;FETCH NEW DURATION 


01 1A 


C600 


0148 


ADD 


A, OH 


TEST FOR VALUE 






149 




IF ZERO JUMP TO BEGINNING 






0150 




ELSE CONTINUE SONG 


01 1C 


C22601 


0151 1 


'EST: JP 


NZ.ANOTH 


I 


01 IF 


DD210004 


152 


LD 


IX.400H 


COMMAND PROGRAM STARTS 400H 


0123 


C3 1 701 


0153 


JP 


NEW 




0126 


08 


0154 t 


N0THR: EX 


AF, AF' 


LOAD CTC CH3 WITH NEW DURATION 


127 


D303 


0155 


OUT 


CH3, A 


OUTPUT CONTROL WORD 


0129 


08 


0156 


EX 


A F,AF' 


SAVE CONTROL WORD 


12A 


D303 


0157 


OUT 


CH3, A 


OUTPUT NEW TIME CONSTANT 


01 2C 


DD23 


0158 
159 


INC 


IX 


INCREMENT COMMAND PC 
JPDATE PHASE INCREMENT REG 


012E 


DD4E00 


0160 


LD 


C, (IX + BA 


iE) ;FETCH LOWER BYTE 


0131 


DD23 


0161 


INC 


IX 


INCREMENT COMMAND PC 


0133 


DD4600 


0162 


LD 


B, ( IX + BA 


iE) ;FETCH UPPER BYTE 


136 


DD23 


0163 


INC 


IX 


INCREMENT COMMAND PC 


0138 


1A 


0164 
0165 
0166 
0167 


LD 


A, (DE) 


LOAD A WITH NEXT SAMPLE 
(EW PITCH WILL BECOME 
SFFECTIVE ON THE NEXT 
> AMPLE 


0139 


FB 


0168 


EI 




ENABLE INTERRUPTS 


13A 


ED4D 


0169 
0170 
0171 


RETI 
************* 


********** 


RETURN FROM INTERRUPT 
******************************* 






0172 




DEFINE Fi 


iKE STAK 






0173 












0174 


SINCE 


THERE IS N( 


) WRITABLE MEMORY THE CPU 






0175 


WILL NOT BE ABLE 


TO STORE THE RETURN ADDRESS 






0176 


OF THE 


INTERRUPT 


:d instruction, it must be 






0177 


PROVIDED IN READ 


ONLY MEMORY. 






0178 









328 March 1981 © BYTE Publications Inc 



Listing 1 continued: 





01 79 


****************************************************** 


01 3C 


0180 


ORG 


1FEH 












IF E 4100 


0181 


DW 


HOLD 


;ADDRESS OF 


THE HALT 








0182 






INSTRUCTION 












0184 


****************************************************** 




0185 


















186 




SINUSOIDAL SAMPLES 












0187 


256 8 BIT SAMPLES OVER 360 DEGREES 








188 


PRINTING OF THE OBJECT CODE 


IS SUPPRESSED 






0189 


NUMBERS 


ARE LISTED IN DECIMAL. 










01 90 


















0191 


****************************************************** 


0200 


0192 


DATA 


128D 


131 D, 134D , 1 37D 


141D 


144D 


1 47D 


150D 


0208 


020 1 


DATA 


153D 


1 56D, 1 59D , 162D 


165D 


168D 


1 71D 


1 74D 


0210 


02 10 


DATA 


1 7 7D 


1 80D , 1 83D , 1 86D 


188D 


191D 


1 94D 


1 96D 


0218 


0219 


DATA 


199D 


202D, 204D, 207D 


209D 


2 12D 


214D 


2 1 6D 


0220 


0228 


DATA 


2 1 9D 


221D,223D,225D 


227D 


229D 


231D 


233D 


0228 


0237 


DATA 


234D 


236D , 238D, 239D 


241D 


242D 


244D 


245D 


0230 


0246 


DATA 


246D 


247D.249D, 250D 


250D 


251D 


252D 


253D 


0238 


0255 


DATA 


254D 


254D, 255D, 255D 


255D 


255D 


255D 


255D 


0240 


0264 


DATA 


255D 


255D, 255D, 255D 


255D 


255D 


255D 


254D 


0248 


027 3 


DATA 


254D 


253D,252D,2513 


250D 


250D 


249D 


247D 


0250 


0282 


DATA 


246D 


245D, 244D.242D 


241D 


239D 


238D 


2 36D 


0258 


0291 


DATA 


234D 


233D,231D,229D 


227D 


225D 


223D 


221D 


0260 


0300 


DATA 


2 1 9D 


2 16D, 2 14D , 212D 


209D 


207D 


2 4D. 


202D 


0268 


0309 


DATA 


199D 


1 96D , 194D , 1 9 ID 


1 88D 


186D 


183D 


1 80D 


0270 


0318 


DATA 


177D 


1 74D , 1 7 1 D, 168D 


165D 


162D 


1 59D 


1 56D 


0278 


0327 


DATA 


1 53D 


150D, 147D, 144D 


14 ID 


137D 


1 34D 


1 3 ID 


0280 


0336 


DATA 


128D 


1 25D, 122D , 1 19D 


1 15D 


1 12D 


109D 


1 06D 


0288 


0345 


DATA 


103D 


100D.097D, 094D 


09 1 D 


088D 


085D 


082D 


0290 


0354 


DATA 


079D 


076D.073D ,070D 


068D 


065D 


062D 


060D 


0298 


0363 


DATA 


057D 


054D , 052D, 049D 


047D 


044D 


042D 


040D 


02A0 


0372 


DATA 


037D 


035D,033D,031D 


029D 


027D 


025D 


023D 


02A8 


0381 


DATA 


022D 


020D.018D ,0 17D 


015D 


014D 


012D 


011D 


02B0 


0390 


1 DATA 


10D 


009D ,007D,006D 


006D 


005D 


004D 


003D 


2B8 


0399 


DATA 


002D 


002D,001D ,001D 


001D 


OOOD 


OOOD 


OOOD 


02C0 


0408 


DATA 


000D 


000D ,000D, 000D 


001D 


001D 


001D 


002D 


02C8 


04 1 7 


DATA 


002D 


003D.004D, 005D 


006D 


006D 


007D 


009D 


02D0 


0426 


DATA 


10D 


011D,0 12D,014D 


015D 


17D 


18D 


020D 


02D8 


0435 


DATA 


022D 


023D.025D ,027D 


029D 


031D 


033D 


035D 


02E0 


0444 


DATA 


037D 


040D,042D,044D 


047D 


049D 


052D 


054D 


02E8 


045 3 


DATA 


057D 


060D,062D,065D 


068D 


070D 


073D 


076D 


02F0 


0462 


DATA 


079D 


082D.085D, 088D 


091D 


094D 


097D 


100D 


02F8 


047 1 


DATA 


103D 


106D, 109D, 1 1 2D 


1 1 5D 


1 19D 


1 22D 


1 25D 



Listing 2: A command program example making use of a macroassembler. The score of 
this music is given in figure 5. 



(0002) 
(0004) 
(0008) 
(00 10) 
(0020) 
(0040) 



0002 
0003 
0004 
0005 
0006 
0007 
0008 
0009 
0010 
001 1 
0012 
0013 
0014 

00 15 
0016 

001 7 
0018 
0019 
0020 
0021 
0022 
0023 
0024 
0025 
0026 
0027 
0028 
0029 
0030 
0031 
0032 
0033 
0034 
0035 
0036 
0037 
0038 
0039 



****************************************************** 



TONE SYNTHESIZER 
COMMAND PROGRAM 
EXAMPLE 



WRITTEN BY 
TOM ORLOFSKY 
12-8-78 



A M 
S YST 
TION 
S YST 
AN U 
CONT 
1H , 2 
AND 
REST 

TEMP 

THE 

SET 

PER 

WITH 

MODI 

SYST 

**** 



THE COMMA 
USICAL SCORE 
EM PROGRAM. 

AND CAN HAV 
EM PROGRAM I 
NCONDITIONAL 
AIN THE PITC 

h, . . . ,aoo 

VALUE ZERO C 

SYMBOLS F 
ERED SCALE A 
TRANSLATION 
AT A TEMPO 
MINUTE. OTH 
EXPRESSION S 
FICATION OF 
EM PROGRAM. 
************ 



ND PROGRAM IS A REPRESENTATION OF 
IN OBJECT CODE EXECUTABLE BY THE 
THE FIRST BYTE IS THE NOTE DURA- 
E VALUE 2H , 3H , . . . , FFH. THE 
NTERPRETS A ZERO NOTE DURATION AS 
REPEAT. THE FOLLOWING TWO BYTES 
H INFORMATION AND CAN HAVE VALUE 
H. VALUES >800H CAUSE ALIASING 
AUSES A DC OUTPUT OR APPARENT 

OR TWO OCTAVES OF THE EQUALLY 

ND COMMON NOTE DURATIONS SIMPLIFY 

PROCESS. THE NOTE DURATIONS ARE 

F APPROXIMATELY 96 QUARTER NOTES 

ER NOTE DURATIONS CAN BE CONSTRUCTED 

OTHER TEMPOS REQUIRE 
THE TEMPO SCALING FACTOR IN THE 

************************************* 



***************************************************** 

SYMBOL DEFINIT ION 

***************************************************** 

DEFINE NOTE DURATIONS 

128 EQU 2D ;128TH NOTE 

64 EQU 4D ;64TH NOTE 

32 EQU 8D ;32ND NOTE 

16 EQU 16D ;16THNOTE 

8 EQU 32D ;8TH NOTE 

4 EQU 64D JQUARTER NOTE 

Listing 2 continued on page 330 




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Listing 2 continued: 



(0080) 
(0 100) 
(0000) 

(0898) 
(091B) 
(091B) 
(09A5) 
(0A38) 
(0AD4) 
(0AD4 ) 
(OB79) 
C0C2 7) 
(OC27) 
(0CE0) 
(0DA4) 
(OE74) 
(OE74) 
(0F50) 
(1038) 
( ! 038) 
(1130) 
(1236) 
(1236) 
( 1 34B) 
(1471) 
( 1 5A8) 
( 1 5A8) 
(16F1) 
(1 84F) 
(184F) 
(19C1 ) 
(1B49) 
( 1CE8) 
( 1CE8) 
( 1EA0) 
(2072) 
(2072) 



0000 




0000 




0000 


40 


000 1 


7 114 


0003 




0003 


04 


0004 


0000 


0006 




0006 


3C 


0007 


7 114 


0009 




0009 


04 


0A 


0000 


oooc 




oooc 


3C 


000D 


7 1 14 


000F 




000F 


20 


0010 


4B1 3 


0012 




00 12 


20 


0013 


3011 


0015 




0015 


20 


0016 


500F 


0018 




0018 


20 


00 19 


A40D 


00 IB 




001B 


40 


00 1C 


500F 


001E 




001E 


20 


001F 


0000 



0040 
0041 
0042 
0043 
0044 
0045 
0046 
0047 
0048 
0049 
0050 
0051 
0052 
0053 
0054 
0055 
0056 
0057 
0058 
0059 
0060 
0061 
0062 
0063 
0064 
0065 
0066 
0067 
0068 
0069 
0070 
0071 
0072 
0073 
0074 
0075 
0076 
0077 
0079 
0080 
0081 
0082 
0083 
0084 
D085 
0086 
0087 
0088 
0089 
0090 
0091 
0092 
0094 
0095 
0096 
0097 
0098 
0099 
0100 
0101 
0102 

0103 + 

0104 + 
0105 

0106 + 

0107 + 
0108 

0109 + 

0110 + 
0111 

0112 + 

0113 + 
01 14 

0115 + 

0116 + 
0117 

0118 + 

0119 + 
0120 

0121 + 

0122 + 
0123 

0124 + 

0125 + 
0126 
0127+ 
0128 + 
0129 

0130 + 

0131 + 
0132 

0133 + 

0134 + 



. 2 
. 1 
REST 

A0 1 

AS01 

BF01 

B01 

CO 1 

CS01 

DF0 1 

D01 

DS0 1 

EF01 

E0 1 

F01 

FS0 1 

GF01 

C01 

GS0 1 

AF01 

A0 

AS0 

BF0 

B0 

CO 

CSO 

DF0 

DO 

DS0 

EF0 

E0 

F0 

FS0 

GF0 

GO 

GS0 

AF0 



EQU 
EQU 
EQU 

EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 
EQU 



128D 
256D 
0D 

2200D 

2331D 

AS0 1 

2469D 

2616D 

2 772D 

CSO 1 

2937D 

31 1 ID 

DS01 

3296D 

3492D 

3^001) 

FS01 

3920D 

4 152D 

GS0 1 

4400D 

4662D 

AS0 

4939D 

5233D 

5544D 

cso 

58 73D 

6223D 

DS0 

6593D 

6985D 

7400D 

FS0 

7840D 

8306D 

CSO 



;I1ALF NOTE 
;WH0LE NOTE 

DEFINE P ITCHS 

FORM XXNN 

XX=L0CATI0N OF THE NOTE 

WITHIN THE OCTAVE 
EXAMPLE: AF=A FLAT 

;NN=L0CATI0N OF THE OCTAVE 
; EXAMPLE: 0=0CTAVE 
;C0NTAINING MIDDLE G 
;EXAMPLE: 01=OCTAVE BELOW 

;C0NVERT TO HZ. BY MULTIPLYING 
;B Y 0.1 HZ . 



*************************************************** 

MACRO DEFINITION 

MACRO N (NOTE) FACILITATES EDITING OF 
COMMAND PROGRAMS AND DEFINES THF. DATA 
STRUCTURE 

*************************************************** 

N: MACRO II TIME, //PITCH 

DB //TIME 

DW //PITCH 

MEND 
************************ * *********************** 

COMMAND PROGRAM 

TRANSLATION OF THE MEASURE OF FIGURE 5 

************************************************ 
ORG on 

N . 4 , CO 

DB .4 

DW CO 

N .6 4, REST 

DB .64 

D W REST 

N .4-. 64, CO 

DB .4 - .6 4 

DW CO 

\i . 6 4 , R E S T 

DB .64 

D W REST 

N .4-. 64, CO 

DB .4 -.6 4 

DW CO 

. 8, B0 



DB 
DM 

N 

DB 

DW 

N 

DB 

DW 

N 

DB 

DW 

N 



DB 
DW 





8, A0 

8 
AO 

8 ,G01 

8 

01 

8.F01 

8 

1 

4 ,G01 

4 

01 

8 , REST 

3 
REST 



Listing 2 continued on page 331 



Text continued from page 325: 

tempered scale, but can experiment 
with other scale temperings. It is 
necessary to choose between the 
benefits of such flexibility and the 
value of considerable data compres- 
sion possible in a table-lookup ap- 
proach. 

System Enhancements 

Once you gain confidence in the 
methods of music synthesis, you may 
wish to add features or otherwise im- 
prove the system. For instance, you 
may decide to generate a second me- 
lodic line, or voice, using the system. 
Careful analysis of the instruction- 
execution cycles in the system 
described in this article show that suf- 
ficient computing time is available to 
generate a second voice. 

The second voice may be synthe- 
sized along with the first, using the 
remaining registers in the control 
microprocessor and counter-timer 
microprocessor. As the last step in the 
synthesis, the separate samples 
should be summed and then scaled by 
a factor of 0.5. 

Control of dynamics (amplitude) of 
the music is made possible by the 
addition of a programmable reference 
voltage for the signal converter. Four 
bits (a nybble) may be added to each 
note specification to select between 
sixteen possible dynamic levels. 

If you are satisfied with the single 
voice, you may decide to improve the 
command interpreter instead. A good 
place to start is to add commands 
such as change tempo, branch condi- 
tionally, and halt. 

If you are willing to try distributed 
processing, you can develop a com- 
mand interpreter of practically 
unlimited capability. One micro- 
processor can be dedicated to the task 
of note synthesis, while another pro- 
cessor can handle the interpretation 
of commands and note specifications. 

In a system that uses distributed 
processing, the command processor, 
unencumbered with calculations of 
samples, has time to execute complex 
routines during the intervals between 
processing of commands. A parallel 



#1 



uisr'iW 



Listing 


2 continued: 










0021 




0135 


N 


.8 


CO 


0021 


20 


0136 + 


DB 


.8 




0022 


7 114 


0137 + 


D'J 


CO 




0024 




0138 


N 


.8 


B0 


0024 


20 


0139 + 


DB 


.8 




0025 


4B 13 


0140 + 


DW 


B0 




0027 




0141 


5 


.8 


CO 


0027 


20 


0142 + 


DB 


.8 




0028 


7114 


0143 + 


DW 


CO 




002A 


00 


0144 


DB 


OH 




002B 


(0000) 


0145 


END 






Errors 












system architecture could enable 
more exact control over individual 
waveform samples. For example, a 
parallel processor could modulate the 



signal on a sample-by-sample basis, 
creating attack and decay envelopes 
or frequency-modulated timbres. 
As new and more powerful micro- 



Figure 5: One measure that has been 
translated into the command program 
example provided in listing 2. 




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on low prices!" 

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CP/M is a registered trademark of Digital Research 



Circle 249 on inquiry card. 



x& 



"0*> 

THE CONFIGURABLE BUSINESS SYSTEM™ 
is a parameter-driven information manager that 
makes the business of applying computers easier 
and more efficient. A pre-defined framework gives 
you the tools to design and implement your own 
well-documented system, including: 

• sophisticated data entry 

• concise data-based management system 

• user customized job streams and menus 

• personalized report generation 



User training and support is minimized by a 
comprehensive operating manual. CBS Disks can 
fit any 8080 or Z80 computer with CP/M* 

Disks and manual, $395; Manual only, $40. 

Your DMA representative can tell you about DMA.DOS, 
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an Asynchronous Communication Control Program. 



DMA • WE SPEAK YOUR LANGUAGE 



processors become available, those of 
us that synthesize music as a hobby 
will use them in our circuit designs. 
And since systems built for hobby use 
do not have to be compatible with 
any previous equipment, we are free 
to use the best ideas currently 
available.! 



Use of equally tempered tuning 
makes it possible to play music in 
any diatonic scale on a keyboard 
instrument without having to 
change the tuning of the instru- 
ment. By international conven- 
tion, the note A4 (second space on 
the treble clef) is defined to have 
the frequency of 440.0 Hz. Since 
raising a pitch by one octave is the 
same as doubling the frequency, 
we can calculate the frequency of 
A in any octave quite easily by 
multiplying and dividing by the 
appropriate power of 2. 

In equally tempered tuning, the 
octave is divided into twelve notes; 
each pair of adjacent notes is 
separated by an interval called a 
semitone. The ratio of frequencies 
between the adjacent notes is equal 
to the twelfth root of 2, or 

f,« / f k = 2'" 2 
Using these relationships, it is easy 
to calculate the frequency of any 
arbitrary note. 




References 
Hillburn, J L and D E Johnson, Manual of 
Active Filter Design, McGraw-Hill Book 
Company, New York, 1973, pages 5 thru 
52. 

Osborne, A, J Kane, R Rector, and S 
Jacobson, Z80 Programming for Logic 
Design, Osborne/McGraw-Hil 
CA, 1978. 

Snell, J, "Design of a Digital 
Which Will Generate Up to 
Distortion Sine Waves in Real Time," 
Computer Music Journal, April 1977, 
pages 4 thru 24. 

Tierney, J, C M Rader, and B Gold, "A 
Digital Frequency Synthesizer," IEEE 
Transactions Audio and Electroacoustics, 
March 1971, pages 43 thru 57. 
Z80-CPU Technical Manual, Zilog Inc, 
Cupertino CA, 1977. 

Z80 Counter Timer Circuit Technical 
Manual, Zilog Inc, Cupertino CA, 1977. 



Berkeley 

Oscillator 
256 Low 



332 



March 1981 © BYTE Publications Inc 



Circle 250 on inquiry card. 



Programming Quickies 



Constellation I: 
An Astronomy Program 



Howard Berenbon, 2681 Peterboro, West Bloomf ield M 1 48033 

Here is an educational program for those interested in 
astronomy. It displays ten of the most well-known con- 
stellations and gives a multiple-choice test to see if you've 
been paying attention. 

Constellation I (see listing 1) is written in BASIC and 
will run on many computers, including the Radio Shack 
TRS-80 Model I Levels I and II and SwJPC 6800. It re- 
quires roughly 4 K bytes of memory. 

Operation 

After running the program, you can review the con- 
stellations by entering a 1. You can enter a to take the 
test. If you choose to review the constellations (highly 
suggested before taking the test), enter another number 
from 1 thru 10. For each number entry, a constellation 
will be displayed using asterisks as stars, along with its 
name (see listing 2). The constellations may be reviewed 
in or out of sequence and for any length of time. 

When you review the tenth constellation, you again 
have a choice of taking or not taking the test. Enter a if 
you are ready. Otherwise, you can continue reviewing. 

The test consists of ten multiple-choice questions. A 
constellation is displayed with four possible answers. 
Enter the number (1 thru 4) of the name that corresponds 
to the constellation. The program will advance to the 

Text continued on page 335 



Listing 1: Constellation I, a program for learning ten constella- 
tions. This program requires only 4 K bytes of memory and will 
run without modification in many BASIC systems. 

5 PRINT'CONSTELLATIDN I" 

10 PRINT 'COPYRIGHT <C> 1979 BY HOWARD BERENB0N' 

2 PRINT 

30 PRINT'THIS PROGRAM DISPLAYS 10 CONSTELLATIONS AND ■ 

35 PRINT 'GIVES A MULTIPLE CHOICE TEST . ■ 

10 PRINT 

15 FORI-1TO10 

50 A(I)=0 

5 5 NEXTI 

100 INPUT'l-REUIEW, 0-TEST'iA 

110 IFA-OTHEN3000 

118 PRINT 

;20 PRINT-ENTER *1- 10" 

125 INPUTE 

130 ONBGDT0210 r 2130 r2160 r250 0, 25 30 , 2540 i 260 Or 2630 , 2660 r 270 

200 PRINT-CASSIOPEIA" 



220 


PRINTTAB<12>> 


1 X" 


230 


PRINTTAB<26>; 


■x" 


210 


PRINT' * 




250 


PRINTTA6(33>> 


1 X" 


260 


RETURN 




300 


PRINT'LEO' 




320 


PRINTTAB(30>! 


■ X ' 


330 


PRINT" 




310 


PRINTTAB(23)i 


' X ■ 


350 


PRINT" 




360 


PRINT' * 




370 


RETURN 




100 


PRINT'URSA MAJOR 


its 


PRINTTAB(32> i 


'X ■ 


120 


PRINT 




130 


PRINT" X 




110 


PRINT "X 




150 


RETURN 




500 


PRINT'CEPHEUS 




520 


PRINTTAB(21 )! 


■x ■ 


530 


PRINT 




510 


PRINT" 


X 


550 


PRINT 




560 


PRINTTAB<23>; 


■x ■ 


570 


PRINT" 




530 


PRINT 




590 


PRINT 




600 


PRINTTABI21); 


■ X ■ 


610 


RETURN 





Listing 1 continued on page 334 



dolosoulh announces.. . 

THE TOTAL PRINTER PACKAGE! 






With so many matrix printers available today, 
it's tough to tinb the right one (or your applica- 
tion. Some oiler the speed you need, others the 
communications flexibility and still others the 
lorms handling capability. But no printer oilers 
all the leatures you need ... until now. 



'data©®Q* 

computer corporation 



The DS 180 provides a total package of performance features for any 
application where quality impact printing is required. Not a "hobby-grade" 
printer, the DS 180 is a real work-horse designed to handle your most 
demanding printer requirements. 

High Speed Printing -Bidirectional printing at 180 cps offers through- 
put ol over 200 1 pm on average text. A 9-wire printhead generates a 
9x7 font with true lower case descenders and underlining. 
Non-volatile Format Retention -A unique keypad featuring a non-volatile 
memory makes programming the DS 180 quick and easy. Top ol form, 
tabs, perforation skipover, communications parameters and many other 
features may be entered and stored from the keypad. The DS180 even 
remembers the line where you stopped printing -eliminating the need 
to reset the top ol form at power-on. 

Communications Versatility -Interfaces include RS232, current loop and 
8-bit parallel. Baud rates from 110-9600 may be selected. A 1K buffer 
and X-on, X-off handshaking ensure optimum throughput. 
Forms Handling Flexibility -Forms ranging from 3"-15" may be fed 
from the front or bottom, and an adjustable printhead provides crisp and 
clear copy on forms with as many as 6-parts. 
For more information on how the DS 180's low-cost total printer package 
can fill your application, contact us at Datasouth. The DS 180 is avail- 
able for 30-day delivery from our sales/service distributors throughout 
the U.S. 

4740 Owight Evans Road • Charlotte, North Carolina 28210 • 704/523-8500 



Circle 251 on inquiry card. 



March 1981 © BYTE Publications Inc 333 



Circle 252 on inquiry card. 




VAK-1 MOTHERBOARD 

• Designed specifically for use with the AIM-65, SYM-1, and KIM-1 microcomputers 

• Standard KIM-4* Bus 

• Fully buffered Address and Data Bus 

• Provides 8 expansion board slots 

• Complete with rigid card-cage 

• All IC's are socketed 

• Provides separate jacks for one audio-cassette, TTY, and Power 

• Completely assembled (except for card-cage) 

We manufacture a complete line of high quality expansion boards. Use reader service 
card to be added to our mailing list, or U.S. residents send $1.00 (International send $3.00 
U.S.) for airmail delivery of our complete catalog. 
'Product of MOS Technology 



PRICE: $139.00 

We also carry the SYM-1 
Microcomputer with manuals $229.00 



m* 


IB>- ENTE RPR I 


c 


-il—^ 


/ 


1 N C 


ORPORATE 


D 


2951 W. Fairmount Avenue • 


Phoenix, AZ 85017 • (602) 265-7564 


Please note 


new address 










1500 


RETURN 








211)0 


GOSUBZ00 








2110 


GOTO 118 








2130 


GOSUB30 








2110 


G0T0118 








2160 


GOSUB100 








2170 


G0T0118 








25 


GOSUE:500 








2510 


G0T0118 








2530 


GOSUE:70 








2510 


G0T0118 








2540 


GOSUB8 








2570 


G0T0118 








2600 


GOSUB900 








2610 


G0TD118 








2630 


GOSUBJ.00 








2410 


G0TO118 








2660 


GOSU61200 








2670 


G070118 








2700 


GOSIJB1100 








2710 


G0T01IK) 








3000 


P=0 








3010 


PRINT-MULTIPLE CHOICE TEST* 




K ' 


3020 


PRINT'ENTER CORRECT ANSWER (tl 


-1) 


* * 


3030 
3010 
3050 


PRINT 

PRINT'D" 

GOSUB320 








3060 


PRINT '(1) 


LEO- 






3070 


PRINT"<2> 


BOOTES" 






3080 


PRINT 1 (3) 


LYRA" 






3090 


PRINT "(1) 


LYNX" 






3100 


GOSUE50 5 








3110 


IFC=1G0SUE 


5000!A<1>=10 






3130 


PRINT'2) ■ 








3150 


GOSUB52 








3170 


PRINT Ml) 


PROCYON' 






3180 


PRINT" (2) 


AURIGA" 






3190 


PRINT "(3) 


CEPHEUS" 






3200 


PRINT" (1) 


ORION" 






3210 


GOSUE5050 








3220 


IFC=3GOSUB5000!A<2>=10 






3230 


PRINT'3) " 








3210 


GOSUE1220 








3260 


PRINT "(1) 


LEO" 






3270 


PRINT" (2) 


AURIGA" 






3280 


PRINT" (3) 


GEMINI- 






3290 


PRINT" (1) 


HYDRA" 






3300 


GOSUB5050 








3310 


IFC=2G0SU 


:5000!A(3)=10 






3320 


PRINT'D" 








3310 


GOSUE720 







Listing 1 continued: 



700 PRINT'GEMINI" 

720 PRINT" X 

730 PRINT 

710 PRINT 

750 PRINTTABODi "X" 

760 PRINT" > 

770 PRINT 

780 PRINT" * 

790 PRINT" * 

795 RETURN 

BOO PRINT-CORONA BOREALIS" 

820 PRINT" 

830 PRINT" * 

810 PRINT" 

850 PRINT" 

860 RETURN 

900 PRINT-SAGITTARIUS" 

920 PRINT" X 

930 PRINT" 

910 PRINTTAB(IZ) i "*■ 

950 PRINT 

960 PRINT" 

970 PRINT" 

980 PRINT" 

990 RETURN 

1000 PRINT'LYRA" 

1020 PRINT" 

1030 PRINT" 

1010 PRINT" 

1060 PRINT 

1070 PRINT" 

1080 PRINT" X" 

1090 RETURN 

1200 PRINT'AURIGA" 

1220 PRINT" 

1230 PRINT" 

1210 PRINT" 

1250 PRINT 

1260 PRINT" * 

1270 PRINT" 

1280 RETURN 

1100 PRINT'CYGNUS" 

1120 PRINT" 

1130 PRINT" 

1110 PRINT" 

1150 PRINT" » 

1170 PRINTTABC29); "X" 

1180 PRINTTAB(32); "X" 

1190 PRINTTABOS) i "X" 




Have you Heard? 



PBS has the UCSD Pascal" 
system for: 



SofTech certified 
system for $450 

(documentation included). 

Run-Time-Only 
system for $350. 



Quantity discounts 
available. 



Contact: 



Cromemco 

Dynabyte 

Onyx 

Vector Graphic 

Ml PROFESSIONAL 

Ml BUSINESS 

\3M software 



(415) 546-1596 119 Fremont St., San Francisco, CA 94105 



334 March 1981 © BYTE Publications Ire 



Circle 253 on inquiry card. 



Circle 254 on Inquiry card. 



Listing 1 continued: 



3350 


PRINT "(l) LEO" 




3360 


PRINT'CZ) CRUX" 




3370 


PRINT' (3) CANOPUS 1 




3380 


PRINT'd) GEMINI 1 




3390 


EOSUB5050 




3100 


IFC=1GOSUB5000SA(1>=10 




3110 


PRINT 'S) 1 




3<I20 


GOSU6220 




3110 


PRINT'd) AURIGA - 




3150 


PRINT' (2) LYNX' 




3140 


PRINT'O) CASSIOPEIA' 




3170 


PRINT'd) LYRA' 




3180 


GOSUB5050 




3190 


IFC = 3GOSUE:5000!A(5) = 10 




3500 


PRINT" 41" 




3510 


GOSUB820 




3520 


PRINT'd) LEO- 




3510 


PRINT' (2) CYGNUS' 




3560 


PRINT'O) CORONA BOREALIS' 




3570 


PRINT'd) CEPHEUS' 




3580 


GOSLIB5050 




3590 


IFC = 3GOSUE:5000 !A<6)=10 




3400 


PRINT '7) ' 




3610 


GOSUB1020 




3620 


PRINT'd) LYRA' 




3610 


PRINT'(2> LEO' 




3650 


PRINT'O) ORION' 




3660 


PRINT'd) CETUS- 




3670 


GOSUB5050 




3680 


IFC=1GOSUB5000!A(7)=10 




3700 


PRINT" B> ' 




3710 


GOSUB920 




3720 


PRINT'd) CRUX' 




3710 


PRINT' (2) CETUS' 




3750 


PRINT'O) DRACO- 




3760 


PRINT' (1) SAGITTARIUS' 




3770 


GOSUB5050 




3780 


IFC=1GOSUB5000!A(8)=10 




3800 


PRINT'9)' 




3810 


G0SUB115 




3820 


PRINT'd) LYRA' 




3810 


PRINT' (2) URSA MAJOR' 




3850 


PRINT'O) CRUX" 




3860 


PRINT'd) UIRGO" 




3870 


GOSUB5050 




3880 


IFC = 2GOSUE:5000:A(9) = 10 




39 


PRINT "lO)" 




3910 


GOSUB1120 




3920 


PRINT'd) CYGNUS' 




3930 


PRINT' (2) LEPUS' 




3910 


PRINT'O) PERSEUS- 




3950 


PRINT' (1) TAURUS' 




3960 


GOSUB5D50 




3970 


IFC = 1GOSUE:5000:A<10) = 10 




3980 


PRINT 




3985 


PRINT'POINTS PER OUESTION' 




3990 


PRINT 




1000 


PRINT-1 = - iAd ) !■ 2 = ";A(2)i' 


3=- iAO) 


1010 


PRINT'6=' iA(6)i ' 7='iA(7)i' 


8=- iA<8> 


1020 


PRINT 




1030 


PRINT-SCORE IS JfMP 




1010 


END 




5000 


P = Pd0 




5005 


PRINT-CORRECT- 




5010 


RETURN 




5050 


iNPUT-d-D ■ ;c 




5060 


RETURN 





FREE your keyboard — interact directly with the 
screen. Why waste time typing? Use a 3-G Light Pen. 



In his business. Al Zenker ol Zenker 
Dental labs in Penndel. Pennsylvania 
uses our pens (or data entry. Harry 
Lee ol Piltsfield. Massachusetts uses 
Ihe pen to select telephone numbers 
to be dialed by his computer Thorwald 
Esbensen ol Micro-Ed, Inc. in Min- 
neapolis, Minnesota writes education 
software lor the 3-G Light Pen Swiss 
Air Dispatch at Kennedy Airport in New 
York uses our pens lo speed up its bus- 
iness operations. Dr. Richard Kerns 
ol East Carolina University incopor- 
ates our pen in a demonstration with a 
voice synthesizer to leach his students 
how to use computers In Holland. Jo- 
han Smilde uses a 3-G Light Pen to 
experiment with graphics. 

I These people have discovered the be- 
nefits ol using a 3-G Light Pen 
Wouldn t a 3-G Light Pen make your 
system more versatile and more lunc- 
tional? Yes, ol course it would! 

I Don't Wait — order your pen today and 
receive 

1) 3-G Light Pen 

2) Demonstration cassettes (with 
Prolessional TRS-80, PET and 
Apple) 

3) Sample program listing 

4) Complete documentation and 
instructions 

5) Olher Light Pen software and 
games available 

I NO ASSEMBLY NECESSARY. READY 
TO PLUG IN AND USE. 

I Complete documentation so you can 
write your own program in BASIC No 
machine language coding necessary 

I All 3-G Prolessional models plug into 
machine ports. Economy model plugs 
into cassette and batteries are in- 
cluded 



■ ■— ™ ~ — ■> Mail Coupon or Call Today for Immediate Delivery ■■■■■ — ■•■ 



3 



3-G Company, Inc. Dept. BT 

Rt. 3, Box 28A, Gaston. OR 97119 

(503)662-4492 



jRemember. 3-G oilers a 30-day J 

unconditional Money back 

GUARANTEE 



□ TRS-BDEconomy □ TRS-BD Prolessional □ PET Prolessional □ Apple Professional 
$24.95 $39,95 537.95 $38.95 

Yes. I want lo make my computer more versatile Rush ""» 3-G Light 

Pens (Add S I 50 for marhng and handling — S6 00 foreign ) 

Enclosed is Q check or money order Q Masier Cnarge Q Visa 



X 



NAME 



ADDRESS. 
CITY 



3-G LIGHT PENS FOR 



POINT PEN TO CORRECT ANSWER 



WHERE IS MT. ST. HE1ENS? 



OREGON D 

WASHINGTON D 

MONTANA D 










A3?fj LIGHT PEN INTERACTING DIRECTLY WITrfTHE SCREE,. 



i = -iA<i)i- 5=-;a<5> Listine3: Part of the ten-question test given by Constellation 1. 

9=";A(9)»"10="JA(10) 

The bottom part of the listing shows the points for each ques- 
tion and the final score. 



1-REVIEW. 0-TEST? 

MULTIPLE CHOICE TEST 

ENTER CORRECT ANSWER (*1-1) 



Listing 2: A sample run of Constellation 1 showing the review 
phase. 



CASSIOPEIA 



(1) LEO 

(2) BOOTES 

(3) LYRA 
<t> LYNX 
(1-1)? 1 



ENTER * 1 - 1 



POINTS PER QUESTION 

1= 10 2 = 10 3= 10 

6= 10 7= 10 B« 10 

SCORE IS V. 100 
READY 



10 
10 



5= 10 
10= 10 



ENTER *1-10 



10 
CYGNUS 



1-REVIEW. 0-TEST? 



Text continued from page 333: 

next question. After all questions are answered, a list of 
points per question is displayed along with your percent 
score (see listing 3). 

You'll be surprised how much you have learned about 
the constellations. Next time you are stargazing, keep an 
eye out for Cassiopeia (it's near Andromeda). You won't 
have trouble recognizing it, if you have been doing your 
homework. ■ 



March 1981 © BYTE Publications Inc 335 



META TECHNOLOGIES 

FOR YOUR DISK SYSTEM 



FILE BOX $24i 5 5 isks 



DISKETTE STORAGE SYSTEM 



for 8" disks . . . $29.95 




MTC brings you the ULTIMATE diskette 
storage system, at an affordable price. Stor- 
ing 50 to 60 diskettes, this durable, smoke- 
colored acrylic unit provides easy access 
through the use of index dividers and ad- 
justable tabs. Unique lid design provides 
dust-free protection and doubles as a carry- 
ing handle. 



PLASTIC LIBRARY CASES 

(not shown) 
An economical form of storage for 10 to 15 
diskettes, and is suitable for your bookshelf! 
Case opens into a vertical holder for easy ac- 
cess. 

5 'A -inch diskette case $3.25 

8-inch diskette case $3.50 



Single Sided, Single Density, Soft-Sectored 
5'A-inch, (for TRS-80™) Mini-floppy 

DISKETTES 
$21 



95 

box of 10 



TRS-80™ PRODUCTS 

Mttitosorr ittsii maoihm 

&.- OTHER MYSTERIES 




N EWDOS/80 by Apparat $ 1 49.95 

NEWDOS+ with ALL UTILITIES 

35-track $69.95 

40-track $79.95 

TRS-80TM DISK 

AND OTHER MYSTERIES $19.95 

MICROSOFT tm BASIC DECODED & OTHER 

MYSTERIES for the TRS-80TM $29.95 



'RINGS' & 
THINGS 

Help prevent data loss and media damage 
due to improper diskette centering and 
rotation with the FLOPPY SAVER™ rein- 
forcing hub ring kit. 7-mil mylar rings in- 
stall in seconds. Kit is complete with 
centering tool, pressure ring, 25 adhesive 
backed hub rings and instructions. 

HUB RING KIT for 5 'A" diskettes ..$9.95 
REFILLS(50 Hub Rings) $4.95 

Protect your expensive disk drives and 
your valuable diskettes with our diskette 
drive head cleaning kit. The kit, consisting 
of a pair of special "diskettes", cleaning 
solution and instructions, can be used for 
52 cleanings. Removes contamination 
from recording surfaces in seconds 
without harming drives. 



CLEANING KIT for 5 1 /." drives 



$24.95 



These are factory fresh, absolutely first 
quality (no seconds!) mini-floppies. They are 
complete with envelopes, labels and write- 
protect tabs in a shrink-wrapped box. 

PLAIN JANE ™ 

DISKETTES 

The Beautiful Floppy 

with the Magnetic Personality™ 

Thousands of people have switched to this 
low-cost alternative. These quality diskettes 
are packaged in a plain white box ... no fan- 
cy printing, fancy names or fancy labels, not 
even our own (labels cost money). Trust us. 

PLAIN JANE™ Diskettes $21.95 

lOboxesoflO ... (each box)$2 1.50 

VERBATIM'S PREMIUM DISKETTES AT 
AFFORDABLE PRICES 

DATALIFE™ 

Seven data-shielding improvements mean 
greater durability and longer data life. 
These individually certified diskettes 
feature thicker oxide coating, longer-lasting 
lubricant, improved liner, superior 
polishing and more! Meets or exceeds IBM, 
Shugart, ANSI, ECMA and ISO standards. 
Buy the best ... buy DATALIFETM. 

VERBATIM DATALIFE™ DISKETTES 

5'/4-inch(boxof 10) 

MD525-01 $26.95 

10 boxes of 10 . . . (each box)$25.95 

8-inch FLOPPIES 

Single-Density, FD34-1000 $29.95 
Double-Density, FD34 8000 $39.95 



CALL FOR INFORMATION ON 
OTHER TRS-80™ PRODUCTS 



Products damaged in 

transit will be 

exchanged. 

Prices, Specifications, 

and Offerings subject 

to change without 

notice. 



MOST ORDERS 

SHIPPED 

WITHIN ONE 

BUSINESS DAY 



PRICES IN EFFECT 

March 1, 1981 THRU 

March 31, 1981 



WE ACCEPT 

• VISA 

• MASTER CHARGE 

• CHECKS 

• MONEY ORDERS 
■ C.O.D. 



Add $2.50 for 
standard UPS 
shipping & handling 
$2.00 EXTRA 
for COD. 
Ohio residents 
add 5' ?.% sales tax. 




FOR PRODUCT INFO 
1-800-321-3640 



CALL 

TOLL 
FREE 



TO PLACE ORDER 
1-800-321-3552 



IN OHIO call (216)289 7500 (COLLECT) 



METfl TECHttLUQGJES CaRPLlRflTJLlN 



26111 Brush Avenue. Euclid. Ohio 44132 



810115 

TRS-80 is a TM ol Tandy Corp 
PLAIN JANE is a TM of MTC. 
M981 by Metatechnologies Corporation. Inc. 



336 



BYTE March 1981 



Circle 255 on inquiry card. 



What's New? 



SYSTEMS 



CMOS Processor from Motorola 




8088-Based 
Board for the S-100 

The CP88 is a 5 MHz 8088-based 
microprocessor board designed for 
the S-100-bus system. It features 
I -megabyte address space, 64 K I/O 
addresses, an instruction set with full 
16-bit mathematics and extensive 
string-handling capabilities, a 3 K-byte 
EPROM, provision for 1 K bytes of 
programmable memory, memory ad- 
dressing in the top 4 K bytes of ad- 
dress space, and the ability to disable 
memory space. The memory-access 
time is 450 ns. The CP88 has switch- 
selectable 5 to 8 MHz clock rates and 
spare sockets for breadboarding. The 
CP88 is available as a bare board 



only. It comes with documentation 
for S 59.95 from Microfuture, POB 
5951, San Jose CA 95150, |408) 
249-0560. 

Circle 401 on inquiry card 



The MC146805E2 is an 8-bit 
CMOS microprocessor with a set of 
61 instructions similar to the 
MC6800's. There's a set of bit-mani- 
pulation instructions to allow any bit 
in programmable memory or any I/O 
|input/output) line to be set or cleared 
with a single instruction. The device 
requires only 20 mW at 1 MHz and 
less than 1 mW in the standby mode. 
The supply-voltage range is 3 to 6 V 
DC. The unit includes an 8-bit timer 
with a software-programmable 7-bit 
prescaler, 1 1 2 bytes of programmable 
memory, and a clock generator. The 
multiplexed bus has an 8 K-byte ad- 
dressing range. A 2 K-byte CMOS 
ROM is available. The processor is 
priced at S45 in unit quantities. Con- 
tact Motorola Semiconductor Prod- 
ucts Inc. 3501 Ed Bluestein Blvd, 
Austin TX 7872 1 . 

Circle 400 on inquiry card 



DTC's Microcomputer 

The DTC Micro 210 contains 64 K 
bytes of programmable memory, a 
2 K phantom ROM fread-only mem- 
ory), an 8085A-2 microprocessor, 
and four RS-232C asynchronous in- 
terface ports. The unit employs two 
BASF 5-inch floppy-disk drives having 
300 K bytes of storage. The operating 
systems available with the Micro 2 1 
are compatible with DTC's other 
microcomputers. Single- and multi- 
user systems are available. Applica- 
tions software can be written under 
CP/M, DTC's Multi-User Business 
BASIC, or DTC's version of Microsoft 
BASIC. The price for the Micro 210 is 
S3295 from DTC, 590 Division St, 
Campbell CA 95008, [408) 378-1 1 1 2. 



Circle 402 on inquiry card 



Where Do New Products Items Come From? 

The information printed in the new products pages of BYTE is obtained from 
"new product" or "press release" copy sent by the promoters of new products. If 
in our judgment the information might be of interestto the personal computing ex- 
perimenters and homebrewers who read BYTE, we print it in some form. We 
openly solicit releases and photos from manufacturers and suppliers to this 
marketplace. The information is printed more or less as a first-in first-out queue, 
subject to occasional priority modifications. While we would not knowingly print 
untrue or inaccurate data, or data from unreliable companies, our capacity to 
evaluate the products and companies appearing in the "What's New?" feature is 
necessarily limited. We therefore cannot be responsible for product quality or 
company performance. 



March 1981 © BYTE Publicalions Inc 337 



What's New? 



PERIPHERALS 



Music Filter 



The Music Sweetener is a low-pass 
filter designed to enhance Software 
Affair's Orchestra-80 and other com- 
mercial and homebrew D/A (digital- 
to-analog) converter music synthe- 
sizers that do not already have a filter. 
The unit attenuates the unwanted 
high-frequency sampling noise better 
than a stereo system's treble tone 



-Music 
Sive «ener 



control. It is designed for use in four- 
part music synthesis on most micro- 
computers. The device is inserted be- 
tween the music peripheral and the 
audio amplifier. The Music Sweetener 
is S39.95, plus S2 shipping, from 
Newtech Computer Systems Inc. 230 
Clinton St, Brooklyn NY J 1201, (212) 

625-6220. Circle 403 on inquiry card 



Apple II Printer 

IMP2-Apple is an impact printer 
designed for the Apple II. It provides 
lowercase characters, single-com- 
mand printer functions, and is com- 
patible with the Pascal operating sys- 
tem. Priced at S895, the printer is 
equipped with friction and tractor 
feed to handle single sheets, roll 
paper, and fanfold forms. The unit 
can print 80, 96, or 1 32 columns at 1 
line per second. The 7 by 7 dot matrix 
has a standard 96-character ASCII 
(American Standard Code for Infor- 
mation Interchange) set; special 
character sets are optional. IMP2- 
Apple can handle user-defined and 
high-resolution graphics under soft- 
ware control. Contact Axiom Cor- 
poration, 5932 San Fernando Rd, 
Glendale CA 9 1 202, (2 1 3) 245-9244. 

Circle 404 on inquiry card 



Vision for Your 
Microcomputer 

Microtex Corporation has devel- 
oped an image-processing subsystem 
that allows microprocessors to be 
used in the gray-scale data acquisition 
from Reticon line-scan and matrix 
cameras. The Microtex 6400 device 
acquires 8-bit (256 gray level) data at 
I or 2.5 MHz, and provides all power, 
control, and clock signals to the 
Reticon camera. A board designed for 
the Digital Equipment Corporation 
LSI- ? 1 family of microprocessors, the 
6400- A has a general-purpose inter- 
face for use with many other 16-bit 
microprocessors. An optional video 
processor will allow the user to see 
real-time data from the 256 by 256 
matrix camera at approximately 30 
frames per second. 

The basic 6400 system includes the 
camera-control logic, an external syn- 
chronization input that initiates the 
scan, an 8-bit A/D (analog-to-digital) 
converter, 64 K bytes of program- 
mable memory, and the Q-bus inter- 
face, which contains all the registers 
for software control of the subsystem. 
The 6400-A costs S4595 for the 
1 MHz version and S4895 for the 
2.5 MHz version. For more informa- 
tion, contact Microtex Corporation 
80 Trowbridge St. Cambridge MA 
02138, (617) 491-2874. 

Circle 405 on inquiry card 





» 










■ 


' 










■ 









Circuit-Board Holder 

The Model 333 circuit-board holder 
from PanaVise Products Inc features 
an 8-position rotating adjustment, in- 
dexing at 45° increments, and 6 lock 
positions in the vertical plane, allow- 
ing a 10-inch height adjustment. 
With cross-bars available up to 30 



inches in length, the holder can sup- 
port circuit boards up to 28 inches 
wide. Extra arms can be added. It is 
built onto a pre-drilled cast-iron base 
for stability and easy mounting. Con- 
tact PanaVise Products Inc, 2850 E 
29th St, Long Beach CA 90806, (2 1 3) 

595-7621. Circle 406 on inquiry card 



338 March 1981 © BYTE Publications Inc 



What's New? 



PERIPHERALS 



40 and 60 W Switching DC Power Supplies 







- «».>...! c i« I 










Jrll M 


.1 — , *";~i'!?Ta*^^^ 




I^^JjMk^ pi MaifMriM 



Sierracin/Power Systems has 
developed a series of 40 and 60 W 
open-frame switching DC power sup- 
plies. The 5A and SB series, 40 and 
60 W respectively, come in single- 
and multiple-output versions. The 
single-output models 5A5 and 5B5 
deliver 5 V at 7 A and 1 2 A at full 
load. Prices for these models are S45 
and S75 respectively. The 40 W mul- 
tiple-output 5AXMP delivers 5 V at 



4 A, ± 12 V at 0.5 A, -5 V at 0.5 A, 
and + 15 V at 1.0 A for S59. The 
60 W multiple-output 5BXMP delivers 

5 Vat 7 A, +12 Vat 1.5 A, -12 Vat 
0.5 A, and -5 V at 0.25 A for S89. For 
complete details, contact Sierracin/ 
Power Systems, 20500 Plummer St, 
Chatsworth CA 91311, [800) 
423-5569; in California (213) 
998-9873. 

Circle 412 on inquiry card 



DIP-85 Printer 

The DIP-85 impact printer features 
a 7 by 7 or 1 4 by 7 dot matrix, 6 char- 
acter sizes, 1 00 cps (characters per 
second) bidirectional print speed, trac- 
tor or friction paper feed, and a ribbon 
cartridge. It has variable line density 
and continuous form-length controls. 
The printer has a high-resolution 
graphic capability and can provide 
plotting, video-display graphics, il- 
lustrations, and special-effects sym- 
bols. The unit has data rates up to 
9600 bps, parallel and serial RS-232C 
ports, and a I K-byte buffer. With a 
96-character ASCII (American Stan- 
dard Code for Information Inter- 
change! set . tne DIP-85 is capable of 
uppercase and lowercase printing at 
80, 96, or 1 32 characters per line on 
standard-sized paper. Paper feed is at 
the rate of 1 lines per second. Oper- 
ator control includes power, select/ 
deselect, line feed, top of form, self- 
test, and variable vertical-tab setting. 
The DIP-85 is priced at S 62 5 in quan- 
tities of 100. For more information, 
contact DIP Inc. 745 Atlantic Ave, 
Boston MA 021 1 1, (617) 482-4214. 



Circle 413 on inquiry card 



*%/> 

T? 



PRINTERS !! 
$499.00 Dip 81 

(Friction Feed) 



• 7x7 DOT MATRIX 



mj\ 



•UPPER/LOWER CASE 

g 1 1 ^§\ I 

■BI-DIRECTIONAL PRINTING 

■FAN COOLED -lOOc.p.s. 



** 



€ PROM PROGRAMMER 



■ IEEE 696/S-100 CARD PROGRAMS 1K, 
2K.4K, 48K PARTS 

k 8 SOCKETS ACCEPT PROGRAMMED 

...& MUCH MORE 



EPROMS or RAMS 



■ SWITCH SETTABLE: EXTENDED ADDRESS 
EXTENDED DEVICE SELECT 

/S-100 KLUGE CARD 

• ADDRESS BUFFERING -DATA BUS BUFFERING 

■ CONTROL LOGIC ■ DEVICE SELECT ETC. 



Other models available with tractor 

feed, & other options. Write for 

complete details. „■!» Ackerman Digital Systems, Inc. C3 12]530-8992 

. y ■;. ■■■..-.■ DOS 110 N. York Rd., Suite 208, Elmhurst, III. 60126 



Circle 256 on inquiry card. 



March 1981 © BYTE Publications Inc 339 



What's New? 



PERIPHERALS 




Idea Box for Experimenters 



jg.- •■.g_ i 



The Idea Box combines three 
regulated, low-ripple power supplies; 
a choice of a solderless breadboard, a 
pre-etched, pre-drilled printed-circuit 
board, or a blank foil board. This com- 
bination allows easy construction of a 
prototype or a built-once-only device. 
The Idea Box is priced from S 1 49.95. 
The circuit cards and printed-circuit 



layout pads are available individually 
from S4.95 to S44.95. Contact Global 
Specialties Corporation, 70 Fulton 
Ter, New Haven CT 06509, [203) 
624-3103. 

Circle 407 on inquiry card 



Interface the Apple II to 

Centronics-Type Printers 

The Model 7728 Centronics Printer 
Interface makes the Apple II compati- 
ble with printers using Centronics- 
type parallel interfaces, such as the 
Okidata Microline 80, the Microtek 
MT-80P, the MPI 88T, and Centronics 
printers. A 256-byte ROM [read-only 
memory) provides driver firmware 
and controls character output to the 
printer. The 7728 supports the inter- 
rupt daisy chain with arbitration logic, 
including jumper-selectable IRQ gen- 



eration, and it provides direct-mem- 
ory-access daisy-chain pass-through. 
The printer interface includes an 8-bit 
data output bus, four status inputs, 
data strobe and acknowledge hand- 
shake signals, and a printer-reset 
signal. The 7728 comes assembled 
and tested, with documentation, for 
S 1 19.95. Cables for different printers 
are available from the manufacturer. 
Contact California Computer Sys- 
tems, 250 Caribbean Dr, Sunnyvale 
CA 94086, (408) 734-5811. 

Circle 408 on inquiry card 



Five-Inch 

Hard-Disk Drive 

Tandon Magnetics Corporation 
has a family of hard-disk drives that 
can store 3.19 to 11.5 megabytes. 
The TM 600 family of 5-inch Win- 
chester-type hard-disk drives contains 
one-, two-, and three-platter models. 
These drives feature a track-to-track 
access time of 3 ms and an average 
access time of 1 68 ms. Recording den- 
sity is 7690 bits per inch and rotating 
speed is 3600 rpm (revolutions per 
minute). Tandon offers two inter- 
faces, the S and the T versions. The S 
version is compatible with higher- 
capacity drives, and the T version is 
compatible with Tandon's TM 100 
floppy-disk drives. The T version 
allows the TM 600 series to run in a 



daisy chain with the TM 100-4 flop- 
py-disk drive. This permits 1 1 .5 mega- 
bytes of fixed-disk storage in a daisy 
chain with 3 megabytes of floppy- 
disk storage. 

The three-platter TM 603E offers a 
capacity of 1 1 .5 unformatted mega- 
bytes with 230 cylinders. The TM 
602E is a two-platter unit offering 
7.66 megabytes of storage with 230 
cylinders. The two-platter TM 602 
model stores 6.38 megabytes, and 
the TM 603 delivers 9.57 megabytes 
with three platters. Up to four TM 
600s can be daisy-chained on a single 
bus. The TM 600 family is priced in 
the S 1 400 to S 1 600 range. Contact 
Tandon Magnetics Corporation, 
9333 Oso Ave, Chatsworth CA 
91311, (213) 993-6644. 

Circle 409 on inquiry card 



80 by 24 Video Display 
for the Apple II 

The Full-View 80 is an 80-column 
by 24-line uppercase and lowercase 
plug-in video-display card for the 
Apple li. Under keyboard or program 
control, Full-View 80 permits user se- 
lection of 80- or 40-column graphics 
on the same monitor. Four character 
generators are offered. One is a 7 by 
9 dot-character font. Two are user- 
programmable EPROM (erasable 
programmable read-only memory) 
types that contain line-drawing 
graphics; one has 1 27 characters and 
the other 255 characters. The fourth 
is a 5 by 7 dot matrix to permit 
80-column display on low-perfor- 
mance monitors. The Full-View 80 
works with Apple Pascal, Microsoft's 
SoftCard, the Hayes Microcomputer 
Products Micromodem, the Apple 
Communications Card, and all Apple 
peripherals. A 2 K-byte ROM provides 
keyboard editing, cursor control, tab- 
bing, and scrolling. Seven other key- 
board-function keys are provided. 
The firmware incorporates Pascal and 
BASIC protocols. A real-time non- 
maskable interrupt clock can be 
software-enabled to permit timing of 
programs in background mode. A 
read-screen capability, a blank-screen 
function, and a light-pen connector 
with firmware support are provided. 
When the keyboard is shift-locked, 
the cursor blinks. The price is S395 
from Bit 3 Computer Corporation, 
1890 Huron St, St Paul MN 551 13, 
(612) 926-6997. 

Circle 410 on inquiry card 



240 Ipm Thermal 
Printer/Plotter 

Printer Systems Corporation's TH 
240 is an 80-column thermal printer 
that prints 240 Ipm (lines per minute). 
This speed permits copying a 24-line 
video display in less than 6 seconds. 
The 240 has an optional plotting 
mode that produces 70 by 560 dots 
per inch resolution. The TH 240 is 
priced at S 1 395 for the alphanumeric 
version and S 1 595 for the alphanu- 
meric-plus-plotting version. For de- 
tails, contact Printer Systems Corpora- 
tion, I W Deer Park Rd, Suite 1 04, 
Gaithersburg MD 20760. [30 1) 

840-1070. Circle 411 on inquiry card 



340 March 1981 © BYTE Publications lnc 



What's New? 



MISCELLANEOUS 



Dual-Output 
DC Power Supplies 

The 200 series dual-output DC 
power supplies from Power General 
include thirteen models with outputs 
of + 5 VDC, + 1 2 VDC, or ± 1 5 
VDC with output currents from + 50 
mA to + 500 mA. Other specifica- 
tions include: input voltage range 1 05 
to 1 25 VAC; input frequency 50 to 
440 Hz; output-voltage accuracy 
± 1%; line regulation +0.05%; load 
regulation ±0.1%; ripple and noise 
I m V RMS: transient recoveiy time 50 
fis; breakdown voltage 1500 VAC; 
and an operating temperature range 
of -25°C to +71°C. Prices range 
from S49 to SI09. Contact Power 
General. 152 Will Dr, Canton MA 
02021. [617] 828-6216. 

Circle 417 on inquiry card 




Let This Program 
Write Your Programs 

PEARL Level 3 is an automatic 
systems generator. PEARL allows you 
to respond to on-screen menus and 
prompts to define a desired program. 
PEARL uses this input to generate 
error-free source code in BASIC and to 
produce desired applications soft- 
ware. It can also create complex 
multiple-file applications programs. 
The program lets you describe perfor- 
mance requirements, then turn the 
linear programming over to PEARL. 
PEARL 3 enables you to create pro- 
grams for menu selection, file update 
and edit, reports, editing control data, 



file reorganization, and general report 
writing. It can define and cross-index 
elements between multiple files with- 
in a single system, define reports 
using data from multiple files, extend 
the standard program menu, define 
the interrelationships between data 
elements in different files, postjournal 
files to a master file, provide extended 
report generation, and support multi- 
ple index keys for a file. PEARL 3 is 
priced at S650, PEARL 2 for S350, 
and PEARL I for S 1 30. PEARL I and 
2 are for beginning and intermediate 
programmers. Contact CPU, POB 
1 2892, Salem OR 97309, [503) 
370-8653. 

Circle 418 on inquiry card 



Mostek Announces a 

64 K-Byte Dynamic 
Programmable Memory 

The MK4 1 64 is a series of 64 K-byte 
programmable memories featuring 
polysilicon lines instead of diffused bit 
lines for a 50% signal increase to the 
sense amplifier. By relocating the bit 
lines to a different level, the distance 
between adjacent capacitors is re- 
duced to 3 microns. This space 
savings permits an increase of the 
storage-capacitor size to 75% of the 
total cell area. To increase the density 
from 1 6 to 64 K bits, the device uses 



512 sense amplifiers. The MK4l64s 
feature an internal refresh counter. 
Another refresh feature permits the 
output to be held valid indefinitely by 
holding CAS (column address strobe) 
active low. The series features single 
+ 5 V supply operation, maximum 
power of 300 mW [20 m W standby|, 
and 1 50 ns access time. The 
MK4164-15 has a 325 ns cycle time. 
The price for the MK4 164-20 in 
100-piece lots is S 59.99. For complete 
details on the MK4164s, contact 
Mostek Corporation, 1 2 1 5 W Crosby 
Rd, Carrollton TX 75006, [214) 

323-6000. Circle 419 on inquiry card 



Built-in 
Foreign Languages 

The ML-32 multi-language system 
offers users the ability to select sets of 
32 different languages, resident in the 
system, and display these languages 
simultaneously on the screen or have 
them printed. The system offers multi- 
language communications in a word- 
processing package. Black-and-white 
graphics are included with color 
graphics provided in the CML-32. The 
ML-32 can interface with any host 
computer system. The screen displays 
34 lines of 80 characters on a high- 
resolution monitor. There are 80 pro- 
grammable function keys on the key- 
board. The system can also utilize 
floppy-disk drives, cassette tape 
players, and hard-disk drives. RS- 
232C, IEEE, and IBM 3270 input/out- 
put ports are provided. The lan- 
guages in the system include English, 
Greek, Arabic, Hebrew, Russian, 
Japanese, Chinese, German, French, 
Italian, Welsh, Dutch, Norwegian, 
Swedish, Turkish, Spanish, Latin, 
Icelandic, Hungarian, Albanian, 
Bulgarian, and Portuguese. The price 
for the ML-32 is SI 7,500, and the 
CML-32 is priced at $26,000. For 
more information, contact Michael 
Root at Computer Systems Con- 
sultants Inc, 225 Main St, Chelmsford 
MA01863, (617) 251-8561. 

Circle 420 on inquiry card 



March 1981 © BYTE Publications Inc 341 



What's New? 



MISCELLANEOUS 



Hayden 
Books Brochure 

Hayden Book Company Inc's new 
brochure lists books on computer 
science, electricity and electronics, 
engineering, mathematics, and other 
special interests. It is available free 
upon request from the Hayden Book 
Company Inc. 50 Essex St, Rochelle 
Park NJ 07662, (800) 827-3777, ext 
302. 

Circle 421 on inquiry card 



Basic Electricity Course 
from Heathklt/Zenlth 

The EE-3I00 Basic Electricity 
Course, from Heathkit/Zenith Educa- 
tional Systems, is designed for the self- 
starter. If you wish to expand your 
knowledge of basic electronics, this 
course will serve as your introduction 
to Ohm's Law, power, series and par- 
allel circuits, electromagnetism, types 
of current, motors, generators, and 
meters. The course is written in a pro- 
grammed-instruction format, and in- 
cludes two audio cassettes. It is costs 
S29.95. Contact Heathkit/Zenith 
Educational Systems, Department 
350-540. Benton Harbor Ml 49022. 
(6 1 6) 982-3210. 

Circle 422 on inquiry card 



Graphics Coprocessor 
Integrated Circuits 

EFCIS, a subsidiary of Thomson- 
CSF, has introduced two graphics de- 
vices. The EF 9365 (512 by 512 pix- 
els! and the EF 9366 (5 1 2 by 256 pix- 
els! graphics processors can directly 
execute high-level-language descrip- 
tors by means of vector-descriptor 
files. The on-chip vector generator 
allows a writing speed of more than 
500 meters per second on a 5 1 cm 
(21 -inch) screen. The devices gener- 
ate all the timing signals required for 
interfacing with video displays. The 
circuits contain a 96-character ASCII 
(American Standard Code for Infor- 
mation Interchange! generator. They 
also have light-pen registers and con- 
trols, three types of interrupt requests, 
and TTL-LS I/O ports. For additional 
details, contact EFCIS at 23, rue de 
Courcelles, B. P. 96.08, 75362. Paris. 
Cedex 08, France. 

Circle 423 on inquiry card 



High-Speed 16 KByte 

ROM Challenges 

Bipolar PROMs 

Synertek has announced the 
SY3316 MOS (metal-oxide semicon- 
ductor) 2048 by 8 high-speed ROM 
(read-only memoy) that can replace 
bipolar PROMs (programmable read- 
only memories) in many applications. 
The device features a maximum ac- 
cess time of 80 ns. It is fully compati- 
ble with 16 K-byte PROMs. The 
SY33 1 6 is compatible with TTL (tran- 
sistor-transistor logic) on all inputs and 
outputs and operates on a single 
+ 5 V power supply. It includes 
three-state outputs. The device uses 
static circuitry and operates asyn- 
chronously. The three circuit-selects 
are mask programmable so that high, 
low, or undecided active states are 
possible. Eight ROMs can be con- 
nected without needing external de- 
coding. In quantities of 250, the de- 
vice is priced at S56. For more infor- 
mation, contact Synertek, 3001 
Stender Way, Santa Clara CA 9505 1 , 

(408) 988-5623. Circle 424 on inquiry card 



Intel's EEPROM 

Intel Corporation has introduced 
an electrically erasable program- 
mable read-only memory (EEPROM). 
The 28 1 6 is a 16 K-bit nonvolatile 
memoiy that is byte-erasable with an 
access time of 250 ns. Users can 
erase, read, and write on the device 
without removing it from the com- 
puter. The 28 1 6 erases and writes by 
causing electrons to tunnel across a 
thin layer of silicon dioxide. At 1 25°C, 
the 2816 will retain data for at least 

20 years. The circuit is fully static and 
it needs no refreshing. Erasing and 
writing requires the application of a 

2 1 V pulse for 1 ms. Any of the 2 K 
bytes of the 281 6 can be erased and 
rewritten in 20 ms. Separate chip- 
enable and output-enable pins permit 
2-line control of the unit, which 
eliminates contention between ad- 
dresses and data on multiplexed bus 
lines. It is pin-for-pin compatible with 
the 2716 ultraviolet EPROM and 
plug-compatible with 2732 and 2764 
EPROMs. The 2816 costs SI 20 in 
1 00-piece lots. Contact Intel Corpora- 
tion, 3065 Bowers Ave, Santa Clara 
CA 95051. (408) 987-6742. 

Circle 425 on inquiry card 



Color Computer 

from Commodore 

VIC 20 (video interface computer) 
is a color computer priced under 
S300. It connects to any television set 
or monitor and provides 5 K bytes of 
memoiy. VIC 20 features color, 
sound, programmable function keys, 
memory expansion to 32 K bytes, PET 
BASIC, expansion ports, a 22-char- 
acter by 23-line screen display, high- 
resolution graphics, graphics char- 
acter set, joystick, paddles, light pen, 
and plug-in memory and program 
cartridges. VIC system peripherals in- 
clude a cassette-tape drive, a floppy- 
disk drive, and a printer. The com- 
puter uses the 6502 microprocessor 
and the VIC (video interface chip), 
which incorporates programmable 
memory, ROM (read-only memory), 
and video-control circuitry on the 
same integrated circuit. Contact Com- 
modore Business Machines Inc. 950 
Rittenhouse Rd, Norristown PA 
19403, (215) 666-7950. 

Circle 426 on inquiry card 



Check Spelling 
with Spellguard 

Spellguard is a program to check 
spelling in documents prepared with 
word processors and text editors. A 
10,000-word document (20 pages) 
can be checked for spelling and typo- 
graphical errors in under one minute. 
Spelling is checked using a dictionary 
supplied with the Spellguard package. 
The dictionary contains the 20,000 
most-commonly used words in En- 
glish and can be expanded. The dic- 
tionary size is limited only by disk-file 
size. One feature of Spellguard is the 
ability to create multiple dictionaries. 
Spellguard also contains a self-diag- 
nostic feature for protection. Spell- 
guard works with most CP/M-based 
word processors, including WordStar, 
Magic Wand, Electric Pencil, and 
Spellbinder. The program requires an 
8080-, 8085A-, or Z80-based system, 
at least 32 K bytes of programmable 
memory, one 8-inch floppy-disk drive, 
and CP/M 1 .4 or a later version. 
Spellguard has a suggested retail price 
of S295; a manual is available for 
S15. Contact Innovative Software 
Applications, 915 Timothy Ln, Menlo 
Park CA 94025, (415) 326-0805. 

Circle 427 on inquiry card 



342 March 1981 © BYTE Publications Inc 



What's New? 



SOFTWARE 



UCSD Pascal for 
the Sprint 68 




Wintek has the UCSD Pascal com- 
piler available for its Sprint 68 
microcomputer. The package in- 
cludes an interactive operating sys- 
tem, Pascal compiler, screen-oriented 
editor, macroassembler, linker, p-code 



interpreter, and a library of utilities. 
The price for the package is S675 
from Wintek Corporation, 1801 
South St, Lafayette IN 47905, |317) 
742-8428. 

Circle 429 on inquiry card 



Duel-IU-Drolds 

Duel-N-Droids is a sound and 
graphics game program for the 
TRS-80 Model I Level II. It features two 
sword-wielding androids that clash 
with each other in both practice and 
tournament duels. Each player con- 
trols his androids with four letter keys, 
causing it to maintain defense, back 
off, or attack. Each win moves the 
rank of the player's android up one 
level on the game scale. In practice 
duels, the player manually controls 
one android while the computer con- 
trols the other. In tournament duels, 
the machine controls both androids, 
using the skills instilled by the player 
during practice sessions. The program 
is priced at SI 4.95 for cassette ver- 
sions and S 20.95 on floppy disks. 
Contact Acorn Software Products Inc, 
634 North Carolina Ave SE, Wash- 
ington DC 20003, (202) 544-4259. 



Circle 430 on inquiry card 



Alpha Micro FIG-FORTH 

Version 3.2 of /jA/FORTH is avail- 
able for Alpha Micro systems. This 
version is aligned with the 1978 stan- 
dard of the FORTH International Stan- 
dards Team. It allows complete access 
to Alpha Micro's AMOS operating 
system. It implements full-length 
names up to 31 characters, checks 
code at compile-time with error 
reporting, and contains string-han- 
dling routines and a string-search 
editor. A FORTH assembler is in- 
cluded. FORTH words |commands) 
may be created from previously de- 
fined words, and even the original 
words supplied with the system can 
be redefined. It comes on an AMS for- 
mat floppy disk and includes all 
source code, an editor, an assembler, 
and a string package. It costs S 1 30 
from Professional Management Ser- 
vices, 724 Arastradero Rd, Suite 109, 
Palo Alto CA 94306, |408) 252-22 18. 



Circle 431 on inquiry card 



Apple II 
Curve Fitter 

Curve Fitter allows you to select an 
appropriate mathematical curve to fit 
your experimental results. Methods 
include scaling and transformations, 
averaging, smoothing, interpolation, 
least-squares fitting, and interpolation 
of unknown values from the fitted 
curve. Using an optional A/D |ana- 
log-to-digital) converter, data can be 
entered directly from instruments. 
Curve Fitter is compatible with 
VisiChart. Curve Fitter runs on a 
48 K-byte Apple II with Applesoft in 
ROM |read-only memory). It is avail- 
able on floppy disk with a 29-page 
manual for S35. The manual is avail- 
able separately for 55. Contact Paul K 
Warme, Interactive Microware Inc, 
POB 771. State College PA 1 680 1, 
|8l4) 238-8294. 

Circle 428 on inquiry card 



UnlFLEX 
Operating System 

UniFLEX is a multitasking, multi- 
user operating system. Several users 
can run different programs simulta- 
neously, and one user can run several 
programs at a time. Users must log in 
with a password before being permit- 
ted to use the system. UniFLEX sup- 
ports a hierarchical file system allow- 
ing file sizes up to I gigabyte |ie: I 
billion bytes) and disk capacities of 
over 8 gigabytes. All system I/O is de- 
vice-independent. Any combination 
of interrupt-driven devices can be at- 
tached to the system. Intertask com- 
munication is supported, and task 
swapping can occur. The basic 
UniFLEX system includes the oper- 
ating system, approximately 50 sys- 
tem utilities, a text editor, macroas- 
sembler, and system-configuration 
programs. System maintenance is also 
available. Software that runs under 
this system includes a C compiler, 
Pascal, word processors, a debug 
package, and BASIC. UniFLEX is 
available for 6809 and 68000 sys- 
tems. The price is S450 for the 6809 
version. Contact Technical Systems 
Consultants Inc, POB 2570, 1208 
Kent Ave, West Lafayette IN 47906, 
|3l7) 463-2502. 

Circle 432 on inquiry card 



March 1981 © BYTE Publications Inc 343 



What's New? 



SOFTWARE 



FORTRAN and COBOL 

for the Apple II 

with the SoftCard 

The Apple II can now have FOR- 
TRAN and COBOL thanks to Micro- 
soft Consumer Products. Both lan- 
guages run under the CP/M oper- 
ating system and are designed to be 
used with Microsoft's SoftCard. 
FORTRAN-80 can compile several 
hundred statements per minute in a 
single pass. The FORTRAN compiler 
creates true Z80 machine code and 
supports double-precision, integer X4 
and integer XI data types. The 
FORTRAN-80 package includes the 



compiler, a linking loader, and a 
user's manual. It also requires 48 K 
bytes of memory and a floppy-disk 
drive. The suggested price is S 195. 

COBOL-80 includes sequential, 
line-sequential, relative, and indexed- 
sequential data files. Program chain- 
ing with parameter passing allows 
systems control from within COBOL 
applications. The program supports 
String, Unstring, Compute, Search, 
Perform, and Varying/Until verbs; ab- 
breviated and compound conditions; 
ASCII (American Standard Code for 
Information Interchange], packed 
and binary data formats; run-time 
assignment of file names; full Copy 



facility; and packed-decimal data for- 
mat. The COBOL-80 package in- 
cludes the compiler, linking loader, 
macroassembler, library manager, 
cross-reference assembler, and docu- 
mentation. It runs on the Apple II 
with SoftCard, 48 K bytes of 
programmable memory, and two disk 
drives. The suggested price is S750. 
For complete details, contact Micro- 
soft Consumer Products, 400 108th 
Ave NE, Suite 200, Bellevue WA 
98004, (206) 454-1315. 

Circle 433 on inquiry card 



Remote Batch 
Terminal Emulator 

The Remote Batch Terminal 
Emulator, RBTE, allows Z80 systems 
to emulate an IBM 3780. 2780. 2770. 
374 1 , or 2968 remote batch terminal. 
It provides the ability to transfer data 
files to and from mainframe com- 
puters or other remote batch ter- 
minals. Data rates up to 19.2 kbps 
(thousand bits per second) can be set. 
IBM bisynchronous protocol, hard- 
ware diagnostics, dynamic terminal 
configuration, on-line communication 
trace, attended and unattended 
operation, and user-customization are 
featured. The RBTE runs under CP/M. 
OASIS, and other special operating 



systems for Z80 microcomputers. It is 
designed for TRS-80, Cromemco, 
North Star, Onyx, Gnat, Vector 
Graphic, Ithaca Intersystems. and 
other Z80 microcomputer systems. 
Versions are available for 8086, 
Z8000. and 68000 microprocessor- 
based systems. Software to emulate 
X.25 protocol is also available. The 
price for the RBTE is S500 for a single- 
use license. The operator manual and 
the programmer manual are available 
for S25 and SI 5, respectively. For 
complete details, contact Winter- 
halter and Associates Inc. 3825 Zeeb 
Rd. Dexter Ml 48130, (313) 
665-5582. 

Circle 434 on inquiry card 



This Program Moves 

Files Through VlslCalc 

VU #3 is a utility program for Per- 
sonal Software's calculating and 
bookkeeping program VisiCalc. 
VU #3 allows the user to enter data 
into VisiCalc from any program by in- 
serting data into an array defined by 
VU #3. The program can transfer 
data generated from VisiCalc into any 
of the user's programs through 
another array as defined in the in- 
structions. VU #3 runs on the Apple 
II. It is available from Progressive Soft- 
ware. POB 273, Plymouth Meeting 
PA 19462. 

Circle 435 on inquiry card 



Wordbank for 

the TRS-80 Model II 

The Wordbank is a word-pro- 
cessing program for writing letters, 
reports, manuals, or other documents 
on a one-time or repetitive basis. Up 
to 7500 document lines are available; 
lines may be added, changed, or de- 
leted; page control is user-assigned or 
automatic; and automatic line num- 
bering and pagination are included. 
Wordbank requires a TRS-80 Model II 
with 64 K bytes of programmable 
memory, one floppy-disk drive, and a 
printer. Wordbank is available from 
Taranto and Associates Inc. POB 
6073. 121 B Paul Dr. San Rafael CA 
94903, (415) 472-2670. for SI 49.95. 

Circle 436 on inquiry card 



Pascal Data Base 

Written In UCSD Pascal 

The Pascal Database can be used 
for mailing lists, accounting, inven- 
tory, job estimates, sales analysis, and 
property management. The data base 
can update, search, and traverse 
data-base files; sort on multiple fields; 
and maintain records in several sorted 
orders. There is user-programmable 
screen formatting and automatic in- 
dexing of information at data entry. 
Users can define file, record, and field 
names. Reports can also generated. 
The Pascal Database for the Apple II 
costs S400, and it is available from 
Arizona Computer Systems Inc. POB 
125, Jerome AZ 86331. (602) 
634-7301. 

Circle 437 on inquiry card 



General Ledger System 
for Prodigy Computers 

Prodigy Systems has a small- 
business accounting package with a 
general-ledger program for its com- 
puters. Features include a user-de- 
fined chart of accounts, current 
balances, audit trail, and the ability to 
produce comparative statements. The 
system allows users to format their 
own reports. The reports include ac- 
count charts, general ledger, trial 
balance, income statements, balance 
sheets, and transaction proof listings. 
The general-ledger system includes 
accounts receivable, accounts pay- 
able, and payroll packages. Contact 
Prodigy Systems Inc. 497 Lincoln 
Hwy. Iselin NJ 08830. (201) 

283-2000. Circle 438 on inquiry card 



344 March 1981 © BYTE Publications Inc 




MC/t. 



P.O. Box 4430X 
Santa Clara, CA 95054 



ELECTRONICS 



INTEGRATED CIRCUITS 



Will calls: 2322 Walsh Ave. 
(408) 988-1640 TWX 910-338-2139 
Sameday shipment. First line parts only. Factory tested. 
Guaranteed money back. Quality IC's and other compo- 
nents at factory prices. 



740irnL 

740DN 

7J02N 
7J04N 
71C9N 
7J10N 
74I4H 



7430N 
7J42N 
7445N 
7447N 
7J4BN 
7450N 
7474N 
7475N 
7485N 
74B9N 
7490N 
7492N 
7S93N 
7495N 
74100N 
74I07N 
74121N 
74I23N 
74125N 
74145N 
74150N 
74151N 
74154N 
74157N 
74161N 
7416JN 
7J 1 63N 
74I74N 
74175N 
74190N 
74192N 
74193N 
74221N 
7429BH 
74365N 
74366N 
74367N 

74LS00 TTL 

74LS0QN 

74LS02N 

74LS04N 

74LS05N 

74LS08N 

74LS10N 

74LS13N 

74LS14N 

74LS20N 

74LS22N 

74152BN 

74LS30N 

74LS33N 

74L53BN 

74L.S74N 

74LS75N 

74LS90N 

74LS93N 

74LS9SN 

74LS107N 

74LS1I2N 

741S113N 

74LS132N 

74LSI36N 

74LS!5IN 

74LS155N 

74LS157N 

74LS162N 

74L5163N 

74LS174N 

74LS190N 

74LS221N 

74LS2SSN 

74LS367N 

LINEAR 

CA3045 

CA304E 

CA30B1 

CA30B2 

CA3089 

LM301AN/AH 

LM3D5H 

LM307N 

LM30BN 

LM309K 

LM3I1H/N 

LM317T 

IM3I7K 

LM310 



C04D2E 
CO4027 

const 

C04029 
C0403D 
CD4035 
C04040 
CD4C12 
CD40J3 
CO4044 

CO40I6 

CD4D49 
CD4D5C 

C04051 

CD4Q6C 

CD40E6 

CD40EB 

CD40E9 

CO4D70 

C04071 

CD4072 

C04073 

C04075 

C04D76 

CD4Q78 

CD40B1 

CD4082 

CD4116 

CO4490 

C04507 

CO450B 

CD4510 

CD4511 

CD4515 

C045IE 

CD451B 

CD452C 

CD4527 

CD452B 

CD4553 

CD45B6 

CD45B3 

C04585 

C040192 

74CO0 

74C04 

74C10 

74C14 

74C20 

74C3Q 

74C48 

74C74 

74C76 

74C90 

74C93 

74C154 

74CI60 

74C175 
74C192 
74C221 
74C905 
74C906 
74C9I4 

65 74C922 

60 A la D CONIfERTEfl 74C923 
74C925 
74C956 
7tC92! 



LM32DK-5 
LM3ZDK-1Z 

LM320K 15 

LM320T-5 

LM320T-B 

LM320T-12 

LM320T-I5 

LM323K5 

LM324N 

LM339N 

I.M340K-S 

LM340K-B 

LM340X-12 

LM340K-15 

LM340K-24 

LM340T-5 

LM340T-B 

LM340T-12 

LM34DT-15 

LM340T-1B 

LM340T-24 

LM3SO 

LM377 

LM379 

LM3B0N 

LM39I 

LM3B2 

LM709H 

LM723H/N 

LM733N 



LM747H/N 

LM74BN 

LMI3C3N 

LM13B4 

LMI305 

LM1307 

LMI310 

LM145B 

LMI8I2 

LM1B89 

IH2111 

LM2902 

LM3900N 

LM3905 

LM3909N 

MC145BV 

NE550N 

NE555V 

NE556A 

NES65A 

NES66V 

NES67V 

NE5708 

78L05 

78L08 

7BMC5 

75108 

75491CN 

75492CN 

75494CN 



21141450ns 4.00 

4116 200ns 4.50 
8,'4116 2Q0ns26.95 

MM5262 .40 

MM5280 3.00 

MM532Q 9.95 

MM5330 594 

P0411D-3 4.00 

PD4UD-4 500 

P5101L B.95 

4200A 9.95 

B2S25 2.90 

91L02A 1.50 

HD0165-5 6.95 

MM57100 4.50 

GIAY38500-1 9.95 

MCM66751A 9.95 

9368 3.50 



BBpin edge 4 00 

100pm edge 4. SO 

100 pin Edge WW 5 25 

IC SOCKETS 

Solrtef Tin Law Profile 
FIN tUP PIN 1UP 



20 29 40 



WIRE WHAP LEVEL 3 



KEYBOARDS 

56 key ASCII keyboard kil 
Fully assembled 
" iy ASCII Kybosrd kil 
assembled 



Fuiy 
Em 

Mclai Em 



I! 




CLOCKS 






MM53M 


5 VI 


CRYSTALS 


MM5312 


inn 


1 MHJ 


MM5314 


3 90 
















MM5B65 


















MM5375AA/I- 


3 90 




MM5375AG/A 


4 90 






16 50 










7208 






7209 


4 95 












3 75 


3.2788 MHJ 






5 0688 Mm 



Green. Orange. Yellow Jumbo 25 

Cllpllll LEO Mounting Clip' B/S1 25 
Ispealy red, amb«r. green, yellow, deaf] 

CONTINENTAL SPECIALTIES In I to CI 
Campleie line ot Breadboard lesi equip 
MAX-100 8 dlgll Freq. CI;. IMS. US 

OK WIRE WRAP TOOLS!* HOC* 

Poitibiu Multimeter 118.00 

CompioK Una ot AP Product* in Hack. 

SPECIAL PRODUCTS 
MM5B65 Stopwatch Timer 

with 10 po spec 9 00 

PC bbjrd 7 SO 

SwHchH Mom Pushbunon 27 



5 11 



iMHt. 



B700U 

B701CN ; 

B750CJ 

LO130 

9400CJV/f 

ICL7103 

ICL7107 I 

CMOS 
C0400Q. 
CO4D0I 
C04002 
CD400E 
CD4007 
CO4O08 
CD4009 
C04010 
CD40II 
C040I2 
COJ0I3 
C04OI4 
CD4015 
C0401E 
CO4017 
CD4018 
C040I9 
CO4020 

C04021 

CD4022 
C04023 
C04024 
C04025 



8228 4 95 

8251 8 95 

B253 15.00 

8255 5 75 

8257 10 95 

8259 14 95 

1802CP : a 13 95 
1802DPpUs 17.95 
1S6IP 9 SO 

COPt802C0 28 95 
CDP1B02O 35 00 
CDPIBIEP 7 95 



5.7143 MHl 4 50 

6.5536 MHl 4.50 

T4 31818 MH: 4 25 

18 432 MHl 4 50 

22.1184 MHl 4 SO 

KETBOAHD ENCODERS 

AY5-2376 S12 SO 

AY5 3600 17.95 

AY5-91O0 1050 

AY5-92O0 '6 50 

74C922 5.50 

74C923 550 

HO0I6S-5 6.95 

AY5-9400 10 50 
Canntdan HS232 

OB25P 3.62 

0825S 5.20 



DE9S 
DA15P 
DA15S 
Compiele Set 



:■ ■ 



TRANSFORMERS 



12V 500 ma wall plug 4 

12V 1 amp wall plug B 
10/15 VACB/1EVAwallpl<ig 9 
DISPIAYLEOS 

MAN1 CA 270 2 

MAN3 CC 125 

MAN72/74 CA'CA 300 1 

DL704 CC 300 1 

OL7O7/OL707R CA 300 1 

0L727/72B CA/CC 500 1 

0L747/75B CA/CC I 



INTERFACE 
8095 

6097 



8!28 
ST97 
6T98 



2102-1 
2102AL-4 
21D2AN-2L 
2104A-4 



.75 2114 3.75 

28 2114L300n!4 25 



.65 UAHT/FIFO 

65 AY5-1013 

65 AY5-1014 

65 3341 
1 25 

4 50 PROM 
3 00 1702A 

5 50 2708 

3 10 2716T1 

3 50 2716 5 Veil 

3 20 8/2716 5 Vol 

1 69 2732 

2 75 2758 
1.69 B741A 
1.69 B74B 

8748-8 

8755A 

RYRAMN82S23 

3 B5 N82S123 
95 NB2512E 

1.45 N82S129 

1.65 N82S131 

4.95 NS2S136 

375 NB2S137 

3 75 DM8577 

3.95 8223 



X.(i.ol3ft01gltLEDmul- 
llmiler B9.95 

StapwltcriKII 26.95 

Aula Clack KM 17. SS 

Digital Clack KI1 14.95 

■KlIK Eprom Kit 
Dllt PROMS) SB9.00 

Motliinaird $39 00 

Eiltiufir lairi SI5 00 



RESISTORS V. 


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:rlype 


01 




25 




(IV, 




100 i 


ll lype 


(IIS 




1000 




(117 




35 D piece pack 




5 per tyoe 6.75 




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5% oo 


(ype 


05 



FND35S 

FNOSO&507 

FND50J/5I0 

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3 digit Bubble 

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FIL31 1 Hb. 

MAN3640 

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MAN4710 

MAN4740 

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MAN67I0 

MAN67AD 



CC 357 

COCA SOO l 

CC/CA 500 

CC/CA ODD 2 



CC 30 
CA 40 
CC 40 



CC 40 1 20 

CC 50 2 05 

CA 60 l 35 

CC GO 135 



MAID02A, C, E 

MA1017A 

10 2P3 tnnltofnw 

MA1D12A TrinilDrmer 



6-positiOn 

7-positioo 



.05 



Complin llntpl HabbrBloi tol- 
dBrlpn hitidbpanjl In Hack. 
IC SlAilei Pack S5.93 

Disciele Componenl Steriei Pick 
tf.57 



PROM Eraser 

assembled. 25 PROM capacity $37.50 
(with timer $69.50). 6 PROM capacity OSH/V 
UL version $69.50 (with timer $94.50). 

Z80 Microcomputer 

16 bitl/O, 2 MHz crock. 2K RAM. ROM Bread- 
board space. Excellent for control. Bare Board 
$28.50. Full Kit $99.00. Monitor $20.00. Power 
Supply Kit $35.00. Tiny Basic $30.00 

S-100 Computer Boards 

BK Static Godbout Econo IIA Kit 149.00 
16K Static Godbout Econo XIV Kit 269.00 
24K Static Godbout Econo XX-24 Kit 414.00 
32K Static Godbout Econo XX-32 Kit 537.00 
16K Dynamic RAM Kit 269.00 

32K Dynamic RAM Kit 326.00 

64K Dynamic RAM Kit 399.00 

Video Interface Kit $139.00 

80 IC Update Master Manual $39.00 

Comp. ICdataselector, 2700 pg. master reference 
guide. Over 51. 000 cross references. Free update 
service through 1980. Domestic postage $3.50. 

Modem Kit $60.00 

State of the art, orig., answer. No tuning neces- 
sary. 103 compatible 300 baud. Inexpensive 
acoustic coupler plans included. Bd. only $17.00. 

LRC 70004 Printer $389.00 

40/20 column dot matrix impact, std. paper. 
Interlace all personal computers. 

64/40/32/20 version $405.00. Optional cables 
available. 

LRC 7000 printer Interface cable lor Super Ell 
with software $35.00 



NiCad Battery Fixer/Charger Kit 

Opens shorted cells that won't hold a charge 
and then charges them up, all in one kit w/full 
parts and instructions. $7.95 

Rockwell AIM 65 Computer 

6502 based single board with full ASCII keyboard 
and 20 column thermal printer, 20 char, alphanu- 
meric display, ROM monitor, fully expandable. 
$405.00. 4K version $450.00. 4K Assembler 
$85.00, 8K Basic Interpreter $100.00. 

Special small power supply for AIM65 assem. in 
frame $54.00. Complete AIM65 in thin briefcase 
with power supply $499.00. Molded plastic 
enclosure to fit both AIM65 and power supply 
$47.50. Special Package Price: 4K AIM, 8K Basic, 
power supply, cabinet $625.00. 

AIM65/KIM/VIM/Super Elf 44 pin expansion 
board; 3 female and 1 male bus. Board plus 3 
connectors $22.95. 

60 Hz Crystal Time Base Kit $4.40 

Converts digital clocks from AC line frequency 
to crystal time base. Outstanding accuracy. 

Video Modulator Kit $9.95 

Convert TV set into a high quality monitor w/o 
affecting usage. Comp. kit w/full instnje. 

Multi-volt Computer Power Supply 

8v 5 amp, ±18v .5 amp, 5v 1.5 amp, -5v 
.5 amp, 12v .5 amp, -12v option. ±5v, ±12v 
are regulated. Basic Kit $29.95. Kit with chassis 
and all hardware $43.95. Add $4 .00 shipping . Kit 
of hardware $14.00. Woodgrain case $10.00. 
$1.50 shipping. 



RCA Cosmac 1802 Super Elf Computer $106.95 



Compare features before you decide to buy any 
other computer. There is no other computer on 
the market today that has all the desirable bene- 
fits of the Super Elf for so little money. The Super 
Elf is a small single board computer that does 
many big things. It is an excellent computer for 
training and for learning programming with its 
machine language and yet it is easily expanded 
with additional memory, Full Basic, ASCII 
Keyboards, video character generation, etc. 

Before you buy another small computer, see if it 
includes the following features: ROM monitor; 
State and Mode displays; Single step; Optional 
address displays; Power Supply; Audio Amplifier 
and Speaker; Fully socketed for all IC's; Real cost 
of in warranty repairs: Full documentation. 
The Super Ell includes a ROM monitor tor pro- 
gram loading, editing and execution with SINGLE 
STEP lor program debugging which is not in- 
cluded in others at the same price. With SINGLE 
STEP you can see the microprocessor chip opera- 
ting with the unique Quest address and data bus 
displays belorc, during and alter executing in- 
structions. Also, CPU mode and instruction cycle 
are decoded and displayed on 6 LED indicators. 

An RCA 1861 video graphics chip allows you to 
connect to your own TV with an inexpensive video 
modulator to do graphics and games. There is a 
speaker system included for writing your own 
music or using many music programs already 
written. The speaker amplifier may also be used 
to drive relays for control purposes. 



plus load, reset, run, wait, Input, memory pro- 
tect, monitor select and single step. Large, on 
board displays provide output and optional high 
and low address. There is a 44 pin standard 
connector slot for PC cards and a 50 pin connec- 
tor slot tor the Quest Super Expansion Board. 
Power supply and .sockets tor all IC's are in- 
cluded in the price plus a detailed 127 pg. instruc- 
tion manual which now includes over40 pgs. of 
software info, including a series of lessons to 
help get you started and a music program and 
graphics target game. Many schools and univer- 
sities are using the Super Elf as a course of study. 
OEM's use it for training and R&D. 
Remember, other computers only offer Super Elf 
features at additional cost or not at all. Compare 
before you buy. Super Ell Kit $106.95, High 
address option $8.95, Low address option 
$9.95. Custom Cabinet with drilled and labelled 
plexiglass front panel $24.95. All metal Expan- 
sion Cabinet, painted and silk screened, with 
room for 5 S-100 boards and power supply 
$57. 00. NICad Battery Memory Saver Kll$6. 95. 
All kits and options also completely assembled 
and tested. 

Questdata, a software publication for 1602 com- 
puter users is available by subscription for 
$12.00 per 12 issues. Single issues $1.50. Is- 
sues 1-12 bound $16.50. 
Tiny Basic Cassette $10.00, on ROM $38.00, 
original Elf kit board $14.95. 1802 soltware; 
Moews Video Graphics $3.50. Games and Music 
$3.00, Chip 8 Interpreter $5.50. 



A 24 key HEX keyboard includes 16 HEX keys 

Super Expansion Board with Cassette Interface $89.95 



This i s truly a n astounding value! This board has 
been designed to allow you to decide how you 
want it optioned. The Super Expansion Board 
comes with 4K of low power RAM fully address- 
able anywhere in 64K with built-in memory pro- 
tect and a cassette Interface. Provisions have 
been made for all other options on the same 
board and it fits neatly into the hardwood cabinet 
alongside the Super Elf The board includes slots 
for up to 6K ot EPROM (2706. 2756, 2716 or Tl 
2716) and is fully socketed. EPROM can be used 
forthemonitorand Tiny Basic or otherpurposes. 
A IK Super ROM Monitor $19.95 is available as 
an on board option in 2708 EPROM which has 
been preprogrammed with a program loader/ 
editor and error checking multi file cassette 
read/write software, (relocatable cassette file) 
another exclusive from Quest. It includes register 
save and readout, block move capability and 
video graphics driver with blinking cursor. Break 



Quest Super Basic V5.0 

A new enhanced version of Super Basic now 
available. Quest was the first company 
worldwide to ship a full size Basic for 1802 
Systems. A complete function Super Basic by 
Ron Cenker including floating point capability 
with scientific notation (number range 
±.17E 3 "), 32 bit integer ±2 billion; multi dim 
arrays, string arrays; string manipulation; cas- 



points can be used with the register save feature 
to isolate program bugs quickly, then follow with 
single step. If you have the Super Expansion 
Board and Super Monitor the monitor is up and 
running at the push of a button. 
Other on board options include Parallel Input 
and Output Ports with lull handshake. They 
allow easy connection ot an ASCII keyboard to the 
input port. RS 232 and 20 ma Current Loop for 
teletype or other device are on board and if you 
need more memory there are two S-100 slots for 
static RAM or video boards. Also a 1K Super 
Monitor version 2 with video driver for full capa- 
bility display with Tiny Basic and a video interface 
board. Parallel I/O Ports $9.85, RS 232 $4.50, 
TTY 20 ma l/F $1.95, S-100 $4.50. A 50 pin 
connector set with ribbon cable is available at 
$15.25 for easy connection between the Super 
Ell and the Super Expansion Board. 
Power Supply Kit tor the complete system (see 
Multi-volt Power Supply). 



Ohio Scientific Computers 

CIP Series 2 $455.00. Like an Apple at less than 
halt the price! CIPMF Series 2 $1199.00. 
Minifloppy version with additional RAM/ROM. 
Complete software and peripherals available. 
Send for free brochure. 



Gremlin Color Video Kit $69.95 

32 x 16 alpha/numerics and graphics; up to 8 
colors with 6847 chip; 1K RAM at E000. Plugs 
into Super Elf 44 pin bus. No high res. graphics. 
On board RF Modulator Kit $4.95 



1802 16K Dynamic RAM Kit $149.00 
Expandable to 32K. Hidden refresh w/clocks up to 4 
MHz w/no wait states. Addl. 16K RAM $63.00 
Tiny Basic Extended on Cassette $15.00 
(added commands include Stringy, Array, Cas- 
sette I/O etc.) S-100 4-Slot Expansion S 9.95 
Super Monitor Vl.l Source Listing $15.00 



sette I/O; save and load, basic, data and ma- 
chine language programs; and over 75 state- 
ments, functions and operations. 
New improved faster version including re- 
number and essentially unlimited variables. 
Also, an exclusive user expandable command 
library. 

Serial and Parallel I/O included. 
Super Basic on Cassette $55.00. 



Elf II Adapter Kit $24.95 

Plugs into Elf II providing Super Elf 44 and 50 pin 
plus S-100 bus expansion. (With Super Ex- 
pansion). High and low address displays, state 
and mode LED's optional $18.00. 



Super Color S-100 Video Kit $129.95 

Expandable to 256 x 192 high resolution color 
graphics. 6847 with all display modes computer 
controlled. Memory mapped. 1K RAM expanda- 
ble to 6K. S-100 bus 1802, 8080, 8085, Z80 etc. 
Dealers: Send lor excellent pricing/margin 
program. 

Editor Assembler $25.00 

(Requires minimum nf 4K for E/A plus user 
source) 

1802 Tiny Basic Source listing $19.00 

Super Monitor V2.0/2.1 Source Listing $20.00 



TERMS: $5.00 min. order U.S. Funds. Calil residents add 6% tax. 

$10.00 min. BankAmericard and Master Charge accepted. $1.00 insurance optional. 
Postage: Add 5%. COD. $10.00 min. order. 



FREE: Send lor your copy ol our NEW 1980 
QUEST CATALOG. Include 48c stamp. 



Circle 81 on Inquiry card. 



BYTE March 1981 345 



What's New? 



PUBLICATIONS 



BYTE Books Brings 

You Two Books from 

Steve Garcia 

Ciarcia's Circuit Cellar, Volume II, 

is a collection of articles from BYTE. 
The book tells you about microcom- 
puters and how you can use them in 
various environments. Construction 
projects show you how to build a 
computer-controlled home-security 
system, computerize home appli- 
ances, make an inexpensive joystick, 
send digital information over a light 
beam, and explore the Intel 8086 
microprocessor system-design kit. 
Each project is presented in such a 
way that even beginners should 
have little trouble making and enjoy- 
ing these useful devices. Ciarcia's Cir- 
cuit Cellar, Volume II, costs S 1 1 .95. 
Build Your Own Z80 Computer is 
for the engineer, computer techni- 
cian, student, and anyone interested 
in building his or her own computer. 
The computer is based on the Zilog 
ZBO microprocessor. Each computer 
subsystem (ie: I/O, serial interface, 
keyboard, memory, etc) is fully ex- 
plained and supported by proven de- 
sign and testing information. The 
board contains a 2 K-byte operating 
system, serial and parallel ports, hexa- 
decimal display, and audio-cassette 
mass storage, with expansion to in- 
clude a video terminal. You can 
modify this system to meet your in- 
dividual needs. All required compon- 
ents are readily available and have 
been selected to allow simple system 
checkout. This book costs SI 5.95. 
Both books by Steve Ciarcia are 
published by BYTE Books, 70 Main St, 
Peterborough NH 03458, |B00) 
258-5420; in New Hampshire (603) 
924-9281. 

Circle 439 on inquiry card 



Microcomputer and 
Minicomputer Supplies 

Daily Business Products Inc's 
68-page catalog features supplies and 
accessories for all microcomputers, 
minicomputers, and word-processing 
systems. For a free copy, contact 
Daily Business Products Inc, 464 New 
York Ave, Huntington NY 1 1 743, 
(800) 645-5332; in New York (212) 
594-8065. 

Circle 440 on inquiry card 



1981 Radio 
Shack Catalog 

Radio Shack's 1981 catalog is 
available free at Radio Shack stores 
and dealers. The catalog features 
computer and stereo equipment, toys 
and electronic games, plus parts and 
accessories for home entertainment, 
or hobbyists and experimenters. The 
TRS-80 Pocket Computer, the Color 
Computer, the Model III system, six 
new stereo receivers, five cassette 
tape decks, twelve new telephone 
products, home-alarm systems, and 
thirteen new electronic calculators are 
among the items in the catalog. 

Circle 441 on inquiry card 



Datapro Directory 
of Small Computers 

This guide is designed to help data- 
processing professionals and man- 
agers locate, compare, and evaluate 
small-computer systems, software, 
peripherals, services, and the com- 
panies that manufacture and distri- 
bute them. This directory service is up- 
dated monthly. More than 200 micro- 
computer systems are reported on, 
with each report giving a summary of 
current models, memory size, base 
price, primary uses, popular options, 
principal applications, and more. The 
reports have details on hardware 
specifications, such as the processor 
used, memory, display, keyboard, 
direct-access storage, printers, data 
communications, and I/O electronics. 
Software information covers lan- 
guages, operating systems, data- 
base-management systems, and ap- 
plications programs. An applications 
index, a section on advice and guide- 
lines on purchasing, a listing of over 
16,000 companies, and sections on 
computer concepts, user ratings, and 
user groups are included. The sub- 
scription rate is S330. Each sub- 
scription to the Datapro Directory of 
Small Computers includes two vol- 
umes, 12 monthly supplements, 12 
monthly newsletters, and use of a 
telephone-inquiry service. Contact 
Datapro Research Corporation, 1805 
Underwood Blvd, Delran NJ 08075, 
(609) 764-0100. 

Circle 442 on inquiry card 



Time-Sharing and 

Remote-Computing 

Services Report 

Details on 11 7 remote-computing 
services, including results of a user 
survey, are available in this report 
from Datapro Research Corporation. 
All About Time-Sharing and Remote 
Computing Services gives you the 
name of the service, areas currently 
served, type of computer, number of 
simultaneous users, conversational 
and batch terminals supported, pro- 
gramming languages, principal appli- 
cations, and pricing information. A 
listing of vendors is included. The 
report provides a discussion of user 
benefits and disadvantages, a guide 
for evaluation and selection of re- 
mote-computing services, and an in- 
dex of application programs and user 
programming aids. The report is avail- 
able for S 1 5 per copy from Datapro 
Research Corporation, 1805 Under- 
wood Blvd, Delran NJ 08075. (609) 
764-0100. 

Circle 443 on inquiry card 



Packaging and 

Breadboardlng 

Materials Brochure 

A brochure from Vector Electronic 
Company Inc describes 1 09 electronic 
packaging and breadboarding prod- 
ucts available at electronic and per- 
sonal-computer component stores. 
Highlighted are microcomputer inter- 
face boards, Vector products, mother- 
boards, cases, tools, wiring terminals, 
and kits. A price list is included. Con- 
tact Vector Electronic Company Inc, 
12460 Gladstone Ave, Sylmar CA 
91342,(213)365-9661. 

Circle 444 on inquiry card 



SDK-85 Experiments 

The 8085 Microprocessor— Fun- 
damentals and Applications: 76 
Control Experiments with the Intel 
SDK-85, by Dr Howard Boyetis avail- 
able from MTI, 1 4 E 8th St, New York 
NY 10003, (212) 473-4947. Other 
books from MTI describe hands-on 
experiments with the 8080, 8085, 
and 8048 microprocessors. 

Circle 445 on inquiry card 



346 March 1981 © BYTE Publicalions Inc 



A-D & D-A CONVERTER 



Z80 MICROCOMPUTER 



6522 APPLE II INTERFACE 



'it 




JBE A-D & D-A Converter can be used 
with any system having parallel ports 

• Interfaces with JBE Parallel I/O Card 

• D-A conversion time — 5 jjls • A-D 
conversion time — 20 fis • Uses JBE 
5V power supply • Parallel inputs & 
outputs include 8 data bits, strobe 
lines & latches • Analog inputs & out- 
puts are medium impedance to 5 volt 
range. JmM 



79-287 

Bare Board $29.95 



ASSM. $79.95 
Kit $59.95 



6502 MICROCOMPUTER 




This control computer has: • 1024 
bytes RAM (two 2114s) • 2048 bytes 
EPROM (2716) • Uses one 6522 VIA 
(comp. doc. incl.) • Interfaceswith JBE 
Solid State Switches & A-D & D-A Con- 
verter «Uses JBE 5V power supply 
• 2716 EPROM available separately 
(2716 can be programmed with an 
Apple II & JBE EPROM Programmer & 
Parallel Interface) • 50 pin connector 
included in kit & assm. 



80-153 

Bare Board $24.95 



ASSM. $110.95 
Kit$ 89.95 



SOLID STATE SWITCH 




Your computer can control power to 
yourl,printer, lights, stereo & any 
120VAC appliances up to 720 watts (6 
amps at 120VAC). Input 3 to 15VDC 
• 2-14MA TTL compatible • Isolation 
— 1500V • Non zero crossing • Comes 
in 1 or 4 channel version • Includes 
doc. for interfacing with Dimmer Con- 
trol. 

79-282-1 ASSM. $13.95 

Bare Board $6.95 Kit $1 0.95 

79-282-4 ASSM. $49.95 

Bare Board $24.95 Kit $39.95 



APPLE II DISPLAY BOARD 





JBE is announcing a single board 
dedicated computer designed for con- 
trol functions. It features: • A Z80 
Microprocessor software compatible 
with the Z80, 8080 & 8085 
Microprocessors • Uses a Z80 PIO chip 
for I/O which has 2 independent 8 bit 
bidirectional peripheral interface ports 
with handshake & data transfer control 
• Uses one 2716 EPROM (2K)& two 2114 
RAM memories (1K) 'Single 5V power 
supply at 300MA req. 'Clock frequency 
is 2MHz, RC controlled • Board comes 
with complete doc. • 50 pin connector is 
included • 2716 EPROM available 
separately. 

10-280 ASSM. $129.9$ 

Bare Board $29.95 Kit $1 1 9.95 



DIMMER CONTROL 




JBE Dimmer Control features: • 4 
channels • 256 brightness levels • On- 
board power supply • Four 8 bit 
parallel input ports 'Interfaces with 
JBE Solid State Switch & Apple II 
Parallel Interface. 



80-146 

Bare Board $25.95 



ASSM. $89.95 
Kit $79.95 



POWER SUPPLIES 



• Use wall transformers for safety 
-•Protected against short circuit and 
thermal breakdown. 

5 VOLT POWER SUPPLY 
Rated at 5V 500MA • Operates JBE A-D 
& D-A Converter, Z80 & 6502 Microcom- 
puters, 8085 & 8088 Microcomputers. 
80-160 ASSM. $20.95 

Bare Board $8.95 Kit $16.95 

± 12 VOLT POWER SUPPLY 
Rated at ± 12V 120MA • Can be used as 
a single 24V power supply • Ideally 
suited to OP-AMP experiments. 
80-161 ASSM. $22.95 

Bare Board $8.95 Kit $18.95 



80-144 

Bare Board $25.95 



ASSM. $49.95 
Kit $42.95 



• Has run-stop, single 
step switch • Has 16 
address LEDs, 8 data 
LEDs & 1 RDY LED 

• All lines are buf- 
fered. 



ICS 



6502 
6522 
Z80 

Z80 PIO 
27165V 



$9.95 
$9.95 
$9.95 
$9.95 
$19.95 




• Interfaces printers, synthesizers, 
keyboards, JBE A-D & D-A Converter & 
Solid State Switches • Has handshak- 
ing logic, two 6522 VIAs & a 74LS74 for 
timing. Inputs & outputs are TTL com- 
patible. 

79-295 ASSM. $69.95 

Bare Board $22.95 Kit $59.95 



2716 EPROM PROGRAMMER 




JBE 2716 EPROM Pro- 
grammer was designed 
ito program 5V 2716 
EPROMS • It can also 
, re«id 2716s. It interfaces 
to the Apple II using 
JBE Parallel I/O Card & 
four ribbon cable con- 
nectors • An LED indicates when 
power is being applied to the EPROM 
• A textool zero insertion force socket 
is used for the EPROM • Comes with 
complete doc. for writing and reading 
in the Apple II or Apple II + • Cables 
available separately. 



80-244 

Bare Board $24.95 



ASSM. $49.95 
Kit $39.95 



BARE BOARDS 



APPLE II EXTENDER BOARD 

3Va" X 2 1 /z". Price includes 50 pin 

Apple Connector. 

80-143 $12.95 

8085 3 CHIP SYSTEM 

State-of-the-art system using an 8085, 
8156 & either an 8355; or 8755 

• Instruction set 100% upward com- 
patible with 8080A. 

Bare Board $24.95 

8088 5 CHIP SYSTEM 

An 8086 family microcomputer system 
using an 8088 CPU, 8284, 8155, 8755A 
& an 8185. 
Bare Board $29.95 

CRT CONTROLLER 

This intelligent CRT Controller is 
based on an 8085A Microprocessor & 
an 8275 Integrated CRT Controller. It 
features: • 25 lines, 80 characters/line 

• 5x7 dot matrix • Upper case only 

• Two 2716s • Serial Interface RS232 
& TTL • Baud rates of 110, 150, 300, 
600, 1200, 2400, 4800 & 9600 

• Keyboard scanning system • Req's. 
unencoded keyboard • Uses + 5V & 
± 12V power supplies. 

Bare Board $39.95 



50 pin connector 
STD. Dip Jumpers 
16 Pin, 2 ft. 



$5.95 
$4.25 



John Bell Eivgiiveeriivg 

ALL PRODUCTS ARE AVAILABLE FROM: JOHN BELL ENGINEERING • P.O. BOX 338 
DEPT 8 • REDWOOD CITY, CA 94064 • ADD 6% SALES TAX IN CALIFORNIA • ADD 5% SHIPPING & HANDLING 

(415)367-1137 



BYTE March 1981 



347 




SNTdldN 
SN7416N 
SN7417N 
SN7420N 
SN7421N 
SN7422N 
SN7423N 
SN742SN 
SN7426N 
SN7427N 
SN7429N 
SN7430N 
SN7432N 
SN7437N 
SN743BN 
SN7439N 
SN7440N 
SN7441N 
SM7442N 
EN7443N 
5N7444N 
SN7445N 
SN7446N 
SM7447W 
SM744BN 
SN7450N 
SN7451N 
SN7453N 
SN74S4N 
SN74S9N 
SN7460N 
SN7470N 
SN7472N 
SN7473N 
SM747-1N 
SN747SN 
SN7476N 
SN7479N 
SN74BON 
SN74B1N 
SN7482N 
EN74B3N 
EN7485N 
EN7486N 
SN74B9N 
SN7490N 
SN7491N 
SN7492N 
SN7493N 
SN7494N 
SN7495N 
SN7496N 



SN74109N 
SN74116N 
SN74121N 
SN74122N 



SN741B5N 
SN741B6N 
SN74188N 
SN74190N 
SN74191N 
SN74192N 
SN74193N 
SN74194N 
SN74195N 
SN74196N 
SN74197N 
SN74198N 
SN74I99N 
SN74221N 
SN74251N 
SN74273N 
SN74279N 
SN74283N 
SN74284N 
SN74285N 
5N74290N 
SN7429BN 



2.15 

3.90 
3.90 



CMOS 



CD4000 

CD4001 

CD4002 

CD40O6 

CD4C07 

CD4008 

CD4O09 

CD4010 

CD4011 

CD40I2 

CD4013 

CD4014 

CD4015 

CD4016 

CD4017 

CD4018 

CD4019 

CD4O20 

CD4021 

CD4022 

CD4023 

CD4024 

CD4025 

CD4027 

CD4028 

CD4029 

CD4O30 

CD4031 

CD4032 

CD4034 

CD4035 

CD4037 

CD40.I0 

CD4041 

CD4042 

CD4043 

CD4044 

CD4046 

CD4047 

CD 40-18 

CD.10.19 

CD4050 

CD4051 

CD4052 

CD.1053 

CD4055 

CD. 1056 

CD4059 

CD4060 

CD-1066 , 

CD4069 

CD4070 

CD4071 

CD4072 

CD4073 

CD4075 

CD4076 

CD4077 

CD4078 

CD40B1 

CD40B2 

CD40B5 

CD4089 



3 95 
2 95 
9.95 



CD4093 
CD4094 
CD4098 
CD4099 



M C 1 4 4 1 9 

CD4501 

CD4502 

CD4503 

CD4S05 

CD4506 

CD4507 

CD4508 

CD4510 

CD4511 

CD4512 

CD4515 

CD4516 

CD4518 

CD4520 

CD4555 

CD4556 

CD4566 

74C0D 

74C02 

74C04 

74C08 

74C10 

74C14 

74C20 

74C30 

74C32 

74C42 

74C4B 

74C73 

74C74 

74CB5 

74CB9 

74C90 

74C93 

74C95 

74C107 

74C151 

74C154 

7-1C157 

74C160 

74C161 

74C163 

74C16J 

74C173 

74C174 

74C175 

74C192 

74C193 

74CT95 

74C922 

74C923 

MM80C95 

f.T.'a0C97 



12.95 
12.95 
12.95 
12.95 
8.95 



2.49 
3 5G 
2 10 
2 39 
2.30 
2.39 
2.39 
2.59 
2 75 
2.75 
2 39 



ADVANCED 

COMPUTER 
PRODUCTS 



74LS78N 



74LSB3AN 
74LS85N 
74LS86N 
74LS90N 
74LS92N 
74LS93N 
74LS95N 



1LS96N 
ILS107N 
ILS109N 



ILS12SN 
ILS126N 
.LS132N 
.LS136N 
ILS138N 
.LS139N 



7.1LS155N 
74LS156N 
74LS157N 
74LS158N 
74LS160N 
74LS161N 
741S162N 
74LS163N 



74LS24BN 

74LS249N 

74LE251N 

74LS253N 

74LS257N 

74LS25BN 

74LS259N 

74LS260N 

74LE261N 

74LS266N 

74LS273N 

74LS275N 

74LS279N 

74LS2S3N 

74LS290N 

74LS293N 

74LS295N 

74LS29BN 

74LS324N 

74LS347N 

74LS34BN 

74LS352N 

74LS353N 

74LS363N 

74LS365N 

74LS366N 

74LS367N 

74LS368N 

74LS373N 

74LS374N 

74LS375N 

74LS377N 

74LS385N 

74LS386N 

74LS390N 

74LS393N 

74LS395N 

74LS399N 

74LS424N 

74LS668N 

74LS670N 

81LS95N 

81LS96N 



LINEAR 



LM10SH 
LM10SAH 
LM300H 
LM301CM/H 
LM304H 
LM305H 
LM306H 
LM307CN;H 
LM308CN/H 
LM309K 
LM310CN 
LM311D/CN/H 
LM312H 
L M 3 1 7 1 
LU318CN/H 
LM319N/H 
LM320K XX- 
LM320T-XX- 
LM320H-XX- 
LM323K 
LM324N 
LM339N 
LM340K-XX- 
LU340T-XX- 
LM340H-XX- 
LM344H 
LM34BN 
LM35BCN 
LM360N 
LM372N 
LM376N 
LM377N 
LU3B0CM/N 
LM381N 
LM383T 
LM36BN 
LM387N 
LU390N 
NE53W/T 
NE555U 
NE556N 
NE561T 
NE562B 
NE565N/H 
NE566HA/ 
NE567V/H 
NE592N 
LM702H 
LM709N/H 
LM710N/H 
LM71 1N/H 
LM715N 
LM723N/H 
LM733N/H 
LM739N 
LM741CN/H 
LM741CN-14 
LM747N/H 
LM748N/H 
LM760CN 
LM1310N 



M1820N 
M1850N 
M1889N 
M21 UN 
LM2900N 
L M 2 9 1 N 
L M 2 9 1 7 N 
CA3013T 
CA3018T 
CA3021T 
CA3023T 
CA3035T 
CA3039T 
CA3046T 
LM3053N 
CA3059N 
CA30eON 
CA3062N 
LM3065N 
CA3080N 
CA308 1N 
CA3082N 
CA3083N 
CA3086N 
CA3089N 
CA3096N 
CA3097N 
CA3130T 
CA3140T 
CA3146N 
CA3160T 
CA3 190N 
CA3401N 
MC3423N 
MC3'I60N 
SG3524N 
CA3600N 
LM3900N 
LM3905N 
LM3909N 
RC4131N 
BC4136N 
RC4 15 1N 
RC4 19-I 
BC4 195 
ULN2001 
ULN2003 
SN75450N 
SN75451 N 
SN75452N 
SM75453N 
SN75^154N 
SN75-191N 
SN75492N 
SM75493N 
SN75494N 



3 49 

299 
2 7 5 



2.49 
2 49 
2 49 



3 95 
3 95 
350 



RETAILSTORESOPEN MON-SAT 



BECKMAN 

Dicnr.il Multimeters 



p3 The TECH 300 has n' 

-$(C the abcte feaiurts. b 



I 

^( \ VC-201 Vinyl Carrying Cfl 

r^T-A DC-SOP Dclu.r C-irryinri < 

y*T \ HV-211 Mitjh V(!lt,it)i> P«, 

.' !\ RP-221 RP Probe 

""'*i\ Cl-P:U AC Curr-nl Cl.irm. 



TECH 300 Digital Multimeter . 
TECH 310 Digital Multimeter .. 
TECH 330 Digital Multimeter . 
VC-201 Vinyl Ciirrymn Case . 

e Probe 



<*?-' DL-241 Deli 
TL-242 Spare 



HP 




r MUSIC MACHINE 9* 

mm WITH 9 VOICES! 

• NEW Jses taint Slate ul me An LSI Tethnolngy • Rraunts 
oily tv sfo1(Di9m!Ce5 • Ui« Ihree Ari-8910 5 loprMuce 
nine voices • PiavsraiiSit censr au.miy iheALFFlcirfl • Alt 
sHIWKKSWted ■ APPlE'-llmrowtiDie 

ASSEMBLED AND TESTED 31 29.95 

FLOPPY DISK DRIVES 

Tandon TMlOO-l 5'V Di5h Drive ,. . 249 95 
MPI B51-5V.4Q tracks . , ,239.95 

Shugan SA400-5'.' 35 tr; lc k 5 . . 295.00 

Shugait800/801B 8" 475.00 

Siemens Shugan Conifiaiibte Model 

FDD-120-8D . .... 429 00 

PERSCI Model 277 Dual l 19500 

WANGO/SIEMENS SV Drive 290.00 

MPI B52 S"V Dual. 348.00 

WANGO/SIEMENS 2B2 Dual 5"." . . . . 395 00 

WANGO/SIEMENS 82 290.00 

MPI 9 1 Double Track Oensily Sinfle Side. 

80 Tracks 375.00 

MPI 92 Double Track Oensily Double Side. 

160 Tracks • ,475 00 

SUBCONTINENTAL SPECIALTIES 

Model LM-3 40-cliannel Logic Momlor 585 00 
Motftl LM-I Logic Monitot . 60 00 

Modtl LH-2 Logic Momlor 14700 

BHU-IOQ 100 MHz PorTabie Frequency Couniei 

. . . 14900 

Modtl LP-I Digital Logic Probe. . 50 00 

Model LP-Z Economy Logic Probe 38 00 

Model LP-3 High Speed Logic Ptobe . . . 7700 
Model LPK-1 Logic Probe Kil . 21.95 

Model LTC-1. LTC-2 Logical Analysis Kits . . .220/250 

a, y Proto Clips 

' .^> 11-Pin Clip PC-14 .,. S 41 
16-PinCiip PC-16 S 4t 

M-PinCl.p PC-24 S 9.50 

40-Pjn Clin PC-40 S14 9S 

Ptoto Boards 

1695 PB-ltW 5400 

00 18 00 P8-203 97.00 

PB-101 21 00 PB-20HA . 14900 

PB-102 25 00 PB-203A-Kil. 129.00 

PB-103 

SEMICONDUCTORS 

SPEAKA*^tV 

DIGITALKER" 

Speech Synthesis System 




Apple® II 16K 
Apple® II Plus 



DISK SYSTEM SPECIAL 

Apple II Plusw/48KSupermod Video Modulator 
Disk II w/Controller Integer Based ROM Card. 
ACP PRICE $1969.00 



$1150 



Centronics Printer I/O 
Applesoft II Firm* 
Apple Clock 
Ifitrol X-lG System 
Introl X-10 Controller 
All Music Synthesiser 
16 Ch Analog Inpul 
2 Cb Analog Output. 
13-Key Keypad 
Visi-Calc 



S18900 DS55 Dig.-Sector 



10.00 Apple Grannies Tab^i 

18900 DC Hayes Modem 11 

26900 CisMI wConlrtftB 1 Ob ill 

17995 oak 11 

26995 Pascal Lang System 

259.95 Parallel Printer Card 

249.95 Communications Card 

164.95 BuSinessSottwarePkg 

119.95 Cwvjs 10 Megabyte Onve 
12500 



534900 'nteger ROM Card 



67500 
I99i 



5-00 



Prcto Carfl 

M 6 R Modulate- 

Cassette. . . . ... 

16K Upg/arJe Kn 
450 00 Desktop Plan 
165 00 8" Floppy Conlrciier 
iB9 00 Hejfisncs Soeecmab 
62500 Romplus + 
Supertaiker 
Cashier 



^?.'. 



\appUz/// $39Q5 

• Aople III Option A: Apple II 96K. 

Inlormahon Analyst Package, • A PP'e l« Option C: Same as 

12" B/W Monitor S3995.00 Option A Plus: Disk II for Apple III. 

.Apple III Option B: Same as Siienlyp- Thermal Pr.nter . S4735O0 

Option A Plus: Disk 11 (or • TO Sbbslilule 1 2QK Apple III tor 

Apple III S4395.00 96K Apple III AddS'150 00 




NEW APPLE PRODUCTS 



tPPLE FAN**- [ 
iiT3*-NrwfH 



5 Iror 



JpW S.1995 

a Aople Complplely 
comwiitue with Pascal S3Z995 

1 HAfi WAND 1 Heihtetl Packard HEDS-3000 Bar Co* 

WeriiCB] la ADKe SI9900 

1 'SEC APPLE A/D"' - B Ctiannel A/TJ Interlace corroietely 
assembled arc! lestea S9950 

1 VISTA APPLE AC TRACK DISK ORIVE" Floppy AcH-ar, lor 

Apple PA" 8Q TPI S45900 

< APPLE FORTRAN" .... . 517500 

i APPLE CRYPTEXr la daia encryption and 

security S>U900 

i B2'A?" GraDhics Interlay Card by 6asc 2 SI5995 

' B" Dish Drives tor Appl e.Cwtloller. DOS. Twd S' 

dines caMM ard cacle .... SM5D0C 
i -MlCBOMODEM"- DC Hayes.. .. S3I995 

i 'OIGISECTOP 1 ConvEHSvifleo input to Hi-Res 

S3499S 



11 Revision Kil 2D«» ( 

dli'ig Add Hiatal error C 
d man al Venito lileei 



• ViSiCac Keypa 






neysad 



!. ESC. 

lir.paWli hly S16900 



S6500 

S55000 
i Pefticed 
S145B0 
S0500 

Avail Soon 
561900 

S3J9CC 



SS49CC 
a Coupv-ter Systems AI'PLE Cioc* 

S1J-J9 5 
Oca-d Iff APPLE CPM 22 I M BASIC 

53250C 
i Mfcrccoducts Keypa 



517500 



NEW APPLE SOFTWARE 



I CTBERSTKIKE- Apple II 



i "Bllh BimU"- Hi-Rcs SumialiM ot Western GunlinM 

andSkeet Srirolnig Sa.it aultilir as Nasir S2995 

5 ■ Afpitui Pinntr PkH;i" S7495 

•;■ 'Nev-dds t»i (or ;»-s-j- : . 

7 MEWIAPPK Z-60 EPVM Soliware Call lor Price 




ON A 
PLUG-IN CARD. 



EXPANSION CHASSIS 



A ATARI 800 & 400 

Personal Computer System 

ATARI 800 $825. OO 
ATARI 400 $449.00 




ATARI BOO Includes: Computer Console. BASIC Lang. Cartridge. Edu> 
System Master Cartridge, BASIC Language Programming Manual. 800 Opet 
I w/Notebook. 16K RAM Modulo. Power Supply, TV Switch Box 



ot 144 word.. S485.00 



Solium- fiOM CirHilm 



Ba5ic SX'tVQi 



S-asiC Gjh» Progtarrn 



9'aru D.ikenti 
Junius Cntniin 



SINGLE BOARD COMPUTER SELECTION GUIDE 



rRuCESsofl «cr 



ENCLOSURE 

Add ?y <J!i 

A(J() ^I'lS 



PROCESEDR ACP PRICE 

Z80 23!! 110 

6502 375(1(1 



Texas Instruments 



99/4 PERSONAL COMPUTER 

Superior Color. Music, Sound S Graphics - 
3, a Powerful Extended Basic- All Buill-ln 
Now' Special TV. ^ 

Adapter lets you use 
your existing T.V. set 
as a computer display. 



INTELLIVISION 

ACP LOW PRICE 

$259.95 

GAME CARTRIDGES 




-, CA 95131 • {408) 946-7010 



P.O. Box 1 7329 Irvine, Calif. 9271 3 

Direct Order Lines: (714) 558-8813 

(800) 854-8230 or (800) 854-8241 



FOR INTERNATIONAL ORDERS: 
1310 E. Edlnger (714) 953-0604 
SantaAna,CA92705 TWX:910-59S-1565 



348 BYTE March 1981 



Circle 275 on Inquiry card. 



^/PRODUCTS 



STATICX /RAM BOARDS 



• S-100 32K (uses 21 14) I^Tb^ 

ASSEMBLED Kit (&* P 

450ns. 389.00 450ns. 339.00 

250ns. 409.00 250ns. 359,00 

Bare Board 39,95 
Bare Board w/all parts less mem. 99.95 



MODEL 2065 

64 K DYNAMIC RAM 

MODULE $600.00 

• CHi^nrftOiEEE PriDCWd S l CO 

• SuccDcisiuSfil-iyiJefioilia^s 

• OWrairs wiih trillion 80S or a ^ 

Z-80 MSMS-tOCI system. 




on power-on and resel 

FLOPPY DISK 
CONTROLLER S400. 
ZBO CPU 
BOARD S300. 



■.# 



TRS80 ADD-ON 

The VISTA V-80 
Disk Drive System 

Mm for lm Speed. Cipictty. Prlca. 

IN Vlitt V-BD mini disk tytltm it S Until filler thin 

llii TRS-BO. 23% more iloiigi cipKlty. inri cot* leu. 

• Visia oners tl)?K bytes to Raft Shack's 89K That's 13K more Bytes per dnvr. 

• The V-BO operates at 12ms versus arjrn; lw TRS-8Q Out drive can operate 
a! 5ms. but wily 50% or TH5-S0 will ooerjte at that speed. I here lore. Vista haj 
puipcsiy set the access Sme at 12ms 

• Totally compatihle wilh all available disfc operating systems 

• Degraded system Increased storage and speed S2B9 OO 



VISTA DUALV-BO i 



S670.00 



THE VISTA V-200 FOR EXIDY 



V200 E-20 400 

woo E-22 aoo 



WOOE-30 SID 



ariinq as low as S 1 1 99.00 

limit C»i il:|MI 

CifKll Ci-IHinll 



i"j';it; 



MJJI=W=WI.VJJ=^J-VI.tY 



TRS 80 16K-UPGRADE KIT 



$49.95 TRS-80/APPLE $49.95 

MEMORY EXPANSION KITS. 

4116's, 16K (200/250 ns.) 

8 pes for $49.95 

w/instructions & jumpers 

Call For Volume Pricing 

* Special: TRS80 Schematic $ 4.95 

* Expansion Interface Schematic . . S 4.95 

* Expansion interface Connector. . . 7.95 



EXPANDORAM II MEMORY KITS 

* Bank Selectable * Uses 41 16 200 ns. 

• Wnte Protect n ug* Power 8VDC. ±16VDC 
+ Phantom «££si * Up to 4 MHz 

Expando 64 Kil (4116) Assem. & Tested Add S50. 
16K $249.00 48K S435.00 
^32K $289.00 64 K S50S.O0 




PERScfflSDEL^gT 

DISKETTE DRIVE 

3.2 Mbytes capacity 
(unformatted), max. seek 
time 100MS. 
ACP Price $2,199.00 

rom^i " ~ 



Pmfcssiona 1 Industrial Model 



raser 

Model UVS-11E $69.95 

Holds 4 Eprom'a at a lime. 

Backed by 45 years 

experience. 

Model S-52T... $265.00 



RAM BOARDS SPECIAL 

16K AltalrMltB Dynamic RAM Boards 
Assam. & Tea tod S119.95 Untestod S95.00 



16K 



154300 ' 

M?taa ) 

193900 



M 



CENTRONICS PRINTER 

Model 737 

• Centronics complete printer 

• The 737 has everything. Check 
and compare the features. 

• New low price $835.00 




The Vista V300 Printer 



ATTENTION VIDEO HOBBYISTS!!! 

* BOX BUILDERS 

* USE AS REMOTE TUNER/TIMER 

* FULL SCHEMATICS AVAILABLE 

* FOR ONLY $5.90! - FREE W/PURCHASE 

A Recent Soec.al Purchase Allows UsTo Present The Following 

NEW, UNUSED COMPONENTS 

From The RCA VDT-201 Vldeocissetle Recorder 

I U»n/VHF Turcr Subj5armblyw,lhallkr»l>s 

am Video DemcOu'.iror 559.95 

? RF MorVa \v *i:nAuJo I VCeo incys 

Chunrw 3D.4Duto.il S3B.95 



Subtoi.il $123.34 

** ' $74.95 

re m 95 Call For Volume Discounts 




LOW COST FLOPPY 
DISK SUBSYSTEM 

Siemens FDD 1 20B (2) VISTA Floppy Control- 
ler (S- lOOl. Case. Power Supply S Cable. CP/M 
Disk Operating System Assembled a ToSIOd 

Walnut Wood Sides S149B.0O 

• CHECK OUR FlOPn DISK PRICING ON THIS PAGE* 
SAVE S300.00 IS1799.00 VALUE) 



WATANABE MIPLOT 



IMS STATIC RAM BOARDS 

250 ns. 450 ns. 

8K Static S209.00 S189.00 

16K Sialic S449.00 ' S399.00 

32K Sialic S729.00 S629.00 



m£- SD SYSTEMS BOARDS 

S* TAKE 10% OFF! kit a 



SBC 100 Single 
SBC 200 Single 
ZBO Slailer Sys' 



S285 00 
299 00 
31900 
335 00 
325 00 
11500 



i 34900 
399 00 
449 00 
489.00 
429.00 
225 00 
699500 
7995 00 



DESCRi 
S-ngie 

Advanced Single BO Comp (68091 
16 SlotMolher Board 
aid Cage 



6600 MICROMODULE'" PRICE LIST 

MODEL NO DESCRIPTION PRICE 

9600A Single Board Micro com pule. S495 00 

9609 Advanced Single BO Comp (68091 S9S.00 

175 00 
7 5 00 
100 00 
275 00 
32500 
39 OD 
49500 
490D 
250 00 



B Slot Mot 



'. Suopiy 



9627 
9629 

9629A 
5 £10 
9640 
9650 
9655 
96103 
96702 



Senai-Parailel I/O Modui 
16K Sialic; RAM Module 
32K Stat.C RAM 450ns 
32K Static RAM 200ns 



32/32 I/O Module 
Contact Closure Module 
UNPOPULATED BOARDS rAiso * 



250 o 



39500 

695 00 
895 00 
6B00 
395 00 
395 
550 00 
27500 
350C0 



I 5*,«(..fiM"w. 




$1895 00 



BASE II PRINTER 



I5/230VAC.50 



WITH ALL OPTIONS 




EG S799.00 



$699. 



Z-80/Z-80A/8080 CPU BOARD 



2708 included (450ns 

* Power on jump * Completely socketed. 

• Z-SO Assembled and Tosled 



8080AKH 

8080A Assembled.. 



. .S1B5.00 
...S12995 
...S 3495 

.S 99.95 

■ S1 49.95 



S-100 MOTHERBOARD SPECIAL 

8 slot expandable w/9 conn. 

reg S69.95 NOW $52.95 



SIEMEN'S FLOPPY 

• Special buy while supply lasts. 

• 8" Drive with Double-Density 

• 90 Onv Warranty 

♦ CHECK OUR FLOPPY DISK PRICING! 
ON THIS PAGE 



SALE 

SIEMENS 
S429.00 
SHUGART 



ACOUSTIC MODEM 



'D' CAT MODEM 




NOW AVAILABLE 
$199.00 



Sanyo VM 4509 

9"B/W 169.00 

Sanyo VM 4212 

15" B/W 249.00 

Sanyo 6013 

13" Color 42900 

leede* 12" 149.00 



NTEL Data Book 



SALE • SYBEX COMPUTER BOOKS • SALE 



rheZSO 

IneZHOOO 
me 6502 



FIRST TO OFFER PRIME PRODUCTS TO THE HOBBYIST AT FAIR PRICES! 

1. PrOVen Quality Factory tested products only. 

2. Guaranteed Satisfaction 

3. Over $1,000,000.00 Inventory 

1981 CATALOG AVAILABLE SOON. 

Send $2.00 for your copy of the most complete catalog of computer products. 
A must for the serious computer user. 
MICROPROCESSORS 



ZB001 16 bit 10 8Mb ., .SIB900 
Z8002 16 bit I064K ,. . 149.00 
ZBO 10.75 

Z80A '* 60 

FBI3850I 16.95 

2650 .... . . 1895 

C01802 1395 

B080A . 850 

B080A-4MHZ . 19 95 

SALE SOBS 14 95 

8008-1 . 1495 

29°! 990 

2901A 1495 

29034. on Superette 2995 

TMS9900JL 49 95 

CP1600 . . , 3995 

6502 H.50 

65D2A 18 95 

IM6100 . ... 29.95 

680O 11.75 

6800B2.0 MH* 1995 

6S02P 17.95 

8035 1995 

8755 49 95 

8748 6995 

6809 , 37 95 

8086 ... . ., .,,, .69 95 

ADVANCED SUPPORT 

AM9511 Arith. Processor 17 500 

9512 A. itn Processor ... 17500 

9513 Univ. Timing ,,.79 95 

AM9517 DMA Controller ., 18 95 
AM95!9UniversalinterruOI 189 5 

Z-80 SUPPORT CHIPS 

Z80-PIO 2 5MHI 8.75 

ZBOAPIO 40 MHz ., 12.95 

ZBO-CTC 25 MHr 8 75 

ZBOA-CTC flOMHl.. . 12 95 

ZBO-OMA 2.5 MHz 29.95 

ZBOA-DMA 4 MHz 36 95 

Z60-SIO/0 25 MHz.. .,,,. 35 95 

Z80ASIO/0 4 MHZ 39 40 

ZaO-SIO/1 2 5 MHz 3595 

Z60A-SIO/1 40MHJ 39.40 

Z60SIO/2 25 MHi. .. 35.95 

Z60SIO/2 4.0MHz ..... 39.40 

8080/8085 SUPPORT 

6155/B156 I/O 2495 

8755 l/Owith Erjrom 84.95 

8202 Dyn Ram Con t 34.95 

B205/74S 138 Decoder 3.95 

82128 bit l/o 275 

8214 Priority int. 5 25 

6218 Bus Oliver 2.75 

8224 Clock Gen 2.95 

B224-4(4MH;) 9 75 

8226 Bus D'iver . 3 95 

BT26 Bus Dnvei 2 95 

8228 Sys Control 5 50 

B238SyS. Con! 5.50 

8251. Piog. I/O 6 95 

B2S3lnt Timer 12.95 

8255 Prog I/O . 6 50 



8257 



.,,j C 



825^1 Prog I 



6800 SUPPORT CHIPS 

6810 128 1 8 Ram. ,. 4.75 

6B20 PIA 5.95 

6821 PIA .... 650 

8834-1 5>2 .8 Eororri . 16.95 

6845/HD46505 CRT Cont.. , 39.9 5 

6847 Color CRT 49 95 

6B50ACIA ... 595 

6852 Serial Adapter ,,.,, 5 95 

6860 Modem .... . 10 95 

6862 Modulalor ,11.95 

6871A 1 OMHiOSC. .... . .25.35 



6d BO Eli-; Di 
MCB6483 
68047 



SHIFT REGISTER SALE 



2528.. 
2529.. 
2533 . 



6502 SUPPORT CHIPS 

6520PIA. , 750 

6522 Mult. .... 11.95 

6530-002.003.004.005 .. 21.95 
6532 . ... 19.95 

6551 1995 

PROMS 

2708 460 ns. 625 

2706-8 850 ns . ,,750 

1702A . 4 95 

2732 ... 74 95 

271B-SV 14 95 

2716 5V. 12V 19.95 

2758-5V 19.95 

5203AO ........ ... 13.95 

5204AO 1495 

IM 5810 . , 3 90 

SALE 8223 32i 8 Z.95 

62S115 512 . 8(TS1 . 16 95 

82S12332 i9 4 90 

82S128 256 1 4 4 90 

B2S129256 < 4 (TSl 4 90 

82S130 512 .4 (OCl 650 

82S23 695 

" 82S131 14 95 

B2S137 14.95 

NOTE: WE PROGRAM PROMS 

CHARACTER GEN. 

2SI3-O01 (5V)Uooer .... 9 50 
2513-005 I5I. 1 ) Lower .1095 

2513-AOM3 15V) Lower 14 95 



Cr.16571 
M CM 657' 



UARTS/BAUD RATE 



COM 5016 ... . .16 95 

KEYBOARD ENCODERS 



AV5-350O 

HD0155 
74C922 



13,75 
13.75 
9.95 
9 95 



STATIC RAMS 


21L07 250ns I\t02 

2, ;;., \& 


\ 1 30 1 25 


'<?<) 


| 1 59 '55 
/3 75 1&5 
2 95 2 8') 


155 








ail4L-8S0ns 146491 




5 50 




5 50 5 25 










4044 450m 






EMM420O* 
EMM440S 


9'5 975 


■■ 95 


AM 031 40AM 






AMD9130/31 


12 95 M95 






1 96 175 










6518 IK . 1 CMOS 


7 95 7 95 






'9 95 189 




93415 


9 95 8 95 




TMS4046 


11 q<". , 0Q f, 


10 50 




DYNAMIC RAMS 


Seto'84ie~[ 




4995 

f-r.r, 

J 95 
4 95 






3 95 
& 75 






4 95 


52S2 195 64K llDrm 


-i- 


W70 495 RAMS 66Di 
5230 4 9 5 "" „ 'X _ 6604 
5290 .245$159.9560O7 


7 95 
1 50 




SOCKETS 


-Pins 


Lo-Pro So Ids 


\ WiilWrnc 


Laval 


:ail 






18 


19 
2" 




59 


H4 


22 
26 


38 




75 


1 20 


36 






1 25 




40 


60 












ZERO INSERTION FORCE 


16Pin E550 24 P,n ?7 


:-.-.- ■:■"•■- 


= '■■■.'■■■ 



FLOPPY DISK I/O 



0L7W 3 

DL7D7 3 

fN0357 3 

FND501 5 

F-\[!f>i»";;:ii! •■. 

I'lGiC'.'.MDi '■ 

FND503 5 
FMD530 

FND550 
;ri(j5ijj!!i'.'j: 

rNDSa/iBiOi 

nP5tM2-73dO 

■loc-; .'tl- 
t. "*■;■?.■'■ ?7'n 

TIL305 



'.i:!i .j:ir-> 
inn r„\ 



Ciinun CJBW* 

i:rvr.m r.i;i-.:rt' 
i:...r:-i Cjrrnli' 



HL3DB 
TIL309 



XAM306? 
V. Pi 3 063 
>■/.!,!.: = .; 

■A\3:ii 

WNMM 

..r.'nrsi 



300 (tet Cornm 



300 Grtcn Canm CgT 



IC SPECIAL PURCHASE 



LF 13508 JFET Analog Mulli 8 t) 
ICM 7045 Precision StooWatcH 
CMOS LED Sioowalcti/T.mer . . 
ICM 7207 Oscillator Controller 
Seven Decade Counter . . 



1433P 3') Digit A/D C 



L8211 
I B50N Gro 



,, p, ...... 



1 95 

3;i 00 



\M 29O0N Quad Amni 
LM 2917N Freg to Won Con. 2/1 99 

AV-3-3550 4'-.dig,l DMM . 2495 

AV-5-3507 40MHz DUM 9 95 

MEM 4983 Moslel Smohe DoledO' 1 1 95 

27S0B3 2 . BPromnr.^ 56001 2 95 

G115M 6 cr.annel MoMel 1 .19 

111. N 2003A 7 channotDfivei 99 

2101AL-4 1.95 

MCM 14 505 84 bit Sialic Ram 8 95 

MOC i003(4N2B)Ooio Couoler 3/100 

SPX33 Oolo Counier 3/100 

IH 5045 CMOS Sw.lch DBST 4.50 

VA 3045 Trans Array 125 

TR 1402AUADT . . 1 95 

MR 1007 Dyn.Mem Stutt Reg 395 

5736 Calc. Can Circuit. . 2/199 

5763 Calc Con. Circuit '95 

531Bl"VCt. Disn Circuit,.,, 4 50 

aOBOABBitCPU ... . 495 

B2S21 32 i 2 SlaticRAM . 2/1.99 

B700 CJ B Sn A/D ... 9 95 

27585V-2708 EPROM. .. 1295 

MM52BOA/PO 4 11/C2 107/TMS4060/ 

4K>> Dynamic 22 Pm RAM 1 75 

6604/VPD 414/4027/2660/MK 4096/ 

4K>1 Dynamic 16 Pin 1 95 

7520/25 50 LM 3B7 1 25 

3302 



M323K 4 95 

IC1372 895 

IM529B-4A/Q 2 95 



LM 4558 
RC-H38 
RC 4131 
COM 5027 
COM 5037 
□ AClOO 



3/1 99 
2/1 99 



VERBATIM DISKETTES 

100% CERTIFIED ERROR-FREE! 



uPd372 N 



1 8" S Minilioopy . 24 95 

Floppy 49 95 

1781 Dual Floppy 29 95 

1791-01 Dual Floppy 3695 

jPd765Floooy 49 95 

A/D CONVERTERS 



1350 



8700 B b.l Binary 

8701 lObn Binary 
8703 8 b.l IS 
9400VOH ia Freo Co 
B7503'i Digit BCD 



DACOI D 10 A 5 g. 

DACOB 99 

DAC 100 ,.. 159 

TV CHIPS/SOUND 

AY38500 1 8 Games B/W 4 9 

AY38515 CoiorCon^ener 29 

AV38603-1 Roadrace Game 8 9 
AV3B6081 WmeoulGame 9 5 

AV3B607-1 Shooting Gallery 8 9 

AY36910 Sound Generator 129 



M&R t. 



29 95 



2 95 



WAVEFORM GEN. 

8038 Function Gen 3 

MC4024VCO 

LM566 VCO , . 1.95 

XR2206 Function Generator 5 25 

SHIFT REGISTERS 

MM500H Dual25 50 

MM5056N Dual 256 . ... 2.95 

MM5050N Dual 128 2 95 

2510A Dual 100 1 95 



3351 40 ( 9 F 



CTS DIPSWITCHES 



CTS206-2 
CTS206-4 
CTS206-5 
CTS206-6 



CTS206-7 
CTS206B 
CTS206-9 
CTS206-10 



CONNECTORS (GOLD) 

DB25PIRS232) 3 25 

DB25S Female 3 75 

Set w/Hood Sale S7 50 

22/44 WAV. S,T. KIM 2 95 

43/86 WAV S/T. MOT 6 50 

50/1COS-1O0 Connector w/w ,4 95 

50/100S-100 Connector s/t 3 95 



NAKED PC 

S-100 Souno Board S34.95 

Z-80 CPU/dlhacal .34,95 

B080ACPU 34 95 

16K Static RAM (21 14> . 29.95 
32K Static RAM (2114) .. 39.95 

BK Eorom(2708) 24 95 

1702 Eprom Board 3000 

270B/2716Eorom 34.95 

Realtime Clock ..... .34 95 

ACPProtoBd (3MConn) 27.95 
Vector 6800 Prolo .. . , 2220 
VeclorB803 11 slot MB .29 95 
ACP Eitender w/Conn.. . 18 95 
13 SiotMoiherBoa<d(WMC>3 2 95 
9SiotMotherBoard(V,'MCI 29 95 
BSIolMoiherlE.pandablel 34 95 
Proc-Techi Bare Boards CALL 

WMC Fmppy PCS 34 95 



COMPUTER SPECIALS 



PE1 2001- 
E'ldySorc! 



OHTS'- 



Pascal Microengme 1995 1 
IPSt 1620DiabioRO 3295 2 
Anade. DP 8000 995 



Sanyo9-Mc 
Sanyo IS" hi 



SOCKET SPECIALS 


14 Pin W/H-2L 
20P.nw/iv2L 
16 Pin 5/1 
22 Pin s/t 

16 Pms/i 


S 35 
7 5 

. . . 15 

15 

..100/12 00 

. 100/1300 


Call to: volume otici 


Q 



RETAI L STORES OPEN MON-SAT 



P.O. Box 17329 Irvine, Calif. 92713 

Direct Order Lines: (714) 558-8813 

(800) 854-8230 or (800) 854-8241 



FOREIGN Add 10V. shi 
andimg COD'sSI B5e<ii 



FOR INTERNATIONAL ORDERS: 
1310 E. Edlngor (714) 9530604 

na,CA92705 TWX:910-595-1565 



Circle 275 on Inquiry card. 



BYTE March 1981 



349 




TERMINAL 

DATA 

CORPORATION 



MODEL 1200 RS-232 BI-DIRECTIONAL 
DATA SPLITTER 

available in kit form 

Model 1200K gives the terminal or micro- 
processor user a second interface for a printer, 
plotter, cassette or tape drive. It operates at any 
speed & isolates the two outpul devices from 
each other, while providing 2 RS-232 interfaces 
from the terminal or microprocessor. 

The kit consists of 3 RS-232 connectors, 
printed circuit board, all necessary components, 
enclosure, mounting hardware & assembly in- 
structions $69.00 

write or call 

TERMINAL DATA CORP. 

11878 Coakley Cir. 

Rockville, MD 2DB52 

(301) 881-7655 



ATARI, OWNERS 



SCREEN PRINT INTERFACE 

Obtain hordcopy of any screen image (graphics and / or 
tent) on elltier a TRENDCOM 2O0 or IDS 440 Paper 
Tiger printer. Simply artach the supplied parallel printer 
coble and load the software from cassette (may be 
transferred to Disk). Obtain a "picture" of the screen 
on your printer under direct (CTRL?) or program (XIO) 
control. Works in all graphics / text modes as well as 
LPRINT and LIST "P" . - _ _ 

Only $139 

Parallel Printer Interlace lor the 
ATARI 400 / 800 

Connects to controller jacks 3&4 works with BASIC /DOS/ 
ASSEMBLER Three printer connectors available: 

ATARI 400 /800 
TRENDCOM100 / 200 A4P-1 ABP-1 
CENTRONICS 730/ 737 A4P-2 A8P-2 
CENTRONICS 36 PIN* A4P-3 A8P-3 

95 



69, 



CA soles add 6% lax 

MC / VISA accepted. 

• Fits all other parallel CenlTonics plus Anadex, Base 2, 

Epson, Comprint and Microtek. Older by port number, 

ATARI is d recognizedtrodemork ot ATARI, Inc. 

AMCROTRONICSJnc.® 

1125 N. Golden Stale Blvd. / Suite G 

Turlock. CA 95380 (A) (209) 667-2888 / 634-8888 



Circle 276 on Inquiry card. 



Circle 277 on Inquiry card. 





for TRS-80 ' 






CUSTOM SOUND 






A progratpablc SOUND GENERATOR for your computer. 






Throe voices, e.icli capable of tones from subauili 






anu U in"v*.luai" v"U" control,""-* "eyc^^thc 






computer or by an internal envelope Boil critter, 






All inputs arc latched, enabling the computer to 












Trie device is capable of producing three 












just octaves) as well as complex sound effects 






(siicns, etc). All this at a fraction of the co 


t 




of comparable units, with the double cable, l«o 






units can be "ganged" together to produce six 






voices for your computer. 






SOUND CCKCRATOK fc IT: (needs only 






cable, 5VIIC 6 speaker) 


S49 




two for 


S80 




CABLE: ritixin cable with PC edge connectors. 












or Bx/lCT. 


S20 




double connector " 


J25 




SVOC REGULATED POKER SUPPLY : 






fully assembled, 1.2 amp, OVP. 


S23 




comihc soon! SPEECH SYNTHESISER 






computer controled phoneme generator 




LNIUfttES WELCOME 






/©UStom >»««f; « 






\leripherals ^/ifS* 






Box 8759 Warwick, Rhode bland 02888 






" rcgestcrcd trademark, of Tandy Co rp . 





Circle 278 on inquiry card. 



DISK DRIVES 

REMEX 

Compatible with lBMand Shugart. 
Double sided, Double Density 

1600 K Bytes. 

RFD4000 S595 

Double Sided, Double Density 

800K Bytes 

RFD2000 $395 

For fast delivery, send certified 
checks, money orders or call to 
arrange direct bank wire transfers. 
Personal orcompanychecks require 
two weeks to clear. California Res. 
add 6% sales tax. Minimum ship- 
ping charge $10.00. No C.O.D. 
Electronic Equipment Unlimited 
3845 Birch Street 
Newport Beach, CA 92660 

PH: (714) 540-5231 
Pricing and availability subject to 
change without notice. 



SURPLUS ELECTRONICS 




ASCII 



ASCII 



TRS-80* COMPATIBLE, IBM 
SELECTRIC® BASED I/O TERMINAL 

with ASCII conversion installed: $645.00 



Many Other Items Available: Tape Drives; 
Cable; Cassette Drives; Wire; Power Supplies 
(5 volt 35 amp, others); Displays; Cabinets; 
Transformers; Heat Sinks; Printers; Com- 
ponents. 

Send for Free Catalog 

WORLDWIDE ELECTRONICS, INC. 

130 Northeastern Blvd. 

Nashua, N.H. 03062 

Phone orders accepted using VISA or MC 

Toll Free 1-800-258-1036 

in NH 603-889-7661 

'TRS-80 is a trademark of the Radio Shack 

Division of Tandy Corporation- 



Circle 279 on Inquiry card. 



Circle 280 on inquiry card. 



J and 5 CamputErs 

2247 Shetland Road 
Livermore. Ca. 94550 



CENTRONIC PRINTER SALE 

730-1 $617.00 

730-3 SERIAL $654.00 

737-1 $760.00 

737-3 SERIAL $795.00 

SCOTCH DISKETTES 

740-0 8 INCH BOX OF 10 132 00 

743-0 DOUBLE DENSITY/ 

DOUBLE SIDED BOX OF 1 $58 00 

California residents add 6% sales lax 
Write for free catalogue 



Circle 281 on inquiry card. 



Special Offer! Limited "Time! 

OWNERS 0fTRS-80 T levelii,I6k 

DERBYn 

Outstanding game of racing designed by a 
scientist and statistician. Six mutual prob- 
ability algorithms precisely coded (not just 
RNDl. Every race a cliff hanger. Bet to win 
place, or show; perfectos; trifectos! Photo 
finishes! Inquiries! Play different odds every 
race! Can be beaten with a lot of skill. I to 
5 players, plus a lout who bets every race 
using exactly the same handicapping infor- 
mation you have (he will even place O bet 
for you-for a fee of course). Excellent spot 
graphics for realistic motion. 

CAN YOU BEATtheTOUT 

ORDER NOW for one of the most 
remarkable games you'll ever play. 
Only $15.00 (check or m.o.) for qual. cassette. 
Add $.50 postage, handling. FL res. odd 4% tax. 

C8A ASSOCIATES, Inc. 

RO. Box 23 6 2 
Solellite Beoch, FL 32937 



(VQ Check Your 
Options! 

Sensors Available: 

□ Temperature $ 64,95 

□ Relative Humidity $82.95 

□ Pressure $ 85.95 

□ Magnetic Field S10895 

Qlow Sensor $ 99.95 

□ Light Level $ 49.95 

□ Liquid Level S 78.95 

□ LiveOb|ect $ 64.95 

These Functions And 
More Available Off" 
The Shelf . . ." 

systems 

*- (602) 299-9831 

'P.O. Box 35879 
Tucson, Arizona 85740 




16-BIT MC68000 
CROSS-ASSEMBLER 

w,:„ En ;n FORTRAN IV 

hos now beer, added to our line of Hock FORTRAN crois -ossembler: 
lor Ine populor B fail microprocessors 16809. 6805. 6B0O, 8080/5. MCS6502 
CDP1802) All of these emit assembler program* con be run on molt or, lor.,* 
or imoll computer intern ifiol support! standard FORTRAN IV. Pockages in 
dude new. exponded user i monuol, printed source lining, ond lDM> r'du 



SOURCE MEDIA 

CARD DECK PACKAGE !026or029 punch) SI25O0 5250 00 
MAGNETIC TAPE PACKAGE (ASCII or 

EBCDIC, IdOOor 800 bpi, blocked) $125.00 $250.00 



MANUAL 8. LISTING ONLY S 50.00 

Ml price! include shipping in the continental USA 10% disc 
= rde.s. 
'Also available: M6800ta M680? Source cade Ire 

'COMING SOON-Gois. assemblers in FORTRAN lor rhe i 
microprocessors: 8086, Z800Q,TM59?00 Send lor our Ire 
on assemblers, simulator!, ond othersoflware products. 



IDM 



Intelligent Devices of Mrt. 

PO Bo*U538 Minneapolis Mn. 55414 
(612) 427-0787 7AM-12Noon 



Circle 283 on inquiry card. 



Circle 284 on inquiry card. 



DIGITAL RESEARCH COMPUTERS 

(214)271-3538 



32K S-100 EPROM CARD 
NEW! 




Blank PC Board - $34 

ASSEMBLED & TESTED 
ADD $30 

SPECIAL: 2716 EPROM's (450 NS) Are $11.95 EA. With Above Kit. 



KIT FEATURES: 
1- Uses +5V only 2716 (2Kx8) EPROM's. 

2. Allows up to 32K of software on line! 

3. IEEE S-100 Compatible. 

4. Addressable as two independent 16K 
blocks. 

5. Cromemco extended or Northstar bank 
select. 

6. On board wait state circuitry if needed. 



7. Any or all EPROM locations can be 
disabled. 

8. Double sided PC board, solder-masked, 
silk-screened. 

9. Gold plated contact fingers. 

10. Unselected EPROM's automatically 
powered down for low power. 

11. Fully buffered and bypassed. 

12. Easy and quick to assemble. 



32K SS-50 RAM 



$ 379 



00 



KIT 



For 2 MHZ 
Add $10 



Blank PC Board 
$50 




For SWTPC 
6800 - 6809 Buss 



Support IC's 

and Caps 

$19.95 

Complete Socket Set 

$21.00 



Fully Assembled, 

Tested, Burned In 

Add $30 



At Last! An affordable 32K Static RAM with full 
6809 Capability. 

FEATURES: 

1. Uses proven low power 2114 Static RAMS. 

2. Supports SS50C - EXTENDED ADDRESSING. 

3. All parts and sockets included. 

4. Dip Switch address select as a 32K block. 

5. Extended addressing can be disabled. 

6. Works with all existing 6800 SS50 systems. 

7. Fully bypassed. PC Board is double sided, 
plated thru, with silk screen. 



16K STATIC RAM KIT-S 100 BUSS 



16K STATIC RAM SS-50 BUSS 



PRICE CUT! 



$ 199 9 „ 5 1T 




L)tJ^lM^diifuuu£aJ 



7$i I II III 1:1 111 IIP ■ 

.|i i.i iiWiiiii '■'■.!■« 



PRICE CUT! 




mm 



$ 195 



KIT 



Illlilillllillll 



S 1 Ml 83 S I I i I 1 1:1111 



KIT FEATURES: 

1. Addressable as four separate 4K Blocks. 

2. ON BOARD BANK SELECT circuitry. (Cro- 
memco Standard 1 ). Allows up to 512K on line! 

3. Uses 2114 (450NS) 4K Static Rams. 
4.- ON BOARD SELECTABLE WAIT STATES. 

5. Double sided PC Board, with solder mask and 
silk screened layout. Gold plated contact fingers 

6. All address and data lines fully buffered. ASSEMBLED & TESTED-ADD $35 

7. Kit includes ALL parts and sockets. 

8. PHANTOM is jumpered to PIN 67. 

9. LOW POWER: under 1.6 amps TYPICAL from 
the +8 Volt Buss. 

10. Blank PC Board can be populated as any 
multiple of 4K. 




BLANK PC BOARD W/DATA-$33 

LOW PROFILE SOCKET SET-$12 

SUPPORT IC'S & CAPS-$19.95 



FOR SWTPC 
6800 BUSS! 



OUR#1 SELLING 
RAM BOARD! 



KIT FEATURES: 

1. Addressable on 16K Boundaries 

2. Uses 2114 Static Ram 

3. Fully Bypassed 
4 Double sided PC Board. Solder mask 

and silk screened layout. 

5. All Parts and Sockets included 

6. Low Power: Under 1 .5 Amps Typical 

BLANK PC BOARD— $35 COMPLETE SOCKET SET— $12 

SUPPORT IC'S AND CAPS— $19.95 



ASSEMBLED AND 
TESTED - $35 



^ STEREO! »w 

S-100 SOUND COMPUTER BOARD 



COMPLETE KIT! 
$3495 

(WITH DATA MANUAL) 



At last, an s-100 Board that unleashes the full power of two 
unbelie/able General Instruments AY3-8910 NMOS computer 
sound IC's. Allows you under total computer control to 
generate an infinite number of special sound effects for 
games or any other program. Sounds can be called in BASIC, 
ASSEMBLY LANGUAGE, etc. 
KIT FEATURES: 

* TWO Gl SOUND COMPUTER IC'S. 

* FOUR PARALLEL I/O PORTS ON BOARD 

* USES ON BOARD AUDIO AMPS OR YOUR STEREO. 

* ON BOARD PROTO TYPING AREA. 

* ALL SOCKETS, PARTS AND HARDWARE ARE INCLUDED 
. PC BOARD IS SOLDERMASKED, SILK SCREENED. WITH GOLD CONTACTS. 

* EASY, QUICK, AND FUN TO BUILD. WITH FULL INSTRUCTIONS. 

* USES PROGRAMMED I/O FOR MAXIMUM SYSTEM FLEXIBILITY. 
Both Basic and Assembly Language Programming examples are included 

SOFTWARE: 
SCL™ is now available! Our Sound Com mand Lan guage makes writing Sound Effects programs 
a SNAP! SCL™ also includes routines fo r Register-Examine-Modify. Memory-Examine-Modify, 
and Play-Memory. SCL™ is available on CP/M* compatible diskette or 270B or 2716. Diskette ■ 
J24.9S 2708 - S19.95 2716 - S29.9S. Diskette includes the source. EPROM'S are ORG at 
EOO0H. 



BLANK PC 

BOARD W/DATA 

$31 



4K DYNAMIC RAM BLOWOUT! 

SAME AS INTEL 2107B! 

4K RAMS AT AN UNBELIEVABLE 504 EACH!!! 

Prime, new. National Semi., 1979 date coded, full spec, parts. N.S. 
*MM5280-5N. Same as INTEL 2107B-4, T.I. TMS4060. NEC uPD411. etc. 
We bought a HUGE QTY. from a West Coast Distributor at truly 
DISTRESS PRICES! One of the most popular and reliable RAM's ever 
made. These parts have been used by almost all Major Computer Main 
Frame Mfg. the world over! Arranged as 4K x 1, 270 NS Access Time. 22 
Pin Dip. These units DO NOT use multiplexed addressing, thus making 
REFRESH and other timing very simple. See INTEL MEMORY DESIGN 
HANDBOOK for full application notes. The NAT. SEMI. MEMORY DATA 
BOOK is available at most Radio Shack Stores. Prime units in original 
factory tubes! 

#5280-5N 4096 BITS x 1 270 NS ACCESS 

8 FOR $4.95 32 FOR $16 

FACTORY CASE (450 PCS) — $180 

Sockets Special: 22 Pin Low Profile (With Purchase of 5280's) 8 FOR $1. 






COMPUTER PARTS SPECIALS 

74LS175- .99 8035 Intel Single Chip CPU 6.95 

74LS240 - 1.19 Signetics 2901 4 Bit Slice - 6.95 

74LS241 - 1.19 AMD 2903 4 Bit Super Slice - 12.50 

74LS244 - 1.19 AMD 29705 Dual Port RAM - 8.95 

74LS373 - 1.29 Intel 2716-1 (350 NS) - 12.95 



NEW! G.I. COMPUTER SOUND CHIP 

AY3-8910. As featured in July, 1979 BYTE! A fantastically powerful Sound & Music 
Generator. Perfect for use with any 8 Bit Microprocessor Contains:3ToneChannels, 
Noise Generator, 3 Channels ofAmplitude Control. 16 bit Envelope Period Control, 2-8 
Bit Parallel I/O. 3 D to A Converters, plus much more! All in one 40 Pin DIP. Super easy 
interface to the S-100 or other busses. $11.95 PRICE CUT! 

SPECIAL OFFER: $ 1 4 .9 5 each Add $3 for 60 page Data ManuaL 



L 



Digital Research Computers 

** (OF TEXAS) ' 

P.O. BOX 401565 » GARLAND, TEXAS 75040 « (214) 271-3538 



TERMS: Add $1.50 postage. We pay balance. Orders under $15 add 75C 
handling. No C.O.D. We accept Visa and MasterCharge. Tex. Res. add 5% 
Tax. Foreign orders (except Canada) add 20% P & H. Orders over $50, add 
85C for insurance. 



I 



•TRADEMARK OF DIGITAL RESEARCH. 



WE ARE NOT ASSOCIATED WITH DIGITAL RESEARCH OF CALIFORNIA. THE SUPPLIERS OF CPM SOFTWARE. 

BYTE March 1981 351 



Know The Reasons Why 

The FORCE-80 is your 

"Best Buy." 

FORCE-80 The computer protector 

• Power dropout protection 

• Suppresses transient voltages 

• Suppresses RFI 

• Disc protection 

• Factory warranty 

• Satisfaction guaranteed 

• Direct from factory 

FORCE-80 

Only $121.50 plus $5.00 shipping & handling 

Check, Mastercharge, Visa accepted 
(5% discount for cash) ^^^m 
No C.O.D.'s please JJJ^ 

P&S Electronics, Inc. 

P.O. Box 23014 Dept. B 
Nashville, TN 37202 

Allow 6-8 weeks for delivery. 
Add 14 days lor personal checks. 




STATISTICAL 
SOFTWARE 

The Winchendon Group an- 
nounces its powerful statistical 
system which includes a data- 
base system, all BASIC trans- 
formations, simple statistics, 
stepwise regression, correla- 
tion, crosstabs, factor analysis 
and more. 

Now available for the Apple 
II + *, 48k with DOS 3.2.1*. 
$ 1 50, for the complete version. 

Write for further information. 

P.O. Box 10114 
Alexandria, Va. 22310 

'Apple 11+ and DOS 3.2.1 are trademarks of 
the Apple Computer Company 



!!!PROGRAMMERS!!! 

$ $ $ $ 



TURN YOUR WILDEST IMAGININGS INTO 
CASH $SS. WE'RE LOOKING FOR NEW CON- 
CEPTS IN COMPUTER VIDEO GAMES AND 
WE'RE WILLING TO PAY PROGRAMMERS 
TOP PRICES FOR ORIGINAL IDEAS. SUBMIT A 
WORKING PROTOTYPE TO: 

MR. DOMINIC SANZO 

GAME-A-TROM CORP. 

931 WEST MAIN ST. 

NEW BRITAIN, CT. 06051 

CALL 1-203-223-2760 
FOR FURTHER INFORMATION 



_GAME 

^^T IDEAS 
WANTED 



GAMEA-TRON 



Circle 285 on inquiry card. 



Circle 286 on inquiry card. 



PRINTERS 

NtW BASE, MODEL 8 SO 
WTJ799 OUR PRICES 73 S 



BASE , MODEL 800B 
mt stn OUR PRICE SS8S 

NEW BASE,/ APPLE GRAPHICS 

INTERFACE 

uiTiittOUR PRICES 140 



0KIDATA i> LINE 80 
tursMoOUR PRICE $550 

•PllASt ADO 3% fOR Sin TO OKDED* 
SCNDFOK IHI0SMAJI0H ON 0U8 OTHIS PSODUCTUMS 



I 



TECHNICAL INNOVATIONS 
P.O. BOX 803 DEPT B2 
HILISB0R0, OR 97123 

503-648-6423 



I 



SOFTWARE 
DESIGN ENGINEER 

BSEE/BSCS. minimum 3 years 
programming experience. Real- 
time systems programming and 
software development for elec- 
tronic switches is a plus. Ex- 
perience with PASCAL or C or 
Assembly language required. Call 
collect or send resume to Ken- 
neth W. Cooper, Harris Corpora- 
tion, RF Communications Divi- 
sion, 1680 University Avenue, 
Rochester, NY 14610, (716) 
244-5830, EXT 3356. 



HARRIS 



An Equal Opportunity Employer M/F 



siyvvv 



MEMOREX 

Floppy Discs 

Lowest prices. WE WILL NOT 
BE UNDERSOLD!! Buy any 

quantity 1-1000. Visa Mastercharge 
accepted Call free (800)235-4137 
for prices and information. All 
orders sent postage paid. 



PACIFIC 
EXCHANGES 

100 Foothill Blvd. 
San Luis Obispo. CA 
93401. (InCal. call 
(805)543-1037.) 




Circle 287 on inquiry card. 



Circle 288 on inquiry card. 



Circle 289 on Inquiry card. 



Save up to 50% 

using our buying power. We buy 
over three million dollars of 
computer equipment wholesale per 
year for clients who range in size 
from the largest manufacturers to 
the home hobbyist. Our fee is one 
fourth of what we save you of f the 
manufacturer's suggested list price, 
so it is to our advantage to save 
you money. 

THE PURCHASING AGENT 

1635 School Street, Suite 101 
Moraga, CA 94556 
(415) 376-9020 




COMPUTERS 

c1p series ii - $479.00 
our price - $399.00 

other OSI discounts available 



CALL NOW TOLL FREE 

1-800-558-0870 

COMPUTERS 
PLUS, INC. 

2749 S. 1DBth St. 
MILWAUKEE. Wl 53227 

[414] 321-1770 

IN WISCONSIN 



EXOTIC 
BASIC PROGRAM 

BATTLE FOR 

GAMMA OMICRON 

OUTPOST #1 

(a game in the tradition of great 

star battles in space) 

$2 postage and handling for 

listing 

* EXTRA BONUS LISTING: * 

* LAS VEGAS BINGO PIN-BALL * 

* (card simulation) # 
************* 

bonus offer expires March 31, 1981 

THE COMPUTER SOCIETY 

P.O. BOX 1056 
WASHINGTON PARK, IL. 62204 



Circle 290 on Inquiry card. 



Circle 291 on inquiry card. 



Circle 292 on inquiry card. 



1858 Evergreen Street, 


Duarte, California 91010 










^^Ki 



Phone 213-357-5005 



page 

DIGITAL INC. If 



INSULATION DISPLACEMENT SOCKETS 



RIGHT ANGLE HEADERS 







Pins 
10 
20 

26 
34 
40 
50 



PC Mounting WtraWrap 

IDH10SR .80 IDH10WR 1.75 
IDH20SR1.25 IDH20WR 2.75 
IDH26SR 1.85 IDH26WR 3.60 
IDS34SR 2.15 IDH34WR 4.15 
IDH40SR 2.50 IDH40WR 4.90 
IDH50SR 3.15 IDH50WR 6.15 



EJECTOR EARS .25 EACH 



25 PIN "D" CONNECTORS 



«-*v 



;''<• 



Styto Part • 

SOLDER STYLE 
Male DB25P .2-25 
Female DB255 3.00 
Hood DB25C 1.10 

INSULATION DISPLACEMENT 
Male IDC25P 4.95 
Female IDC255 5.25 
Hood IDC25C 1.35 



CARD EDGE 
CONNECTORS 




Plnj 


Part No. 




10 


IDE10 


3.25 


20 


IDE20 


3.50 


26 


IDE26 


4.05 


34 


IDE34 


4.B5 


40 


IDE40 


5.65 


50 


IDE50 


5.90 



SOCKETS 




Pins 

10 
20 
26 

34 
40 
50 



Part No. 
IDS10 

IDS20 
IDS26 
IDS34 
IDS40 
IDS50 



1.25 
2.02 
2.65 
3.50 
4.05 
5.06 



Stain 
Sttli.1 

.25 

.25 

.25 

.25 

.25 

.25 




Conductors: Solid Color 



Color Coded 



10 
14 
16 
20 
24 
26 
34 
40 
50 



10 ft. 

2.90 
3.40 
3.70 
4.40 
5.00 
5.40 
6.80 
7.80 
9.50 



too It. 
17.00 
23.80 
27.20 
34.00 
40.80 
44.20 
57.80 
68.00 
85.00 



10 n. 

4.00 

5.00 

5.60 

7.00 

8.00 

8.60 

11.00 

13.00 

16.00 



too II. 

30.00 

42.00 

48.00 

60.00 

72.00 

78.00 

102.00 

120.00 

150.00 



CABLE PLUGS 




Pins 
14 
16 
24 
40 



Pait No. 

IDP14 1.25 

IDP16 1.40 



IDP24 
IDP40 



2.25 
3.65 



WIRE WRAP WIRE 



WIRE KITS 



Length 100/Bag 


500/Bag 1 K/Bag 


Length 100/Bag 500/Bag 


1 K/Bag 


Kit No. 1 


$9.95 


Kit No. 3 


$32.95 


2.5" $1.25 
3.0" 1.30 
3.5" 1.37 
4.0" 1.42 
4.5" 1.48 
5.0" 1.54 
5.5" 1.58 
6.0" 1.65 


$3.58 $ 6.19 
3.86 6.78 
4.15 7.37 
4.44 7.94 
4.74 8.54 
5.04 9.13 
5.38 9.72 
5.66 10.31 


6.5" $1.92 $6.44 
7.0" 1.99 6.76 
7.5" 2.08 7.07 
8.0" 2.14 7.38 
8.5" 2.18 7.69 
9.0" 2.24 8.11 
9.5" 2.30 8.32 
10.0" 2.39 8.71 


$11.81 
12.44 
13.09 
13.73 
14.36 
15.01 
15.65 
16.28 


250 
250 
100 


3" 

3W 

4" 


100 
100 
100 


4Va" 

5" 
6" 


500 2 '/*• 
500 3" 
500 3%' 
500 4" 


500 4%" 
500 5" 
500 5'/ 2 " 
500 6" 


Kit No. 2 


$24.95 


Kit No. 4 


$59.95 


250 
500 
500 
500 
250 


2</s" 

3" 

3'/*" 

4" 

AW 


250 
100 
250 
100 
100 


5" 

5Vi" 

6" 

6V4" 

7" 


1000 2%' 
1000 3" 
1000 3 '/a' 
1000 4" 


1000 4V2" 
1 000 5" 
1000 5" 
1000 6" 


Kynar precut wire. AH lengths are ov 
Colors and lengths cannot be mixed tc 
Red, Blue, Black, Yellow, White, Gre 


erall, including 1 " strip on each end. 
r quantity pricing. Choose from colors 
en, Orange, and Violet. 



ORDERING 
INFORMATION: 



• Orders under $25 include $2 handling 

• All prepaid orders shipped UPS Ppd. 

• Visa, MC & COD's charged shipping. 

• All prices good through cover date. 

• Most orders shipped same day. 

• Byte must be mentioned to get sale price. 



Write or call for 1981 catalog 

• IC Sockets 

• Vector Board & Pins 

• Bishop Drafting Aids 

• OK Tools 

» RN IDC Crimp Connectors 



"NEW" WIRE WRAP SOCKETS 

FEATURING A SELECTIVE PLATING METHOD THAT WILL SAVE YOU 
MONEY BY HAVING GOLD ONLY WHERE IT COUNTS. 



GOLD PLATED CONTACTS 



TIN PLATED TAILS 




3 Level closed entry. 

RN Side Wipe contact design gives 
twice the contact area for high reliability. 



Size 

8 


Quantllv/Tube 
52 


Price ea.* 
.41 


Price/Tube 
21.32 


14 


30 


.47 


14.10 


16 


26 


.51 


13.26 


18 


23 


.70 


16.10 


20 


21 


.87 


18.27 


22 


19 


.94 


17.86 


24 


17 


.96 


16.32 


28 


15 


1.25 


18.75 


40 


10 


1.70 


17.00 



•FOB REFERENCE. MUST BE 
ORDERED IN TUBE QUANTITIES. 



Circle 294 on inquiry card. 



TOLL FREE ORDERING NUMBER 1-(800)-423-7144 



Eleusis and The TI-59 

Your TI-59 can now act as 
God (well, dealer) in the 
New Eleusis (the card game 
introduced in the October 
1977 Scientific American). 
The Eleusis-Dealer program 
randomly chooses a rule then 
accepts or rejects the cards 
played. 

To obtain magnetic cards for 
the program, along with 
documentation, Eleusis in- 
structions, and the latest 
newsletter, send $6 to 

Robert Abbott 

Box 1175, General P.O. 
New York, NY 10116 






>*» 






Skylcs Electric Works 

231 E South Whisman Road 
Mountain View, CA 94041 



"Attention 
Computer Owners" 

If you own a mini or micro... 
you could be on your way to fan- 
tastic riches. Put your computer 
to a new use by monitoring real 
estate investments. Set up your 
own office in your home. ..never 
work for the other guy again. It is 
the most ingenious program ever 
devised. Make six digits annually. 

First time offered. Complete 
package — $36.00. We pay post- 
age & handling. Send check or 
M.O. to: 

C.B.A.S. 

P.O. Box 163 
Ontario, OH 44862 



Circle 295 on inquiry card. 



Circle 296 on Inquiry card. 



LETTER QUALITY 

DAISY WHEEL 
PRINTER $2,195.00 

* Based on latest version of electronic 
typewriter by Olivetti, Ltd. 

* Use offline as typewriter 

* RS232C Interface Standard 

* Over 200 words per minute 

* 10, 12 &. 15 C.P.I. 

* International Type Fonts 

* Available Immediately 
Money order or C.O.D. to: 

Vertical Data Systems, Inc 

1215 Meyerside Dr., Unit 2A 

Mississauga, Ontario, Canada 

L5T 1H3 

(416)671-1752 



A ATARI" 

COMPLETE LINE OF ATARI 
COMPUTER PRODUCTS 20-25% OFF 

Atari 800 with I6K $810 Atari 610 Disk Drive. $460 

Atari 400 with 8K $399 Atari 410 Cassette Player. $69 

Vlsicalc $170 Kurla Graphics Tablet $560 

Ramcram 32K Modules (upgrade 400 or 600) $256 

ALL ATARI SOFTWARE 20% OFF 
BIT BUCKET SOFTWARE FOR ATARI: 
Utilities Disk with Disassembler, Basic 
Renumberer, Character Generator, Cruncher 

Utility (requires 24K) S45 

Games: Mastercode, Mr. Simon, City 

Bomber (each) $12.95 

Hex, Cryptogram, 

Flying Saucers (each) $14.95 

Any 3 Of above $30.00. (specily disk or cassette) 

ALSO: Commodore Pet at Similar Savings 
PLUS: Centronics, NEC, Zenith, Intertec, 
and More! 

The Bit Bucket 

Hardware. Software. Consulting 
168 North Beacon Street 
.P.O. Box 365 

Newton Highlands. MA 02161 
Phone: (617) 783-3144 




EVERY MONTH 

BUY, SELL OR TRADE ALL TYPES OF 
COMPUTER EQUIPMENT AND SOFT- 
WARE (pre-owned and new) among 
20,000 readers nationwide in BIG 
(11x14") pages. Classified ads are 
only 10' per word and are indexed for 
easy and fast location. Subscription: 
$10 a year/ 12 issues. Money back 
guarantee. Sample copy, $1.50. 
campurea SHOPPSR 

P.O. Box F-14 

Titusville, FL 32780 

(305)269-3211 

MasterCard or VISA subscription orders only, 

call TOLL FREE 1 BOO 528 6050 Ex. 184. 



Circle 297on Inquiry card. 



Circle 298 on Inquiry card. 



Circle 299 on inquiry card. 




□ YES I Sign me up as a charter 
subscriber. Enclosed is my 
$20.00 for 10 issues. C$24 
to Canada. $30 elsewhere.) 

D Not sure. Enclosed is $2 for 
a sample issue. 




Circle 300 on Inquiry card. 





You may be in danger of spending 
almost $200 for a so-called FORTH' 
system that is not interactive! 

Timin FORTH has a memory 
resident editor and a virtual 
memory subsystem, as well as all 
the features of true FORTH. 

Our heavily advertised f^Sr™] 

competitor does not! 

Place your order today— ( 

then go FORTH and conquer! 

■InrCP/M IDigit.il K.-M-.ird, ( cir|i ] 

Q.'O MITCHELL E. TIMIN 

Q O ENGINEERING COMPANY 

OO 9575 GENESEE AVENUE- SUITE E2 
V\J SAN DIEGO. CALIFORNIA 92121 

714-455-9008 



Circle 301 on Inquiry card. 






MICROPROCESSOR SUPPORT IX.'S 1 


WE GUARANTEE FACTORY PRIME PARTS | 


We are going to become 


the largest supplier of prime 


NEC 16Kx1 DYNAMIC RAM 200 N.S. 




microprocessor support I.C.'S. We guarantee that our I.C.'S 
are purchased from manufacturer authorized distributors. 
This is the only way to deliver prime parts at the lowest 


These are prime 41 1 6 's from one of the 
MOS RAM manufacturers in the world. 


best 


possible prices. Our committment is to offer the best price 
and the fastest delivery to our customer. We give many 




4i id zuuns 
8 for $25.00 32 for 96.00 




thanks to our valued customers who have helped us grow. 




Only prepaid orders on this special. 




8080A CPU 


4.95 


2708 EPROM 1Kx8 4.95 




NEC 1Kx4 STATIC RAM 250 N.S. 




8085A CPU 


8.95 


2716 EPROM 2Kx8 8.95 


These 


are prime low power static ram's 


NEC 


8086 CPU 


99.95 


2732 EPROM 4Kx8 21.00 


for the finest in MOS MEMORY. 




8088 CPU 


44.95 


4118 STATIC 1Kx8 15.00 




2114L 250ns 




Z-80 CPU 


10.50 


4164 200ns 64Kx1 Call 




8 for $25.00 32 for $96.00 




Z-80A CPU 


12.95 


Z80B CPU 21.00 




Only prepaid orders on this special. 




Z80-P10 7.75 


8289 ' 


19.95 


4050 .69 


4531 


.99 


74C925 6.95 


74LS107 .45 


74LS244 


1.95 I l 


Z80A-P10 9.75 


4000 


.35 


4051 1.10 


4532 


1.25 


74LS00 .35 


74LS109 .45 


74LS245 


4.95 I ! 


Z80-CTC 7.75 


4001 


.35 


4052 1.10 


4539 


.99 


74LS01 .28 


74LS112 .49 


74LS247 


1.10 1 


Z80ACTC 9.75 


4002 


.35 


4053 1.10 


4543 


1.99 


74LS02 .28 


74 LSI 22 .55 


74LS248 


1.10 1 


Z80-DMA 22.25 


4006 


1.39 


4055 3.95 


4553 


3.50 


74LS03 .28 


74LS123 1.19 


74LS249 


1.69 I 


Z80A-DMA 27.75 


4007 


.29 


4056 2.95 


4555 


.75 


74LS04 .39 


74LS125 1.35 


74LS251 


1.79 1 


Z80-S10/0 24.95 


4008 


1.39 


4059 9.95 


4556 


.75 


74LS05 .28 


74 LSI 26 .89 


74LS253 


.98 1 


Z80A-S10/0 29.95 


4009 


.49 


4060 1.39 


4581 


1.99 


74LS08 .39 


74LS132 .79 


74LS257 


.98 1 


Z80-S10/1 24.95 


4010 


.49 


4066 .75 


4582 


1.01 


74LS09 .39 


74LS136 .59 


74LS258 


.98 1 ] 


Z80A-S10/1 29.95 


4011 


.35 


4068 .35 


4584 


.55 


74LS10 .28 


74 LSI 38 .89 


74LS259 


2.95 


Z80-S10/2 24.95 


4012 


.29 


4069 .35 


4585 


.99 


74LS11 .39 


74LS139 .89 


74LS260 


.69 


Z80A-S10/2 29.95 


4013 


.49 


4070 .49 


4702 


9.95 


74LS12 .39 


74LS145 1.25 


74LS261 


2.49 


3205 3.45 


4014 


1.39 


4071 .35 


74C00 


.39 


74LS13 .47 


74LS148 1.49 


74LS266 


.59 


3242 10.00 


4015 


1.15 


4072 .35 


74C02 


.39 


74LS14 1.25 


74LS151 .79 


74LS273 


1.75 


8155 11.25 


4016 


.59 


4073 .35 


74C04 


.39 


74LS15 .39 


74LS153 .79 


74LS275 


4.40 


8185 29.95 


4017 


1.19 


4075 .35 


74C08 


.49 


74LS20 .26 


74LS155 1.19 


74LS279 


.59 


8185-2 39.95 


4018 


.99 


4076 1.29 


74C10 


.49 


74LS21 .38 


74LS156 .99 


74LS283 


1.10 


8202 45.00 


4019 


.49 


4078 .35 


74C14 


1.65 


74LS22 .38 


74LS157 .99 


74LS290 


1.29 


8205 3.45 


4020 


1.19 


4081 .35 


74C20 


.39 


74LS26 .39 


74LS158 .75 


74LS293 


1.95 


8212 2.00 


4021 


1.19 


4082 .35 


74C30 


.39 


74LS27 .39 


74LS160 .98 


74LS295 


1.10 


8214 3.95 


4022 


1.15 


4085 1.95 


74C32 


.99 


74LS28 .39 


74LS161 1.15 


74LS298 


1.29 


8216 1.85 


4023 


.38 


4086 .79 


74C42 


1.85 


74LS30 .26 


74LS162 .98 


74LS324 


1.75 


8224 2.65 


4024 


.79 


4093 .99 


74C48 


2.39 


74LS32 .39 


74 LSI 63 .98 


74LS347 


1.95 


8226 1.85 


4025 


.38 


4099 2.25 


74C73 


.85 


74LS37 .79 


74LS164 1.19 


74LS348 


1.95 


8228 5.00 


4026 


2.50 


4104 1.99 


74C74 


.85 


74LS38 .39 


74LS165 .89 


74LS352 


1.65 


8238 5.45 


4027 


.65 


4501 .39 


74C85 


2.49 


74LS42 .79 


74LS166 2.49 


74LS353 


1.65 


8243 4.65 


4028 


.85 


4502 1.65 


74C89 


4.95 


74LS47 .79 


74LS170 1.99 


74LS363 


1.49 


8251A 5.55 


4029 


1.29 


4503 .69 


74C90 


1.85 


74LS48 .79 


74LS173 .89 


74LS365 


.99 


8253 9.85 


4030 


.45 


4505 8.95 


74C93 


1.85 


74LS51 .26 


74LS174 .99 


74LS366 


.99 


8255A 5.40 


4031 


3.25 


4506 .75 


74C95 


1.85 


74LS54 .35 


74LS175 .99 


74LS367 


.73 


8255A-5 5.40 


4032 


2.15 


4507 .95 


74C107 


1.19 


74LS55 .35 


74LS181 2.20 


74LS368 


.73 


8257 9.25 


4033 


2.15 


4508 3.95 


74C151 


2.49 


74LS73 .45 


74LS190 1.15 


74LS373 


2.75 


8257-5 9.25 


4034 


3.25 


4510 1.39 


74C154 


3.50 


74LS74 .59 


74LS191 1.15 


74LS374 


2.75 


8259A 7.30 


4035 


.95 


4511 1.39 


74C157 


2.10 


74LS75 .68 


74LS192 .98 


74LS375 


.69 


8271 60.00 


4037 


1.95 


4512 1.39 


74C160 


2.39 


74LS76 .45 


74LS193 .98 


74LS377 


1.95 


8275 32.95 


4040 


1.29 


4514 3.95 


74C161 


2.30 


74LS78 .65 


74LS194 1.15 


74LS385 


1.95 


8279 10.80 


4041 


1.25 


4515 3.95 


74163 


2.39 


74LS83 .99 


74LS195 .95 


74LS386 


.65 


8279-5 10.80 


4042 


.95 


4516 1.69 


74164 


2.39 


74LS85 1.19 


74LS196 .89 


74LS390 


1.95 


8282 6.70 


4043 


.85 


4519 .99 


74173 


2.59 


74LS86 .45 


74LS197 .89 


74LS393 


1.95 


8283 6.70 


4044 


.85 


, 4520 1.39 


74174 


2.75 


74LS90 .75 


74LS221 1.49 


74LS395 


1.70 


8284 5.85 


4046 


1.75 


4522 .99 


74C175 


2.75 


74LS92 .75 


74LS240 1.95 


74LS399 


2.95 


8286 6.70 


4047 


1.25 


4526 1.15 


74C192 


2.39 


74LS93 .75 


I 74LS241 1.90 


74LS424 


2.95 


8287 6.70 


4048 


.99 


4527 1.75 


74C193 


2.39 


74LS95 .88 


74LS242 1.95 


74LS668 


1.75 


8288 25.40 


4049 


.69 


4528 .99 


74C195 


2.39 


74LS96 .98 


74LS243 1.9 5 


74LS670 


2.29 


! MAIL 
I P.O. Be 

Telephc 


ORDERS 
>x 21432 

>ne Order 


SHOULD BE SENT TO: 
Seattle, Washington 98111 

5 & Inquiries (206) 453-0792 




HANLEY ENGINEERING 

RETAIL STORE 
1644 116th NORTHEAST 


I Minimu 


m Order 


$10.00 Add $3.00 Shipping 


_ 


BELLEVUE, WASHINGTON 98005 


| FOR T 


HE Fl 


NEST IN MICROPRO* 


CESSOR SUPPORT I.C 


s 



Circle 304 on inquiry card. 



BYTE March 1981 



355 



10,000 WORDS 
IN 1 MINUTE, 
PROOFREAD FOR SPELLING 

20,000 word user expandable diction- 
ary, easy to use, Requires CP/M* 8080/ 
Z80 with 32K memory. Compatible w/ 
Magic Wand*,WordStar*,Electric Pen- 
cil* and many others. $269.00 

New Crystal-Clear* Ope- 
rator's Training Manual 
for Magic Wand* and re- 
lated CP/M* is designed 
for the secretary and non- 
computerist use. Dual col- 
umn pages present instruc- 
tions and explanationson 
left, drawings, pictures & 
screen displays on right. 
Small black circles pre- 
cede user action steps for 
clarity and quick future 
reference. $35.00 

Free Crystal-Clear * Ope- 
rator's Training Manual 
with Magic Wand * cus- 
tomized for your CPU, 
terminal, Printer & disk. 
$299.00 




PELICAN 
PROGRAMS 

*Trademark 



Pelican Programs 
49 Pelican Court, Syosset, N.Y. 11791 



SMARTNET 



| printer) -— 



SATELLITE 
COMPUTER 



HUB 
COKHITERI 



J DISK | 



SATELLITE 
COMPUTER 



|ter kii:al | 
features 

-Automatic spooling and despooling. 
-Levels 1-15 of the hub computer are 

password protected. 
-No modifications needed to the BIOS 

or XI0S. 
-Block data transfer with checksum. 
-Low memory requirements. 
-Complete source code provided. 

REQUIREMENTS 

-Hub computer must be running RP/K , 
- Smartnet requires CP/K* 2.2, 20k of 

memory and at least one disk drive. 
- Dumbnet requires at least 16k of 

memory. Disk drives not needed, 

PRICE 

SMARTNET .5150.00 DUMBNET .1175.00 

PURCHASE TOGETHER 3500.00 

LIHI-IAR 

541 Ingraharn Ave. 

Calumet City, IL. 60409 

312-868-4866 Ask for Mark 

* Trademark of Digital Research. 



SUBMINI DPDT 
DIP RELAY 

AROMAT #HB2-DCfiV 

jjfefl ' 6 VDC co " ' Flls dip '''-'-■' 

h«j -Nofm power 5B0 mW 

^^HP . Contacts raled @ 120V 

'^Sl.50each i0iorSi3S0 



40 PIN RT ANGLE P £ .B . 

mum HE 

J iJtttt«H*W* l -pHINTED CIRCUIT 
^"" RIGHT ANCLE 

Jl .50 EACH mount 

40 PIN RIBBON CABLE 
SOCKET CONNECTOR 



22/44 EDGE CONNECTOR 

TIN SOLDERTAIL .156"x .200' 



LARGE QUANTITIES AVAILABLE 
S1.35each 10tOfS12.50 



7-17vdc 
S.S. BUZZER 




CMOS compdlib 



$1.25 each 



FLAT LEVER 
HANDLE 
(/' MINI TOGGLE 

SPOT 
RATED 

6 AMPS [SI 125 V 
/4 - 40 BUSHING 

51,00 each 

10 lor SB 50 



Litronix FRL-4403 

FLASHER 

A LED 

W dillused red lad 

^Pwllh built in Mashing unit 



ALL CLECTROniCS CORP. 

905 S. Vermont Ave. terms 

Los Angeles, Calif. 90006 
(213)380-8000 
Mon.-Fri. Saturday 
9 AM -5 PM 10 AM 

SEND FOR FREE CATALOG 



Quantities Limited 
Min.OrderSlO.OO 
Add $2.00 
Shipping USA 
3 PM • Calif. Res. Add 6% 
Prompt Shipp' 



Circle 305 on inquiry card. 



Circle 306 on inquiry card. 



Circle 307 on inquiry card. 



$94.20* 

Single Board Computer 



j^isgii. 



Mlik| 

11111° 



"100 piece price, model MCL11 



6800 MPU, serial I/O, parallel I/O, RAM, 
EROM, 44-pin 4VS'-x 6W' PCB 

EXPANSION MODULES 
RAM, ROM, CMOS RAM/battery, analog 
I/O, serial I/O, parallel I/O, counter/ 
timer, 488 GPIB, EROM programmer, 
power tail detect/power on reset 



UT|V'l 1 l7l r I 1801 South Street 
i ■ k» I I j Ik. Lalayette, IN 47904 



SPELLING 




eliminated with 

SPELLGUARD™ 

Proofreads 100 pp. per minute 
with Wordstar or Magicwand. 



Spcllguard 

Wordstar 
w/Spellguard 

Magicwand 
w/Spellguard 



$295 

$325 
$585 

$275 
$510 



TPA 



1635 School St. 
Moraga. CA 94557 
415) 376-3753 



WANTED I 




v^*-» 



The Blacksburg Group wants to evaluate 
your software for publication in the 
Blacksburg Continuing Education Series 
(Howard W. Sams and Co.) We're 
interested in circuit design, scientific 
application and data handling programs, 
among others. Please send us acopy of your 
orginia/ software, with documentation for 
our review. We'll send you a complete 
author kit. Competitive advances & 
royalities. All software treated as 
confidential. Let's see how we can work 
together. 

The Blacksburg Group, Inc., P.O. Box 242, 
Blacksburg, VA 24060 (703) 951-9030. 



Circle 308 on inquiry card. 



Circle 309 on inquiry card. 



Circle 310 on inquiry card. 



LETTER QUALITY 



$1600 




6 OUTPUT POWER SUPPLY 
FLOPPY, EPROM, CPU ETC. 



1AND NEW NORTH: »3676. seaiei 
rminaiu 5W3A. 2JV/1 2A. i6W2.e: 
rifling); 12W0 1A. -24W03A (ooth 



Orig used in NCR 
djuslable, w/OV proi 
pro!.); -I2V/01A (ad 



TERMS: UPS COO- \ 



•r Ciaige on approval COD • S2. c 



ELECTRAVALUE INDUSTRIAL 

P.O BOX 157-9 f. S\ 

MORRIS PLAINS, NJ 07950 C""/T~- 



201/267-1117 




ONE BOARD CP/M SYSTEM! 



only $750 

Assm., Tested 

& Burned-In 

for one week 



• %Vi by 12 inches 

• 10 MHZ 8085 CPU 

• 64K HAM 

• 3 RS-232 channels 

• 8272 Floppy Disk Controller 

■ Handles Single/Double Density 

• One to Four Drives. 801H or 
850R. 

Documentation S15. 

CP/M Floppy Disk Operating System S150 

Check or Money Order 



( 



nuroconrroll 

11744 Westline Industrial Drive 

St. Louis. MO 63141 

(314)432-1313 



) 



BELOW DEALERS COST! 



NorthSta^ 



32KDD -2295.00 
32 K QUAD- 2600.00 




General Ledgei 
SB25 00 



COD CASH IN ADVANCE-VISA/ MASTER CHARGE' 

"ADD t PERCENT ON CHARGE ORDERS 



CUSTOM BUSINESS COMPUTERS 

103 ATLANTIC AVENUE, LYNBROOK. NEW YORK 11563-1516)867.3340 



Circle 311 on inquiry card. 



Circle 312 on inquiry card. 



16K MEMORY — $ 24.00 

FOR APPLE - TRS-80 - EXIDY 

4116 EQUIVALENT 

MITSUBISHI 4116 M58759-20 150ns 8for$ 28.00 

NATIONAL MM5290N-3 200ns 8for$ 24.00 

2114-300ns 

NATIONAL MM2114N-3L 8for$ 26.00 



IMSAI COMPATIBLE 
PRODUCTS 

STILL A GREAT DEAL! 

I 8080 ENCLOSURE KIT w/o front panel $ 95.00 

(After March 31, 1981 — $115.00) 

8015 JUMPSTART FP $ 32.50 

8035DUALSA400FP $ 78.50 

PS-28D Improved 28A @8V and 3A@ ± 1 6V power supply for S-1 00 kit ...$ 95.50 

PIO 4-4 4 parallel inputs and outputs $160.00 

SIO 2-2 2 serial I/O ports, good to 19,200 baud $175.00 

DIO-C/D 2 board disk controller for 8" or 5 V*" $350.00 

CPM 2.2® For DIO including documentation $175.00 

CPA Improved Imsai style front panel works with Z80, etc $225.00 

VIO-X Improved video board w/8085 controller, 8275 crt controller, port mapped, 
on board memory, keyboard port $275.00 

MDX Dual SA400 drive enclosure $ 75.00 

DE 8 Dual 800R/801 R horizontal style enclosure w/power supply and fan$240.00 

Ask about documentation, repair service, firmware and software for your system. 



component supply, me. 

WW 



1771 Junction Avenue 
San Jose, California 951 1 2 

(408)295-7171 



TERMS: (1) PREPAID Send check or M.O. for merchandise amount only -we pay the shipping. 
(2) UPS COD or Bankcard orders by phone or mail - shipping charges added. 
California Residents add 6.5% Sales Tax. 



Circle 314 on Inquiry card. 



BYTE March 1981 



Circle 315 on inquiry card. 



SAVE! SAVE! SAVE! 

We have discounts, free shipping and 
a TOLL FREE NUMBER available 

Call Us! 800/531-7466 

Pan American 



TRS-80's 



Microcomputers 



Electronics 



INCORPORATED 

Dept. B 

1117 Conway, Mission, Texas 78572 

TOLL FREE ORDER NUMBER 800/531-7466 

Texas & Principal Number 512/581-2765 

Telex Number 767339 




Radio /hack 

AUTHORIZED SAMS (I NTLK 




MiutaffCivd 



Q) 



What should you do if your local computer store doesn't have 
the products you want? 

1) GO CRAZY or 2) GO TO HOBBYWORLD 

Hobby world Electronics is the nation's leading supplier of mail order electronics. We have thousands of brand 
name computer products in stock. 




Microsoft 
Z-80 Softcard * 

Doubly the versatility of your Apple 11' 
with the power ol a Z-80 Microprocessor 
Fully compatible with all Apple II systems 
Requires 48K RAM and disk drive In 
eludes Microsoft BASIC 5.0 Wt. 1 lb 
Cat No. 269H 4>nn IT 00 



Datasoft Mychess 

The world champion Microcomputer 
chess yarne. winner of the Fifth West Coasl 
Computer [-"aire, can now be enjoyed by 
Apple II owners. Mychess is the most ad 
v a need microcomputer chess yami* 
available Requires any Apple II, 4HK. 
disk. Z-80 soflcard and CP M. " Wt. b 01 



Special Offer: Purchase the Z-80 
Softcard from this ad and we'll in- 
clude Datasoft's Mychess at no extra 
charge! (a $34.95 value) 



$295° 



Cal No 2919 



$34 



95 



* Z-80 Softcard is a registered trademark 

of Microsoft. Inc. 
' Apple is a registered trademark of Apple 

Computer 
' CP/M is a registered trademark of Digital 

Research 



HOW TO ORDER: Pay by check. Mastercard, Visa or C.O.D. Charge cards include expira- 
tion date and bank no. Add $1.25 add), for C.O.D, Include S2.25 for shipping and handling 
(J.P.S. ground. Prices valid thru month of issue. Not responsible of typographical errors. 




HOBBYWORLD 

ELECTRONICS ,INC. 

19511 Business Center Dr. Dept. B3 

Northridge, CA 91324 

Call Toll Free: (800) 423-5387 

Local & Outside USA: (213) 886-9200 



Free Hobbyworld Catalog 

Send for your FREE, 44 page Hobbyworld 
catalog today! If your local computer store 
doesn't have something you want, make the right 
choice . . . Come to Hobbyworld! 

Name 



Company 
Address 



City. 



State. 



.Zip. 



358 BYTE March 1981 



Circle 316 on inquiry card. 



VISTA 

Your Supermarket 

For Add-ons and 

1 Peripheral Products 



The Vista V80/800/8000 

Family Disk Drive System 



Full compatible with TRS-80, 

Heath/Zenith 

120 Day Warranty 

40 Track Patch at NO CHARGE 



V-80 Single drive system (102K) .... $ 395.00 

V-60 Two drive system (204K) $ 770.00 

V-600 Single drive, B52 drive (204K) . $ 595.00 

V-800-2 Double dirve, B52 drives (408K) $1175.00 

V-8000 Single drive, B92 drive (408K) $ 775.00 

V-8000-2 Double drive B92 drives (816K) $1450.00 




The Vista Model II 



Totally Compatible with the TRS-80* 
Model II 



Provides one, two or three drives 

Adds up to 1 .5 million bytes of on-line 

storage 

120 day warranty 

Does everthing Radio Shack's 

expansion system will do. . . for less! 




Single drive (non-expandable) 
Single drive expansion system 
Two drive expansion system . 
Three drive expansion system 
Additional drives alone 



$ 900.00 
$1000.00 
$1550.00 
$2100.00 
$ 525.00 



Vista 

V-300 Daisy 
Wheel Printer 



Letter Quality 




• Print Wheel — Industry standard 96-character Daisy 
Wheel (Including the extended-life dual plastic wheels) 

• Printable columns (136) 

• Proportional, bi-directional printing 

• Interface — Industry standard parallel (RS232-C 
optional) 

• Service - Prompt maintenance/service agreements 
available nationwide 

• Warranty - 90 days partsand labor, one year parts only 

V-300-25 $1895.00 

V-300-45 $2195.00 

Tractor Option $ 300.00 



Vista V-100 Printer $745.00 



9 x 7 dot matrix 

125 cps bi-directional print speed 

136 column 

Industrial quality 




Vista Music Machine 9 

NEW! Uses latest State of the Art 

LSI Technology 

Requires only one slot for 9 voices! 

Uses three AY3-8910's to produce 9 voices 

Plays music generated by the ALF 

board 

APPLE II T " compatible 

ALF'" software reauired $129.95 



Price: 



On Drlvei 

MPI BS1 40 Track, 'Double 

Density 204K .... 
MPI B52 'Dual Head, Double 

Density408K 

Siemens FDD 100-5 40 Track Double 

Density 204K 

Siemens FDD 100-8 8" Single 

Sided Drive 

Shugart 801 R Single Sided Drive ... 



Other Products 

T.16K RAM upgrade kits $ 49.95 

2. NEW DOS 80 ... . $149.00 

3. LNW 80 (computer board) $ 86.95 

4. LNW expansion board . , $ 66.95 

5. H.C. Pennington books: 

TRS-80 DISK AND OTHER MYSTERIES 5 18.95 

E ROSOFT BASIC DECODER AND 
OTHER MYSTERIES $ 27.95 



The Vista V-200 for Exidy 

Completely packaged system, tested and 
ready to plug in 

Includes: power supply, two 40 track drives, 
case, double density controllers, and all cabling 
and total CP/M'" documentation. 
Storage capacity from 400K to 1.2 meg. 
System software-VISTA CP/M Disk Operating 
System and BASIC-E Compiler recorded on 
5%" diskettes Price: Starting as low as 

$1199.00 



S-100 version as low as 
$699.00 





3448.00 
$448.00 



The Vista V-1000 Floppy Disk Drive 
Subsystem 




Deluxe chassis with internal slide allows 
easy access for drive positioning 
and mounting. 

Built to mechanically and electrically 
accomodate single sided drives, double 
sided drives — including, the most popular 
8-inch Winchesterand Shugart floppy 
disk drives, , and 8-inch streaming tape 
cartridge units. 



Storage capacity from 0.5 to 40 megabytes 

Industrial quality cabinet with die cast 

front bezel 

Meets all UL and OSHA standards 

Additional Savings! Front and rear retma 

rail mounts provided at no extra charge 

(no external slides) 

Desk or rack mountable 

Features modular construction with 

removable sub-assembly that allows easy 

cabinet positioning and mounting 

Drives pull out for easy service and 

maintenance 



Cabinet $ 395.00 

Cabinet with (2) single sided drives $1595.00 
(Includes power supply and cable) 
Cabinet with (2) double sided drives $2295.00 
(Includes power supply and cable) 



232 



The Vista Computer Company 

1317 E. Edinger Avenue, Santa Ana, California 92705,(714)953-0523 1 

CALL TOLL-FREE 800-854-8017 

'TRS-80 is a registered trademark ofRadio Shack, a Tandy Corporation 
™ Apple is a registered trademark of Apple Computer Co. 
'" CP/M is a registered trademark ofDisital Research 



Circle 317 on Inquiry card. 



BYTE March 1981 



359 



apple II plu/ 

With 48Kof 
memory! 

51199 

With thepurchase of 
the APPLE III, 
select Iromthe below 
SPECIAL PRICING: 
/ 

'Base 2 printer. .^599' 
OisklMcont....S85 t 

Diskll 475"< 

Ser.PrinterCd. . /79~' 

SupRMod 23" 

3wayl/0Selecl.. 33* 
Video 100 EL. 119" 
FirmwareCard. 179" 
JHFtoRCACable.5" 

74LS00 .26 74LS155 US 

74LS02 .26 74LS158 .75 

74LS03 .26 74LS160 .95 

74LS04 .26 74LS161 

74LS08 .28 74LS162 95 

74LS09 .26 74LS163 1.60 

74LS10 .26 74LS164 .65 

74L'S20 .26 74LS165 .65 

74LS21 .28 74LS170 175 

74LS22 .26 74LS174 75 

74LS26 .49 74LS175 .75 

74LS27 .26 74LS190 .75 

74LS30 .28 74LS193 95 

74LS32 .32 74LS195 95 

74LS38 .32 74LS196 85 

74LS42 .65 74LS221 1.40 

74LS4B .78 74LS240 165 

74LS51 .25 74LS241 1.65 

74LS54 .35 74LS243 145 

74LS74 .38 74LS244 145 

74LS75 60 74LS245 2 25 

74LS83 44 74LS253 95 

74LS85 .95 74LS257 95 

74LS86 .95 74LS258 95 

74LS90 .69 74LS259 2 85 

74LS93 .69 74LS279 .44 

74LS107 .45 74LS283 100 

74LS112 .38 74LS293 185 

74LS113 .48 74LS298 1.20 

74LS122 .48 74LS366 95 

74LS123 .95 74LS367 .55 

74LS126 .69 74LS368 55 

74LS138 69 74LS373 1.39 

74LS151 .44 74LS374 1.39 




kll/oppkllpki, 



With 64Kof 
memory! 

51389 

nppic imtRPACE cbrdj 

cEimtonKi nmnii t tit 

communKnnoni ■"*<>**. a uw* m 

DUHIICOrtTTKMLIft d.o./.JJ H« 

WTHn BAIK nWMBMH m 

tvnuorr nmwMH m 

MWCAl mnCUOCJ MCHMf 4«4 

mmhw pmtnn m 

WWTOTVFfOq/HOMV M 



i/idec 
100 



APPLE EXPANSION KIT | 
16K Memory Add-On 

nHTAtCW ADO -ON Kir 
INCLUDES IHSTRUCTIOHS 



*39° 



'125 



12' 

Ldsdex Corp 



COLOR 




^Oy/MON|TO|13 



EPROMS 
270B Ik x 5.95 
8 FOR 40.00 
2716 2k x 8 9.95 
single ps. 8 FOR 80.00 
2732 4k x 8 24.95 
2716 2k x 8 6.95 
triple p.s. 



^pk deck/cakndaf 
*124 95 

On board batteries with one year lite. 

UsesMSM5832<xysa/coHroMed 

California Computer Systems 



MISCELLANEOUS 



803 ec 

NE555V 

7905 . 

7908 ' 

7915 

7918 

7805 

7806 

7808 . 

7812-' 

MC1330AIP 

MC1350P 

MC1358P 

LM380N 

NE565N 

MC1458P 

IS410 SCR 

IT410 TRIAC 



2.65 
.27 



1.60 
1.15 
1.50 
1.75 
1.25 
.50 
.95 
.95 




LOGIC 
NOIE 

KIT 



BUY FIVE OR MORc 



S16.9S each 



CARRY 

Titer 



COnCORD 

COfflPUTCR 

componenn 



HEATHKfT* 

COMPUTER OWNERS 



H47 COMPATABLE 
DISK OPERATING SYSTEM 
8"DuatSided,Doubfe Density 
Intelligent MASTER /SLAVE 

BY REMEX 



$2450°° 



SWITCHES 



2114 200ns 3.50 

2114L 300ns 3.75 

2114L 200ns 4.25 

4116 300ns 4.95 



1971 SOUTH STATE COLLEGE 

ANAHEIM, CALIF. 92806 



CHECK OR M 0. 
NO COD. 
CAL.RES.AD0 6/ 



(714)9370637 



A0D»1 50 FORFHT.ON 
ORDERS UNDER *50. 
5°/o IF OVER »50. 



SN7400N 
SN7402N 
SN7404N 
SN7408N 
SN7410N 
SN7412N 
SN7413N 
SN7414N 
SN7416N 
SN7417N 
SN7423N 
SN7425N 
SN7430N 
SN743/N 
SN7438N 



20 SN7440N 
.22 SN7442N 
.22 SN7443N 
.24 SN7445N 
.22 SN7451N 

28 SN7454N 
.35 SN7474N 
.49 SN7475N 
.29 SN7482N 

29 SN7492N 
.28 SN7493N 

25 SN7495N 
.23 SN7496N 
29 SN74122N 
24 SN74136N 



MSM5832 $ "7 c 

MICROPROCESSOR i HO 
REAL-TIME CLOCK 

The MSM533? is .. monolnn.r maul-gale CMOS ■meg' 



ntje addressable 4-tji 
hours BAY-QF-WEEK 

is conirolleO by « tn 



22 SN74141N 
57 SN74151N 
78 SN74153N 
.78 SN74154N 
20 SN74155N 
20 SN74157N 
.32 SN74160N 
32 SN74161N 
1.05 SN74163N 
.50 SN74164N 
.48 SN74165N 
.60 SN74174N 
.70 SN74175N 
.39 SN74180N 
.95 SN74181N 



.651 
.651 
1251 
80l 
.691 
.951 
.651 
.85 1 
.87 I 
.871 
.951 

69 I 
.75 I 

1.1 5l 



TRS80 , 

16K MemofyAddfln J 

'4395 

KIT CONTAINS I 
DIP SWITCHES! 
AND DETAILED! 
INSTRUCTIONS! 



SOROC 




IQ12tr^6S9 



O o 

© ® w 



No"Glitches'\ Surges 
Or Interference 

IMC MPDTI7 TURNS AN 
OflONARY OUTLET INTO 
A CONTROL LED FILTERED 
POWER SOURCE TOR UP 

TOElGHTOeVrCES 



S8P° 




Dual Trace Oscilloscope 



HITACHI 30 MHz 

• TV sync-separater circuit 

• High-sensitivity 1 mV/div 
(5MHz) 

9 Sweep-time magnifier 
(10 times) 

• Z-axis input (Intensity 
modulation) 

• Signal delay line 

• X-Y operation 

• Trace Rotation 

Model V302B 

$995 



More sensitive to your input 



EPROMS 

2708 2716 



$4?o 



$790 



2114L 



5375 



4116 



(200ns) 
$375 



ANCRONA SPECIAL 

64K Dynamic RAM 

HM4864 $97.00 



€ 



California 
Computer 
Systems 



32K STATIC HAM MODULE 

[ASSEMBLED AND TESTED) 

2032A 450ns RAM $710.00 

2032B 300ns RAM 79S.O0 

2032C 200ns RAM 830.00 

B4K DYNAMIC RAM MODULE 

(ASSEMBLED AND TESTED) 
2065C 200ns RAM. . . . S700.00 
16K STATIC RAM MODULE 

(ASSEMBLED AND TESTED) 

211GA 450ns RAM S349.95 

211GB 300ns RAM 389.35 

211BC 200ns RAM. . . . 399.95 



MAINFRAME 
220DA Assy and Tesled S399.95 
2200K Complete Kil 349.35 

Note: Spec. color-Black, Blue. 

Brawn, Office Cream, or Grey. 
FLOPPY DISK CONTROLLER 
2422A Assy £1 Tesled . $400.00 
4-Port Serial I/O Interface 
2710A Assy&Tesied. . S340.00 
Serial/Parallel I/O Interface 
2718A Assy6 Tesled. $360.00 
4-Port Parelle! I/O Interface 
2720A Assy&Tesied. . . $250. 

Z-BO" CPU 
2810A Assy&Tesied. . S300.00 




PROGRAMMABLE 
TIMER 



7440A Assembled and Tested $114.95 




PARELLEL 
INTERFACE 



7720A Assy 6 test cable 6 std firmware. $119.95 

7720 B Assembled and tested, cable & Centronics- type 

firmware included S1 19.95 




STORES 00 NOT ACCEPT MAIL ORDERS 



MAILORDER 

P.O. BOX 2208Y CULVER CITY. CA 90230 



PHONE ORDERS (213) 641-4064 



Gidei pricing \ 




ARITHMETIC 
PROCESSOR 



781 1 B Assembled and tested: CCsoft diskette included 
(Compatible with Apple II" computers with 
a disk drive.) $399.95 

7SI1C Assembled and tested, CCsoft ROM included 
(Compatible with Apple II PLUS" compu 
lers and Apple II" computers with an 
Applesoft" card) $399.95 



Assy & Tesled Less ball . 



ASYNCHRONUS 

SERIAL 

INTERFACE 



Assy & tested: cable included . . $159.95 




CALENDER/ 
CLOCK 
MODULE 



SYNCHRONUS 

SERIAL 

INTERFACE 

Assy & tested, cable included . - $179.95 

GPIB 
(IEEE-4BB) 

INTERFACE 

Assy & tested; cable included . . $300.90 

CENTRONICS" 
PRINTER 
INTERFACE 

7728A Assy Er tested, cable not included. . . $119,95 



Quite Portable 
Very Affordable 
and Unbelievable 

Versatile! 
the PET computer may 

very well be a 
lifetime investment 

• Large Keyboard 

• Separate Numeric 
Pad 

• Graphics on Keys 



$995 




* I 6% * 

DISCOUNT 
COUPON 

Bring this 4'01 T l*OIN T intooneofourstoresor 
mail to our Mail Order address shown below 

and receive a IO%»IS<OI\T 
on purchases from this Ad of S1 00.00 or more. 
Offer I \ l> llll N on Miiri-h ;t I . I !rU I 

NAME ... 

ADDRESS 

CITY STATE 

ZIP PHONE NO 

Coupons accepted only with full name and address filled m. 



VISIT A STORE NEAR YOU TODAY - We stock a large selection of Technical Books, Discrete Components, Integrated Circuits, Test Equipment and Electronic Supplie 



ATLANTA 

3330 Piedmont Rd. N.E. 

Atlanta. GA 30305 

(404) 261-7100 



CULVER CITY 

11080 Jefferson Blvd. 

Culver City. CA 90230 

|213| 390-3595 



HOUSTON 

2649 Richmond 

Houston. TX 77098 

(713) 529-3489 



PORTLAND 

1125 N.E. 82nd Ave. 

Portland. OR 97220 

(503) 254-5541 



SANTA ANA 

1300 E. Edinger Ave 

Santa Ana. CA 92705 

(714) 547-B424 



SUNNYVALE 

1054 E. El Camino Real 

Sunnyvale. CA 94087 

(408) 243-4121 



TUCSON 

451 8 E. Broadway 

Tucson. AZ 8571 1 

(602) 881-2348 



360 



BYTE March 1981 



Circle 319 on inquiry card. 




THE STAR MODEM 

From Livermore Data Systems 



RS232 MODEM 
IEEE 488 MODEM 
RS232 CCITT 
IEEE 488 CCITT 



SALE $135 

SALE $245 

$170 

$280 



STAR Modem is the price performance leader with a full 
2 YEAR FACTORY WARRANTY. 




WE CARRY THE BLACK APPLE 



I BelleHdluell 

MAOl ( Xl'UJSIVt LV rOH OF LI >. HOWF LI BY 

' qpplc computer inc. 



EBS Business System for PET/CBM 

Extremely comprehensive package for small business. 
Fully integrated inventory and accounts receivable system 
including invoices, packing slips, mail labels, statements, 
bank deposit slips, and 17 reports. Allows any of 10 
standard letters to be merged with customer record info on 
either a selective or complete file basis. Demo disk and 
system description available for $3.00. 

Piper-Mate Word Processor $29.95 

PET/CBM full featured 60 command system by Michael 
Riley. Uses either tape or disk and any printer. Includes 
in- text commands, floating cursor, scrolling, etc. 





6502 


7.45 10/6.95 50/6.55 100/6.15 


6502A 


8.40 


10/7.95 50/7.35 100/6.90 


6520 PIA 


5.15 


10/4.90 50/4.45 100/4.15 


6522 VIA 


6.45 


10/6.10 50/5.75 100/5.45 


6532 


7.90 


10/7.40 50/7.00 100/6.60 


2114-L450 




3.45 20/3.35 100/3.25 


2114-L200 




4.15 20/3.95 100/3.75 


2716 EPROM (5 volt) 


9.90 5/9.45 10/8.90 


TMS 2532 EPROfv 




23.50 


4116-200 lit RAM 




8 for 30.00 


S-100 Wire Wrap 




2.65 



KM MM Pascal for PET $75 

Subset of standard Pascal with true machine language 
translator for faster execution. 16 K with tape or disk. 



EARL for PET (disk file based) $65 

Editor, Assembler, Relocater, Linker to generate relocat- 
able object code. 

fuMFORTH-r- for PET/CBM $65 

A full-featured FORTH with extensions conforming to Forth 
Interest Group standards. Includes assembler, string process- 
ing capabilities, disk virtual memory multiple dimensioned 
arrays, floating point and integer processing. 



MIPL0T Intelligent Plotter 
by Watanabe Instruments (Digiplot) 



SPECIAL 
$1145 




Has all intelligent functions for producing graphs and 
drawings including 8 vector and 4 character commands. 
Solid and broken lines can be specified. Character gen- 
erator for alpha, numeric, and symbols. Characters can be 
rotated in 4 orientations, and can be 1 6 sizes. Coordinate 
axes drawn by specifying graduation inteival and number 
of repetitions. Parallel ASCII interface, 11x17 paper. 



FLEX-FILE Data Base for CBM/PET $60 

Random file handling system with Report Writer and 
Mail Label Handler. By Michael Riley 



DISKS 



(write for quantity prices) 




SCOTCH (3M) 514" 
SCOTCH (3M) 8" 
Maxell 5%" 
Maxell 8" Disks 
Verbatim 5V*" 

(add 1.00 for Verbatim 
Verbatim 8" Dbl. Dens. 
BASF 5%" 
BASF 8" 

Diskette Storage Pages 
Disk Library Cases 



10/2.90 50/2.80 100/2.70 
10/2.95 50/2.85 100/2.75 
10/4.25 50/4.10 100/3.95 
10/4.65 50/4.50 100/4.35 
10/2.45 50/2.40 100/2.35 
5'A" plastic storage box) 
10/3.45 50/3.35 100/3.25 
10/2.60 20/2.50 100/2.40 
10/2.65 20/2.55 100/2.45 
1 for 3.95 
8" - 2.85 5%" - 2.15 




commodore 



CBM-PET SPECIALS 

,<<, Up to $235 FREE 
/^ mirehindlsi with purchase of 
^ one of following CBM-PET Itemtl 




CASSETTES - AGFA PE-611 PREMIUM 

High output, low noise, 5 screw housing, labels. 
C-10 10/5.65 50/25.00 100/48.00 

C-30 10/7.30 50/34.00 100/66.00 

All other lengths available. Write for price list. 



• 



FREE 
$1795 235 
1795 235 
795 75 
995 150 
1295 205 
1295 205 
795 100 
95 12 
395 50 



4 PART HARMONY MUSIC SYSTEM for PET 

Allows you to easily enter, display, edit and play 4 part 
harmony music. Includes whole notes thru 64ths (with 
dotted and triplets), tempo change, key signature, 
transpose, etc. The KL-4M unit includes D toA converter 
and amplifier (add your own speaker). 
KL-4M Mmk Burt with VMM Pufrmi $59.90 



8032 32K - 80 column CRT 

8050 Dual Disk Drive- 1 megabyte 

8N Full size graphics keyboard 

16K Business or Graphic Keyboard 

32K Business or Graphic Keyboard 

2040 Dual Disk Drive- 343,000 bytes 

2022 Tractor Feed Printer 

C2N External Cassette Deck 

CBM Voice Synthesizer 

WRITE FOR SYSTEM PRICES 

♦"EDUCATIONAL DISCOUNTS*** 

Buy 2 PET/CBM Cimittin, rtcilii 1 FREE 

WordPro 3 - 32K CBM, disk, printer WO 

WordPro 4 - 8032, disk, printer 255 

OZZ Data Base System for CBM 8032 335 

VISICALC for PET, ATARI 170 

BPI General Ledger, AVP, A/R for PET/CBM 270 

Programmers Toolkit - PET ROM Utilities 34.90 

2 Meter IEEE to IEEE Cable 43.00 

PET Spacemaker Switch 24.90 

Dust Cover for PET 6.90 

IEEE-Parallel Printer Interface for PET 1 05 

IEEE-RS232 Printer Interface for PET 149 

The PET Revealed 1 7.00 

Library of PET Subroutines 1 7.00 

Source Hookup 88 

Over 1000 programs and services available. 



EPSON MX-80 Printer 


$545 


STARWRITER Daisy Wheel Printer 


$1500 


Centronics 737 Printer 


$790 


NEC Spinwriter - parallel 


$2500 


XYMEC Hl-Q 1000 Intelligent Daisy Wheel 


$2150 


Leedex Video 100 12" Monitor 


$129 


ZENITH DATA SYSTEMS 




Zenith Z19 Terminal (factory asm.) 


$735 


Zenith Z89 with 48K 


$2150 


SYM-1 


$209 


SYM BAS-1 BASIC or RAE-1/2 Assembler 


$ 85 


KTM-2/80 Synertek Video Board 


$349 


KIM-1 (add $34 for power supply) 


$159 


Seawell Motherboard - 4K RAM 


$195 


Seawell 16K Static RAM - KIM, SYM, AIM 


$320 



A 



ATARI 800 $777 

All Atari Modules 20% OFF 




115 E. Stump Road 
Montgomeryville, PA 18936 



215-699-5826 



A B Computers 



ATARI EDUCATIONAL PLAN writ, lor d.t.n. 



A P Products 15% OFF 
APHobby-Blox 15% OFF 



ALL BOOK and SOFTWARE PRICES DISCOUNTED 

The 8086 Book (Osborne) $12.75 

Z8000 Assembly Language Programming $10.60 

PET Personal Computer Guide (Osborne) $12.75 

PET and the IEEE 488 Bus (Osborne) $12.75 

6502 Assembly Language (Osborne) $ 9.90 

Programming the 6502 (Zaks) $10.45 

6502 Applications Book (Zaks) $10.45 

6502 Software Cookbook (Scelbi) $ 9.45 

CP/M Handbook (w/ M P/M) Zaks $ 1 1 .85 



WRITE FOR CATALOG. 

Add S 1 25 per order for shipping We pay balance of UPS surface charges 
on all prepaid orders Prices listed are on cash discount basis Regular 
prices slightly higher 



Circle 320 on inquiry card. 



BYTE March 1981 



361 



Circle 321 on inquiry card. 



HICKOK DIGITAL MULTIMETERS 




MX-333 



Model 
LX303 

$6950 



V1IZ Tech DMM 3Vz- 
Digit LCD Readout 

Model WD 747 $"7Q95 




Beckman DIGITAL MULTIMETERS 

Model TECH 300 1 09 
Model TECH 310 1 40 




Model TECH 330 



*199 95 





DIGITAL MULTIMETERS 

Model 462 Model 463 £$£2 

M99 95 M69 95 S» ' - 



Complete with nickel- 
cadmium batteries, AC 
charger/adapter, test 
leads 



<5ES) 

Magnifier 
Lamp 




Precision ground and polished ■ 
magnification lens 

Model LFM-1A *65. 



Casio Calculator- 
Calendar Watclu 

Model C-80 

$4250 




SMB 15 MHz Miniscope 



■ Rise time 11.7 nS or 
less ■ Built-in signal 
delay line ■ Flat 



«1 




1. <a 


h a Ljjja _ 1 1 



Model 
1420 




Dual Trace fi u ]S„ ran 9' n 9 
5 "30 MHz 
(Triggered 
Scope 

Model 1479A 

Digital 

Pulsar Probe Model dp-ioo 

50 MHz 

Pulsar Probe moiici dp so 




3V 2 -Digit 0.1% Digital 
~A Capacitance Meter 

j Model 3001 *233 7 ^ 



Function Generator 

Model 2001 $-j 5795 

Proto Boards 



ModeH 
PB-104 ' 

Fully assembled 

*59 95 



Logic Monitor 

• Automatically 

displays static and 

dynamic logic • 

Workswith DTL, Model LM-1 

HTL, TTL. and 

CMOS 



*59 95 



.Touch Test 20 Multimeter 

~^| A portable/ 

I bench-type 
I meter 




15 MHz Dual 
Trace Triggered 



SMSigJfA Miniscope 

B»^6$[M»J?// Model MS-215 



30 MHz Dual Trace Triggered 
Miniscope Model Ms-230 




PK40D 

4 Pc Standard Starter Kit • One (1) Slandard Command 
ConsolE ■ Two |2| Lamp Modules ■ Ore (I) Appliance Module' 

PK500 5 Pc Ultrasonic Starter Kit "One (1) Oeluie J, 
Ultrasonic Command Console ■ One (I) Hand Held Remote *' 
Unit ■ Two (2) Lamp Modules ■ One (1] Appliance Uml 



LM50I Lamp Module $13-95 

AM601Applianct Module $13.95 
WS7C1 V/ail Switch Modulasi3.9S 
WS711 Wall Switch Module 

withindepencJenl On-Otl 
power bjllons S15.95 



74" 

todule 

9995 

The Time r $5995 



Miniature 
High Fidelity 
3-Way Stereo 
Speakers 

*59 95 



BB1 



Model 
TC201 




FIDELITY 

Chess Challenger 7 
$7995 



Model 
BBC 




Sensory Chess 
Challenger $ 110. 

Voice Sensory 

Challenger 

$24995 



WAHL* 

Cordless 
Soldering 
Iron 
$2995 




Th&iunaE-Spat 

Circuit Tester 

Finds faulty components \ 
quickly and easily 

*29 95 Model 
5800 



MURAPHONE 
Cordless 
Telephone 
System 

Model $11 fl 
300 I • V. 




Welter" 

WTCPN Controlled 
Output Soldering 
Station 

Model WTCPN 

$5750 



Service 
Master 
Tool Kit 



Soldering 
Station 




Vim SupeTGase 

Model 
70260 



$4g95 




24995 



In-Dash Car Stereos 

8-Track AM/FM $CO50 , 

Model JCS 420 yJ£m | 

Cassette AM/FM $575<T 

ModelJCS505 *" 

Digital Cassette AM/FM $8995 

With ClOCk Model JCS 607 



Graphic Equalizer 

Model GE 5000 $3Q9S 





6x9 3-Way $1295 ea. 

Speakers ■ 20 oz. magnet 
Model BP2000-69 TRD 



855 Conklin Si. Farmingdale, N.Y. 11735 



■ VISA ■ COD 

■ Money Order 

■ Check 

N.Y. Stale residem 
appropriate sales lax 



ADO FOB SHIPPING AND INSURANCE 

to! 250.00 S 150 

S2M.0CU MO 00 5.00 

SOI. nolo 750.00 7 50 

751.0010 1000.00 10.00 

mil 10DO.00 12.50 

COO't Kill 



^(800)645-9518 

in N.Y. Stale call (516) 752-0050 I 



Add-On 

Disk Drive 

Subsystems 

FOr Apple, TRS-80, S-100 
Based Computers 




Expansion and enhanced capabilities are key words in achieving full utilization of your computer system. Our complete line of LOBO disk 
drive subsystems are the ideal, cost-effective way to provide the expansion capabilities you need to meet your system growth requirements. 
All of our subsystems are complete, thoroughly-tested, 100% burned-in, and leature a 1 year 100% parts/labor warranty. 



APPLE 



3101 Minifloppy, 31011 Minifloppy w/interface card 

B101CA One SA800 in cabinet w/power, ODC* Controller, cable and manual 
B202CA Two SA800 in cabinet w/power, DDC* Controller, cable and manual 
5101CA One SAB50 in cabinet w/power, DDC* Controller, cable and manual 
5202CA Two SAB50 in cabinet w/power, DDC* Controller, cable and manual 
'Double Density Controller 



S-100 BASED 
COMPUTERS 

MODEL NO. DESCRIPTION 

4101C SA400 in cabinet w/power 

621 2C Two SA801 in cabinet w/power 

521 2C Two SAB51 in cabinet w/power 



GENERAL 



MODEL NO 

B212 

B212C 

5212 

5212C 



DESCRIPTION 

Two SA801 in cabinet 

Two SA801 in cabinet w/power 

Two SA851 in cabinet 

Two SA851 in cabinet w/power 



TRS80 






MODEL NO DESCRIPTION 

41 01C SA400 in cabinet w/power 

B101C II One SA800 in cabinet w/power lor Mod. I 

B202C II Two SA800 in cabinet w/power tor Mod. 

C802 Cable for Mod. II 

CB05 Cable for TRS80 Minifloppy 



MODEL NO 


DESCRIPTION 


C808 


Cable for TRS80 Eight inch Floppy 


LX80 


Double density expansion interface 


RS232 


Dual Serial Port Option 


16K 


16K Byte RAM for LX80 (32KB max 


VTOS 


4.0 Disk Operating System 



INVENTORY CO., 

P.O. Box 185, Santa Yhez,Ca., 93460 
(805) 688-8781 



362 BYTE March 1981 



Circle 322 on inquiry card. 



WE WILL NOT BE UNDERSOLD 




DISK DRIVES 



$314 PRINTERS 



40 track, 102K Bytes. Includes power sup- 
ply and TRS-80* compatible silver 
enclosure. Ready to plug-in and run the 
moment you receive it. Can be intermixed 
with each other and Radio Shack drive on 
same cable. 90 day warranty. One year on 
power supply. Available for 220 Vac (50 Hz) 
operation. External card edge included. 



FOR TRS-80* 

CCI-100TEAC 

CCM00MPI 

CCI-280 

For Zenith Z89 

CCI-189 
Z-87 



5% ", 40 Track (102K Bytes) for Model I 
5'/.", 40 Track (102 K Bytes) for Model I 
5V« ", 80 Track (204K Bytes) for Model I 

5 V« ", 40 Track (102K Bytes) add-on drive 
Dual 5 Va " add-on drive system 



|gk7gaiiIiMtMtM:liM 

MAINFRAME, Z-80 CPU, CONTROLLER, 
RAM, and 2P + 2S CARDS 

8" SHUGART SA801R DISK DRIVES 



$314 

$319 
$429 

$394 
$995 



$CALL 

$425 



DISK OPERATING SYSTEMS 



PATCHPAK#4by Percom Data 

CP/M® for Model I, Zenith $145 
NEWDOS Plus 40track $79 



$ 8.95 

for Model II, Altos $169 
NEWDOS 80 $135 



DISKETTES — Box of 10 with plastic library case 
5'/i" Scotch $35 Maxell $40 BASF/Verbatim $24 

8" Scotch $50 Maxell $55 BASF/Verbatim $36 

CLEAR PLASTIC CASE-Holds 50 5% "diskettes $19 



$CALL 
APPLE III-96K $3749 



COMPLETE SYSTEMS 

ALTOS ACS8000 Computers 
APPLE II-16K $1075 

Call for other Apple products 

TRS-80* Model II-64K $3499 • Model III-16K $899 
Used TRS-80* Model I Computers, tested and guaranteed $CALL 

ZENITH Z89, 48K all-in-one computer $2395 

ZENITH Z19 $735 

TELEVIDEO 920C $748 

ATARI 400 $479 ATARI 800 $769 

APF Game Only $95 Complete System $489 

MATTEL INTELLIVISION $229 



$129 
$379 
$155 
$226 
$238 
$416 
$120 



MONITORS 


LEEDEX 


12' 


B&W Video 100 


ZENITH 


13' 


Color 


SANYO 


9' 


B&WVM4509 


SANYO 


12' 


B&W DM5012 


SANYO 


12' 


Green Screen DM5112 


SANYO 


13' 


Color DMC6013 


APF 


9' 


B&WTVM-10 



TELECOMMUNICATIONS 

LIVERMORE STAR MODEM 2-year guarantee 
UNIVERSAL DATA SYSTEMS UDS-103 
D-CAT HARD WIRED DIRECT MODEM 
AUTO-CAT Auto Answer, Direct Connect Modem 



$145 
$179 
$189 
$229 




R.O. with Tractor Feed 



NEC Spin writer 

Letter Quality High Speed Printer 

Includes TRS-80* interface software, quick 
change print fonts, 55 cps, bidirectional, 
high resolution plotting, graphing, propor- 
tional spacing: R.O. $2395 
$2595 KSR with Tractor Feed $2895 



C.ITOH Starwriter, 25 CPS, daisy wheel printer $1795 

C.ITOH Starwriter II, 45 CPS, daisy wheel printer $1995 
Letter quality printers. Use up to 15" paper. 1 year warranty on 
parts. 3 months on labor. Proportional spacing and bidirectional 
printing. Same as VISTA V300. 

EPSON MX-80 $CALL 

PAPER TIGER IDS445 Graphics and 2K buffer $699 

IDS 460 Bidirectional, 160 cps, graphics and 2K buffer $1050 

IDS 560 132 Columns, graphics $1599 

ANADEX DP-9500/01 $1345 DP-8000 $849 

OKIDATA Microline 80 Friction and pin feed $499 

Tractor Feed, friction, and pin feed $625 

Microline 82 Bidirectional, friction and pin feed $719 

Microline 83 Bidirectional, 120 cps, uses up to 15" paper $995 

CENTRONICS 

737 Friction & pin feed $780 

730 Friction & pin feed $595 

779Tractorfeed $969 

EATON LRC7000+ 64 columns, plain paper $269 

TI-810 Includes TRS-80* software and 

Compressed print, vertical form control $1865 

16K RAM KITS 2 for $56 $30 

200 ns for TRS-80*, Apple II, (specify): Jumpers $2.50 

ACCESSORIES 

Z-80 SOFTCARD: Your key to software expansion. The plug- 
in Z-80 Softcard transforms your Apple into a Z-80 while 
keeping all the benefits of the 6502. Comes with CP/M in 
two disk format, MBASIC and GBASIC, full documentation 
and utility programs. $339.00 

SCOTCH HEAD CLEANING DISKETTE: Cleans drive 
Read/Write head in 30 seconds; specify 5 Va "or 8". $25.00 

FLOPPY SAVER: Protection for center holes of 5Vi" floppy 
disks. Installation tools and rings for 25 diskettes. $ 11.95 

Re-orders of rings only $ 6.95 
VIDEX BOARD 80 Column, U/L case conversion card $279.00 
CRT FILM: Helps eliminate external glare, 9" 
RF MODULATOR: Adapts video to TV 
TRS-80 & OTHER MYSTERIES 

NEC SPINWRITER THIMBLE $11.95 RIBBON 

CCS CARDS: Parallel or serial printer interface cards 
RS232: For Radio Shack Interface. 
DISK-DRIVE EXTENDER CABLES: Fits all mini-disk drives. 
SIX (6) PRONG ISOLATOR: ISO-2 
AC FILTER/6 PRONG POWER STRIP 
DISK DRIVE CABLES: 2 drive $29.00 4 drive 

DUST COVERS: TRS-80/Apple 
PLASTIC DISKETTE HOLDER: For ring binder, holds 20 

COMMUNICATIONS SOFTWARE 

CCI-TELNET COMMUNICATIONS PACKAGE: 

Communications with mainframes and micros. CP/M 

compatible $149.00 



$ 29.00 
$ 29.00 
$ 18.95 
$ 6.00 
$115.00 
$ 84.00 
16.95 
54.00 
39.00 
35.00 
7.95 
8.00 



For fast delivery, send certified checks, money orders or call to arrange direct bank wire transfers. Personal or company checks require two 
to three weeks to clear. All prices are mail order only and are subject to change without notice. 



dealer (national/international) inquiries invited Send for FREE Catalogue 



TO ORDER CALL TOLL FREE 1-800-343-6522 

TWX: 710-348-1796 Massachusetts Residents call 617/242-3361 



The CPU SHOP 



5 Dexter Row, Dept. B03M 

Charlestown, Massachusetts 02129 

Hours 10AM-6PM (EST) Mon.-Fri. (Sat. till 5) 



Technical Information call 617/242-3361 
Massachusetts Residents add 5% Sales Tax 
Tandy Corporation Trademark/^'Digital Research 



l#Ws 


VISA' 


\&iWC, 



Circle 323 on inquiry card. 



BYTE March 1981 363 



Circle 324 on inquiry card. 



ii 



CALIFORNIA COMPUTER SYSTEMS 



32K RAM BOARD A&T. 




450 NSEC . . $579.95, 200 NSEC 


$62995 


16K RAM A&T. 




450 NSEC $255.95. 200 NSEC 


S285.95 


64K DYNAMIC A&T 




200 NSEC . . 


S579.95 


Z80 PROCESSOR A&T. 


S259.00 


DISC CONTROLLER 


S339.95 


APPLE IEEE INSTRUMENTATION INTERFACE 


KIT 7490. A&T 


S275 00 



ARITHMETIC PROCESSOR FOR APPLE 7811A. 
A&T $342.80 

APPLE ASYNCHRONOUS SERIAL INTERFACE 
7710A. A&T $137.10 

APPLE SYNCHRONOUS SERIAL INTERFACE 

7712A. A&T $153.95 

ALL OTHER CCS PRODUCTS AVAILABLE 



SStTJ 



PB-1 2708 & 2716 Programming Board with pro- 
visions for 4K or 8K EPROM. No external supplies 
required. Textool sockets. Kit S 143.00 

CB-1A 8080 Processor Board. 2K of PROM 256 
BYTE RAM power on/rest Vector Jump Parallel 
port with status. Kit S146.00 PCBD . ...S31.95 

VB-3 80x24 VIDEO BOARD. Graphics included. 
4MHZ. Kit $379.95 

IO-4 Two serial I/O ports with full handshaking 
20/60 ma current loop: Two parallel I/O ports. 
Kit ...$168.00 PCBD S31.95 

VB-IC 64x16 video board, upper lower case Greek 
composite and parallel video with software. S-100. 

Kit S 1-43.00 

CB-2 Z80 CPU BOARD. Kit $199.95 

AIO APPLE SERIAL/PARALLEL Kit S144.95 

ALL OTHER SSM PRODUCTS AVAILABLE 



W777C, 



inc. WAMECO INC. 

MEM-3 32K STATIC RAM 2114 24 bit 

addressing $36.95 

FDC-1 FLOPPY CONTROLLER BOARD will drive 
shugart, pertek, remic 5" & 8" drives up to 8 drives, 
on board PROM with power boot up, will operate 

with CPM'" (not included). PCBD $43 95 

FPB-1 Front Panel. IMSAI size, hex displays. Bytrj, 
or instruction single step. PCBD $48 50 

QM-12 MOTHER BOARD. 13 slot, terminated, S-100 
board only $39 95 

CPU-1 B080.A Processor board S-100 with 8 level 
vector interrupt. PCBD $28 95 

RTC-1 Realtime clock board. Two independent in- 
terrupts Software programmable. PCBD $25 95 

EPM-2 2708/2716 16K-32K EPROM CARD. 
PCBD $2895 

QM-9 MOTHER BOARD. Short Version of QM-12. 
9 Slots. PCBD $33 95 

MEM-2 16Kx8 Fully Buffered 2114 Board. 
PCBD $2895 

PTB-1 POWER SUPPLY AND TERMINATOR BOARD. 

PCBD $28 95 

IOB-1 SERIAL AND PARALLEL INTERFACE. 
2 parallel, one serial and cassette. 

PCBD $28.95 

2708 .... $7.50 2114L 450 NSEC $4.99 

2716 ..$25.95 2114L 200 NSEC ... $5.99 



M 




(415) 728-9121 
P.O. Box 955 • El Granada, CA 94018 

Please send for IC, Xistor and Computer parts list 



MARCH SPECIAL SALE 
ON PREPAID ORDERS 

[Charge cards not included on this offer) 
A & T 8K X 8 RAM BOARD SALE 

ON SSM, MB-6B, PCBD $74.95 

ON WAMECO MEM-1, PCBD $74.95 

450 NSECONDS ASSEMBLED AND TESTED. 
PART MAY BE REMARKS. 2.5 AMPS TYPICAL. 
WAMECO PCBD 

IOB-1. CPU-1 $24.95 EA. 

PTB-1, RTC-1 $22.95 EA. 

MIKOS PARTS ASSORTMENT 
WITH WAMECO AND CYBERCOM PCBDS 

MEM-3 less RAM $ 95.95 

With 2114L-4 .5350.00 

With 2114 L-2 S390.00 

CPU-1 with MIKOS =2 8080A CPU $99.95 

QM-12 with MIKOS 'A 13 slot mother 

board $1 10.95 

RTC-1 with MIKOS =5 real time clock $65.95 

EPM-2 with MIKOS »11 16-32K EPROMS 

less EPROMS $65 95 

QM-9 wilh MIKOS M29 slot mother 

board $99.95 

FPB-1 with MIKOS »14 all parts 

for front panel $144.95 

MIKOS PARTS ASSORTMENTS ARE ALL FACTORY MARKED 
PARTS. KITS INCLUDE ALL PARTS LISTED AS REQUIRED 
FOR THE COMPLETE KIT LESS PARTS LISTED. ALL SOCK- 
ETS INCLUDED 

LARGE SELECTION OF LS TTL AVAILABLE 

PURCHASE S50.00 WORTH OF LS TTL AND GET 
10°oCR EDIT TOWARD ADDITIONAL PURCHASES. 
PREPAID ORDERS ONLY. 

VISA or MASTERCHARGE. Send account number, interbank num- 
ber, expiration date and sign your order. Approx. postage will 
be added. Chech or money order will be sent post paid in U.S. 
[I you are not a regular customer, please use charge, cashier's 
check or postal money order. Otherwise there will be a two- 
week delay for checks to clear. Calif, residents add 6% tax. 
Money back 30-day guarantee. We cannot accept returned IC's 
that have been soldered to. Prices subject to change without 
notice. SID minimum order. $1.50 service charge on orders 
less than 550.00. 




BUILD YOUR OWN LOW COST 
MICRO-COMPUTER 

POWER SUPPLIES 

FOR S-100 BUS, FLOPPY DISKS, ETC. 




POWER TRANSFORMERS (with mounting brackets) 



ITEM 


USED IN 


PRI. WINDING 


NO. 


KIT NO. 


TAPS 


Ti 


1 


0V, 110V, 120V 


T2 


2 


0V, 110V, 120V 


T 3 


3 


0V, 110V, 120V 


Tn 


4 


0V, 110V, 120V 


T 5 


— 


0V, 110V, 120V 



SECONDARY WINDING OUTPUTS 
2x8 Vac 2x14 Vac 2x24 Vac 



SIZE 
WxDxH 



UNIT 
PRICE 



2X7.5A 
2X12.5A 
2X9A 
2x4A 
2x3A 



2X2.5A 
2X3.5A 
2X2.5A 
(28V, CT) 
2x2A 



2X2.5A 
48V, CT, @3A 



POWER SUPPLY KITS (open frame with base plate, 3 hrs. assy, time) 

ITEM USED FOR @ + 8 Vdc ® - 9 Vdc @ + 16 Vdc @- 16 Vdc @ + 28 Vdc 



3V«"x3%"x3'/," 
3y<"x4 3 /i"x3y," 

3 3 /4"x3%"x3'/„" 
3"x3"X2V2" 



SIZE W X D X J 



21.95 
27.95 
29.95 
22.95 
14.95 



UNIT PRICE 



KIT 1 15 CARDS SOURCE 15A 

KIT 2 SYSTEM SOURCE 25A 

KIT 3 DISK SYSTEM 15A 



1A 



2.5A 
3A 
2A 



2.5A 
3A 
2A 



4A 



12"x5"x4 7 /," 
12"x5"x47," 
14"x6"x4'/," 



52.95 
59.95 
67.95 



DISK SYSTEM PWR SUPPLY S3 assy. & tested, open frame, size io"(W)x6"(D)x4%"(H) 92.95 

UNREGULATED OUTPUTS: +8V@15A, ±16V@3A. 

REGULATED OUTPUTS: +5V@3A, -5V@1A, + 24V@4A, SHORTS PROTECT. IDEAL FOR THE SYSTEM WITH 12 SLOTS MAINFRAME & TWO 8" DISK 

DRIVES, SUCH AS SHUGART 801R OR SIEMANS FDD 100-8. (OPTION: OVPfor + 5V @ ADD $5.00) 

DISK DRIVE POWER SUPPLY "R3" assy. & tested, open frame, size:9"(W)x6%"(D)x4>/,"(H) 67.95 

SPECS: +5V @ 5A REGUL, OVP, - 5V @ 1A REG., + 24 @ 5A REG., SHORTS PROTECT. OPTIONS: 1. REPLACE + 24V BY + 12V 

2. ADD ± 12V @ 1A, $12.00 MORE. 
IDEAL FOR 2 SHUGART 801/851 OR SIEMANS FDD 100-8/200-8 DISK DRIVES & ROCKWELL AIM-65. 
SHIPPING FOR EACH TRANSFORMER: $4.75. FOR EACH POWER SUPPLY: $5.00 IN CALIF. $7.00 IN OTHER STATES. CALIF. RESIDENTS ADD 6% SALES TAX. OEM WELCOME. 



MAILING ADDRESS: 
P.O. BOX 4296 
TORRANCE, CA 90510 



SUNNY INTERNATIONAL 

(TRANSFORMERS MANUFACTURER) 
(213) 328-2425 MON-SAT 9-6 



SHIPPING ADDRESS: 
22129V* S. VERMONT AVE\ 
TORRANCE, CA 90502 ! 



364 



BYTE March 19B1 



Circle 325 on Inquiry card. 



HOT WINTER PRICES ON PERSONAL 
COMPUTERS AND COMPONENTS. 



Look at this! 



, , .- 







Ohio Scientific 
Superboard II 

$299 



• It's the first complete computer 
system on a board. 

• Superboard II uses the ultra 
powerful 6502 Microprocessor 

• 8K Microsoft BASIC-in-ROM 

• 4K static RAM on board, 
expandable to BK 

• Full 53-key keyboard, with upper 
and lower case. Plus user 
expandability. 

• Video interface and audio 
cassette interface. 

The Ohio Scientific Superboard II at 
$299 — in today's economy — has 
got to be the best buy by far. It will 
entertain you with spectacular 
graphics made possible by its ultra 
high resolution graphics and super 
fast BASIC. It will help you in school 
or industry, as an ultra powerful 
scientific calculator. Advanced 
scientific functions and a built-in 
"immediate" mode allow you to 
solve complex problems without 
programming. 

The Superboard II can be 
expanded economically, for business 
uses, or to remotely control your 
home appliances and security. Even 
communicate with other computers. 

Read what's been written 
about Superboard II: 

"We heartily recommend Super- 
board II for the beginner who wants 
to get into microcomputera with a 
minimum coat. A real computer 
with full expandability." 

—POPULAR ELECTRONICS, MARCH 1979 

"The Superboard II ia an excellent 
choice for the peraonal computer 
enthusiast on a budget." 

-BYTE, MAY 1979 



Look at these easy hardware prices: 

610 Board For use with Superboard II and Challenger 1 P. 

BK static RAM. Expandable to 24K or 32K system total. 

Accepts up to two mini-floppy disk drives. Requires + 5V 

@4.5 amps. S 298 

Mini-Floppy Disk Drive Includes Ohio Scientific's PICO COS 

software and connector cable. Compatible with 61 

expander board. Requires + 1 2V @ 1 .5 amps and + 5V @ 

0.7 amps. [Power supply S. cabinet not included.] 299 

630 Board Contact us for important details. 229 

AC-3P 12" combination black and white TV/video monitor. 159 

4KP 4K RAM chip set. 79 

PS-005 5V 4.5 amp power supply for Superboard II. 35 

PS-003 1 2V power supply for mini-floppies. 29 

CS-600 Metal case for Superboard II, 610 and 630 board 

and two power supplies. [While stock lasts.] 49 

CS-900B Metal case for single floppy disk drive and power 

supply. [While stock lasts.] 49 

AC-12P Wireless remote control system. Includes control 
console, two lamp modules and two appliance modules, for 
use with 630 board. 175 

AC-17P Home security system. Includes console, fire 

detector, window protection devices and door unit for use 

with 630 board. 249 

C1P Sams C1 P Service manual 8 

C4P Sams C4P Service manual 16 

C3 Sams Challenger III manual 40 

Ohio Scientific and independent suppliers offer hundreds of programs for the 
Superboard II, in cassette and mini-floppy form. 



FrBight Policies Allordersof£100ormoreere 
shipped flight prepaid. Orders of less then SI QQ please add 
$4.00 to caver shipping costs. Ohio residen s adds. 5% Sales Tax. 



VISA 




€5* 



Hours: Call Monday thru Friday. 
8:00 AM to 5:00 PM E.O.T. 
TOLL FREE: 1-800-321-5805 



Guaranteed Shipment 

Cleveland Consumer Computers 5. Components 
guarantees shipment of compu er sys ems 
within 48 hours upon receipt of your order. 
Our failure to snp within 48 hours 
ontitlss you to S3 5 of sof twsre, FREE. 



To Order: Or to get our free catalog CALL 1-800-321-5805 TOLL FREE. Charge your 

order to your VISA or MASTER CHARGE account. Ohio residents call: [21 6] 464-8047. 
Or write, including your check or money order, to the address listed below. 

CLEVELAND CONSUMER 
COMPUTERS & COMPONENTS 

P.O. Box 46627 
Cleveland, Ohio 44146 




I 
I 
I 
I 
I 

I 
I 
I 
I 

I 



Onrlian Cnpm> Cleveland consumer 

Ul UCI rill lie COMPUTERS & COMPONI 



P.O. Box 46627 
, COMPONENTS Cleveland, Ohio 44146 

D Superboard II $299. D 630 Board SS299. 

D 610 Board $298. □ AC-3P 12" B/W Monitor $159. 

□ Mini-Floppy Disk Drive $299. D 01 P Sams Manual $8. 

[Attach separate sheet for other items.] 

NAME 



ADDRESS: 


CITY: 
PHONE: 


STATE: 


ZIP: 


Payment by: VISA 


MASTER CHARGE 


MONFY DRDFR 


Credit Card Account # 







Expires . 



.Interbank #[Master Charge] 



TOTAL CHARGED OR ENCLOSED $. 



. [Ohio Residents add 5.5% Sales Tax] 



Orders of less then $1 00, please add $4.00 to cover shipping costs. 

All orders shipped insured UPS unless otherwise requested. FOB Cleveland, Ohio. 



Circle 326 on Inquiry card. 



BYTE March 1981 



365 



ok™®®^©!]^© 



□ □□ 



INTRODUCTORY G 
PRICE ONLY 




REGULAR $3250.00 LIST 
INCLUDING CP/M2.2® 



320K 

MINI DRIVES 
SHOWN. 8" 

and 554" 10MB 
HARD DISK 
OPTIONAL 



IMMEDIATE DELIVERY! 



1 YEAR PARTS WARRANTY! 

(90 DAYS ON DRIVE PACKAGE, KEYBOARD AND LABOR) 



ftfjfj. M IC R SALES 



S-100-8 



©KH§©K ™i 

TERMINAL 



• Feather Touch Capacitance Keyboard 

• 60 Key Standard ASCII 
PLUS + Hex Keypad 

PLUS + 8 Special Function Keys 
PLUS + 20 Screen Editing Keys 

• SO ROC Type Screen Attribute Set 

• Half Intensity 



COMPUTER 

8SlotS-100 

64K Dynamic Ram 

4MHZ Z-80 

Serial Printer Port (150- 19. 2K) 

Double Density Disk Controller 

Programmable Baud Rate 

Programmable Keyboard Set 





D 

DISK 
STORAGE 

• Dual Double Density 
5% Single Sided Drives 

• DOUBLE SIDED Option 

• Double Sided, 77 
Track, Option 

• Color Matched Enclosure 

• Self Contained Power Supply 



OPTIONS: 



♦ Dual 5%" Double Sided MPI B51 (640K) add $225.00 

♦ Dual 5%" Double Sided MPI B91 (1.2MB) add $360.00 

♦ Dual 8" SIEMANS FDD120-8 Drives (1MB) add $250.00 

♦ Dual 8" QUME Double Sided Drives (2MB) add $625.00 



CP/M2.2 is a Registered Trademark of Digital Research Inc. 



DEALS □ DEALS □ 0£>US 



OUR BUYERS ARE IN 

CONTACT WITH EVERY MAJOR 

SUPPLIER AND O.E.M. 

BUY HERE AT 1000 PIECE 




QUANTITY PRICES 

ALL MERCHANDISE 100% 

GUARANTEED! 15 DAY FULL 

CASH REFUND! 

WRITE FOR FULL CATALOG! 



664 N. MICHIGAN AVE. * SUITE 1010 * CHICAGO, ILLINOIS 60611 

CALL TOLL FREE: 1-800-435-9357 * MONDAY thru SATURDAY 

(ILLINOIS RESIDENTS CALL: 815-485-4002) * 8:00 a.m. to 6:30p.m. 

TERMS: Prepayment - C.O.D. up to $100.00 - M/C, Visa 

Please allow personal check to clear before shipment. 



JUST HOT STUFF 



POWER SUPPLIES 



(f you can beat these 
prices we will be truly 
amazed. OEM's at 500 
lot pay more than this. 
Call or write for full 
spec, sheets. 




DISK POWER SUPPLIES 


PRIAM-SHUGART-CENTURY-MICROPOLIS 


+5V@9A |-5V@.8A [+24V@7A ] US-384 1 89.00 


SHUGART-SIEMANS-MPI 5%" 


+5V@.5A 


+12V@.9A 




US-340 


33.50 


+5V @ 2A 


+12V@4A 




US-323 


56.25 


SHUGART-SIEMANS-CDC 8" 


+5V@1A 


-5V@.5A 


+24V@1.5A 


US-205 


52.50 


+5V@2A 


-5V@.5A 


+24V @> 3A 


US-206 


69.00 


+5V 6> 3A 


-5V@.6A 


+24V @ 5A 


US162 


89.00 


+5V@1.7A 


-5V@>1.5A 


+24V @ 2A 


US-272 


69.00 


+5V @ 2A 


+ I2V@.4A 


-12V<°>.4A 


US-HTAA 


37.50 



TELEVIDEO 912C 

SOROCIQ120- $675.00 
Televideo 912C- 665.00 
Televideo 920C- 720.00 
ADDS R 25 - 710.00 

Also have920C, SOROC, 
HAZELTINE, etc. What 
we don't have is room on 
this page. Call Toll Free 
800 number for prices. 




C-ITOH PRINTER 



$499.00 



Look closely at the 

photo and see other 

adds in this rag at 

$995.00. Perfect units, 

warranteed. Only 500 pes. Same story, 

manufacturerer had too many. 




S-100 CARD EXTENDER 



$12.50 

(Gold Contacts) 

As long as there is a 
price war, we will fight 
your battle. Compare 
at your local Dept. 
store and buy U$ MICRO. 




MEM0REX - VERBATUM - WABASH 
BASF FLOPPIES 

BOX OF 10 ONLY: 



5'/." 

5%" 

5%" 

8" 

8" 

8" 



SOFT 
HARD 10 
HARD 16 
SOFT 1D 
SOFT 2D 
SOFT 2DDS 



$2.65 ea? 
2.65 ea. 
2.65 ea. 
3.25 ea. 
3.85 ea. 
5.00 ea. 



3* 



SPECIAL OF THE QUARTER SPECIALS OF THE MONTH 



S1-MOD (KIT) 



$189.00 



8®r 




Complete S-100 12 Slot Computer. Ample 
system powerwith regulated power for drives. 
Excellent for Subsystem or Hobby use. 
4 hours to build. (6 conn, inch, less fans) 



DUAL DRIVE SUBSYSTEM 



$995.00 

$195.00 w/no Drives 



If this looks like a Lobo 
Drive System, don't be 
fooled. Just because it 
looks like one, works like 
one, smells like one, 



m±=r 



2SHUGART801R 
POWER SUPPLY 

and tastes like one (?) 
doesn't mean it has to cost like onel 



EXPANDABLE RAM 

*SPECIAL*SPECIAL*SPECIAL* 



This is the best all 
around 64K board 
you can buy. If after 
you see it, you don't 
agree return for full 
refund. Bank Select 
by extended address 
lines or I.O. 40H. 



* $389.00 A &T* 



S-100 POWER 
$79.50 

Simple Brute Force! 

S-100 Power Supply, 

30A@ +8V, 

6A@>+16V, 

6A@>-16V, 

PC Board Design. 





Z-80 CPU (KIT) 



The first time this 

world popular CPU 

offered in Kit. 2 serial, 

3 parallel, CTC, EProm 

Z-80 at 4 mhz. Software 

buad rate, etc. (less Prom fit cable) 




$212.00 



12 SLOT MOTHER 



We have connectors and power 
supply too. Start your system 
with quality components. 
Terminated. 




$22.50 



CONNECTORS $2.50 ea. 



FANS $14.95 







These are brand new, 

in the box fans. Not 

noisey bearing pull outs. 

Never again at these low prices! 



3-1/8' 



4-5/8" 



4116s 



Expansion 16K Dynamic 
RAMs for Apple, TRS-80 
S-100 systems. T.I., Mostek 
Intel, Call for manufacturer. 



$3.75 

200 NS 



DIP 80 $399.00 

Don't be mislead by this Jg 
LOW price. This is a rug- Iji 
ged 100% Duty Cycle ■ 
7 by 7 Dot Matrix Printer. MMMMM 
Brand new, factory warr. I ^— 

• RS-232 ADD $65.00 
• TRACTOR FEED ADD $70.00 



2114s 



One of the world's two. 

most popular STATIC ., M 

RAMs. Factory prime yjr 200 NS 

tested units. Sold in lots of 8 only. 

FUJITSU, HITACHI, etc. 




$3.45 



TMS-4044 
MM-5257 
INTEL 2147 



$4.25 

250 NS 



The other of the world's most popular STATIC 
RAMs. This one is 4K by 1 organization. Don't 
buy Gold, buy these, the price won't last! 



2716s 
2708s 



$9.50 (450 NS) 
$6.95 (450 NS) 



Remember when 2716s were $50.00 and hard 
to get? These units are so beautiful it's hard to 
part with them. But we will, for a small price. 
Guaranteed! 



SHUGART DRIVE 
8" 801R 

$395.00 

Manufacturer had 

too many, buys at 8" 851 R $585.00 

1000 piece rate, 

sales dropped, so we got' em. Fantastic buy, get 

them while they last! Full warranty. 




SIEMANS DRIVE 



8" 120-8 



$375.00 



Very Special Price on 

these BRAND NEW current production units 

Add $10.00 for Extended 1 Year Warrantee! 



Circle 327 on inquiry card. 



BYTE March 1981 



367 



I SN7400N 
I SN7401N 
I SN7402N 

| SN7403N 
SN7404N 
SN74Q5N 
SN7406N 
SN7407N 
SN7408N 
SN74Q9N 
SN7410N 
SN7411N 
SN7412N 
SN7413N 
SN7414N 
SN7416N 
SN7417N 
SN7420N 
SN7421N 
SN7422N 
SN7423N 
SN742SN 
SN7426N 
SN7427N 
5N7429N 
SN7430N 
SN7432N 
SN7437N 
5N743SN 
SN7439N 
SN7440N 
SN7441N 
5N7442N 
SN7443N 
SN7444N 
5N7445N 
SN7446N 
SN7447N 
SN7448N 
SN7450N 
SN74S1N 
SN7453N 
SN7454N 
SN74S9A 
5N7460N 
5N7470N 



74LSOO 
74LS01 
74LS02 
74LS03 
74LS04 
74L505 
74LSD8 
74LSQ9 
74L510 
74L511 
74LS12 
74LS13 
74LSI4 
74LS15 
74LS20 
74LS21 
74LS22 
74LS26 
74LS27 
74LS2B 
74L530 
74L532 
74LS33 
74LS37 
74LS3B 
74LS40 
74LS42 
74LS47 
74L548 
74LS49 
74L551 
74LSS4 
74LS55 
74LS73 
74LS74 
74LS75 
74LS76 
74LS7B 
74L5S3 
74LSB5 
74LS86 
74LS9Q 



7400 



SN7472N 
SN7473N 
SN7474N 
SN7475N 
SN7476N 
SN7479N 
SN7480N 
SN74B2N 
SN7483N 
SN748SN 
5N7486N 
SN74B9N 
SN749QN 
SN7491N 
SN7492N 
SN7493N 
SN7494N 
SN7495N 
SN7496N 
SN7497N 
SN7410ON 
SN74107N 
SN74109N 
SN74116N 
SN74121N 
5N74122N 
SN74123N 
SN74125N 
SN74126N 
SN74132N 
SN74136N 
5N74141N 
SN74142N 
SN74143N 
SN74144N 
SN74145N 
SN74147N 
SN7414BN 
SN741S0N 
5N74151N 
SN74152N 
SN74153N 
SN741S4N 
SN741SSN 



3.25 
3.49 
3.49 



SN74156N 
SN74157N 
SN74160N 
SN74161N 
SN74162N 
SN74163N 
5N74154N 
SN7416SN 
SN74166N 
SN74167N 
SN74170N 
SN74172N 
SN74173N 
SN74174N 
SN74175N 
SN74176N 
SN74177N 
SN74179N 
SN741BON 
SN741B1N 
SN741B2N 
SN741B4N 
SN7418SN 
SN7419QN 
SN74191N 
SN74192N 
SN74193N 
SN74194N 
SN74195N 
SN74196N 
SN74197N 
SN7419BN 
SN74199N 
SN74221N 
SN742S1N 
SN74276N 
5N74279N 
SN74283N 
SN74284N 
5N742B5N 
5N7436SN 
SN74366N 
SN74367N 
SN74368N 
SN74390N 
SN74393N 



.59 



74LS 



74LS92 
74LS93 
74LS95 
74LS96 
74LS107 
74LS109 
74LS112 
74LS113 
74L5114 
74L5122 
74L5123 
74LS125 
74LS126 
74LS132 
74L5133 
74L5136 
74LS13B 
74LS139 
74L5151 
74LS153 
74L5154 
74LS155 
74L5156 
74LS157 
74L5158 
74L5160 
74L51G1 
74LS162 
74LS163 
74L5164 
74L5165 
74LS16B 
74L5169 
74LS170 
74LS173 
74LS174 
74LS175 
74L51B1 
74LS190 
74L5191 



74LS192 

74LS193 

74L5194 

74LS195 

74LS197 

74LS221 

74L5240 

74LS241 

74L5242 

74LS243 

74L5244 

74LS245 

74L5247 

74LS24B 

74L5249 

74LS251 

74LS2S3 

74LS2S7 

74L52S8 

74LS26Q 

74LS266 

74LS273 

74LS279 

74L52B3 

74LS290 

74L5293 

74L529B 

74LS3S2 

74LS353 

74L536S 

74LS366 

74L5367 

74LS3&3 

74L5373 

74LS374 

74LS375 

74LS386 

74LS393 

74LS399 

74L5670 

S1L595 

81LS97 



74SOQ .50 

74502 .50 

74503 .50 

74504 .55 

74505 .55 

74508 .50 

74509 .50 

74510 .50 

74511 .50 
74515 .50 
74520 .50 
74522 .50 
74530 .50 
74S32 .55 
74S40 .55 
74551 .50 
74S64 .50 
745G5 .50 
74574 .79 
74SS6 .79 

745112 .79 

745113 .79 

745114 .79 

• LIMITED A\ 



74S 



745133 

745134 
74513S 
745136 
74513B 
745139 
74S140 
745151 
745153 
745157 
745158 
745174 
745175 
745188 
745194 
745195 
74S19G 
745240 
74S241 
745242 
745243 
AILABILITV 



745244 
745251 
745253 

745257 
74S258 
745260 
7452B0 
74S2B7* 
745268* 
745373 
745374 
745387* 
745471* 
74S472* 
745473* 
74S474* 
745475* 
745570* 
745571 * 
745572* 
745573* 
745940 
745941 
HE5E PROr 



2.49 
2.49 
2.49 



19.95 
19.95 
19.95 
21.95 
21.95 
7.95 
7.95 
19.95 
19.95 



CA3013H 
CA3023H 

CA3039H 
CA3W6N 
CA3059N 
CA306QN 
CA3080H 



2.15 



CA-LINEAR 

CA3081N 2.00 

CA3DS2N 2.00 

CA3083N 1.60 

CA3086N .85 



CA30B9N 
CA3096N 
CA3130H 
CA3140H 
CA3160H 
CA3401M 
CA3600N 



CD4000 
CD4001 
CD4002 
CD4006 
CO4007 
CD4009 
CD4010 
CD4011 
CD4012 
CD4013 
CD4014 
CD4015 
CD4016 
CD4017 
CD401B 
CD4019 
CO4020 
CD4021 
CD4022 
CD4023 
CD4024 
CD4025 
CO4026 
CD4027 
CO402B 
CD4029 
CD4030 
CD4035 
L CD4O40 



CD-CMOS 



CD4041 
CD4042 
CD4043 

CD4044 
CD4046 
CD4047 
CD404B 
CD4049 
CD405O 
CD4051 
CO4052 
CD4053 
CD4056 
CD4059 
CD40S0 
CD4066 
CD4068 
CD4069 
CD4070 
CD4071 
CD4072 
CD4073 
CD4075 
CD4076 
CD4QB1 



CO40B2 

CD4093 

CD409B 

CD4506 

CD4SQ7 

CD4508 

CD4510 

CD4511 

CD4514 

CD4515 

CD4516 

CD451B 

CD4519 

CD4520 

CD4526 

CD452B 

CD4529 

CD4543 

CD45G2 

CD4S66 

CD4583 

CD4723 

CD4724 

MC144W 

MC14410 

MC14411 

MC14412 

MC14419 

MC 14433 



1.29 
3.95 
2.95 



11.95 
2.79 
2.49 



14.95 
14.95 
14.95 
11.95 
4.9S 
13.95 




LITRONIX DISPLAY SALE 



MULTI DIGIT REFLECTOR ARRAYS FOR 




'■"»-'- 


& 


rOLARITV 


nmmm 


u»tt«umn 


FOHIYAHO VOLT»Gr 


IS;:;' 


™» 


TYP 


MIN 


»» 


Tvr 


MA. 


OL4MJl"2! 


» 


«« 


WSL 


± 


ID 


m 


" 


u 


„ 


2.49 
2.49 


Sl«™ ti 


«„ m 


■* 


J 


4.9S 
4.9S 
2.49 


DL41MA|r,dl 


,.0 


C.C....MPX 


IS 


3 


3* 


40 


4.9S 



MULTI DIGIT REFLECTOR A! 



DlZJOQtR.II 


M 


CC.HPX 


ISn JO.g.lDP R>*l 


M 


.1 


W 


a 


:o 


M 


.99 




OLC 143* (b-i^I 


50 


C.A MPK 


ttHionn 




IS 


:■.. 




35 


' 15 


1.49 




OL4SMIHMI 


W 


C.CMPX 


>Sq4D*lD.F.H.|ni 


s 


5 


10 


17 


10 


30 


2.49 




DLSMdlHHI 


50 


cawra 


IStt SOHpl DP Righl 


e 


5 


10 


1.7 


10 


30 


2.95 




01 «» IXMI 


Uj 


C* MPX 


'>, i, [j.(, . n " H vi 


8 


& 


10 


17 


ID 


30 


2. S3 




MWflM 


10 


c^im 


J Sn a d»i o p B,oh. 


US 


U 


,0 


34 


40 


30 


3.99 





DISCRETE LEDS 



XC556R .200" red 

XC556G .200" green 

XC556V .200" yellov 

XC556C .200" clear 

XC22R .200" red 

XC22G .200" green 

XC22Y .200" yellov 



B/H 

4/11 
4/11 

4/11 

S/Sl 
4/11 
4/11 
4/11 



MV50 .085" red 

XC209R .125" red 

XC209G .125" green 

XC209Y .125" yellow 

XC526R .185" red 

XC526G .185" green 

XC526Y .IBS" yellow 

XC526C -IBS" clear 



6/11 

s/ii 

4/$l 
4/11 
5/S1 
4/J1 
4/11 
4/11 



XC111R .190" red S/Jl 

XCU1G .190" green 4/J1 

XC111Y ;I90" yellow 4/J1 

XC1I1C .190" clear 4/1 1 

^ 



RL-2 . .S.39ea.or3/$1.00 



C.A. — 

Type 
MAN 1 
MAN 2 
MAN 3 
MAN 52 
MAN 54 
MAN 71 
MAN 72 
MAN 74 
MAN82 
MAN 84 
MAN 3620 
MAN 3630 
MAN 3640 
MAN 4610 
MAN 6610 
MAN 6630 
MAN 6G40 
MAN 6650 
MAN 6660 
MAN 6710 
MAN 6750 
MAN 6780 
DLD304 
OLD307 
DLGSO0 



Polarity 
C.A.— red 
5x7 D.M.— red 
C.C.-red 
C.A. — green 
C.C.— green 
C.A. —red 
C.A.— red 
C.C.-red 
C.A. -yellow 
C.C.— yellow 
C.A.— orange 
C.A. — orange ± 1 
C.C.— orange 
C.A. —orange 
C.A.— orange— DD 
C.A.-orange ± 1 
C.C.— orange— DD 
C.C.— orange i 1 
C. A.— orange 
C.A.— red— DD 
C.C.-red ± 1 
C.C.-red 
C.C.— orange 
C.A. —orange 
CO— green 



DISPLAY LE0S "-«™- 



Type 

DLG507 

DL704 

DL707 

DL72B 

DL741 

DL746 

DL747 

DL750 

DLDS47 

DLO850 

DL33B 

FND358 

FND359 

FND503 

FND507 

HDSP-3401 

HDSP-3403 

SOB2-77S1 

5OB2-7760 

50B2-730O 

5032-7302 

5082-7304 

4N28 

LIT-1 

MOC3010 



Polarity 

C.A. — green .5 

C.C.-red .3 

C.A.— red .31 

C.C.-red .5 

C.A.— red .6 

C.A.— red t l .6 

C.A.— red .6 

C.C.-red .6 

C.A. —orange .8 

C.C.— orange .8 

C.C.-red .1 

C.C. t 1 .3 

C.C. .3 

C.C. (FNDSOO) .5 

C.A. (FNDS10) .5 

C.A. —red .8 

C.C.-red .B 

C.A.,R.H.D.— red .4 

C.C.R.H.D.— red .4 

4x7sgl.dlg. RHD .6 

4x7sgl.dlg. LHD ,6 

Overnge.char.Ul) .6 
Photo XslstorOpto-l 
Photo Xslstor Opto-I 
Optically Isoi.TrlacD 



22.00 
22.00 
19.95 




POTENTIOMETERS 



$2.95 each 



vieets Mll-R-94 



RV4NAY SD 


102A 


IK 


RV4NAY SD 


502A 


5K 


RV4NAY SD 


103A 


10K 


RV4NAY SD 


253A 


25K 


RV4NAY 5D 


M3A 


SDK 


RV4NAY SD 


I04A 


100K 


RV4NAY SD 


105A 


lMeg 



LOW PROFILE 

(TIN) SOCKETS 



8 Pin LP 
14 pin LP 
16 pin LP 
IB pin LP 
20 pin LP 
22 pin LP 
24 pin LP 
2B pin LP 
36 pin LP 
40 Pin LP 



SOLDERTAIL (GOLD) 
STANDARD 



8 pin 5G 
14 pin SG 
16 pin SG 
18 pin SG 
24 Pin SG 
2B pin SG 
36 pin SG 
40 pin 5G 



$1.35 each 

3/4 Wan @) 70°C 
1 5 turn pot. Linear 
taper. Printed cir- 
cuit mount. 

Part No. Pai 

830P-50ohm 
S30P-100ohm 
_830P-SOOohm 
830P-1K 
B30P-2K 



E£j|jte 



830P- 5K 
83OP-10K 
B3OP-20K 
S30P-50K 



83OP-1O0K 
B30P-200K 
B3QP-5O0K 
830P-lMeg 



SOLDERTAIL 

STANDARD (TIN) 



14 pin ST 
16 pin ST 
IB pin ST 
24 pin ST 
28 pin ST 
36 pin ST 
40 Pin ST 



WIRE WRAP SOCKETS 
(GOLD) LEVEL #3 



S pin 


WW 


.59 


10 pin 


WW 


.69 


14 plr 


WW 


.79 


16 pin 


WW 


-B5 


18 pin 


WW 


.99 


20Pin 


WW 


1.19 


22 pin 


WW 


1.49 


24 pin 


WW 


1.39 


2B pin 


WW 


1.69 


36 Pin 


WW 


2.19 


40 pin 


WW 


2.29 



1/4 WATT RESISTOR ASSORTMENTS -5% 



ASST. 1 


Sea. 


10 Ohm 
27 Ohm 


12 Ohn 

3.1 On- 


15 Ohm 

39 Ohm 


18 Dhm 
47 Ohm 


22 Ohm 

56 Ohm 


50 pes. 


$1.95 


ASST.2 


5ea. 


68 Ohm 
180 Ohm 


82 Ohn 
220 Ohn 


l 100 Ohm 
270Ohm 


120 Ohm 
330 Ohm 


ISO Ohm 
390 Ohm 


50pcs. 


$1.95 


ASST. 3 


5ea. 


470 Ohm 560 Ohm 680 Ohm 820 Ohm 
1.2K 1.5K UK 2.2K 


IK 
2.7K 


50 pes. 


$1.95 


ASST. 4 


Sea. 


3.3K 

8.2K 


3.9K 

10K 


4.7K 
12K 


S.6K 
15K 


6.BK 
18K 


50 pes. 


$1.95 


ASST. 5 


5ea. 


22K 
56 K 


27K 

6SK 


33K 
82K 


39K 

10OK 


47K 
120K 


50 pes. 


$1.95 


ASST. 6 


Sea. 


150K 
390K 


iaoK 

470K 


220K 

560K 


270K 

680K 


330K 

S20K 


50 pes. 


$1.95 


ASST. 7 


5ea. 


1M 
2.7M 


1.2M 
3.3M 


1.5M 
3.9M 


l.SM 
4.7M 


2.2M 
5.6M 


50 pes, 


$1.95 



ASST. 8 R 



Includes Resistor Assts. 1-7 (350 pes.) 



$10.95 ea. 



$1 0.00 Min. Order - U.S. Funds Only 
Calif. Residents Add 6% Sales Tax 
Postage-Add5%plusSl Insurance 




ameco 



ELECTRONICS 



Spec Sheets- 25rf 

Send 41d Postage for your 

FREE 1981 JAMECO CATALOG 



PHONE 

ORDERS 

WELCOME 

(415) 592-8097 



MAIL ORDER ELECTRONICS - WORLDWIDE 

1355 SHOREWAY ROAD, BELMONT, CA 94002 

PRICES SUBJECT TO CHANGE 



Part No. 

7045IPI 

JWSCV/KIt* 

7106CPL 

7106EV/KH* 

7107CPL 

71Q7EV/Klt* 

7116CPL 

7117CPL 

7201IDR 

7205IPG 

726 EV /Kit* 

7206CJPE 

7206CEV/KU' 

7207 A IP D 

7207AEV/Kit' 

7303IPI 

7209IPA 

7215 IPG 

721SEV/Kit* 

7216AIJI 

7216CIJI 

7216 DIP I 

72171 Jl 

7218CIJI 

7224 [PL 

7226AIJL 

7226AEV/KU 

7240IJE 

7242IJA 

72S0UE 

7260IJE 

7555 IP A 

7556IPD 

7611BCPA 

7612BCPA 

7621BCPA 

7631CCPE 

7641CCPD 

7642CCPD 

7660CPA 

S069CCQ 

8211CPA 

8212CPA 

• INT 



DtMlRli^DlL 



Puncti 

CMOS Precision Timer 
Stopwatch Chip, XTL 
3Vl Digit A/D (LCD Drive) 
IC, Circuit Board, Display 
3Vi Digit A/D (LED Drive) 
IC, Circuit Board. Display 
3W Digit A/D LCD OtS. HLI 
3Vz Digit A/D LED Dis. 



attery ^ 



sit I 



oicato 



alor 



Price 

14,95 
22.95 
16.95 
34.95 
15.95 

2i.« 

18.95 
17.95 
2.25 
12.95 
19.95 
5.15 
9.95 



Tone Generator Chip, XTL 

Dscillator Controller 

Freq. Counter Chlo, XTL 

Seven Decade Counter 

Clock Generator 

4 Func. CMOS Stopwatch CKT 

4 Func. Stopwatch Chip, XTL 
8-Diglt Univ. Counter C.A. 
S-Dlglt Freq. Counter C.A. 
8-Diglt Freq. Counter C.C. 
4-Diglt LED Up/Down Counter 
8-Dlglt Univ. LED Drive 
LCD4V 1 Dlglt UpCounterDRI 
8-Digtt Univ. counter 

5 Function Counter Chip, XTL 
CMDS Bin Prog. Timer/Counter 
CMOS DWIde-Dy-256 RC Timer 
CMDS BCD Prog. Timer/Counter 
CMOS BCD Prog. Timer/Counter 
CMDS555Timer (8'plnJ 
CMDS 556 Timer £14 pin) 
CMDS Op Amp Comparator 5MV 2.25 
CMOS Op Amp Ext. Cmvr. 5MV 2.95 
CMOS Dual Op Amp Comp. SMV 3.95 
CMOS Trl Op Amp Comp. 10MV 5.35 
CMOS Quad Op Amp Comp. 10MV 7.50 
CMDS Quad Op Amp Comp. 10MV 7.50 
Voltage Converter 2.95 
SOppm Band— GAP Volt Rel. Diode 2.50 
Volt Ref/lndicator 2.50 
Volt Ref/lndlcator 2.50 

ERSIL'S EVALUATION KITS 



26.95 
21.95 
12.95 
10.95 
11.25 
31.95 
74.95 
4.95 



2.20 



74C0Q 

74C02 
74CW 
74C0S 
74C10 
74C14 
74C20 
74C30 
74C42 
74C4B 
74C/3 
74C74 
74CB5 
74C86 
74C89 
74C90 
74C93 
74C95 



.39 



74C 



74C106 

74C107 
74C151 
74CI54 
74C157 
74C160 
74C161 
74C162 
74C163 
74C164 
74C173 
74C174 
74C175 
74C192 
74C193 



2.95 
3.95 
2.25 



74C195 
74C221 

74C240 
74C244 
74C373 
74C374 

74C901 
74C903 
74C911 
74C912 
74C915 
74C917 
74C922 
74C923 
74C92S 
74C926 
S0C95 
B0C97 



2.25 
2.25 
2.49 
2.59 



.79 



LH0002CN 

LM10CLH 

LM11CLH 

LH0070-OH 

TL071CP 

TL072CP 

TL074CN 

LH0082CD 

TL082CP 

TLD84CN 

LH0094CD 

LM300H 

LM301CN 

LM302H 

LM304H 

LM30SH 

LM307CN 

LM30BCN 

LM309H 

LM309K 

LM310CN 

LM311H 

LM312H 

LM317MP 

LM317T 

LM317K 

LM318CN 

LM319N 

LM320K-5 

LM320K-12 

LM320K-15 

LM320T-5 

LM320T-12 

LM320T-15 

LM323K-5 

LM324N 

LM329DZ 

LM331N 

LM334Z 

LM33SZ 

LM336Z 

LM337T 

LM337MP 

LM33BK 

LM339N 

LM340K-5 

LM340K-12 

LM340K-15 



4.50 
4.75 
6.05 
.79 
1.39 
2.49 
35.80 



LINEAR 



LM340T-5 

LM34QT-12 

LM340T-15 

LM341P-5 

LM341P-12 

LM341P-15 

LM342P-5 

LM342P-12 

LM342P-15 

LM348N 

LM3S0K 

LF3S1N 

LF353N 

LF35SN 

LF356N 

LM35BN 

LM359N 

LM370N 

LM373N 

LM377N 

LM3B0N 

LM3B1N 

LM382N 

LM384M 

LM3S6N-3 

LM387N 

LM389N 

LM392N 

LF39BN 

LM399H 

TL494CN 

TL496CP 

NE510A 

NE529A 

NE531H 

NE536H 

NE540H 

NE544N 

NE550A 

NE555V 

LM5S6N 

NE564N 

LM565M 

LM566CN 

LM567V 



6.00 
4.95 
3.95 



4.95 



NE570N 

LM702H 

LM703CN .89 

LM709N .29 

LM710N .79 

LM711N .79 

LM723N .69 

LM733N 1.00 

LM739N 1.19 

LM741CN .35 

MC1741SCG 3.00 

LM747N .79 

LM74BN .59 

LM10i4N 

LM1310N 

LM1458CN 

LM1488N 

LM14B9N 

LM1496N 

LM1556V 

LM1B00N 

LM1877N-9 

LM1889N 

LM1896N 

LM2O02T 

LM2B77P 

LM2878P 

LM2896P-1 

LM3189N 

LM3900N .69 

LM3905CN 1.25 

LM3909N 1.15 

LM3914N 

LM3915N 

LM3916N 

RC4136N 

RC4151NB 

RC4194TK 5.95 

RC419STK 5.49 

KB442B 

KB4429 

LM4500A 

ICLS038B 

LM13080N 

LM1360ON 

7513SN 

75450N 

75451CN 



2.75 



2.95 
3.25 
3.20 



2.05 
2.25 
2.25 
2.95 



3.95 
3.95 
3,95 
1.25 
3.95 



4.25 
5.95 
3.25 
4.95 
1.29 
1.49 



CAPACITOR CORNER 

50 VOLT CERAMIC DISC CAPACITORS 



10 pf 
22 P( 
47 pf 
100 pf 
220 Pf 
470 Pi 



19 10-99 100 + 



.06 .06 .05 
.06 .06 .05 



.004 7uF 

,0UiF 

.Q22J1F 

-047uF 

■IMF 



1-9 10-99 100* 



.09 .07 .06 



100 VOLT MYLAR FILM CAPACITORS 

.OOlmf ,12 .10 .07 I .022mf .13 .11 .0B 

.D022mf .12 .10 .07 .047mf .21 .17 .13 

.0Q47mf .12 .10 .07 .lmf .27 .23 .17 

,01mf .12 .10 .07 I .22mf .33 .27 .22 

+20% DIPPED TANTALUMS (Solid) CAPACITORS 



1/35V 
.15/35V 
.Z2/3SV 

.33/35V 
.47/35V 

.6B/35V 
1.0/3SV 



1.S/3SV 
2.2/35V 
3.3/2SV 
4.7/HV 
6.8/2SV 
15/25 V 
22/6V 



.63 .56 .45 



MINI. ALUMINUM ELECTROLYTIC CAPACITORS 



.47/50V 

1.0/50V 

3.3/50V 

4.7/25V 

10/25V 

10/50V 

22/25V 

22/50V 

47/25V 

47/50V 

100/25V 

lOO.'SOV 

2M/25V 

220/50V 

470 /25V 

10O0/16V 

2200/16V 



Axial Lead 



.47/25V 

.47/SOV 
1.0/16V 
1.0/25V 
1.0/SOV 
4.7/16V 
4.7/25V 
4.7/50V 
10/16V 
10/25V 
10/50V 
47/SOV 
100/16V 
100 /25V 
100/50V 
220/16V 
470/25V 



368 



BYTE March 1981 



Circle 328 on inquiry card. 



AaSLoor Clock Modules 



12VDC 

AUTOMOTIVE/ 

INSTRUMENT 

CLOCK 

APPLICATIONS: 

* In-dash au toclocks 
■ After-market auto/ 

RV clocks 

• Aircraft-marina elks 



Features: Bright 0.3" green display. Internal crystal time- 
base, t 0.5 sec/day accur. Auto, display brightness control 
logic. Display color filterable to blue, blue-green, green fit 
yellow. Complete— just add switches and lens. 

MA 1003 Module $16.95 




MA 1023. 7" Low Cost Digital LED Clock Module 8.95 

MA1026 .7"Dig.LED Alarm Clock/Thermometer 18.95 

MA5036 .3" Low Cost Digital LED Clock/TimBr 6.95 

MA1002 .5" LED Display Dig. Clock fit XforrriBr 9.95 




'2 National Semiconductor 

RAM SALE 



MM5290N-4 (mk4H6/upd416) . - $4.95 each 

16K DYNAMIC RAM (250NS) 

(8 EACH S39.95) (100 EACH S<J50.00/lot) 

MM5290J-2 (MK4H6/UPD416) . . $6.95 each 

16K DYNAMIC RAM (150NS) 

(8 EACH S49.95) (100 EACH S550.00/lot) 

MM5298J-3A $3.25 each 



MM2114-3 $5.95 each 



MM2114L-3 $6. 25 each 

4K STATIC RAM (LOW POWER 300NS) 
(8 EACH S44.95) (100 EACH Sd75,00/lot) 



EPROM Erasing Lamp 




• Erases 2708, 2716, 1702A, 5203Q, 5204Q, etc. 

• Erases up to 4 chips within 20 minutes. 

• Maintains constant exposure distance of one inch. 

• Special conductive foam linereliminates static build-up. 

• Built-in safety lock to prevent U V exposure. 

• Compact - only 7-5/8" x 2-7/8" x 2" 

■ Complete with holding tray for 4 chips. 

UVS-11E $79.95 



Jumbo 6-Digit Clock Kit 

• Four.630"ht. and two .300"ht. 
common anode displays 

• Uses MM5314 clock chip 

• Switches for hours, minutes and hold functions 

• Hours easily viewable to 30 feet 
■ Simulated walnut case 

• 1 15VAC operation 

• 12 or 24 hour operation 

• Includes all components, case and wall transformer 

• Size: 6%" x 3-1/8" x 1%" 

JE747 $29.95 



6-Digit Clock Kit 




• Bright .300 ht. 
□ de display 

•Uses MM5314 cl 

• Switches for ho 
and hold modes 

• Simulated walnut 

• 115 VAC operatic 

• 12 or 2d hr. opera 



able to 20 ft. 



JE701 $19.95 




Regulated Power Supply 

Uses LM309K. Heat sink ^fc-. \ 

provided. PC board con- — 
struction. Provides a solid 
1 amp @ 5 volts. Can supply up 
to ±5V, *9V and ± 12V with 
JE205 Adapter. Includes compo- 
nents, hardware and instructions. 
Size: 3'/ a " x 5" x 2"H 

JE200 $14.95 



ADAPTER BOARD 
- Adapts to JE200- 
±5V, ±9Vand ±12V 



DC/DC converter with +5V input. Toriodal hi- 
speed switching XFMR. Short circuit protection. 
PC board construction. Piggy-back to JE 200 
board. Size: 3W x 2" x 9/16"H 

. JE205 $12.95 




MICROPROCESSOR COMPONENTS 



DPKSt 






- 6800/6800 SUPPORT DEVICES - 



P8085 CPU 

INSB900 CPU-; 

TMSWMJL MPU- 



.-.;,vw. 

flMMlH 
1M50&H 



■ SHIFT REGISTERS- 



DATA ACQUISITION- 



-DATA ACQUISITION (CONTINUED)- 



?M«4 Static 

I DM ■) Sialic 

lOMx] Static 

Ettx* Static 

256x4 Static MOS 

10M>4 Sialic 450m 

1024x4 Sialic 450ns Low Power 



IcWOmlhcui 



IrUBI.) 
16k Dy 
J0»»] I 
2Wx4 S 



UPD4H/MK4027 «K Dynamic 16-pin 
TMS40444SNL 4K Static 
TMS404S 1024x4 Stalk 

PROMS/EPROMS- 



SK EPROM 



NMOS READ ONLY MEMORIES- 

MCM66J10P ITBxSxl ASCII Smilea w/Qieeb 

MCM66JJ0P 12S*9x/ Math SymDol & Pictures 

WCM667S0P 128x9x7 Aloha. Control Char. Con. 

MICROPROCESSOR MANUALS" 



- SPECIAL FUNCTION - 



COP402N 
COM02MN 



HSeg.VAC Flgor. Driver (JO-Oin pki 

TELEPHONE/KEYBOARD CHIPS- 



DESIGNERS' SERIES 
Blank Desk-Top Electronic Enclosures 




High strength epoxy molded 
end pieces in mocha brown 
finish. 

Sliding rear/bottom panel for 
service and component ac- 
cessibility. 

Top / bottom panels .080 thk 
alum. Alodine type 120D 
finish {gold tint color) for 
best paint adhesion after 
modification. 

Vented top and bottom 
panels for cooling efficiency. 
Rigid construction provides 
unlimited applications. 



CONSTRUCTION: 

The "DTE" Blank Desk Top Electronic Enclosuresare designed to blend and complement 
today's modern computer equipment and can beused in both industrial and home. The 
end pieces are precision molded with an internal slot (all around) to accept both top and 
bottom panels. The panels are then fastened to V thick tabs inside the end pieces to 
provide maximum rigidity to the enclosure. For ease of equipment servicing, the rear/ 
bottom panel slides back on slotted tracks while the rest of the enclosure remains in- 
tact. Different panel widths may be used while maintaining a common profile outline. 
The molded end pieces can also be painted to match any panel color scheme. 




Enclosure 
Model No. 


Panel 
Width 


PRICE 


1 DTE-8 


8.00" 


$29.95 


DTE-11 


10.65" 


$32.95 


! DTE-14 


14.00" 


$34.95 



S10.00 Min. Order - U.S. Funds Only 
Calif. Residents Add 6% Sales Tax 
Postage— Add 5%plusSl Insurance 




Spec Sheets - 25c 1 

Send 414 Postage for your 

FREE 1981 JAMECO CATALOG 



PHONE 

ORDERS 

WELCOME 

(415)592-8097 



MAIL ORDER ELECTRONICS - WORLDWIDE 

1355 SHOREIAIAY ROAD, BELMONT. CA 94002 

PRICES SUBJECT TO CHANGE 



JOYSTICKS 





I JVC-40 



JS-5K 5K Linear Taper Pots S5.25 

JS-100K 100K Linear Taper Pots $4.95 

JVC-40 40K (2) Video Controller in case . . . S5.95 



AC and DC Wall Transformers 




Pan No. Input Output Price 

AC 250 1l7V/60Hz 12 VAC 250mA S3.95 

AC 500 117V/60Hz 12 VAC 500mA S4.95 

AC1000 1 17V/60Hz 12 VAC 1 amp S5.95 

DV9200 1l7V/60Hz 9 VDC 200mA S3.25 

DC 900 120V/60Ht 9 VDC 500mA S3.95 

CONNECTORS 

w " 

DB25P D-Subminiature Plug $2.95 

DB25S D-Subminiature Socket S3.50 

DB51226 Cover for DB25P/S $1.75 

22/44SE P.C. Edge (22/44 Pin) $2.95 

UG88/U BNC Plug $1.79 

UG89/U BNC Jack $3.79 

UG175/U UHF Adapter $ .49 

S0239 UHF Panel Recp $1.29 

PL258 UHF Adapter $1.60 

PL259 UHF Plug $1.60 

UG260/U BNC Plug $1.79 

UG1094/U BMC Bulkhead Recp $1.29 

TRS-80 
16K Conversion Kit 

Expand your 4K TRS-80 System t o 16K. 
Kit comas complete with: 

*8ea.MM5290(UPD416/4l16)16K Dyn. RamsCNS} 

* Documentation for Conversion 

TRS-16K2 -isons $49.95 

TRS-16K4 -250IMS $39.95 

JE610 ASCII 
Encoded Keyboard Kit 

Si 

The JE610 ASCII Keyboard Kit can be interfaced into 
most any computer system. The kit comes complete 
with an industrial grade keyboard switch assembly 
(62-keys). IC's, sockets, connector, electronic compo- 
nents and a double-sided printed wiring board. The 
keyboard assembly requires +5V <S> 150mA and -12V 
@ 10 mA lor operation. Features: 60 keys generate the 
126 characters, upper and lower case ASCII set. Fully 
buffered. Two user-define keys provided for custom 
applications. Caps lock for uppercase-only alpha charac- 
ters. Utilizes a 2376 (40-pin) encoder read-only memory 
chip. Outputs directly compatible with TTL/DTL or 
MOS logic arrays. Easy interfacing with a 16-pin dip or 
18-pin edge connector. Size: 3&"H x 14VS"W x B»"D 

JE610/DTE-AK ( a5 pictured above) . . .$124.95 

1 1- j- in iy -^ 63-Key Keyboard, PC Board, a -,-. -._ 
JE610 Kit & Components (nocase) S 79.95 

K62 62-Key Keyboard (Keyboard only) . . .$ 34.95 

DTE-AK (case only -3ft-Hxll"Wx8'.VD)$ 49.95 

JE600 
Hexadecimal Encoder Kit 



FULL 8-BIT 
LATCHED OUTPUT 
19-KEY KEYBOARD 



The JE500 Encoder Keyboard Kit provides two separate 
hexadecimal digits produced from sequential key entries 
to allow direct programming for 8-bit microprocessor 
or B-bit memory circuits. Three additional keys are pro- 
vided for user operations with one having a bistable 
output available. The outputs are latched and monitored 
with 9 LEO readouts. Also included isa key entry strobe. 
Features: Full 8 bit latched output for microprocessor 
use. Three user-define keys with one being bistable 
operation. Debounce circuit provided for all 19 keys. 
9 LED readouts to verify entries. Easy interfacing with 
standard 16-pin IC connector. Only +5VDC required 
for operation. Size; 3fc"H x 8V1"W x BX"D 

JE600/DTE-HK (.« pictured above) . . . .$99.95 




irrcnn \f ■* 19-Key Hexadec. Keyboard, r>rr»r»r- 

JE600 Kit PC Board aCmnnts. [no case) . .$59.95 

K19 19-Key Keyboard (Keyboard only) .... $14.95 

DTE-HK (case only -3ft"HX«»"W««»."D) $44.95 . 



Circle 328 on inquiry card. 



BYTE March 1981 



369 



<T 



COMPUTER 
SYSTEMS 
IMC. 



15620 South lnglewood Avenue 
I.awndale. California 90260 
<21.i> 970-0952 



PLACE ORDERS TOLL FREE 

1-800-421-5150 

(CONTINENTAL U.S. ONLY) 

(EXCEPT CALIFORNIA) 



Retail Store Open 

10:00 A.M. to 6:00 P.M. 

Daily Except Sunday 

QT CATALOG NOW AVAILABLE 



The QT System+ is designed for both 
businessmen and engineers in accord- 
ance with latest IEEE standards. Among 
other functions, it can be used for 
accounting and word processing, as well 
as a variety of scientific applications. The 
system will soon be available with 
MP/M® to allow multi-user, multi-tasking 
operations. This means, forexample, that 
an engineer could be working on 
scientific applications in the lab while an 
accountant is writing payroll checks in 
.the office. QT also offers a full line of 



QT SYSTEM + 



business and applications software, 
ranging from a business package to word 
processing. 

Technical specifications: 4MHz Z-80A 
CPU • Dbl-sided, dbl-den. 5'A" & 8" 
floppy disk controller (handles both 
drives simultaneously) • Includes tele- 
video terminal • Two 8" dbl-den., sgl. or 
dual sided disk drives, expandable to 4 
floppy drives • CP/M® 2.2 included • 64K 
RAM, expandable peryour requirements 
• Comes complete in single mainframe • 



EPROM/ROM in any combination to 8K • 
Two RS232C serial I/O ports • Two 
parallel I/O ports • Hard disk compatible 
• Real time clock • Std. 2K monitor 
program & disk routines included on 
ROM • Power-on/Reset jump to monitor 
program • 2716 (5V) EPROM program- 
mer (software incl. on monitor ROM; ext. 
25.5V @ 50ma req.) • Uses Z-80A CPU 
•vectored interrupts • Assembled, tested 
& burned in at factory • Documentation 
included. 



SYSTEM + I (1MB+) 



SYSTEM + II (2MB+) 



SYS+SS Computer System with 8" Single Sided Drives (801R) 
without Terminal 

A&T (6 slot) $3495.00 

A&T (8 Slot) $3595.00 

A&T (12 slot) $3695.00 

With Terminal Add $900.00 



MINI-SYSTEM + I (V2MB+) 



Computer System with 5'A" Single Sided Drives (uses B-51 Disk 
Drives) No Terminal 

A&T (6 slot) $2495.00 

A&T (8 slot) $2595.00 

A&T (12 slot) $2695.00 



SYS+DS Computer System with 8" Dual-Sided Drives (Qume 
DT-8) without Terminal 

A&T (6 Slot) $4195.00 

A&T (8 slot) $4295.00 

A&T (12 slot) $4395.00 

With Terminal Add $900.00 



MINI-SYSTEM + II (1MB+) 



Computer System with 5V'«" Double Sided Drives (uses B-52 Disk 
Drives) No Terminal 

A&T (6 slot) $2795.00 

A&T (8 slot) $2895.00 



A 



A&T (12 slot) $2995.00 



J 



S-100 PRODUCTS 



PARTS 



Double Density - Cal Comp Sys 

5V." or 8" disk controller with Iree CP/M 2.2 
CCS-2422A A&T $374.95 

SALE SBC-100-SD Systems 

2.5 MHz 280 CPU with serial & parallel I/O ports 

SDS-SBC100K Kit $280.00 

SDS-SBC100AT A&T $350.00 

SBC-200 - SD Systems 

4 MHz Z60 CPU with serial & parallel I/O ports 

SDS-SBC200K Kit $348.00 

SDS-SBC200AT A&T $408.00 



SM- E 



CB2 - S.S.M. 

2 or 4 MHz switchable Z80 CPU with RAM, ROM & I/O 

SSM-CB2K Kit $200.00 

SSM-CB2AT A&T $275.00 

2810 Z-80 CPU - C«l Comp Sys 

2 or 4 MHz Z80A CPU w/serial I/O port 

CCS-2810 A&T $275.00 

Expando RAM II - SD Systems 

4 MHz RAM board expandable Irom 16K to 256K 

SDS-RAM216K 1 6K kit $289.95 

SDS-RAM216AT 16K A&T $339.95 

SDS-RAM232K 32K kit $329.95 

SDS-RAM232AT 32K A&T $379.95 

SDS-RAM248K 48K kit $369.95 

SDS-RAM248AT 46K A&T $419.95 

SDS-RAM264K 64K kit $409.95 

SDS-RAM264K 64K A&T $459.95 

PROM-100 - SD Systems 

2708, 2716, 2732, 2758 & 2516 EPROM programmer 

SDS-PROM-100K kit $220.00 

SDS-PROM-100AT A&T $275.00 



ITHACA AUDIO REV 2.0 Z-80 BD 



Bare Board $35.00 each 

10 for $300.00 A 



SEALS ELECTRONICS 32K STATIC BD 



Uses TMS-4044 or 5257L $35.00 each 



I/0-4 - S.S.M. 

2 serial I/O ports plus 2 parallel I/O ports 

SSM-I04K kit $179.95 

SSM-I04AT A&T $259.95 

SSM-I04BB Bare board $ 35.00 

Versatloppy II - SD Systems 

New double density controller lor both 8" & 5W 

SDS-VF2K kit $385.00 

SDS-VF2AT A&.T $450.00 

VDB-8024 - SD Systems 

80 x 24 I/O mapped video board with keyboard I/O 

SDS-VDBK kit $406.00 

SDS-VDBAT A&T $475.00 

VB3 - S.S.M. 

80 x 24 x 48 memory mapped with graphics 

SSM-VB3-4mhzK kit, 4 MHz $399.95 

SSM-VB3-4mhzAT A&T, 4 MHz $464.95 

SSM-VB3-4mhzUPG 80 x 48 upgrade, 4 MHz . . $ 89.00 

T1 Active Terminator 

SSM-T1K kit $ 34.00 

SSM-T1AT A&T $ 64.00 

VB2 I/O Mapped Video Interface 

SSM-VB2K kit $160.00 

SSM-VB2AT A&T $210.00 

XB1 Extender Board 

SSM-XB1K kit (with Connector) $ 22.00 

SSM-XB1AT Assembled & tested $ 30.00 

Z-80 STARTER KIT - SD Systems 

2-80 computer with RAM, ROM, I/O & keyboard 

SDS-Z80K kit $374.00 

SDS-Z80AT A&T $454.00 



QT MEMORY EXPANSION KITS 



TRS-80» APPLE •EXIDY 

4116 200 ns 8 for $32.00 

2716 (5V-450 ns) $ 9.00 

2716 (5 & 12V-450 ns) $ 9.00 

2732 (5V) $40.00 

2114L 300 ns 8 for $36.00 

100 - $3.50 ea. 



.A. 



y^z 



MICROPROCESSORS 

Z80 (2MHz) ... $10.95 
Z80A (4MHz) . . $12.95 

6502 $11.25 

6800 $12.50 

6802 $18.00 

8035 $20.00 

8080A $ 3.50 

8085A $20.00 

8086-4 $60.00 

8088 $60.00 

8748 $60.00 

TMS 9900 JL . . $29.95 

8080A SUPPORT 

8212 $ 3.50 

8214 $ 4.50 

8216 $ 2.95 

8224 $ 4.00 

8228 $ 6.00 

8238 $ 6.00 

8243 $ 5.00 

8251 $ 7.00 

8253 $19.00 

8253-5 $20.25 

8255 $ 6.25 

8257 $17.95 

8257-5 $19.00 

8259 $19.95 

8275 $69.95 

8279 $17.50 

8279-5 $18.00 

8295 $16.50 

KEYBOARD CHIPS 

AY5-2376 $13.75 

AY5-3600 $13.75 

BAUD RATE 
GENERATORS 

MC14411 ... $11.00 
1.8432 XT AL ...$ 4.95 

DISK CONTROLLER 

1771B01 $24.95 

17B1A01ICER) $37.95 



EPROMS 

1702A $ 4.95 

2708 $ 6.25 

2516 (5V) $18.00 

2716 (5V) .... $13.50 
2716 (5 & 12V) $13.50 

2758 $19.95 

2532 $55.00 

2732 $55.00 

USRT 
S2350 $ 7.95 

MISCELLANEOUS 
OTHER COMPONENTS 

N8T20 $ 3.25 

N8T26 $ 2.50 

N8T97 $ 2.00 

N8T98 $ 2.00 

1488 $ 1.25 

1489 $ 1.25 

D3205 $ 3.00 

D3242 $14.00 

P3404 $ 6.75 

TMS5501 $19.00 

DM8131 $ 3.00 

UARTS 

TR1602B $ 4.50 

AY5-1013A $ 4.50 

CHARACTER 
GENERATORS 

2513 $10.95 

UP CASE (5&12V) 
2513 $10.95 

LWR CASE (5&12V) 
2513 $ 9.75 

UP CASE (5V) 
2513 $10.95 

LWR CASE (5V) 

6800 PRODUCTS 

6802P $18.00 

6821P $ 5.25 

6840P $18.25 

6845P $22.00 

6850P $ 4.80 

6860P $11.55 

6875P $ 7.40 



SBC+2/4 
SINGLE BOARD COMPUTER 



Features: 1K RAM (which can be located at 
any 1K boundary) plus one each Parallel and 
Serial I/O parts on board • Power on jump to 
on-board EPROM (2708 or 2716) • EPROM 
addressable on any 1 K or 2K boundary 'Full 
64K use of RAM allowed in shadow mode • 
Programmable Baud rate selection, 110-9600 
• 2 or 4MHz switch selectable • DMA 
capability allows MWRTsignal generation on 
CPU board or elsewhere in system under DM A 
logic or front panel control • Two program- 
mable timers available for use by programs 
run with the SBC+2/4 (timer output and 
controls available at parallel I/O connector; 
parallel input and output ports available for 
use on CPU board). 

Bare Board $ 60.00 

Kit $190.00 

A&T $295.00 



J 



Z+80 CPU 



Features: Power on jump toon-board EPROM 
(2708, 2716 or 2732) • EPROM addressed on 
any 1K or 2K boundary; also shadow mode 
allows full 64K use of RAM • On-board USART 
for Synchronous or Asynchronous RS-232 
Operation (Serial I/O port) • Programmable 
Baud rate selection, 110-9600 • Switch select- 
able 2 or 4 MHz • MWRITE signal generated 
if used without front panel • Front panel com- 
patible. 

Bare Board $ 50.00 

Kit $150.00 

A&T $210.00 



J 



CLOCK/CALENDAR+ 
FOR APPLE II, S-100 OR TRS-80 



Features: Date/Month/Year • Day of week 
• 24 hour time or 12 hour (a.m. /p.m.) select- 
able • Leap year (perpetual calendar) • 4 
interval interrupt timer; 1024Hz (approx. 1 
millisec), 1 sec, 1 min., 1 hr. • On-board bat- 
tery backup • Simple time and date setting • 
Simple software interface • Time advance 
protection while reading. 

S-100 or Apple TRS-80 

A&T $150.00 A&T Only . . . $150.00 

Kit $100.00 

Bare Bd $ 60.00 



SMART PROTO BOARD+ 



Features: Wire-wrap or solder sockets • 
Accepts all std. sockets — .30" & 60" center 
• Allows grid distributed power • Three volt- 
age regulators • Kluge area for discretes, ext. 
drives • Two bus bars for ± voltages — int. & 
ext. • Accepts std. edge connector on .1" 
center • K it includes 3 regulators/3 heat sinks/ 
filter capacitors/2 bus bars/Manual. 

Bare Board $ 35.00 

Kit $ 60.00 



QT PRODUCTS 



EXPANDABLE+ REV II 
DYNAMIC MEMORY BOARD 



Features: Runs at 4MHz • 3242 refresh con- 
troller with delay line • Four layer PC board 
insures quiet operation • Supports 16K, 32K, 
48K or 64K of memory • 24 IEEE-specified 
address lines • Optional M1 wait state allows 
error free operation with faster processors • 
Optional Phantom disable • Uses Z-80 or on- 
board refresh signal • Bank on/off signal 
selected by industry standard I/O port 40 
(Hex) • Convenient DIP switch selection of 
data bus bits determines bank in use • 3 watts 
low power consumption • Convenient LED 
indication of bank in use. 

Definitely works with 
Cromemco and North Star. 

Bare Board $ 75.00 

KIT A&T 

No RAM .... $230.00 16K $350.00 

16K $280.00 32K $450.00 

32K $360.00 48K $575.00 

48K $480.00 64K $675.00 

64K $525.00 



RAM+16 



Features: S-100, 16Kx8 bitstatic RAM • 2or4 
MHz* Uses 2114 1K x 4 static RAM chip* 4K 
step addressable • 1K increment memory 
protection, from bottom board address up or 
top down • Deactivates up to six 1K board 
segments to create "holes" for other devices • 
DIP switch selectable wait states • Phantom 
line DIP switch • Eight bank select lines 
expandable to Vi million byte system • Data, 
address and control lines all input buffered • 
Ignores I/O commands at board address. 

Bare Board $ 35.00 

4Mhz Kit $180.00 

4Mhz A&T $210.00 



WATCH FOR THE FOLLOWING NEW BDS: 



• 4 Port Serial Bd (FEB) 

• E-PROM Programmer (MAR) 

• Floppy bisk Controller (APR) 

• Hard Disk Controller (MAY) 

• Color Video Bd (JUN) 



V 



I/0+ 
INDUSTRIAL GRADE I/O BD 



Has two serial Sync/Async ports (RS-232, 
current loop or TTL) with individual Xtal 
controlled programmable baudrate genera- 
tors • Four 8-bit Parallel ports; one latched 
input port and otherthree can be programmed 
in combinations of input, output or bidirec- 
tional • Also, has three 16-bit Programmable 
Timers and an 8-level Programmable Interrupt 
Controller w/Auto restart (8080/ Z80) • Other 
features include; on-board clock divisor for 
timers, completely socketed, wire wrap posts 
for easy port configuration plus more. 

Bare Board $ 70.00 

Kit $200.00 

A&T $375.00 



SILENCE+ 
MOTHERBOARDS 



These motherboards are among the quietest 
on the market. A unique grounding matrix — 
with each line completely surrounded by 
ground shielding — eliminates need for ter- 
mination and gives high crosstalk rejection • 
They're customer-proven, without crosstalk 
sometimes operating at 14MHz • A LED power 
indicator helps eliminate zapped circuits • 
IEEE S-100 std. compatible, available with 6, 8, 
1 2, 1 8 or 22 slots • (The 22 slot board fits Imsai 
chassis and has slot for front panel.) 

6 Slot 

Bare Board $ 25.00 

Kit $ 40.00 

A&T $ 50.00 

8 Slot 

Bare Board $ 27.00 

Kit $ 55.00 

A&T $ 70.00 

12 Slot 

Bare Board $ 30.00 

Kit $ 70.00 

A&T $ 90.00 

18 Slot 

Bare Board $ 50.00 

Kit $100.00 

A&T $140.00 



r QT MAINFRAMES . } 


57." Disk Mainframe with 18A Pw 
MF+MD12 (12 slot M/B) 


r Sup 
$500.00 
$450.00 
$400.00 

$450.00 
$500.00 
$600.00 


MF+MD6 (6 slot M/B) 


MF+MD w/0 M/B 


QT. Mainframe 
MF+12 (12 slot M/B) 


MF+18 (18 slot M/B) 


I MF+22 (22 slot M/B) 




MAINFRAME+ DISK DRIVE 



Includes cabinet, 30 
amp power supply, 
IEEE S-100 compat- 
ible 6, 8 or 12 slot 
motherboard and dual 8" disk drive with disk 
drive power supply. 

MF+DD6 $625.00 

MF+DD8 $650.00 

MF+DD12 $675.00 



DDC-8 
SINGLE 8" DISK CABINET 



Accepts one 8" disk drive (Shugart, Remex, 
PerSci, Siemens, etc.) • Fan cooled, with data 
cable and AC line filter to eliminate EMI • 
Operates from 100-1 25 VAC/200-250VAC at 
50-60HZ • Disk drive NOT included. 
DDC+8 $175.00 




COMPUTER 
SYSTEMS 
INC. 

15620 South Inglewood Avenue 
Lawndale, California 90260 
(2U) 970-0952 



PLACE ORDERS TOLL FREE 

1-800-421-5150 

(CONTINENTAL U.S. ONLY) 

(EXCEPT CALIFORNIA) 

Apple is a trademark of Apple Computer, Inc. 
CP/M and MP/M are trademarks ol Digital Research. 
TRS-80 is a trademark of Radio Shack. 

Circle 329 on inquiry card. 



TERMS OF SALE: Cash, checks, money orders, 
credit cards accepted. Also C.O.D. orders under 
$100.00. Minimum order $10.00. California resi- 
dents add 6% sales tax. Minimum shipping and 
handling charge $3.00. Prices subject to change 
without notice. International sales in American 
dollars only. .^^_ 

VISA 



l ^^g 



SALE SALE SALE 



Disk Drives 




JADE's new dual disk sub-assemblies include: 
Handsome metal cabinet with proportionally 
balanced air flow system, rugged dual drive power 
supply, cooling fan. cable kit, lighted power 
switch, approved fuse assembly, line cord. Never* 
Mar rubber feet, and all necessary hardware to 
mount 2-8" disk drives ■ it's all American made, 
guaranteed for six months, and it's in stock! 
Dual 8" Sub-Assembly Cabinet 

END-000421 Cabinet kit $225.00 

END-000420 Bare cabinet $59.95 

Single sided, double density disk drive sub-system 
END-000423 Kit w/2 8" drives .... $975.00 
END-000424 A & T w/2 8" drives $1195.00 

Double sided, double density disk drive subsystem 
END-000426 kit w/2 8" drives .... $1495.00 
END-000427 A & T w/2 8" drives $1695.00 

JADE DISK PACKAGE 

Double density controller, two 8" double density floppy 
disk drives, CP/ M 2,2 (confiffured for controller), hard ware 
and software manuals, boot PROM , cabinet, power supply, 
fan, & cables 
Special package price $1395.00 

8" Disk Drive Sale 

Highly reliable double density floppy disk drives 
Shutfart 801 R single sided, double density 

MSF-10801R SA-801R $425.00 

Special Sale Price 2 for $790.00 

Siemens FDDlOO-BDIi single sided, double density 

MSF-201120 f, mo warranty $385.00 

Special sale price 2 for $750.00 

Real Double-Sided Drives 

8" Double-Sided Double-Density Sale 

* Shugart SA-H51R double-Hided, double-density * 

* only $625.00 ca 2 for $1 100.00 * 

MFE M701 8" double-sided, double-density driues 
only $526 ea 2 for $1040.00 

Qume Data Track 8 double-sided, double-density drives 
only $575.00 2 for $1100.00 

Printers 

~ CENTRONICS 737^1 

.9 x N dot matrix, letter quality, proportional spacing 

PRM-15737 Parallel $795.00 

With interface for Apple $895.00 

MX-80 - Epson 

1112 column, II x 9 dot matrix, multiple fonts 

PRM-27080 Save $100.00 $545.00 

Interface for Apple $1 10.00 




SPINWRITER- NEC 



ti5 cps. bi-directional, letter quality printer with deluxe 

tractor mechanism, both parallel and serial interfaces on 

board, 16K buffer, ribbon, print thimble, graphics, micro 

space justification, data cable, and self test/diagnostic 

ROM. 

PRD-55511 without WK buffer ... $2795.00 

PRD-55512 with 16 K buffer $2895.00 



S-100 Systems 



S-100 SYSTEM - Calif Computer Sys 

Complete S-100 system including 12 slot mainframe. 4 
MHz Z-80 CPU. S4K RAM memory, double density disk 
controller. RS-2.12 cable. 8" & 5W'disk drive cables. Cl'/M 
2.2, manuals, auto boot ROM. completely assembled & 
tested. 

2210A Integrated & tested $1995.00 

2210B Not integrated $1795.00 



S-100 Memory 




64K RAM - Calif Computer Sys 

4 MHz bank port / bank byte selectable, extended 
addressing. ItiK hank selectable. PHANTOM line allows 
memory overlay, 8(18(1 / Z-80 / front panel compatible. 
MEM-64565A A & T $449.95 

MEMORY BANK -Jade 

; Mil;. IKKK S-IOtl, hunk selectable. 8 or Iti bit 

MKM-99730B Bur,' hoard $55.00 

M KM-99730K Kit. no NAM $21 9.95 

M KM- 1 073OK WK kit $2 19.95 

M KM -3273 1 K H2K hit $289.95 

MKM-48732K -IHK hit $324.95 

MKM-0I733K (UK kit $359.95 

Assembled & tested add $50.00 

EXFANDORAM II - S I) Systems 

/ Mlh RAM hoard expandable from WK to ■JtfKK 

M KM- 1 6630K ItiK kit $275.95 

M KM-3263 1 K :i2K Id! $295.95 

M KM- I8632K -IKK kit $31 5.95 

MKM-HHJ.I3K (i IK kit $335.95 

Assembled & tested add $50.00 

32K STATIC RAM - Jade 

:>. or I Mlh expanilahle static RAM board tttte.i :U I II. 's 

MK M-I (> 1 5 1 K / (IK I MHz kit $ 1 09.95 

M KM-32 1 5 1 K -I2K I MHz kit $299.95 

Assetlihiecl & tested add $50.00 

16K STATIC RAM - Cal Comp Sys 

2 or 4 MHz IKK static RAM board, IEEE S-lilt), bank 
selectable. Phantom capability, addressable in 4K blinks 
MEM-16160A 1SK 2 MHz A & T ... $286.95 
MEM-16162A 1GK 4 MHz A & T . . . $289.95 
MEM-16160B Bare board $50.00 

PB-1 -S.S.M. 

271)8. 2710 HPROM board with built-in programmer 

MEM-99510K Kit $154.95 

MEM-99510A A&T $229.95 

PROM-100 - SD Systems 

271)8. 27lti. 27112. 2758. & 2,5/6 EPROM programmer 

MEM-99520K Kit $219.95 

MEM-99520A Jade A & T $269.95 

S-100 Video 

VB-3 - S.S.M. 

HO characters x 24 liiws expandable toHO.x 48 for a full pay.e 
of text, upper & lower case,2,'~)6 user defined symbols, HiOx 
192 f.raphics matrix, memory mapped, has hey board 
input. 

IOV-1095K 4 MHz kit $375.00 

IOV-1095A 4 MHz A&T $450.00 

IOV-1096K 80 x 48 upgrade $39.95 

VIDEO BOARD -Jade 

64 characters x 16 lines, 7 x ,9 dot matrix.f till upper /lower 
case ASCII character set, numbers, symbols, and t>reek 
tetters, normal/ reverse/blinking video, S-100. 

IOV-1050K Kit $99.95 

IOV-1050A A&T $125.00 

IOV-1050B Bare board $19.95 



S-100 CPU 



2810 Z-80* CPU - Cal Comp Sys 

2 -I MHz Z-80A* CPU mi 111 RS-232C serial I Oport and on- 
board MOSS 2.2 monitor PROM . front panel compatible. 
CPU-30400A A&T $269.95 




THE BIG Z* - Jade 

2 or 4 MHz su-itcltablc Z-80* CPU with serial I/O. 
accomodates 2708. 2716. or27.!2 EPROM. baud rates from 

7r> to Willi) 

CPU-30201K Kit $145.00 

CPU-30201A A&T $199.00 

CPU-30200B Bare board $35.00 

CB-2 Z-80 CPU - S.S.M. 

2 or 4 MHz Z-8II CPU board with provision foruptoHKaf 
ROM or -IK of RAM on board, extended addressing. IEEE 
S 11)0. front panel compatible. 
CPU-30300A A & T $229.95 

SBC-200 - SD Systems 

■/ MHz Z-80* CPU with serial & parallel I/O ports, up to8K 
of onboard PROM, software programmable baud rate 
generator. IK of onboard RAM. Z-8II CTC. 

CPC-30200K Kit $339.95 

CPC-30200A Jade A&T $399.95 

S-100 Disk Controller 

DOUBLE DENSITY - Cal Comp Sys 

h'/i" and 8" disk controller, single or double density, with 
onboard boot loader ROM. and free CP/M 2.2* and 
manual set. 
IOD-1300A A&T $369.95 

DOUBLE-D -Jade 

Bon hie density controller with the insi d e track. on- boar d Z- 
8I1A*. printer port. IEEE S-ttlt). can function on an 
interrupt driven buss 

IOD-1200K Kit $299.95 

IOD-1200A 8" A & T $389.95 

1OD-1205A 5>/t" A & T $389.95 

IOD-1200B Bare board $65.00 

VERSAFLOPPY II - SD Systems 

New double density controller for both 8" & 5'/i" 

IOD-1160K Kit $379.95 

IOD-1160A Jade A & T $439.95 

Motherboards 

ISO-BUS - Jade 

Silent, simple, and on sale ■ a better motherboard 

6 Slot (5 1 /." x 8'A") 

MBS-061B Bare board $19.95 

MBS-061K Kit $39.95 

MBS-061 A A&T $49.95 

12 Slot (•>'/," x 8-Vx") 

MBS-121B Bare board $29.95 

M BS- 1 2 1 K Kit $69.95 

MBS-121A A&T $89.95 

18 Slot (H 1 /." x 8V«") 

MBS-181B Bare board $49.95 

MBS-181K Kit $99.95 

MBS-181A A&T $139.95 

Card Cages 

S-100 CARD CAGE - Jade 

Metal cage with card guides & fan mntintin/.'. 

KNX- 1 0600 I Six slot $29.95 

S-100 CARD CAGE - Vector 

HI" ruck iiinlinlolilr. adjustable, holds :>.! curds 

VCT-C'CK 1 00 Armdizvd Al $49.95 



SALE SALE SALE 



S-100 I/O 



S.P.I.C. -Jade 

Our new I/O card with 2 SIO's, 4 CTC's. and 1 PIO 
IOI-1045K 2 CTC's, 1 SIO, 1 PIO .. $199.00 

IOI-1045A A & T $259.00 

IOI-1046K 4 CTC's, 2 SIO's, 1 PIO $259.00 

IOI-1046A A & T $319.00 

IO1-1045B Bare board w/ manual ...$59.95 
1OI-1045D Manual only $20.00 

1/0-4 - S.S.M. 

2 serial I IO parts plus 2 parallel I/O parts 

IOr-1010K Kit $179.95 

IOI-1010A A &T $249.95 

1OI-1010B Bare board $35.00 

TERMINATOR - S.S.M. 
Active terminator far S-100 has 

TSX-195K Kit $29.95 

TSX-195A A & T $54.95 

TSX-195B Bare board $22.95 

S-100 EXTENDER - Cal Comp Sys 

Put those problem hoards (the ones you probably bought 
from one of our competitors) within easy reach. 
TSX-160A A & T $37.95 

S-100 PROTO BOARD - Jade 

Universal design, plated thru hales, gold fingers 
TSX-140B Bare board $24.95 

TERMINATOR & EXTENDER - CCS. 

Can he used as hath an S-100 extender and terminator 
TSX-150K Kit $43.95 



Diskettes 



DISKETTES - Jade 

Bargain prices an magnificent magnetic media 
rr/\" single sided, single density, box of 10 

MMD-51 10103 Soft sector $27.95 

MMD-51 11003 10 sector $27.95 

MMD-5111603 16 sector $27.95 

5'/i" double sided, double density, box of 10 

MMD-5220103 Soft sector $39.95 

8" single sided, single density, box of 10 

MMD-81 10103 Soft sector $33.95 

8" single sided, double density, box of 10 

MMD-8120103 Soft sector $39.95 

8" double sided, double density, box of 10 

MMD-8220103 Soft sector $49.95 



Video Monitors 

9" B & W MONITOR - A.P.F. 

High quality, high resolution video monitor 
VDM-750900 9" monitor $159.95 

13" COLOR MONITOR - Zenith 

The hi res color you've been promising yourself 
VDC-201301 $449.00 

12" GREEN SCREEN - NEC 

20 MHz. P.'il phosphor video monitor with audio, 
exceptionally high resolution ■ A fantastic monitor at a 
very reasonable price 
VDM-651200 12" monitor $259.95 



Mainframes 



MAINFRAME - Cal Comp Sys 

I2slat SIOO mainframe with 20 amp power supply 

ENC-1 12105 Kit $359.95 

ENC-112106 A & T $419.95 

DISK MAINFRAME - NNC 

Holds 2 8" drives and an 8 slot SIOO system. Attractive 
metal cabinet with 8 slat mallie rboard , powc r supply , f an, 
key switch, and other professional features 
ENS-112320 with 30 amp p. s $699.95 



Accessories-Apple/TRS-80 




16K MEMORY UPGRADE 

Add UiKaf RAM to your TltS-80. Apple, or Exidy in just 
minutes. We've sold thousands of these 10K RAM 
upgrades which include t he appropriate memory chips (as 
specified by the manufacturer), all necessary jumper 
blocks, foolproof instructions, and our 1 year guarantee. 

MEX-16100K TRS-HO kit $29.00 

MEX-16101K Apple kit $29.00 

M EX-16102K Exidy kit $29.00 

DISK DRIVE for APPLE 

o'/i" dish drive with controller for your Apple 

MSM-12310C with controller $499.95 

MSM-123101 wl out controller $375.00 

DISK DRIVES forTRS-80 

23% more storage, 8 times faster, 40 track with free patch. 
120 day warranty, includes case, power supply, and cable 
MSM-12410C Saue $125.00 .'.'.' $299.95 

DOS 3.3 UPGRADE - Apple 

Upgrade your old DOS to t he improved ,'1.,'f 
IOD-2233A Complete kit $64.95 

APPLE STICK - Micromate 

Joy slick with puts for Apple II 
SYA-1510A A &T $35.95 

Z-80* CARD for APPLE 

Z-SO* CPU card with CP/M2.2 for your Apple 
CPX-30800A A & T $279.95 

AIO -S.S.M. 

Parallel & serial interface for your Apple 

1O1-2050K Kit $155.95 

IO1-2050A A & T $194.95 

PRINTER INTERFACE - CCS. 

Centronics type 1/Ocard w/ firmware 
IOI-2041A A & T $99.95 

APPLE CLOCK - Cal Comp Sys 

Real time clock le battery back-up 
1OK-2100A A & T $109.95 

Modems 

••••••••••••••••••••••••• 

LEX-ll MODEM - Lexicon 

A rval star! :W(I baud, answer/originate, US 'JI12C 

IOM-5511A Best buy .'.'.' $128.00 

••••••••••••••••••••••••• 

NOVATION CAT 

300 baud, answer/originate acoustic modem 
IOM-5200A I year warranty $179.00 

D-CAT 1100 baud, direct connect modem 
IOM-5201A Special sale price $189.00 

AUTO-CAT Auto answer origiate. direct connect 
IOM-5230A Special sale price $239.95 

MICROMODEM - D.C Hayes 

Aula answer dial modem card for Apple or SIOO 

IOM-2010A Apple modem $349.95 

IOM-1100A S-100 modem $375.00 

MICRONET MODEM - Micromate 

Direct connect with extra features - a best buy 
IOM-2020A Best Apple modem $275.00 

* Z-80. Z-80A, and the letter Z are recognized 
trademarks of Zilog, Inc. *C1VM is a registered 
trademark of Digital Research Corp. "CBASIC is a 
trademark of Compiler Systems, Inc. 

Circle 330 on Inquiry card. 



Single Board Computers 




AIM-65 - Rockwell 



(J502 computer with alphanumeric display, printer, & 
keyboard, and complete instructional manuals 

CPK-50165 IK AIM $374.95 

CPK-50465 4K AIM $449.95 

SFK-74600008E SK BASIC ROM ...$99.95 
SFK-64600004E 4K assembler ROM $84.95 

PSX-030A Power supply $64.95 

E NX-000002 Enclosure $49.95 

-IK AIM. UK BASIC, power supply. & enclosure 
Special package price $625.00 

Z-80* STARTER KIT - SD Systems 

Complete Z-80* computer with RAM. ROM. I/O, display. 

keyboard, manual, and kluge area. 

CPS-30010K 



CPS-30010A J 


ade A & T $459.95 


MICROPROCESS 


OILS 

10.95 
12.95 
1 1.50 
11.95 
17.95 
:19.95 
2-1.00 
6.59 
15.95 
59.95 

r 

9.50 
1 1.50 

9.50 
1-1.95 
211.50 


I'ROMS 

2708 -1311ns- 

Ill for St.90 em 
2716 ISLIu 


. 6.25 






6302 


11.95 
11.95 




10 for- S8.90 <M 

25;a 5v 




0809 


39.95 




2732 &• 


39.95 




2758 ;>!' . . 




8U85 

87-18 


RAMS 
21UI2 2 MHz 






. 1.25 


:1881 PIO 


211j02A / MHi 


. 1.50 


:l881-4 PIO 1 MHz 










3882-1 CIV I Mill. 
iWcVA SIO 


. 4.25 


4161 frlK xl 

5257 2 Mllz 

5257A I MHz .... 


59.95 
. 6.75 




3 
l(UK) 
. 1.95 

5.25 
8.25 
. 5.25 
5.95 
9.00 


. 7.25 




MK1H8 . . 




MAUD UATK 
CKNKKATOK 
MC1441I 


SUPPORT 
DKVICKS 




1.84:1 Mllz xtal ... 




UARTS 


8214 


. . 4.65 


AY5-101.1A 


8216 


. . 2.95 


AY3-1014A 






TK1602B 

TMS601I 


8224-4 

8226 

8228 

8S18 


. 5.75 




4 95 
4.95 


SWH) 




SUPPORT 


8250 

825 1 


14.95 




11.95 

22.50 

18.75 

1.80 

5.79 

7.40 

«S 00 




(S828P 


8:25:1 .... 










8255 

8257 


















8275 










8279 








68188 P 







PLACE ORDERS TOLL FREE 



Continental U.S. 

800-421-5500 



Inside California 

800-262-1710 



For Technical Inquiries or Customer Service call 

213-973-7707 



Computer Products 

4901 W. Rosecrans, Hawthorne, Ca 90250 

TERMS OF SALE: Cash, checks, credit curds, or 
I I'lirchn.st Orders from qualified firms and institutions. 
■ Minimum order $15,00. California residents add fi}U tax. 
■ Minimum shipping and handling charge IfcUJO Pricing 
= and availability subject to change without notice. 



CaMFornja DiqiTAl 

Post Office Box 3097 B • Torrance, California 90503 




FREE PLASTIC LIBRARY CASE INCLUDED WITH THE 
PURCHASE OF EVERY BOX OF DISKETTES 



labeled lor California Digital by one of 
ii respected prot.'uccrs ol magnetic medi 
skeite la certified double density at -10 
To insure extended media life each dis 



MMD-CDS(OUIlO) 



2495 

(■ I. BOX 



Ten boxes $22.75 



MINIDISKETTES 



One hundred boxes $21.50 



Scotch 74-)IO)llO)(lG} 831. 



EIGHT INCH Scotch 


box 10 bx 


Dysan box 10 bx. .MUX box 10 bx 


Single side/ slui;le den. 740-0 


535. $33. 


3740/1 S49. S47. 3060 S-.S. $-:3, 


Single aide/ dim bio den. 741-0 


45. 43. 




Single side/33 suet or 740-32 


35. 33. 




Double side/ double D. 743-0 


65. 59. 


na. 3115 49. 45. 


SCOTCH brand head cleaning k 


It. $24.85 


i\IMA-CK{5)(8> please specify 5 1/4 8" 


PrlceB available on request for 


: tape, cart 


ridges, diskpacks, volumn diskettes. 



MEMORY 



TRS-80 • 
APPLE II 

16k memory (8) 4116 's 





Installation is simple. Anyone who has 
ever changed a spark plug should be able <. 
to up-grade his microcomputer. 
How can California Digital offer these 
memory up-grade sets at 25% below our competition? 
Simple, we buy in volume, wholesale to dealers and 
sell the balance directly to owners of personal micro- 
systems. These 16K dynamic memory circuits are 
factory prime and unconditionally guaranteed for one 
full year, NOW, before you change your mind, pick 
up the telephone and order your up-grade memory 
from California Digital. Add S3 for TRS80 jumpers. 

1K+ 



4.75 4.50 



STATIC 


1 


31 


32 


-99 


100-5C 


21L02 450nS. 


1 


19 




99 






21L02 250nS. 


1 


49 


1 


39 






2114 1KX4 450 


5 


95 


5 


50 


5 


25 


2114 1KX4 300 


8 


95 


8 


50 


a 


00 


4044 4tetl 450 


5 


95 


5 


5 


5 


25 


4044 4Kxl 250 


9 


95 


9 


50 


9 


00 


4045 1Kx4 450 


B 


95 


8 


50 


8 


00 


4045 1KX4 250 


9 


95 


9 


50 


9 


00 


5257 lowpow. 


5 


95 


5 


50 


5 


00 



2716 EPRQM 



We have slashed price in an effort to reduce our over 
stocked inventory. These are single five volt EPROMs 
manufactured by one of the Worlds largest producers 
| of semiconductors. All are first quality prime devices. 
Ceramic 450 nS. 




UItr/vVioIet PnoducTs UVS11-E 

UV EPR0M ERASER 

With purchase of 
FORTY 

2716 EPROM's 

* //rvalue 



Jra' 1 



NEW 

from 

Shugart 
Technology 



SURPL 




Megabyte 
Hard Disk Drive 

Packaged in the same physical size as the industry stan- 
dard 5 1/4" minifloppy disk drive. The micro-Winches- 
ter stores thirty times as much data (6.38 megabytes 
unformatted), accesses data twice as fast (170 milli- 
seconds) and transfers data twenty times faster (5.0 
megabits per second. ) 

The ST506 is factory sealed to protect the media from 
environmental contaminates. Requires only DC voltage. 
Dual California Digital 5 1/4" enclosure, 
ST506 drive and power supply. 

Shugart Associates SA400 removable 
media disk drive for above package, add: 
S-100 & Apple controller scheduled for 
spring release. 



H500 
*300 



%/5-Sh 



ugart Associates 




801/ R Disk Drive 

Shugart B01/H with CP 206 po\ 



15 lbs 



supply, muffin cxtinu 
piete in aual enclosure witn au tne necessary harness! 
Documentation included. 30 pounds. M5D- 1801 
Same as above but with two Shugart B01R disk di-lvcn. 
50 pounds. MSD-2H01 

Disk drive cable. G feet 50 conductor with edno card c 
at both ends. WCA-G50S $25.00 
ExpoctJ^isk drives. 220V. 50Mlli add S50.00 per disk drlvi 



♦795 
U195 




The new BSR timer runs your home jus 


like clockwork. Turn* 


on lamps and 


appliances while your awav from home. 


Completely compatible 




istlng System X-10 devices. 






HSR Timer eight channel 565.00 


Appliance Module 5 


W. SI 3. 9 5 


Master control console 34.95 


Lamp Module 300 V 




Ultrasonic Controller 19. D5 


NEW full control wa 


1 switch 14.50 




Rotron Wisper Fan 
*1477 

115 VAC. 7 Watts WB2A1 
Factory fresh Muffin fans 
NOT pull-outs, EMF-4M 



ONHECTOIiS 



mumma* 



El 



22° 



GOLD KUC.l. CUNM ClOKS 



•«*«rrap IT™* 

l-Rel. .isr 
i-Rel. WAV 



.156" Centers (standard) 

22/44 KJn. Eyelet 2.50 2.: 

36/72 Digital Croup S/T S.B5 5.; 

36/72 Digital Croup W/W S.60 6.: 

■13/86 Motorola G80D5/T 6.60 6.: 

43/86 Kioto. 6800 WAV 7.00 6.! 

LNTECK.1TED CIRCUIT SOCKETS 



1.50 1.35 



I),mS female 
JJA hood 2/r" 
JJB2SP male 
UBZSS female 



DUSOF mole 5.5 
DL150S female 9.4 
UDaOhood 2/P2.6 



3.10 2.50 



RIBBON CABLE CONNECTORS 

17/34 5" disk 4.85 4.15 3.S5 
20/40 TRS-80 5.65 5.05 4.70 
25/50 B" disk 5.90 5.15 4.90 



VISA 



mmmmmm 



. merchandise sold by California Digital is premium grade, 
inds $2.00; each additional add $.40 
ipping. Excess will be refunded, 
lifornia residents add 6% sales tax. COD's discouraged, 
"in accounts extended to state supported educational institu- 
s and companies with a "Strong Dun & Bradstreet. " 

it. 



Split 



3 



18v -^ S-IOO 

POWER 



^-" 22V. ct 
% 24V disk 

£Z 15V - 
f 15V. 

f~Fan 



upable of supporting 
; and T»Q I2.000/J0\ ; 



SUPPLY 
KIT 



$ 



59 



tifiers five computer Er; 
Im.irv transformer UlO/2 
1 30 Amp S-10O system al 

ach Bi.000 UF/15V-. 3-5.00' 



□ATA INPUT 
TERMINAL 



CMC division of Hie Pert 
as originally deslgnt 
gnetfe tape. 




PORTABLE DATA ENTRY SYSTEM 



lll'-Sf 



sed data terminals were originally designed for retail store order en! 
terns. The operator enters tfas Inventory control number, merchandise 01 
d and the unit price. After all pertinent data has been entered, the main v 
se is telephoned. Hie handset Is placed in the acoustic coupler an all the n 
ded Information is transmitted back the master computer. 
:h system includes: Casselte drive unit: Removable hex keyboard with LED I 
display; Five Gould "D"N"iCads with charger; AcoustLcal coupler and DB25 cab 
ed from service In working condition. Original cost over S2.51 



Regulated 

Power Supply 

5volt5amp 



$1195 



This USED surplus power Ripply was removed 
Pass transistor regulation outputs five volts at ; 
Suitable for TTL hubby applications. SPC-PS1 



■on i working ■ ■ j :i;i: 




J59 Sankyo Magnetic 
Card Transport 



a single 2x4" HP style mapic-tle date card. 
Motorized mech:mi;mi pulll tin: magnetic card across the four channel road/writ 
head in under two seconds. Ideal for any data processing application where sin; 
amounis of information must be randomly retrieved. Original cos*, over $200. (H 
Documentation and sample card included. Ne< 



WESTERN UNION 

ENCLOSURE 



vernal Technology. The exacl 
purpose of the product is still a 
mys:rrv but ;r;e enclosure Is 
ieoiily sjited for an S-100 molhc 
board with shielded power supply 
Removable hood and plexlglaa 
front make this enclosure an at- 
tractive home for any hobby prothi' 
New surplus in factory boxes s: 
22/44 edge connectors; DB 25S 

101/ 




TOLL FREE ORDER LINE 

800)421-5041 

TECHNICAL & CALIFORNIA 

213679-9001 



CaMForni'a DiqiTAl 

Post Off if 3 Box 3097 B • Torrance, California 90503 




MEMOREX MEMOREX 
1 
^ MEMOREX -MEMOREX 



SUPER BUY 



IBM direct price '1295 

CALIFORNIA DIGITAL 

discount price 

$11 OC immediate 

IKK) deliver 

j5cftpdaaaiaQQDQ| 




NEW 

from 
INTEGRAL DATA 



Paper Tiger 

GRAPHICS '1150 



NjE"C Spin writer 
551QP/I 

*279 





The word processing quality Spii.wrili.-r prints at speeds uplo Sj char 
aclers per second. The Model 3510 I'/S is supplied with bolh parallel 
and HS-232 serial Inter faciei k- Also included is (he tractor teed mec 
anism. along With prim t him tile ,lid riiibola. I'ilN-a.iiepS TO lbs. 

Keyboard <KSil) Model 5520 P/S available 3299',. PRN-5520 PS 75 lbs. 



JEC V-300 

®Word Processing 

DaisyWheel Printer 

*1595 



Finally a 
25 cliara. 
1/120" lit 



d Diablo brand (nterchangal 
1 8085 CPU microprocessor conlroil 
nector. Shipping 58 lbs. PRV-300. 



TELETYPE MODEL 43 



4320 KEYBOARD MODELS 

TTL serial output AAA $ 995 

RS232 serial AAK 1050 

Friction 80 column AAE 1100 

Friction 80 RS232 AAL 1195 

Bell 103 Modem AAB 1495 




nsr 




EPSON 

MX-80 *495 



The MX-tlO idiSvll 110 char- 
:t second dot matrix printer, 
feed n:uch;inism adjusts to accept Ven 
. ..or. Requires.' Eight bit" 
arallel interfacing I'RE-.MXSi 17 Lb. 



CEnTRonics 
730 $595 
737 $750 



Botli the Centronics 730 and the 73? are cap: 
standard office letterhead or pin feed contfni. 

matrix print liead. Parallel interfacing. Add S65 
RS232. PRC-730P (S). PRC-737P (S) 17 lbs. 




HEWLETT PACKARD 

2650 




HP 



plete. low cost portable con-.pi 
system. This self contained p 
includes CPU. keyboard, prin 
Cltr display ;ind cassette (ape 
SVS-lll'S;. 30 lis. 



26 Megabyte 
Hard Disk Drive 

from 

George Morrows 

Thinker Toys 

$ 



omruller £343 




AMPEX 

DIALOGUE 80 
CRT TERMINAL 



s 995 




BMC 



VI 
MONITOR 

$ 259 



mposil video input make the EMC 

, tit..'' resolution 12' display. 
nipact pljstic enclosure assures that llii> UMC monitor is a rugged 
nvwhere instrument. lor added p rs-ii.-eiic.il the unit Is ftuiLppt:d with 
o'vable st.iokednod-cl.ire n lexU'lns icrtvn. VP.M-BMC III lbs. 




direct connect 

MODEM 

Direct cinnucl modems elimL-latt: loss of inf orma-.ioi 
associated with acoustic modems. Choose cither oft 

The Universal Data Systems I03L.P is snitch selects 
Inate modes, Fully Bell 10:1 compatible. Directly c 

prosimity 10 A.C.iiowur reoupUclc. MOU-103L1 1 



Your Choice 

*169 



V/SA 



t of ihs new "Heir modular handsets, ideal f. 



All merchandise sold by California Digital is premium grade.. 
Shipping: First five pounds $2.00; each additional add $.40 
Foreign orders 10% shipping. Excess will be refunded. 
California residents add 6% sales tax. COD's discouraged.' ' 
Open accounts extended to state supported educational institu- 
tions and companies with a "Strong Dun & Bradstrect. " 
Warehouse: 15608 Inglewood Blvd. Visitors by appointment. 

Circle 321 on.inquiry card. 



ACCESSORIES FOR THE 



COMPUTER 




CALIFORNIA COMPUTElt SVSTEMS 
Arithmetic Processor 7811 B/C S31 



12 K PROM 
Calendcr/C 
Parallel Int 
Profii 



lat. back-up 742-t 
lei Interface 7720A 
■amablc Timer 7740A 
g/Digital converter T-170A 



MICROSOFT PRODUCTS 
Apple to 2-80 CPU card 
D.C. H.AYF.S PRODUCTS 
IMiciomodem for Apple 
COMPUTER STOP PRODUCTS 
Double Vision / BO Column Video 
INTERACTIVE STRUCTURES 
IB Channel A/D card A 10/2 



MOUNTAEi COMPUTER PRODUC 

Intro X-10 system for BSR 

Intro X-10 card otflv 

16 channel AD/DA B bit 

Apple Clock battery back-up 

Sipertalker SD200 

ROW Plus with filter 

ROM Wrilor/Prograr.imer 

APPLE BRAND PRODUCTS 

Apple Language card 

Floppy disk with controller 



r\pple pai 



lei t 



SSM MJCROCOMPUTE 



S-IOO BOARDS 

Assembled • Tested • Burned in 




GODBOUT/COMPUPRO 
Dual 8088/8085 16 bit CPU 
Z-SO CPU 2 



licit A 



1 32K (Alpha MiC 
:olor graphics be 



Spectrum color gra 
Intcrfacer 11 I/O c 
SEATTLE COMPUTER PRODUCTS 
80B6 16 bit CPU 2 card set/88 dos S9S 
CALIFORNIA COMPUTER SYSTEMS 
S-100 Mainframe 22O0A 329 

Disk controller/2. 2 CPM 2-122 329 

Z-80 CPU 4MFIzD;i1A 2810A 250 

DIGITAL RESEARCH 

32K 2716 EPROMboard 99 

EPROMS for above 2716 16 rcq. 13 
CALIFORNIA DATA CORPORATION 
A/D board 16 channel 12 bits 
QT COMPUTER SVSTEMS 



MORROW/ THINKER TOYS 
Multiboard "HEW" Daisy wheel p 
real time clock, power on jump, 
program interrupt cont'l 3P/3S 
Switchboard Interface -1P/2S 
Disk Jockey I disk controller 
Disk Jockey II double density 
SD SALES 
PROM-100 programmer 



MULLEN PRODUCTS 
Extender board/Logic probe I 
Relay Opto/control board 
D.C. HAYES PRODUCTS 
Mlcromodem S-100 FCC reo 
AIITEC ELECTRONICS 
Wire Wrap prolo board WW/1 
General Purpose proto GP /1< 
CALCFORNIA DIGITAL 
8086 CPU 4K on board static 



TELETEK 



SINGLE BOARD COMPUTER 
FLOPPY DISK CONTROLLER 



The l'DC-1 features the 2-80 CPU 
along .Vith the NEC 765 lloppy disk 
controller. The boartl suppor-.a both 
Singh; or double densltv :. 1/4 or 0" 
dish drives. Two serial <-l3-»600ud) 
ami iwo parallel |>Oi'tS add to the flex- 
ibility of this single board computer. 



anil potential for conlrolliiie a Winchester li.inl disk tlri 
liltion of an EXUTIKtl ^"' volt power Supply lie Telctek 
mus capable otprogramini; 2716 t;p»tUlS. 



7:.:." -; 



:; $ 695 



S-100 Mother Board $35 



Quiet 
Suss 

8803-18 
18 slot 
IMSAI 




TOLL FREE ORDER LINE 

(800)421-5041 

TECHNICAL & CALIFORNIA 

(213)679-9001 



IMAGINE THE 
8 INCH FLOPPY 



315K BYTES PER SIDE ON 5 1/4" OF COURSE! Micropolis, 
the worlds largest manufacturer of high density 5 1/4" disk drives, - 
has been doing it for years. And reliably at that! I II 

An ordinary 5 1/4" floppy provides, just 35/tracks per side .. 
and stores only 70K bytes. This is not nearly enough for 
anything useful, so instead, Micropolis uses 77 tracks per side. 
Each track is then formatted with 16 sectors (hard) at 256bytes 
per sector yielding an impressive 315K bytes per side. 

Micropolis drives have a larger capacity than many 8" disk 
drives, though it only occupies the space of a 5 1/4" floppy. 
The 315K byte capacity is roughly 4 times the capacity ol a 
standard 5 1/4" drive. This is what we call QUAD DENSITY. 

To achieve the high density capability, you may think 
Mcropolis had to sacrifice speed or reliability. NOT SO! The 
track to track access time is only 30us with a high speed data 
transfer rate of 250,000 bits per second. 

By creating this high density format, Micropolis is able to 
keep your initial subsystem costs to a minimum. Your cost is 
less than S.002 per byte. Thais a BIG VALUE in a small 
package. 

MICROPOLIS disk subsystems are expandable to keep up 
with your ever increasing needs. Up to four drives/heads 
may be daisy-chained on one S400 controller board With 
all four drives/heads in operation, you have access to over 1.2 
MEGABYTES ol on-line storage. 

WITH MICROPOLIS, complete means COMPLETE. Each sub- 
system comes complete with controller interlace, cable, and 
software. The software includes the MDOS operating system, 
extended basic, assembler and editor. Everything you need 
to get "On Line" in one complete package, 

MCROPOLIS provides total integration which means they 
control everything from beginning to end, The result is a 
better drive lor you, backed by a full 120 day factory 
guarantee, 



Anyone can cut price by cutting out capacity or valuable 
features: But there'smo- long term advantage in it. Not for the 
user, Or -the builder. „**"!-' 7~." . ~"~L 

"MICROPOLIS takes" a better approach, even though it's 
harder, using advanced design to provide more capability 
while alsclowering cost. - -•- - 

For example, most 5 1/4-inch floppy disks cut costs by using 
a cheap, less accurate plastic cam or cam follower to posi- 
tion the read/write head. Most 8-inch floppy disks use a better 
approach, with a rolled steel lead'screw for this function. 

We go them one better and use an all-steel system, with a 
precision-ground steel lead screw and steel follower. It costs 
more but gives us greater storage capacity with lower cost 
per thousand bytes. Not so incidentally, our steel construction 
(compared to plastic) significantly increases reliability, too. 
There's even a built-in File Protect feature that prevents ac- 
cidental loss of valuable data. (A file protected diskette can- 
not be written on.) 

Heat can cause numerous read and write errors that can 
become hazardous to your data. The major heat producing 
power supply components are mounted to a large heat sink, 
external to the cabinet by the power switch and fuse 
(located at the rear of the cabinet). This design is to assure 
that the drive components are kept as cool as possible to 
assure reliable data recovery. 

MICROPOLIS has a reputation lor getting along with most 
everybody, Compatability is not a problem with 
MICROPOLIS. Their disk drives and/or subsystems can be 
easily integrated into systems such as Polymorphic, 
Cromemco, CCS, Ithica Intersystems, Godbout. Northstar, Jade 
Big Z, QT SBC 2/4, and many others. Many OEM manufac- 
turers rely on MICROPOLIS to get the job done efficiently. 
Companies like Commodore, Exidy. Harris, and Vector 
Graphics to name just a lew. Years from now, you can look 
back with a secure feeling knowing you made the best 
choice, MICROPOLIS. '• 




CAPACITY OF AN 
IN 5 1/4" FORMAT 



THIS 




/Vt#C"'/<C'?l*C Jl.l*i 



NOT THIS 



minim, , 




Because of our incredible purchasing power, PRIORITY ONE 
ELECTRONICS is able to buy MICROPOLIS disk drives by the 
thousands and receive special pricing. That special pricing 
we receive is passed on to you in the form of tremendously 
discounted prices. Now all that remains is for you to take ad- 
vantage of this truly incredible buy. 



DESCRIPTION 



S-100 SUBSYSTEMS 



MCP 
MCP 
MCP 
MCP 
MCP 
MCP 



■1053-4 
■1053-2 
■1043-2 
■1041-2 
•1042-1 
■1041-1 



1.2 MB 2 HEAD DUAL 

630 KB DUAL 

315 KB SINGLE 

315 KB SINGLE, NO PS 

143 KB SINGLE 

143 KB SINGLE, NO PS 



$2605.00 
$1895.00 
$1145.00 
$1045.00 
$795.00 
$695.00 



SALE 
PRICE 



$1395.00 
$995.00 
$695.00 
$639.00 
$625.00 
$595.00 



COMPLETE W/S-100 CONTROLLER, CABLES, 
MANUALS AND MICROPOLIS MDOS AND BASIC 



ADD-ON DRIVES 



MCP 
MCP 
MCP 
MCP 
MCP 



■1033-2 
•1023-2 
■1021-2 
•1022-1 
■1021-1 



630 KB DUAL 

315 KB SINGLE 

315 KB SINGLE. NO PS 

143 KB SINGLE 

143 KB SINGLE, NO PS 



$1395.00 
$645.00 
$545.00 
$545.00 
$445.00 



$895.00 
$495.00 
$475.00 
$375.00 
$360.00 



REQUIRES ACCESSORY ADD-ON CABLES 



GOOD NEWS FOR TRS-80* OWNERS 

We now have a complete line of TRS-80* Model 1 compati- 
ble MICROPOLIS add on drives in matching colors. These 
drives simply plug into the expansion interface via a disc 
data cable. 

197K BYTES PEE SIDE FOR YOUR TRS-80*, that's easy! Just 
order a 77 track add on drive and the New DOS-80 operating 
system. Among the many features of New DOS-80, is its ability 
to control any mix of 35, 40, or 77 track drives on the same 
cable. 



TRS-80® DISK DRIVES 



MCP-1027-1 
MCP-1037-1 
MCP-1027-2 
MCP-1037-2 



35 TRACK SINGLE 
35 TRACK DUAL 
77 TRACK SINGLE 
77 TRACK DUAL 



$545.00 
$1195.00 

$645.00 
$1395.00 



ACCESSORIES 



PR1-34CEEE-2 
PR1-34CEEE-4 



NEW DOS/80 TRS-80" 

35 Ihru 77 SUPPLIED 

TRACK OPERATING 35 TRACK 

SYSTEM $149.00 

Two Drive Data Cable 
Four Drive Data Cable 

GOODTHRU MARCH 1981 



$279.95 
$695.00 
$439.00 
$795.00 



ON 

77 TRACK 

$159.00 

$29.95 
$39.95 



THIS COULD BE THE START OF 
SOMETHING SMALL. 

1-800-423-5633 PRIORITY ONE ELECTRONICS (213)894-8171 

16723 B ROSCOE BLVD. • SEPULVEDA, CA. 91343 

Terms: Visa. MC BAC, Check, Money Order, U.S. Funds Only. CA residents add 6% sales tax, Minimum order $15.00 Prepaid U.S. orders less than 
$75.00 include 5% shipping and handling. MINIMUM $2.50. Excess refunded. Just in case ... please include your phone no. Prices subject to change 
without notice. We will do our best to maintain prices thru March 1981. 
•SOCKET and CONNECTOR prices based on GOLD, not exceeding $700 per oz. 

'Sale Prices are lor prepaid orders only. Credit card orders will be charged appropriale freight 





'TRS-80 is a rectislered trademark of Tandy Corn 



Circle 322 on inquiry card 



S-100 HEADQUARTERS 




THE DUAL PROCESSOR BOARD 
IS HERE! 




GBT161 8085 CPU BOARD 
GBT1612 8085/8088 CPU BOARD 

• 8088 & 8085A CPU 

• S-100 IEEE COMPATIBLE 

• SWITCHABLE CPU'S 

• 5 MHZ OR 2 MHZ SWITCHABLE 

• POWER ON JUMP TO ANY 256 BYTE BOUNDARY 

• POWER ON JUMP CAN BE DISABLED 

• CPU CAN JUMP ON POWER ON ONLY OR POWER 
ON AND RESET. 

• 24 BIT EXTENDED ADDRESSING 

• IMSAI FRONT PANEL COMPATIBLE 

• AVAILABLE WITH 8085A ONLY 

BOARD WITH B085 ONLY 

List Price Our Price 
GBT161A Assembled & Tesled $325.00 S305.00 

BOARD WITH 8085 & 8088 



GBT1612A Assembled & Tesled $42500 



S399.00 



ENHANCED Z80 S-100 CPU 
BOARD 




GBT160 
Z80 CPU 

• 4-6 MHz Z80 CPU 

■ IEEE S-100 Bus Compalible 

■ On Board Prom Sockets For Up To 8K Prom 

• Power On Jump Start To Any 256Byte Boundary 

• On Board Memory Manager For Direct Addressing For 
Up To 16 M-Byles 

■ Fully Maskable Vectored interrupts 

• Wait Stale Generation For All Machine Cycles 

■ Bypassing Of All Supply Line To Suppress Transients 

• All IC's Are Socketed 



List Price 



GBT160U Unkil 

GBT160A Assembled & Tested 




SPECTRUM 
S-100 COLOR GRAPHICS BOARD 

• Uses the MC6B47 LSI IC 

• Uses 1372 color encoded/generator 

• Alphanumeric/graphics in 8 colors 

• Ultra dense 256 x 192 lull graphics 

• 8K bytes, on-board low power RAM 

• One lull duplex parallel 1/0 port with attention, enable & 
strobe bits with powerfor running joysticks, keyboards, etc. 

• A parallel port for graphics mode control 

• Board may be used as a 4MHz RAM for program storage 

LIST PRICE OUR PRICE 



GBT144U 
GBT144A 



UNKIT 
A&T 



S399.0D 



GBT2D SUBL0GIC UNIVERSAL GRAPHICS 
INTERPRETER SOFTWARE 



S299.00 
S349.0D 



$35.00 





INTERFACER I 

Our 1/0 board gives you inparalleled flexibility and operating 
convenience. We include suchteatures as: 

• 2 independently addressable serial ports (dip switch selec- 
table addresses) 

• Real LSI Hardware UARTs lor minimum CPU housekeeping 

• RS232C, current loop (20mA). & TTL signals on both ports 

• Precision, crystal-controlled Baud rates up to 19.1 KBaud 
(Individually dip switch selectable) 

• Transmit & receive interrupts on both channels, jumperable 
to any vectored interrupt line 

• Industry standard RS232 level converters with five RS232 
handshaking lines per port 

• Optically isolated current loop with provisions for both on- 
board & olf-board current sources 

• UART parameters, interrupt enables. & RS232 handshaking 
lines are software programmable with power-on hardware 
default to customer specified hard- wired set tings for maxi- 
mum flexibility 

• Port connectors mate directly to ribbon cable & DB25con- 
nectors in standard pinouts 

• RS232 lines will conform to either master or slave 
configurations 

• Board gives full feature operation with both 2 & 4 MHz 
systems 

• Low power consumption :+8V@ 450m A; +16 V@ 150m A; -16V 
@ 70mA max. 

• No software initialization required for board operation, 
although board parameters may be altered by software 

LIST PRICE OUR PRICE 
GBT133U UNKIT S199.G0 

GBT133A AST $249.00 S219.00 




INTERFACER II 3PTS 

• 1 independently addressable serial port 

• RS232C: 20mA current loop, & TTL signals 

• Precision cry st a I controlled Baud rate generator 

• Up to 19. 2K Baud 

• Transmit and receive interrupts, jumperable to and vectored 
interrupt line 

• Five RS232 handshaking lines 

• Optically isolated current loop 

• 3 parallel I/O 

• Utilizes LSTTL octal latches for latched I/O data with 24mA 
drive current 

• Enable & strobe bits on each port (each with selectable 
polarity) 

• Interrupts for each input port 

• Separate 25 pin connector with power (or each channel and a 
status port for interrupt mask & port status 

LIST PRICE OUR PRICE 




ECONOROM 2708 



Has provisions for wait states for 4MHz operations. Con- 
figured as four 4K blocks— each independently addressa- 
ble and disabable. Power-on jump. Does NOT include 
2708s. Includes all support chips, sockets, regulators, 
heat sinks, etc. Sold in UNKIT form only. Shipping Weight 
2 lbs. 
GBT125U Unkit S85.00 



;.M 



Afrit 



Order No. 
GBT129A32 



CONORAM XA32K RAM 

Reg. $689.00 

Sale Priced 
$429.00 



' 4MHz with Z80 

■ 5MHz with 8085 
• Assembled and Tested 
' S-100 Compatible 

■ Fully Static 
' 24 Bit Extended 

Addressing 



Static S-100 Memory 




32K ECONORAMXX 

32K Bank Select. IEEE S-100 compatible. Features one 
32K block that can be addressed on 4K boundaries. Com- 
patible with the IEEE proposed standard of 24 address 
lines as well as all currently used bank select configura- 
tions. Any or all of the eight 4 K byte blocks may be disabled 
to create as many windows in memory to avoid any system 
memory conflicts. 

List Price Our Price 

GBT164A16 16K RAM A&T $399.00 S329.00 

GBT164A24 24K RAM A&T $539.00 S455.00 

GBT164A32 32K RAM A&T $699.00 $569.00 




8K ECONORAM HA 

We realize that this may not look like the 8K. Econoram 
II board you've known and loved for so many years; 
however, at Godbout, good things don't come to an 
end — they just get better! Our NEW 8K Econoram HA 
board retains all the best selling features of the old 
Econoram II PLUS is now 4 MHz STANDARD — still 
static— with ultra low power consumption. S-100 com- 
patible. Single supply required— guaranteed maximum 
current under 900mA. Typical boards draw 700 to 
800mA. Phantom feature is included on the new 
Econoram MA & is switch selectable. Orgai itzed as two 
4K independently addressable blocks. Includes switch- 
ed WRITE protect — block & board disable. Also, has 
provision for memory management. Shipping Weight 2 
,bs - Lisf Price Our Price 

GBT139U Unkit S159.00 

GBT139A A&T S189.00 S179.00 




PRIORITY ONE ELECTRONICS 

16723 B ROSCOE BLVD. • SEPULVEDA, CA. 91343 

Terms: Visa. MC. BAC, Check, Money Order. U.S. Funds Only. CA residents add 6% sales tax 
Minimum order $15.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling. 
MINIMUM $2.50. Excess refunded. Just in case ... please include your phone no. Prices subject to 
change without notice. We will do our best to maintain prices thru March 1981. 
•SOCKET and CONNECTOR prices based on GOLD, not exceeding $700 per oz. 

'Sale Prices are for prepaid orders only. Credit card orders will be charged appropriate freight 



ECONORAM XIV 

16Kx8forS-100. Addressable on any 4K boundary Direct 
addressing on up to 24 address lines. Fully meets IEEE 
S-100 buss specs. Low power, hi-speed static memory. 
Operates up to 5 MHz with newest 8085/8086/8088 
CPUs. Can be used with 8080, Z80. 8085, 8086. 8088, 
Z8000, etc. 

List Price Our Price 

GBT143U Unkit S279.00 

GBT143AA&T $349.00 $299.00 



ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 



BITS & PIECES 



TRS-80/APPLE 

MEMORY EXPANSION KITS 
c 4116's RAMS 

A/ from Leading Manufacturers (Eft. # 

4^ (16Kx1 20Qns) W 

/8 for *29 00 < 

ADD S3.00 FOR PROGRAMMING JUMPERS 
FOR TRS-80 KEYBOARD 

4116's 100 pes & UP $3.00 each 
1000 pes & UP $2.75 each 



2114-3L 

I4096 BIT (1024x4) 300ns 
I LOW POWER STATIC RAM 

8/ s 30 00 

100 + s 3 00 



5257-3L 

(TMS 4044) 

4096x1 300ns 

| LOW POWER STATIC RAM 

8/ s 50 00 

100 pes. + s 4 75 



2716 

450ns 5 Volt only 
16 K EPR0M 

s 11 95 each 
or 10/ s 85 00 



2708 

450ns 8K 
EPR0M 

s 8 50 each 
or 8/ s 54 00 



2732 

450ns 5 Volt only 
32 K EPR0M 8x4K 

$ 25.00 
8/M60.00 



ZERO INSERTION 
FORCE TEST SOCKETS 

I I"' ^-- 




\" 



1 



1-9 10-24 25-99 

2IP-1 60IP S5.50 5.35 4.95 

ZIP-24DIP S7.50 7.25 6.95 

ZIP-40DIP S10.25 9.85 9.50 



3 LEVEL GOLD WIRE WRAP SOCKETS 
PRICE* 





-•-■• S»K, 



DIP SWITCHES 
SPST 



PART ND. NO. Of POSITIONS |-9 



PRICE 
1 024 



25-99 



DIP-SW4 
DIP-SW5 
DIP-SW6 
0IPSW7 
DIPSW8 
DIP-SW9 
OIPSWIO 



SI. 50 
S1.B0 

SI. 70 
SI. 80 
S2.00 
S2.25 

S2.50 



SI. 40 
SI. 49 
SI. 59 
SI. 66 
SI. 86 
S2.I0 
S2.33 



S1.28 
SI. 36 
SI.45 
SI. 53 
SI. 70 
SI.92 
S2.I2 



^.Shugort 

ISA801 R 
SALE 

/ 



SHU-SA801R 



2 OR 
MORE 




395 



$410° 

00 

ea. 



Capacity 


Single Density 


Double Density 


Unformatted 






Per Disk 


3.2 megabits 


6.4 megabits 


Per Track 


41 7 kilobits 


83.4 kilobits 


IBM Format 






Per Disk 


2.0 megabits 


n/a 


Per Track 


26.6 kilobits 


n/a 


Transfer Rate 


250 kilobits/se 


c. 500 kilobits/sec. 


Latency (average) 


83 ms 


83 ms 


Access Time 






Track to Track 


8 ms 


8 ms 


Average 


260 ms 


260 ms 


Setting Time 


8 ms 


8 ms 


Head Load Time 


35 ms 


35 ms 




CT/M 




vi 


*sum2.*Z 




; SI CCS2422A 
FLOPPY DISK CONTROLLER ,_ 

WITH CP/M VERSION 2.2 $375.00 



LIST $400.00 



SALE 



IEEE S-100 COMPATIBLE SINGLE/DOUBLE DENSITY 
5'. '78" DISK DRIVES 
SINGLE/DOUBLE HEADED 
ASSEMBLED & 
TESTED 



' ;; V 





Aferbatim 



Pari No. 



VRB-MD 525-01 
VR8-MD 525-10 
VRB-NID 525-16 
VRB-MD 577-01 
VRB-MD 577-16 
VR8-F032-1000 
VRB;F034-1000 



Sectoring 



Soft Sector 
Hard to Sector 
Hard 1G Sector 
Sott Sector 
Hard 1G Sector 
Hard Seclor 
Solt Sector 



Application 

TRS-80 Apple 
North Star 
Micropolis 
77 Track Cert 
77 Track Cert 
Sliugart 801R 
IBM 3740 



S29 
S29 
S29 
S48 
S48 
S37 
S37 



MODEI 

$129.00] 




THE STAR 

MODEM 

from LIVERMO 

FEATURE 

FITS GTE HANDSETS! 

2 YEAR WARRANTY 



EXCLUSIVE ACOUSTIC CHAMBERS 

The exclusive triple seal of Livermore s new flat mounted 
cups locks the handset into the acoustic chamber yielding 
superior acoustic isolation and mechanical cushioning. 
Designed to adapt to most common handsets used 
throughout the world, the STAR offers the utmost in flex- 
ibility and transmission reliability. 




Specifications: 

■ Data Rate: to 300 baud 

• Compatibility: Bell 103 and 113; CCITT 

■ Frequency Stability: ±0.3 percent. Crystal controlled 

• Receiver Sensitivity: -50 dBm ON, -53 dBm OFF 

• Modulation: Frequency shiftkeyed (FSK) 

■ Carrier Detect Delay: 1.2 seconds ON; 120 msec OFF 

■ EIA Terminal Interface: Compatible with RS 232 
specifications 

■ Teletype Interface: 20 milliampere current loop 

■ Optional Interfaces: IEEE 488; TTL; TTY 43 

• International (CCITT) frequencies available 

• Switches: Originate/Off/Answer: Full Duplex/Test/Half 
Duplex 

• Indicators: Transmit Data, Receive Data. Carrier 
Ready, Test 

• Power: Supplied by 24 VAC/150 MA UL/CSA listed wall- 
mount transformer Input 115 VAC. 2.5 watts. (A 220 
VAC. 50 Hz adaptor is available upon request.) 

• Dimensions: 10" x 4" x 2" 

■ Weight: 1.74 lbs. (3 lbs shipping weight including AC 
adaptor.) 

■ Warranty: Two years on parts and labor, excluding the 
AC adaptor which carries the manufacturer's warranty 



List SALE 

Price PRICE 

S19900 S129.00 

S19900 S129.00 

$229.00 S209.00 

$395.00 $249.00 

S465.00 S388.00 



Part No Description 

LIV-STAR RS232,TTL Modem 

LIV-STAR20M RS232, 20MA Current Loop 

LIV-STAR-V21 CCITT European Standard 

LIV-IEEE IEEE 488 Standand 

LIV-IEEE-V21 IEEE 488. CCITT Standard 



CABLES 

Part No. Description -^H |^ Price 

CND-RS2328F RS232 8 Cond 8 ft 7WTT. . S19.95 

LIV-I2I IEEE to IEEE 2 Meter .» $59.95 

LIV-I2PET IEEE to Pet 2 Meter S59.95 

PROTECT YOUR INVESTMENT 
PROTECT YOUR DATA WITH 




<*^ 



ISDBflR 



GOF-IBAR46 



♦/ 



)95 



LIST PRICE S 79 9 
SALE PRICE S 39 95 



GOLD S-100 CONNECTORS 

PRIORITY ONE distributes the Tl S-100 Card Edge 

Connectors at tremendous volume for prices 

others only wish they could duplicate. 



SOLDER TAIL PRICE 
10-24 25-99 100-249 




TI-S100STCT 3.20 2.90 2.50 2.20 

WIRE WRAP PRICE 

Part No. 1-9 10-24 25-99 100-249 

TI-S100WWG 4.00 3.75 3.50 3.25 



PRIORITY ONE ELECTRONICS 

16723 B ROSCOE BLVD. • SEPULVEDA, CA. 91343 

Terms: Visa, MC. BAC. Check. Money Order, U.S. Funds Only CA residents add 6% sales tax. 
Minimum order $15.00 Prepaid U.S. orders less than $75.00 include 5% shipping and handling. 
MINIMUM $2.50. Excess refunded. Just in case ... please include your phone no. Prices subject lo 
change without notice. We will do our best to maintain prices thru March 1981. 
•SOCKET and CONNECTOR prices based on GOLD, nol exceeding $700 per oz. 
'Sale Prices are fcr prepaid orders only Credit card orders will be charged appropriate freight 



lA 



ORDER TOLL FREE 1-800-423-5633 ORDER TOLL FREE 1-800-423-5633 

Circle 323 on Inquiry card. 



Best Prices and Delivery^ 



I 



SU;: , tIN byfntertec 




Selt contained computer with duat disks and 
two RS232C ports. Complete with CP.'M' 2.2 
and BASIC. 

32K Double Density, List $2995 . 

64K Double Density, List $3345 $2883 

64K Upgraded to Quad Density w/ Special 
MiniMicroMart Warranty SPECIAL $3395 

VIDEO TERMINALS 

/VflrV EMULATOR (Intertec), List $895$ 749 
NEW INTERTUBE IIIList $895 . . ONLY $ 749 
SOROC 120, List $995 SPECIAL $ 729 

1Q140, List $1495 SPECIAL $1149 

PERKIN-ELMER 550, List $997 $ 799 

with anti-glare screen, $1027 $ 829 

HAZELTINE 1410, List $900 $ 749 

1420 $ 849 

1500, List $1225 $ 879 

1510, List $1395 $1089 

1520, List $1650 $1389 

LEAR SIEGLER ADM3A, Assembled $ 849 

TELEVIDEO 912C, List $950 $ 789 

920C. List $1030 $ 849 

950C, List $1195 NEW $1039 

PRINTERS 

ANADEX DP-8000 $ 849 

DP-9500, List $1650 $1399 

DP-9501, List $1650 $1399 

PAPER TIGER IDS-445, List $995 $ 695 

w/graphics op., incl. buffer, $1195 .. $ 789 

PAPER TIGER IDS-460, List 1149 

PAPER TIGER IDS-460G List 1199 

NEW IDS PAPERTIGER460 . List 1295 11149 
NEW IDS PAPERTIGER 460G List $1394 {1199 

NEC Spinwriters Call for Price 

TELETYPE 43 KSR $1087 

CENTRONICS 
730-1 parallel interface . . NEW LOW $ 649 
737 parallel interface . SUPER VALUE $ 829 
779 w/Tractor, List $1350 $1049 

703 w/Tractor, VFU, List $2975 $1695 

704 w/Tractor, VFU, List $2350 $1595 

Tl 810 Basic, List $1895 $1695 

810/serial & Centronics-style 

parallel interface, List $1940 $1735 

810 w/full ASCII (U/LC), Vertical 
Forms Control, Compressed Print . . $1895 

Tl 820 KSR, List $2165 $1835 

Tl 745 w/full ASCII, List $1695 $1399 

COMPRINT 912 w/parallel interface . . $ 559 

912 w /serial interface, List $699 $ 589 

AXIOM IMP I $ 699 

MICROTEK, List $750 $ 675 

OKIDATA Microline 80, List $949 $599 

Tractor Feed Option $109 

RS232 Serial Interface $ 99 



NORTH STAR HORIZON" 

HORIZON 1 ASSEMBLED it TESTED 

32K, Double Density, List $2695 .... $2279 
32K, Quad Density, List $2995 $2539 



HORIZON 2 ASSEMBLED & TESTED 

32K, Double Density, List $3095 $2619 

32K, Quad Density, List $3595 ... $3049 

48K, Double Density, List $3590 $3039 

48K, Quad Density, List $4090 $3469 

64K, Double Density, List $3830 $3239 

64K, Quad Density, List $4330 $3669 



FLOPPY DISK SYSTEMS 

NORTH STAR MDS-A 
Assembled, List $899 SPECIAL $ 719 



MORROW THINKER TOYS" Discus 2D, 

List $1199 OUR PRICE % 998* 

Discus 2D, dual-drive. List $1994 $1694* 

Discus 2 + 2, A&T, List $1549 $1319* 

Dual Discus 2 + 2, A&T, List $2748 . . . $2335* 
•Now includes CP/M - 2.2 

Prom Programers 

SSM PB1 Kit List $1 25 $106 

SSM PB1 A&TList$190 $161 

SD Computer Prom 100 Kit$236 $201 

SD Computer Prom 1 00A&T List $31 1 . . $264 

FLOPPY DISK 
CONTROLLER BOARDS 

NORTH STAR, DD, 

Assembled, List $499 

MORROW Disk Jockey 1, A&T ($213) 

Disk Jockey 2D, A&T, List $479 

SD Versafloppy 1 , Kit, List $284 

Versafloppy II, DD Kit, List $413 

Versafloppy II, DD, A&T, List $507 . . . 
DELTA double density A&T ($385) . . 
CONDUCTOR, double density A&T 
INTERSYSTEMS FDC-2, A&T, $495 
MICROMATION Doubler, DD, A&T 
TARBELL Floppy Disk Interface Kit . 

double density, A&T, List $495 .... 



$399 
$189 
$429 
$239 
$349 
$429 
$345 
$269 
$439 
$429 
$199 
$444 



: 



ESCON CONVERSION 
FOR IBM SELECTRIC 



Complete w/microprocessor controller qnd 
power supply Factory built. User installs 
solenoid assembly or it can be done at Escon 
factory at nominal cost. 
Parallel (TRS-80, Sorcerer, etc.), $575 $514 

RS232 Standard Serial, List $599 534 

IEEb-'t88 (for PET), List $660 584 

TRS-80 Cable 25 



CALIFORNIA COMPUTER SYSTEMS 

Z80 CPU BOARDS List $299 $269 

DISK CONTROLLER 2422 List $399 $359 

16K Static, A&T, List $349.95 $259 

32K STATIC List $71 $599 

64K DYNAMIC BOARD List$699 $589 



CPU BOARDS 

(assembled unless noieoi 
NORTH STAR Z80A (ZPB-A/A), $299 $254 
CROMEMCO 4 MHz (ZPU-W), List $395 $335 

4 MHz (SCC-W), List $450 $382 

INTERSYSTEMS (formerly Ithaca Audio) 
new Series II Z-80, 4 MHz. List $395 . $349 

SSM CB1 8080 A&T List $252 $214 

CBIAKit, List $183 $156 

CB2 Z-80, A&T, List $344 $289 

CB2 Kit, List $60 $221 

DELTA Z-80, with I/O $289 

SD SBC-1 00, List 413 $349 

SBC-1 00 Kit, List $341 $289 

SBC-200, List $471 $399 

SBC-200 Kit, List $373 $317 

MEMORY BOARDS 

32K SD ExpandoRAM Kit 

! I 

CALL FOR PRICES 



NORTH STAR 16K Dynamic RAM Board, 

A&T (RAM-16-A/A), List $499 $420 

32K A&T (RAM-32/A), List $739 $620 

CROMEMCO 16KZ-W, List $49b $419 

64KZ W, List $1795 $1269 

MEASUREMENT SYSTEMS & CONTROLS 

(Guaranteed performance, incl. labor/parts 1 yr) 
DM6400 64K Board w/all 64K, $795 . . . $659 

DM4800 with 48K, List $695 $650 

DM3200 with 32K, List $595 $509 

DMB6400 64K Board w/all 64K $859 

DMB4800 with 48K $789 

MORROW SuperRAM - all static, all A&T 

16K, 4 MHz or 2 MHz, List $349 $299 

32K, 4 MHz, List $699 . $629 

16K Memory Master, List $399 $339 

24K Memory Master, List $549 $465 

INTERSYSTEMS (formerly Ithaca Audio) 

8K Static 2 MHz, A&T, List $165 $149 

8K Static 4 MHz, A&T, List $195 $176 

16K Static 2 MHz, A&T, List $475 $427 

16K Static 4 MHz, A&T, List $495 ..... $445 
64K Dynamic, List $995 $895 

CALIFORNIA COMPUTER 

16K Static, A&T, List $349.95 $259 

VIDEO BOARDS 

I/O Mapped 
SD COMPUTER VDB-8024, kit, List $437 . 369 

Assembled, List $556 $469 

XITEX SCT-100K, Kit ONLY $169.95 

SCT-100A Assembled $189.95 

SSM VB2 I/O, Kit, List $199 $169* 

Assembled & Tested, List $269 $229* 

Memory Mapped 
SSM VB1C, 16x64, Kit, List $179 $152 * 

Assembled & Tested, List $242 $206 * 

SSM VB3, 80-Char.,4MHz,Kit, List$425 . . $359* 

4 MHz, A&T, List $499 $424 

INTERSYSTEMS, lbxt>4, A&T, List $1bb $149 
*Subject to change. 



NEW CROMEMCO 
16FDC 

DISK CONTROLLER 

List $595 OUR PRICE 



SHIPPING AND INSURANCE: Add $2.50 (or boards, $6 for Selectric Convener or Floppy Disk Drives, $7.50 for Floppy Disk Systems, $15 for Horizon SHIPPED FREIGHT COLLECT; SupeiBram, Centronics 

and T.I printers. Contact us for shipping information on other terminals and printers. 

Above prices reflect a 2% cash discount (order prepaid prior to shipment) Add 2% to prices lor credit card orders. C.O.D.'s. etc. Prices are subject to change and offers subject to withdrawal without notice. 

- WRITE FOR FREE CATALOG - 

Circle 324 on inquiry card. 

MiniMicroMart, Inc. 

1618 James Street, Syracuse NY 13203 (315)422 4467 TWX 710-541-0431 



Terminals anH Printers! 

mm ^tmmW mm mm mm mm mm Bm mm m wwmm mm m *mmW fo^f m m ^mm mm mm JSb mm mm m mm ^tmlm^ mm ^9mm^ mm 






TELEVIDEO TVI-912C 



SOROC 



TI-810 



in inn niiiiiiiu wvvww 

mum wwww 



Mtmftv 




Upper and lower case, 15 baud rates: 75 to 
19,000 baud, dual intensity, 24 x 80 character 
display, 12 x 10 resolution. Numeric pad. Pro- 
grammable reversible video, auxiliary port, 
self-test mode, protect mode, block mode, 
tabbing, addressable cursor. Microprocessor 
controlled, programmable underline, line and 
character insert/delete. "C" version features 
typewriter-style keyboard. List $950 

OUR PRICES? 6a 
920C (with 11 function keys, 6 edit keys and 
2 transmission mode keys, List $1030 

ONLY $849 

New 950C $1195 $1039 

Intertec 

EMULATOR 

Software compatible with a Soroc IQ-120, 
Hazeltine 1500, ADM-3A or DEC VT-52. Fea- 
tures block mode transmission and printer port; 
12" anti-glare screen; 18-key numeric keypad; 
full cursor control. List $895 




NEW INTERTUBE III 

List $995 
12" display, 24 x 80 format, 18-key numeric 
keypad, 128 upper/lower case ASCII charac- 
ters. Reverse video, blinking, complete cursor 
addressing and control. Special user defined 
control function keys, protected and unpro- 
tected fields. Line insert/delete and character 
insert/delete editing, eleven special line draw- 
ing symbols. 




IQ-120 

List $995 



-140 List $1495 



afCi<iAl. ? l I-*:! 



HAZEi™e 



1500 



1410 w/numeric keypad, List $900 $749 

1420 w/lower case and numeric pad 849 

1510, List $1395 1089 

1520, List $1650 1389 




Terminal/Keyboard as well as 

RO Printer Only models available. 

CALL FOR PRICES! 



PRINTERS 

NEW 730-1 , parallel, friction, tractor . . $649 
NEW 730-3 RS-232 friction, tractor . . . .$699 
NEW 737-1 parallel, friction, tractor .... $829 
NEW 737-3 RS-232 friction, tractor . . . .$899 
779-2 w/ tractor (Same as TRS-80 Line 

Printer I), List $1350 $849 

704-11 parallel 1 80 cps $1698 

704-9 RS232 serial version, $2350 . . $1595 





TI-810 Basic Unit, $1895 . 

TI-810 w/full ASCII (Lower case), vertical 

forms control, and compressed print . $1795 
TI-745 Complete printing terminal 
with acoustic coupler, List $1695 .... 



RNRD6X 

DP9500/DP9501 PRINTCRS 

DP-9500, List $1650 $1349 

DP-9501, List $1650 $1349 

OKIDATA 
Microline80 

Tractor Feed Option $109 

Serial interface $ 99 

AXIOM IMP I $699 

COMPRINT 912 w/parallel interf. $559 
912 w /serial interface. List $699 $589 

MICROTEK. List $750 $675 

NEW MODELS.'.'.' 

DP9500 $1349 

DP9501 $1349 

^% M. ■"* HP* P^§ *W*U tf"% f~ 9% * 



i E 




IDS-445 Paper Tiger, $695 

w/graphics option, incl. buffer, $1194 . . $789 

TRS-80 cable $45 

NEW IDS PAPERTIGER 460List $1295 . $1099 
NEW IDS PAPERTIGER 460G List $1394 $1149 

NEW IDS 460 

QUALITY PRINTING AT MATRIX 

SPEEO-LOGIC SEEKING 

PROPORTIONAL SPACING 

w/aufo text justification 



Above prices reflect a 2% cash discount (order prepaid prior to shipment). Add 2% to prices for credit 
card orders, C.O.D.'s, etc. Prices are f.o.b. shipping point. Prices are subject to change and offers 
subject to withdrawal without notice. WRITE FOR FREE CATALOG. 



MiniMicroMart, In 

1618 James Street, Syracuse NY 13203 (315) 422-4467 TWX 710-541-0431 

Circle 325 on Inquiry card. 



VISA' 



Smtm 



Unclassified Ads 



UNCLASSIFIED POLICY: Readers who are soliciting or giving advice, or who have 
equipment to buy, sell or swap should send in a clearly typed notice to that effect. To be 
considered for publication, an advertisement must be clearly noncommercial, typed double 
spaced on plain white paper, contain 75 words or less, and include complete name and 
address information. 

These notices are free of charge and will be printed one time only on a space available 
basis. Notices can be accepted from individuals or bona fide computer users clubs only. We 
can engage in no correspondence on these and your confirmation of placement is ap- 
pearance in an issue of BYTE. 

Please note that it may take three or four months for an ad to appear in the magazine. 



FOR SALE: Two cassette interfaces: Tarbel I; $75, Da Jen; 
$120. Seven 8 K static programmable memory boards; 
$90 each. Expandorom 2708/16 (less PROMs); $50. Two 
SSM 4 K 1708 boards; $35 each. 8-Inch single disk drive 
cabinet with power supply which will run two drives, 
Shugart Siemans compatible; $175. PTC VDM-1 video 
driver board; $150. Ail working and assembled. Ail S-100 
bus. Dick Drain, 6730 Alter Rd, Dayton OH 45424, (513) 
233-8055. 

FOR SALE: S-100 and other items; Cromemco: ZPU pro- 
cessor board, 8 K Bytesaver, 16 K programmable 
memory, PRI printer interface, D + 7A analogue I/O. IM- 
SAI: card cage and 28 A supply, 16 K programmable 
memory board, 32 K programmable memory board, MIO 
multiple I/O, VIO-C video with all read-only memories. 
TDL: 16 K programmable memory Z16. OAE paper-tape 
reader. Radio Shack keyboard. Keytronlc capacitive 
keyboard. Ail items like new and guaranteed working. 
Very reasonable prices. Bob Waber, 2590 #14 E 
Michigan, Ypsilanti Ml 48197,(313)484-1826. 

WANTED: Assembly/Applesoft graphics programs, 
game programs, subroutines. All welcome for ex- 
periments with graphics. Stamps for interesting 
responses. Alan M Leder, 246 Lenox Ave, Paterson NJ 
07502. 



FOR SALE: Used S-100 boards: TDL Z80 processor 
board; $100, Scitronlcs control board; $100, MITS 
parallel I/O board (one port); $50, 8080 processor; $80. 
Paul Jacobs, 5201 E 3rd St, Tucson AZ 85711, (602) 
795-2366. 

NEEDED: Information, kit, schematics, or advice for 
adapting CP/M or equivalent operating system to the In- 
tel SBC 80/10. Goal Is to run Pascal on the 80/10. Also, 
have DEC LA-36 for trade or sale. Scott Nlntzel, 3843 
Granada Ln N, Oakdale MN 55109, (612) 770-6926. 

FOR SALE: Pen plotter: Houston Instruments HIPLOT 
(tm) plotter. Uses 8 by 11 paper. Has serial and parallel 
interfaces. Perfect shape; $900. (New price is $1100.) 
Will ship COD. Harold Hedelman, 1020 Triphammer Rd, 
Ithaca NY 14853,(607)256-4880. 

FOR SALE: Jade Z80 processor boar'd, 4 MHz, assem- 
bled and tested, unused, $140; GRI keyboard #753 (5 V), 
$50. K B Clark, 158 Creel, Palm Bay FL 32905, (305) 
725-5130. 

WANTED: Radio Shack expansion interface with or 
without RS-232C board. K or 16 K memory. Marc 
Gedert, 619 W Broadway, Maumee OH 43537, (419) 
893-0544. 



WANTED: Need SwTPC MP-A or MP-A2 processor card 
or similar for S-50 bus. Prefer to have operating card, but 
will consider one that needs repair if necessary. (US 
Post Office domestic rates, $0.15 letters) George Keim, 
POB 160, Yap Island GU 96910. 

FOR SALE: Used and unused hardware and software for 
TRS-80 Model I and CP/M systems. Send SASE for com- 
plete list. R Lee, 25 Amaryllis Ave, Waterbury CT 06710. 

FOR SALE: Two EXECuport portable terminals: 10 thru 
30 cps, 80-column printer modems. Both parallel and 
serial I/O ports for use as printer. See ad on page 217 of 
the March 1980 BYTE for details. Both units in good 
working condition. Will ship UPS COD, no risk, pay on 
delivery. Model #300-5375, #320-$475. Warren V Bell, 
1604 N Smith St, Spokane WA 99207, (509) 534-8088 
evenings. 

WANTED: Apple, Pascal, and dual disks are the base of 
our research project to develop automated tools for 
high-level software and systems design architecture. 
Based on the Design by Objectives methods. We seek 
contact with hard-working colleagues prepared to con- 
tribute to development. MARK I system exists. Tom Glib 
and Lech Krzanik, Box 102, N-1411 Kolbotn, Norway. 

FOR SALE: CAT-100 video digitizer with frame capture, 
full instructions, CP/M software, and source listing. It is 
a two-board system for S-100 bus and includes 32 K of 
programmable memory with full video and software I/O 
capability. It has sixteen levels of gray scale or sixteen 
colors arranged as 240 lines of 256 pixels. $1600 in- 
vested. $950/offer. John Underwood, 1171 NE 72nd, 
Portland OR 97213, (503) 252-7394. 



FOR SALE: Ithaca Audio Z80 processor. 2.5 MHz with 
power on jump and selectable wait states, 2708 not in- 
cluded; $99. Vector 8803 motherboard with active ter- 
mination and three S-100 connectors; $35. Roy Ortiz, 265 
Beech St #21, Hackensack NJ 07601, (201) 488-5405. 



The Sight 
of Music 




Digital Harmony 

by John Whitney 



BYTE BOOKS is pleased to offer DIGITAL HARMONY a 

major new work by John Whitney, a pioneer of the special effects 
technology used in STAR WARS and 2001: A SPACE 

ODYSSEY. His book explores the special union of music and 
computer graphics, and expands the frontier between sight and 
sound, synthesizing the two to create a new art form. Whitney tells 
how it's done, provides a thorough theoretical background, and in- 
cludes listings and programs for those interested in joining in the 
discovery of this new art form. DIGITAL HARMONY lays the 
foundation for audio-visual art made possible by microcomputers. It 
is must reading for all art, music and home computer enthusiasts. 

Illustrated in Color. 



Please remit in U.S. funds or draw on a U.S. Bank 
Please send G 



copies of 



Digital Harmony 



Name 


Title 




Company 


Street City 




State/Province 


Code 


D Bill Visa D Bill Master Charge 
Card No. 


F*n Rate 



Add 75« per book to cover 
postage and handling. 



KM* 



Call TOLL FREE: 800-258-5420 
or Mail To: 



70 Main Street. 
Peterborough. N H 034S8 



FOR SALE OR TRADE: Current model Mlnlterm portable 
computer. BASIC, 6800 programming, resident debugger 
and editor, 32 K programmable memory, built-in 
microcassette (60 K storage), acoustic coupler, and 
serial interface. Also has all the features of a portable 
printing terminal. Disk system available. Other features 
too numerous to list. Will supply information. Sells new 
for $5000; will sell for $2500 or trade for 48 K Apple II 
with two disks and Pascal or similar system. Bob 
Edison, 215 Newton St, Waltham MA 02154, (617) 
891-5618. 

SWAP:KIM-1 microcomputerwith manuals, barely used, 
for a pair of Acoustic Research AR-3 speakers (not AR- 
3a). Will pay shipping both ways. C Lee, 1021 Merritt Dr, 
Tallahassee FL 32301, (904) 878-1983. 

FOR SALE: S-100 compatible, 16-bit 8088 single-board 
computer; all documents included. Never been used. 
Original cost of $400, will sell for$300. Trung Dae Lieu, 
Box 292, 303 Stadium PI, Syracuse NY 13210. 

FOR SALE: Two Pertec disk drives and controller. The 
drives worth $5000 when new; I will take $1500 or best of- 
fer. Both of the drives need some work. Comes complete 
with power supply, multiplexer boards, 8-Inch DOS disk, 
and complete documentation. (MCI— if wanted.) Will 
work on various microprocessors. Heinan Landa, 12109 
Greenleaf Ave, Potomac MD 20854, (301) 279-9356. 



FOR SALE: Computer Mart PME1 32 K memory board, 
which lifts an 8 K PET to a full 40 K. 8 K of this is ad- 
dressable through machine language only. The PME1 
board installs entirely inside the PET. I used it lightly for 
three months. Cost $750; asking $350. Philip Restagno, 
2910 DeWitt PI, Bronx NY 1 0469, (212) 231 -2753. 

FOR SALE: Back issues of BYTE, postpaid. Also, want 
1975 and 1976 issues of BYTE. P Gray, 1505 NW 124th 
Ave, Portland OR 97229, (503)641-2747. 

FOR SALE: Centronics P-1 printer, parallel, with cable; 
$250. SwTPC CT-64 terminal; $250. Hitachi 9-inch 
monitor; $75. SwTPC AC-30 tape controller; $75. All in- 
clude manuals. Send 10% for COD, ppd orders sent ppd. 
Charles Shilling, 2003 Fair Meadow, Arlington TX 76012, 
(817)461-2239. 

FOR TRADE: Want to swap cassette programs for 
TRS-80 Level II. Games, educational, and mathematics. 
No business programs. Send cassette with your ad- 
dress. Bob Trent, POB 298, Hardinsburg KY 40143. 

FOR SALE: TRS-80 disk drive. Less than six hours use. 
Includes cable. $225. K J Morrison, 10513 Si Iverdale Way 
NW, Silverdale WA 98383. 



FOR SALE OR TRADE: Assembler for 8080/85. Runs 
under North Star DOS V5.0. Written in BASIC, creates 
object file in North Star format. Included are source 
creator/editor and file dump programs (also in BASIC). 
Requires one minifloppy drive plus 32 K. Cost: $25; 
manual only: $5. W T Shaw, 13521 Blenheim Rd N, 
Phoenix MD 21131, (301) 667-4800. 



USED COMPUTERS: Send information on microcom- 
puters you or a friend have sold— make, model, con- 
figuration, month sold, price. I'll send a summary of 
other people's prices in return. Bruce Lynch, 2905 Blue 
Robin, Herndon VA 22071. 

FOR SALE: ESCON Universal Interphase RS-232 for 
IBM Selectric II typewriter. B K Parekh, (406)365-3393. 

FOR SALE: Novation Model 4202B modem, 1200 bps, 
originate/auto-answer, direct connect, 2-wire dial-up or 
4-wire; $496. Philip Nunn, 201 Netherfield, Comstock 
Park Ml 49321, (616)361-8681. 

FOR SALE: Heath H-9 video terminal expertly assem- 
bled, in very good condition; $200. Also, YAESU FR-101, 
FL-101 with converter boards, filters, clock, and all 
documentation in English; $900. Mint condition. Mark 
Miller, 9573 Walley Ave, Philadelphia PA 19115, (215) 
698-1905. 



FOR SALE: Apple graphics tablet, cost $795, sell $600. 
Mountain Hardware 388 day clock, cost $199, sell $140. 
Mountain Hardware Romplus with keyboard filter, cost 
$169, sell $125. Above items in like new condition and 
were used less than three hours each. Will be shipped in 
original cartons with all documentation. Earl A Loobey, 
FSI/POB 487, Fairbanks AK 99701. 

FOR SALE: Digital Group microcomputer. Z80 and 6800 
processors, 50 K memory, sixteen parallel ports, front 
panel, 16 by 64 video display, Marantz tape deck, key- 
board, Sanyo monitor, Maxi-BASIC, Super Games, Fig- 
FORTH documentation, plus much more software and 
full hardware documentation. Complete system $2000or 
best offer. Dennis Ruffer,423 Garfield St, Kalamazoo Ml 
49001, (616)381-8747. 

FREE PROGRAMS: As a high school science teacher 
using a 16 K Apple II Plus, I have had difficulty in 
locating programs for class use. Since commercial pro- 
grams are expensive and often not suited for use with 
high school students, I have written several programs in 
Applesoft BASIC for use in my physical science, 
biology, and chemistry classes. If anyone is interested 
in obtaining a copy of one of these programs, please 
send me a SASE and I will send you a complimentary 
copy. William R Ground, J L Mann High School, 61 Isbell 
Ln, Greenville SC 29607. 



FOR SALE: Heath H-11 system, LSI-11 with 40 K bytes 
memory, CRDS double-density floppies, H-10 paper-tape 
reader/punch, serial and parallel interfaces. $6400 value, 
asking $4800. Add $650 for factory-assembled H-19 ter- 
minal. Jeff Goldberg c/o CRDS, 4 Tech Cir, Natick MA 
01760, (617)655-1800. 

FOR SALE: Apple II DOS 3.3 upgrade kit, including read- 
only memories, disks, and manual; $35. Joel Buckley, 
1212 Broadway, Hanover PA 17331. 

FOR SALE: Heathkit ET-3400 and program for same. 
Good condition. Will sell to the best offer. Ralph 
Swearingen, 7213 Loras Ln, Wonder Lake IL 60097, (815) 
653-7821. 



BOMB 

BYTE's On g oing Monitor Box 



Article # 

1 



Page 
20 

36 



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Article 

Structured Programming and Structured 

Flowcharts 

Build the Disk-80: Memory Expansion and 

Floppy-Disk Control 

Three-Dimensional Computer Graphics, Part 1 

The Micro Matrix Photopoint Light Pen 

What's Inside Radio Shack's Color Computer? 

What Is Good Documentation? 

A Beginner's Guide to Spectral Analysis, Part 2 

A Simple Approach to Data Smoothing 

The New Literacy: Programming Languages as 

Languages 

Computer Music: A Design Tutorial 



Author(s) 

Williams 

Ciarcia 

Crow 

Gray 

Ahrens, Browne, 

and Scales 

Howard 

Zimmermann 

Ruckdeschel and 

Krinsky 

Handel 
Orlofsky 



FOR SALE: North Star disk controller board. Single- 
density, excellent condition. Selling due to an upgrade 
on my present system. Lots of software, including North 
Star DOS and BASIC, CP/M, assemblers, games, and 
lots more. Will run Pascal, FORTRAN, ALGOL, C, and 
many others. Asking $250. Mark Sauerwald, 7872 
Caminito Huerta, San Diego CA 92122, (714) 453-1206. 

FOR SALE: North Star controller and software (fifty 
diskettes); $350. Eprom board, holds sixteen 2708s; $60. 
Rack-mountable Integrand cabinet; $120. Vector eleven- 
slots motherboard with connectors; $50. TDL processor; 
$100. TDL monitor board; $150. TDL cassette software 
(Assembler, 12 K BASIC, Text Editor, text output pro- 
cessor); $200. Mohammad Mandurah, POB 4272, Stan- 
ford CA 94305, (415) 328-3959. 



WANTED: Apple II with at least 32 K memory and disk 
drive. Prefer dual-disk drive. All replies will be answered. 
Send complete name, address, and phone. Scott 
Emmons, 1225 Nord Ave #166, Chico CA 95926, (916) 
893-5311. 

WANTED: Data for Processor Technology GPM-1 board 
(9 K read-only memory, 1 K programmable memory). 
Also require for S-100 bus, a cassette UO prom program- 
mer and disk controller, any make. Consider anything 
from bare board with data, to working. Please state price 
required. Larry Dass, 4, Nancevallon, Brea, Camborne, 
Cornwall, England, phone 0209 714475. 

FOR SALE: Heathkit H-14 printer ready to connect to 
Heathkit, Zenith, or North Star Horizon computer. Fea- 
tures include RS-232 interface, uppercase/lowercase, up 
to 132 columns wide, adjustable tractor feed to 9.5 
inches wide, maximum 165 cps print speed. Unit is in 
perfect condition. Full documentation and original car- 
ton included; $575. Brian Stotesbery, 2544 Second Ave 
S, Minneapolis MN 55404, (612) 872-0804. 

SWAP: TRS-80 machine language and BASIC programs, 
Level II and Disk BASIC. Send your list of programs to 
trade, and I'll send mine. Steven Kliewe, 9005 Vickery 
Rd, Tacoma WA 98446. 

FOR SALE: Hewlett-Packard 608D VHF signal gener- 
ator. Like new, $350. Also, eight computer power sup- 
plies, four chart recorders, pulse generator, square-wave 
generator. W L Pierce, 703 23rd St S, Arlington VA 22202, 
(703) 525-3223. 

WANTED: Processor board for SwTPC 6800 computer. 
Garth Fisher, Department of Industrial Technology, 
Walla Walla College, College Place WA 99324. 



Opinions and Games 
Win December BOMB 

Computer games of all 
kinds caught our readers' 
fancy. Jerry Pournelle's 
popular User's Column 
won first place in the 
December 1980 BOMB; this 
time, Jerry wrote about 
"BASIC, Computer Lan- 
guages, and Computer 
Adventures." P David 
Lebling's article "Zork and 
the Future of Computer- 
ized Fantasy Simulations" 
captured second. The next 
three places went to 
"Multimachine Games" 
(Ken Wasserman and Tim 
Stryker), "On the Road to 
Adventure" (Bob Liddil), 
and "Pirate's Adventure" 
(Scott Adams). 



March 1981 © BYTE Publications Inc 383 



Reader Service 



Inquiry No. 



Page No. 



63 

91 

320 

141 
256 
272 

36 

82 
275 
307 

32 
263 
123 
148 

48 
319 

12 
192 
147 



244 
116 
131 
268 

311 
188 
199 
150 

115 
298 
310 
128 



16 
321 
202 
248 
296 
162 
117 
168 

17 
326 
223 

39 
217 
206 
100 

120 
238 

181 

299 

292 

43 

243 

291 
59 

227 
38 

318 
59 
42 

221 
64 

323 

1 

44 

312 

278 



35 

18 
251 

57 
118 

97 
157 
130 

61 
166 
156 

72 

19 

137 
231 

250 
138 

210 
329 
176 



Aardvark Software Inc 117 

Aardvark Software Inc 162 

AB Computers 361 

Abbott, Robert 354 

ABM Products 222 

Ackerman Digital 339 

ACOM Electronics 277 

Action Computer 63 

Adaptive Data & Energy Sys 146 

Advanced Comp Prod 348, 349 

ALL Electronics 356 

Alpha Byte Storage 59 

Alpha Omega Comp Sys 275 

Am Micro Prod Inc 198 

American Square Comp 231 

Anadex 89 

Ancrona 360 

Anderson Jacobson 16 

Anderson Jacobson 279 

Andromeda Systems Inc 230 

Apple Computer 13 

Applied Analytics 318 

Artec Electronics 328 

ASAP 187 

Ashton-Tate 211 

Atlantis Computerized Serv 277 

ATV Research 354 

autocontrol Inc 356 

Automated Equip Inc 274 

Automated Equip Inc 283 

BASF Systems 233 

John Bell Engineering 347 

Beta Comp Devices 186 

Bit Bucket, The 354 

Blacksburg Grp Inc, The 356 

Bower-Stewart & Assoc 204 

BYTE Books 51, 201, 382 

C & A Associates 350 

Calif Comp Systems 21 

Calif Digital 374, 375 

Cambridge Develop Labs 285 

Cawthon Scientific Grp 330 

CBAS 354 

Central Data 251 

Cexec Inc 190 

Chrislin Industries 255 

C. ITOH Electronics Inc 23 

Clev Con Comp & Compnts 365 

Cognitive Systems 297 

CompuMart 68, 69 

Computer Age Inc 293 

Computer Case Co 287 

Computer Disc of Am 174 

Computer Factory, The 115 

Computer Furn & Access 194 

Computer Marketing Corp 320 

Computer Plus 268 

Comp Prof Book Club 208, 209 

Computer Shopper 354 

Computer Society 352 

Computer Specialties 76, 77 

Computer Tech Inc 326 

Computer Warehouse 85 

Computers Plus Inc 352 

Computers R Us 108, 109 

Computex 302 

Compuview Products Inc 67 

Concord Comp Components 360 

Consumer Computers 108, 109 

Corvus Systems 73 

Cover Craft 295 

CPI 119 

CPU Shop, The 363 

Cromemco 1, 2 

Crystal Computer 79 

Custom Business Comp 356 

Custom Peripherals 350 

Cybernetics Inc 98 

Data Discount Center 327 

Datamax 62 

Data Safe Products 24 

Datasouth Computer Corp 333 

Decision Master 105 

Delta Products 191 

Denver Software Co, The 171 

DG Electronics 245 

Diablo (Div of Xerox) 207 

Digiac Corp 112 

Digital Graphic Systems 254 

Digital Marketing 243 

Digital Pathways 133 

Digital Research 25 

Digital Research Computers 351 

DIP Inc 217 

Discount Sftw Grp, The 312 

Disk Supply Co 248 

DMA 332 

Dual System Control Corp 218 

DWP277 

Dymarc Industries 289 

Dynabyte C III 

Dynacomp Inc 263 



Inquiry No. 



Page No. 



47 Ecosoft 88 

104 Edmund Scientific 178 

" Electravalue Industrial 356 

132 Electronic Control Tech 212 

279 Electronic Equip Unltd 350 

191 Electronic Specialists 279 

213 Ellis Computing 291 

94 Epson America Inc 165 

69 Escon 128 

20 ESP Comp Resources Inc 26 

241 Essex Publishing Co 324 

80 Exatron Inc 143 

240 Faircom 322 

198 Farnsworth Comp Center 283 

260 Feith Software 275 

51 John Fluke Mfg Co 97 

321 Fordham 362 

222 Frederick Comp Prod 297 

* Game-A-Tron 352 

79 General DataComm Ind 139 

78 GNT Automatic Inc 138 

140 Godbout Electronics 220, 221 

10 Mark Gordon Computers 14 

122 H & EComputronics 196, 197 

165 H & EComputronics 253 

304 Hanley Engineering 355 

288 Harris Corp 352 

184 Hayden Book Co Inc 271 

34 Hayes Microcomp Prod Inc 61 

207 Hayes Microcomp Prod Inc 287 

121 Hazeltine Corp 195 

13 Heath Company 17 
74 Hewlett-Packard 135 

33 High Technology Inc 60 

316 Hobby world Electronics 358 

40 Houston Instruments 71 

41 Houston Instruments 71 
284 IDM 350 

* Illinois Comp Mart Inc 275 
68 IMS International 127 

14 Info Unltd Software 18 
177 Innovative Sftw Appl 265 

66 Integral Data Sys 121 

169 Integrand 256 

29 Intel 53 

201 Intelligent Control Sys 285 

151 International Microsystems 235 

56 Intertec Data Systems 103 

204 Ipex Int'l Inc 286 

5 Ithaca Intersystems 8 

6 Ithaca Intersystems 9 
281 J & S Computers 350 

330 Jade Computer Prod372, 373 

328 Jameco Electronics 368, 369 

233 JDR MICRODEVICES314 

322 JR Inventory Control 362 
179 KeeSoft 266 

" Konan Corp 145 

164 Lax Computer Products 252 

235 Lax Computer Products 316 

* Leading Edge Products 91 

76 Lifeboat 125 
145 Lifeboat 228 
174 Lifeboat 260 

* Lifelines 131 
306 Lin mar 356 

149 Livermore Data Sys Inc 232 

203 LNW Research 285 

71 Lobo Drives Int'l 136 

77 Lobo Drives Int'l 137 
46 Lomas Data Prod 84 

163 McClintock Corp 252 

277 Macrotronics Inc 350 

187 Mann, Charles & Assoc 274 

194 Marymac Industries Inc 281 
200 Mattel Inc 284 

183 MBC Systems Inc 270 

* Meas Sys & Controls 29, 129 
255 Meta Technologies Corp 336 
212 MFJ Enterprises Inc 290 

85 Micro Age Computer Store 151 

195 Micro Architect 281 

215 Micro Business World 291 

* Micro Comp Discount Co 304 
245 Micro Comp Store, The 329 

96 Micro Data Base Sys 169 

155 Micro Management Sys 241 

26 Micro Mikes 49 



Inquiry No. 



Page No. 



182 

265 

237 

67 

107 

106 

90 

249 

242 

173 

175 

257 

161 

324 

53 

196 

324 

325 

62 

15 

89 

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220 

70 

183 
186 
136 
95 



52 
330 

60 
216 
230 
126 
139 
228 

197 
83 
84 

171 

285 
264 
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315 
3 
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25 
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167 
178 
93 
73 
322 
323 
253 
270 
239 
267 
246 
290 
283 
229 
329 
142 
261 
105 
154 
81 
258 



Micro Pro International 269 

Micro Products Unltd 275 

Micro Works, The 319 

MicroAce 123 

MicroByte 183 

Microcomp Tech Inc 180, 181 

MicroDaSys 161 

Microhouse 331 

Micromail 325 

MICROMATE ELECT 260 

MicropolisCorp 261 

MicroTech Exports 275 

Microware Sys Corp 250 

Mikos 364 

Miller Microcomputer Serv 100 

Mini Computer Suppliers 281 

Mini Micro Mart 380 

Mini Micro Mart 381 

Morrow Designs 113 

Mountain Computer Inc 19 

mpi 159 

MT MicroSYSTEMS83 

MTI Inc 272 

Mt. View Press 295 

MUSYS 130 

Multi Business Comp Sys 270 

NCC '81 273 

NCE Supply Corp 216 

NEECO 167 

Netronics 303, 305 

Noesis Computing Co 317 

NRI Schools 193 

Ohio Data Products Corp 82 

Ohio Scientific Instr C IV 

OK Machine & Tool 111 

OlympicSalesCo 293 

Omega Micro Computers 310 

Omega Research 202 

Omega Sales Co 219 

Omikron 306 

onComputing 225 

Optimal Technology 283 

Orange Micro 147 

Osborne/McGraw-Hill 148, 149 

OSM Computer 258 

Owens Associates 28, 308, 309 

P & S Electronics 352 

Pace Age Tech 275 

Pacific Exchanges 330 

Pacific Exchanges 352 

Page Digital 353 

Pan American Elec 358 

PCD Systems Inc 6 

PC Newsletter, The 354 

Pelican Programs 356 

Percom Data 15 

Percom Data 35 

Percom Data 185 

Percom Data 185 

Percom Data 185 

Percom Data 185 

Percom Data 185 

Percom Data 185 

Personal Micro Computers 213 

Personal Software 31 

Phase One Systems 249 

Pickles & Trout 254 

pk systems inc 266 

Potomac Micro Magic 164 

Power One Inc 134 

Priority One 376, 377 

Priority One 378, 379 

Professional Business Sftw 334 

Professional Comp Store 277 

Prometheus Products Inc 321 

Purchasing Agent, The 277 

Purchasing Agent, The 330 

Purchasing Agent, The 352 

Q Systems 350 

QT Computer Systems 310 

QT Computer Systems 370, 371 

Qantex 223 

Quality Computer Parts 275 

Quality Software 179 

Quasar Data Products 239 

Quest 345 

Quintrex Inc 275 

R & B Computer Systems 12 



Inquiry No. 



Page No. 



211 
209 

45 

119 
108 
252 
159 
21 
219 
103 
271 
190 
2 
226 

180 



295 
259 
234 

54 

88 
134 
102 
232 
153 
205 
144 
328 
129 
7 

92 
208 
218 

28 
325 



172 
225 

30 
287 
152 
276 
4 
254 

50 
189 
301 
309 
170 
266 
143 



24 
327 
146 
269 

87 

31 
297 
135 
158 

86 
317 

23 
75 
125 
193 
224 
308 
65 
286 
280 
314 
101 



Racet Computes 289 

Radgo Sales Co 289 

Radio Shack 81 

Rainbow Computing 258 

RCA Solid State 192 

REI Sales Co 184 

RNB Enterprises 334 

Rochester Data 299 

S & M Systems 30 

S-100 Inc 295 

Howard W SamsCo 177 

SC Digital 277 

Scientific Eng Labs 279 

Scion Corp 5 

SciTronics Inc 299 

Scottsdale Systems 144 

Seattle Computer Prod 267 

Shugart 7 

Silverman Assoc 291 

Sinclair Research 87 

Skyles Electr Works 354 

Sluder 275 

Small Business Appl 315 

Snapp Inc 101 

Softech Microsystems 157 

Softech Microsystems 214 

Software Toolworks, The 176 

Solid State Sales 313 

Sorcim 238 

Sorrento Valley Assoc 286 

Southern Semiconductors 227 

Southwest Tech Prod Corp Cll 

Spectrum Software 205 

SSM 11 

Standard & Poors 163 

Street Electronics 287 

SubLOGIC 293 

Summagraphics 52 

Sunny Int'l 364 

SuperSoft 10, 92, 93, 102, 311 

Super Star Int'l Corp 155 

Sybex 107 

Synchro Sound 75, 292 

Systems Plus 259 

Tarbell Electronics 299 

Tech Sys Consultants (TSC) 55 

Technical Innovations 352 

TecMar Inc 237 

Terminal Data Sys 350 

Texas Instruments 27 

3G Company 335 

3M Company 95 

Thunderware 276 

Mitchell E Timin Eng Co 354 

TPA 356 

TNW Corp 256 

Toolsmith, The 277 

TransNET 226 

TSE/Hardside 172 

TSE/Hardside 173 

United Software of Am 140, 141 

Urban Software Corp 34 

US Micro Sales 366, 367 

US Robotics 229 

Vamp 277 

VAN DATA 104 

Vector Graphics 57 

Vertical Data 354 

VictorData 215 

Videx 247 

Vista Computer Co 153 

Vista Computer Co 359 

Westico Inc 188, 189 

White Computer Sys 33 

Whitesmith's Ltd 99 

CJ Wigglesworth Software 200 

Wild Hare Comp Sys 280 

John Wiley & Sons 297 

Wintek Corp 356 

Winterhalter & Assoc 120 

Winchendon Group, The 352 

Worldwide Electronics 350 

WW Component Supply Inc 357 

Xerox 175 

XPS Inc 277 

Zobex 257 



To get further information on the products advertised in BYTE, fill out the reader service card with 
your name and address. Then circle the appropriate numbers for the advertisers you select from the 
list. Add a 1 5<ent stamp to the card, then drop it in the mail. Not only do you gain information, but 
our advertisers are encouraged to use the marketplace provided by BYTE. This helps us bring you a big- 
ger BYTE. The index is provided as an additional service by the publisher, who assumes no liability for 
errors or omissions. 'Correspond directly wjth company. 



384 



March 1981 © BYTE Publications Inc 



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City 
341 361 
















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READER SERVICE 



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PLACE 
FIRST 

CLASS 
POSTAGE 

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READER SERVICE 
PO BOX 2114 GPO 
NEW YORK NY 10116 
USA 



PLACE 
FIRST 
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HERE 



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READER SERVICE 
PO BOX 21 14 GPO 
NEW YORK NY 10116 
USA 




No one has a broader line of micro-based business 
computers than Dynabyte. Memory to 400KB. 
Mini-floppies, eight inch floppies, Winchesters and 
cartridge module hard disks; capacity from 630KB 
to 96MB. Satisfy all your clients' needs with Dynabyte. 
Start small, expand the system as computing 
needs grow, with modular add-ons from Dynabyte. 
With complete software and hardware compatibility 
across the entire line.- 

But expandable memory and the broad range 
of storage capacities are only part of the DYNABYTE 
DIFFERENCE. How about multiple terminals? 
Foreground/background? With Dynabyte you can 
have up to eight partitions, driven from up to 
eight terminals. And each terminal can have its own 
spooler; or all can share a system spooler. How 
about up to sixteen printers, and they don't require 
any partition space either. The DYNABYTE 
DIFFERENCE. 

Our operating systems are the standard CP/M™ for 
single user sites and Dynabyte-enhanced MP/M™ 
for multiple user sites. As a seller of business systems 
you already have a whole library of applications 



software. So to help protect your software investment 
we offer COBOL and BASIC and FORTRAN and 
PASCAL and PL/1. ' \ 

Or you can use BUSINESS MANAGER!" Dyna- 
byte's fully integrated accounting system. Menu 
driven, well documented, easy to install; it fits the 
needs of most wholesalers and distributors as is. 

With no direct sales outlets, we are totally com- 
mitted to our resellers. We don't compete with 
them. We support them with full service others only 
promise. Another DYNABYTE DIFFERENCE. 

If you're tired of only promises from your computer 
suppliers; if you're losing sales because of price 
or limited storage capacity, or lack of modular expan- 
sion capability, call Dynabyte. Ask about the 
DYNABYTE DIFFERENCE. Ask about our advertis- 
ing and lead referral programs. Ask about our 
warranty program.' You'll be surprised. 

Call our toll-free hotline: (800) 227-8300. ' 
In California (415) 329-8021. Dynabyte, 
115 Independence Drive, Menlo Park, California 
94025. Call or write today for the DYNABYTE . 
DIFFERENCE. ,' 



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Ohio Scientific: 
The leader in 
Winchester 
based micro- 
computers. 



Ohio Scientific produced the first large capacity 
fixed media hard disk (Winchester) based 
microcomputers in 1977. Since then we have 
shipped more of these systems than the rest of 
the microcomputer industry combined. 

Family Features 

All standard C3 features including: 

• 3-processor CPU with 6502, Z80 and 6800 

• .7MIPS6502A 
•48K static RAM 

• Dual 8" floppies 

• Free standing rack for direct expansion capabilities 

• 17-slot OSI 48 line BUS architecture for large system 
expansion 

• Directly accepts up to 8 users with currently available 
memory boards, more with higher density boards in the 
future 

• Directly expandable for use as Network data bases 

• Slide-mounted subassemblies, removable side panels and 
locking rear door for easy expansions and service. 

C3A 

The floppy only rack based C3 for users who anticipate 
expansion to hard disk, multi-user and/or networking in the 
future. Under $7000. 

C3B 

The world's most powerful microcomputer (when GT 
equipped). Features the highly advanced and extensively 
field proven OKIDATA 3306 Winchester disk. 

Features 

• System boots from floppies or hard disk on power up 

• 74 megabytes end user workspace under OS-65U, 80 
megabytes unformatted 

• Ultra-high performance disk 
74 millisec worst case access 
38 millisec average 

10 millisec access on cylinder (215K user workspace) 
8 megabits per second transfer rate 

• Simple on/off disk operation with elaborate internal 
protection from improper temperature, line voltage and 
controller failures 

• Features spindle brake and designated head landing areas 
for much longer operational life than the newer low-cost 
Winchesters 

• Highly advanced OS-65U operating system: 
Multiple level pass word security 
Multiple operating systems on disk 

Ultra-high speed "FIND" command for high speed string 
searches (Associative Access) 

Upward compatible with multi-user and network systems 
with full file, peripheral and communications arbitration 
between users 







• Available factory configured for up to 8 users and network 
data base operation 

• Expandable to CP/M operation by adding 4K (CM-2 
memory) Under $14,000 

C3C 

A medium performance Winchester disk based system 

which provides the ideal cost/performance ratio in typical 

small business applications. The C3-C uses the Shugart 

SA4008 29 megabyte Winchester disk. 

Performance specifications, hardware configuration and 

software is identical to the C3-B with the following 

exceptions: 

• 23 megabytes of end user workspace under OS-65U 

• 29 megabytes unformatted capacity 

• Medium performance Winchester 
240 millisec worst case access 
87 millisec average access 

10 millisec access on cylinder (110K user workspace) 

• Simple on/off disk operation Under $11,000 

Ohio Scientific has a new OEM program that is easy to 
start with, and provides generous discounts for quantity 
purchases. 



For literature and the name of your local 
dealer, CALL 1-800-321-6850 TOLL FREE. 



1333 SOUTH CHILLICOTHE ROAD 
AURORA, OH 44202 • [21 6] 831-5600 



Circle 355 on inquiry card.