A History of the Personal Computer

Chapter 7 Other Software in the 1970' s

7.1... Operating Systems

Prior to the introduction of disk drives, software
was developed to facilitate the loading or "booting" at
startup. An example of this is the Motorola mini
operating system for automatic loading called "Mikbug."

IBM developed the floppy disk drive in 1971 and
the hard disk drive in 1973. Shugart Associates released
their 8-inch floppy disk drive in 1973. With the
availability of disk drives, many manufacturers released
their own operating systems. However, the dominant
system was CP/M from Digital Research.

Digital Research

Gary A. Kildall received a Ph.D., in computer
science from the University of Washington, founded
Microcomputer Applications Associates (MAA) and became a
professor at the Naval Postgraduate School in California
in 1972 . MAA was the predecessor to the founding of
Intergalactic Digital Research by Kildall and his wife
Dorothy McEwen, in 197 6. The company name changed to
Digital Research, Inc., in 1979.

In 1972, Kildall purchased an Intel 4004
microprocessor and developed emulator and assembler
programs for it on an IBM System/360 computer at the
naval school. While continuing to teach at the naval
school, Kildall' s MAA provided consulting services to
Intel. This resulted in the development of an emulator
for the Intel 8008 microprocessor to run on Intel's DEC
PDP-10 time sharing system. Kildall also developed a new
systems programming language called PL/M (Programming
Language for Microcomputers) that was released in 1973.
Around this time MAA made a proposal to Intel to develop
a disk operating system for the 8000 series
microprocessors .

Intel rejected the proposed operating system.
However, Kildall continued working on the program and
named the new operating system Control Program for

7/1

7/2 Part II 1970's-TheAltair/Appleera

Microprocessors (CP/M) . Initially, it would form the
basis for the resident programming of PL/M for 8080-
based computers with 16K bytes of main memory and
Shugart' s new disk drive. This reguired the design of a
disk controller and the assistance of a friend John
Torode to get it working. The operating system had
features such as commands and file naming conventions
similar to those used on the DEC PDP-10 system. CP/M
included a single-user file system, and used recoverable
directory information to determine storage allocation,
rather than a traditional linked-list organization. MAA
completed CP/M in 1974 and retailed the program for $70.
It soon became successful as the dominant 8-bit
operating system for microcomputers using the Intel 8000
and Zilog Z-80 series of microprocessors.

In the mid 1970' s after several implementations on
computer systems with different hardware interfaces, the
CP/M software was restructured. CP/M was decomposed into
two parts : an invariant part that was written in PL/M
and a small variant part was written in assembly
language. This small variant module for interfacing to
various hardware platforms became known as the Basic
Input/Output System (BIOS) . Computer suppliers and end
users could now create their own physical input/output
drivers for CP/M.

In late 1979, Digital released an enhanced Version
2.0 of CP/M that sold for $150. The program had been
completely redesigned to support floppy disk drives and
high-capacity Winchester disk drives. All disk
parameters were moved from the invariant part to a table
driven concept in the variant module.

Kildall also developed other programs for use with
CP/M. Some of those were an assembly language, text
editor and various utilities. Digital Research also
developed a multi-terminal operating system called MP/M
(Multi-Programming Monitor) . It provided real-time
processing with multiprogramming and multi-terminal
features . The program was compatible with CP/M and sold
for $300.

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Apple Computer

DOS (Disk Operating System) Version 3.1 was the
operating system released with the Apple Disk II drive
in June 1978. The disk had 35 tracks with thirteen 256
byte sectors on each track for a total storage capacity
of 113K bytes . Earlier versions were not completely
functional and therefore not released. Apple released a
more stable version, DOS 3.2 in mid-1979.

DOS 3.3 evolved from the release of Apple Pascal
programming language in 1979. This release changed the
35 track disk format to sixteen 256 byte sectors with a
total disk storage capacity of 143K bytes. Apple
developed a utility called Boot 13 to boot the 13-
sector-per-track disks.

Other Operating Systems

Bill Levy developed PT-DOS for Process Technology
around 1976/77. Radio Shack released TRSDOS for the TRS-
80 Mini Disk System in the late 1970' s. It was not
compatible with CP/M.

7.2 ... Programming Languages

BASIC

A history of the BASIC programming language is
provided by Thomas E. Kurtz in History of Programming
Languages 36], pp. 515-549 and by John G. Kemeny and
Thomas E. Kurtz in Back to BASIC [115], pp. 1-23. A time
chart depicting the evolution of BASIC is provided by
Russ Lockwood in a periodical article entitled The
Genealogy of BASIC [397] . Bill Gates of Microsoft has
provided an interesting history of BASIC in a periodical
article entitled The 25th Birthday of BASIC [394] .
Reference Section 2.2 for the initial development of
BASIC and Chapter 6 for the Microsoft development of
BASIC interpreters for the Altair and other
microcomputers .

Dartmouth College made a significant upgrade to
their BASIC compiler with the release of version six in
September 1971. In 1974, the American National Standards
Institute (ANSI) formed a committee to develop standards

7/4 Part II 1970's-TheAltair/Appleera

for the BASIC programming language. This resulted in the
release of a standard for Minimal BASIC in 1976 and its
official approval in 1978. Work then proceeded on a
standard for a "full" BASIC. Dartmouth released version
seven of its BASIC compiler in 1979.

Various hardware manufacturers such as Apple
Computer, Digital Group, IBM, PolyMorphic Systems and
Processor Technology developed BASIC languages for their
own computers. However, Tiny BASIC and the following are
some of the more significant releases.

Dennis Allison who was a member of the computer
science faculty at Stanford University developed Tiny
BASIC. The initial version of Tiny BASIC developed by
Allison was a simplified BASIC oriented to younger
programmers. The program reguired less than 4K bytes of
memory. The PCC Newsletter and the initial issue of Dr.
Dobb ' s Journal of Computer Calisthenics and Orthodontia
in January 1976 provided a detailed description of an
extended version of the software. Other programmers such
as Tom Pittman and Li-Chen Wang developed and
distributed variations of the program for different
computers [393] .

Robert Uiterwyk developed SwTPC BASIC for the
SwTPC 68 00 microcomputer in 1975. SwTPC provided low-
cost BASIC programs at $1 per kilobyte. A 4K BASIC
interpreter cost $4, 8K $8 and 12K $12.

Gordon E. Eubanks developed E-BASIC while working
on a masters degree in computer science at the Naval
Postgraduate School in California. Eubanks was
associated with Gary Kildall and E-BASIC became widely
used with the CP/M operating system. Gordon Eubanks,
associates Alan Cooper and Keith Parsons developed C-
BASIC and founded Compiler Systems, Inc., to market the
software. Eubanks subseguently sold the Compiler Systems
company to Digital Research and became one of Digital's
vice presidents. C-BASIC was a pseudocompiled language
developed in 1977 for IMSAI and was included with the
CP/M operating system in 1979.

Radio Shack released Level-I BASIC with the TRS-80
Model I computer in August 1977. Steven Leininger
developed the interpreter by adapting it from Tiny
BASIC. Radio Shack released Level II BASIC developed by

Other Software m the 1 970 ' s 7/5

Microsoft for business and advance applications in 1978
and an enhanced Level III version in 1979.

c

Dennis M. Ritchie created the C language at AT&T's
Bell Laboratories in 1972 . The language was designed to
be portable, fast and compact. The UNIX operating system
was later reprogrammed using the C language.

FORTRAN

Reference Section 1.4 for the initial development
of FORTRAN. Microsoft developed a FORTRAN-80 compiler
for the Intel 8080 microprocessor. They announced the
program in April 1977 and sold it for $500.

Pascal

Niklaus Wirth developed the Pascal language at the
ETH (Eidgenossische Technische Hochschule) in Zurich
Switzerland. Pascal evolved from the ALGOL 60
programming language. The main development principals
were to provide a language suitable for structured
programming and teaching. Wirth drafted a preliminary
version in 1968 and the first compiler became
operational in 1970.

Kenneth L. Bowles directed the development of UCSD
Pascal at the University of California in San Diego.
UCSD released the program to users in August 1977 as a
complete interactive system for microcomputers and
minicomputers. It was initially released for Digital
Equipment Corporation (DEC) LSI-11 or other PDP-11
processors, 8080 and Z80 microprocessors. The software
system cost $200. Bill Atkinson of Apple Computer,
adapted the UCSD Pascal for the Apple II computer in
1979.

7/6 Part II 1970's-TheAltair/Appleera

Other Languages

Gary Kildall of Digital Research, developed PL/M
(Programming Language for Microcomputers) for Intel in
1972 . PL/M was a system programming language that
developed to provide a simpler alternative to assembly
language for the Intel 8000 series of 8-bit
microprocessors. It was a refinement of the Stanford
University XPL compiler writing language with elements
from Burroughs Corporation's ALGOL and IBM's PL/I. Intel
marketed the program for the 8000 series of
microprocessors in 1973.

BCPL and MESA were systems programming languages
developed at the Xerox PARC (Palo Alto Research Center)
for the Alto personal computer in the early 1970 ' s.

Alan Kay developed Smalltalk at the Learning
Research Group (LRG) of Xerox PARC in 1972. It was the
software part of the Dynabook concept and was created
for the Alto computer. It is one of the first object-
oriented languages and used interactive graphical
concepts to create a user friendly environment.

7.3 ... Word Processors

Bravo was a word processing program developed by
Butler Lampson and Charles Simonyi for the Xerox Alto
personal computer in the early 1970' s. It was one of the
earliest word processors to feature What-You-See-Is-
What-You-Get (WYSIWYG) text display on the terminal
screen. Between 1976 and 1978 improvements were
incorporated by Simonyi in a new version of the word
processor called BravoX. During this time Tim Mott and
Larry Tesler developed a text editor called Gypsy that
included a new cut-and-paste feature.

The Electric Pencil evolved from a public domain
software package called Software Package One (SP-1) . The
package was distributed by the Southern California
Computer Society (SCCS) in the fall of 1975. Michael
Shrayer improved the editor portion of the package and
called it Extended Software Package 1 (ESP-1) . A further
upgrade of ESP-1 was called Executer. ESP-1 and Executer
were the basis for the first word processor for a

Other Software m the 1 970 ' s 7/7

microcomputer. Shrayer named it "The Electric Pencil"
and it became available in December 1976. The first
version was written for the MITS Altair microcomputer.
Shrayer founded the Michael Shrayer Software company and
other versions of the program were developed for various
microcomputers. An improved version, The Electric Pencil
II was announced in early 1978 .

Seymour Rubinstein was the director of marketing
for IMSAI when he left to start his own company,
MicroPro International Corporation in late 1978 . He
hired Bob Barnaby, a programmer who had also worked at
IMSAI and created a program called NED (New Editor) .
Barnaby extended this program into a full-scale word
processor for microcomputers. Barnaby developed two
programs, a video text editor named Word-Master and a
sort /merge program named Super-Sort. MicroPro released
Word-Master at a price of $150 in August 1978 and then
an improved version named Word-Star at a price of $495
in June 1979. Word-Star was a success and became a
dominant word processor used on early CP/M
microcomputers .

Apple Writer was created for the Apple II computer
by Paul Lutus , at a mountain cabin in the wilderness of
Oregon in 1978. Lutus sold the program to Apple Computer
for a flat fee of $7,500. Apple Computer released the
program that sold for $75 in 1979. It featured automatic
search and replacement of words or phrases,
justification of text and uppercase and lowercase type.

John Draper developed EasyWriter for the Apple II
computer in 1978 . Shortly after, Draper met Bill Baker
of Information Unlimited Software (IUS) at the third
West Coast Computer Faire in the spring of 1979. This
meeting resulted in an agreement being reached for IUS
to market the program.

Magic Wand was introduced as an easy-to-use word
processor in late 1979 by Small Business Applications,
Inc .

7/8 Part II 1970's-TheAltair/Appleera
7.4 ... Spreadsheets

Daniel S . Bricklin conceived the concept for a
spreadsheet during his studies for an MBA at the Harvard
Business School in the spring of 1978 . Bricklin already
had a degree in electrical and computer science from
MIT. He had also been a software engineer at Digital
Eguipment Corporation (DEC) . The impetus for this
concept was the desire to find a way of utilizing a
computer to facilitate the financial analysis of varied
business situations . A prototype of the program was
written in BASIC and called Calculedger, a combination
of calculator and ledger.

It was at MIT that Bricklin had become friends
with Robert Frankston who would co-develop the software
for the spreadsheet program. Frankston had done some
programming for Daniel Fylstra of Personal Software, who
loaned Bricklin and Frankston an Apple II computer to
develop the software.

Bricklin and Frankston formed their own company
called Software Arts, Inc., in January 1979 to complete
the development of the spreadsheet software. The program
was now called VisiCalc, that is an acronym for Visible
Calculator. Bricklin developed many of the concepts,
data structures, documentation and specifications.
Frankston did most of the program coding using assembler
language and macros. Assembler was used to improve the
speed and to allow the program to run on a 2 4K byte
Apple II computer, 32K bytes with a disk. The limited
memory restricted the spreadsheet to 63 columns by 254
rows and reduced the number of features incorporated.
Recalculation was limited to across rows or down
columns, column widths could be varied, but had to be
the same and text could not span columns .

Fylstra offered to sell the program to Apple
Computer in January 1979 for $1 million. However Steven
Jobs and Mike Markkula rejected the offer. Bill Gates of
Microsoft is also reported to have rejected an offer to
purchase the program. However, subseguently Arthur Rock
and Venrock Associates assisted in financing Personal
Software and the new program.

Other Software m the 1 970 ' s 7/9

Software Arts signed an agreement with Fylstra of
Personal Software, Inc., to market VisiCalc in April
1979. VisiCalc was introduced at the West Coast Computer
Faire in May, demonstrated at the National Computer
Conference in June, advertised in the September issue of
Byte (page 51) and released in October for the Apple II
computer. VisiCalc was priced at $99.50 then guickly
increased to $150 after sales increased dramatically.
One limitation was that it could not run on the CP/M
operating system, however it was an instant success.
The term "killer application" has been credited to the
success of VisiCalc. It also became a significant factor
in helping to sell Apple II computers.

7.5 ... Databases

Lyall Morill developed a simple database program
for microcomputers called WHATSIT? in 1977. WHATSIT? is
an acronym for "Wow! How' d All That Stuff get In There?"
Morill improved WHATSIT? and Information Unlimited
Software (IUS) introduced the program at the second West
Coast Computer Faire in the spring of 1978 . Bill Baker
had previously founded IUS while attending college.

C. Wayne Ratliff was an engineer who adapted a
NASA Jet Propulsion Laboratory mainframe database to his
IMSAI 8 08 microcomputer in his spare time. On
completion of the software in August 1979, he named it
Vulcan. The software was marketed by Software
Consultation Design and Production (SCDP) company and
advertised in the Byte magazine at a price of $490
without success. The software was subseguently marketed
by Ashton-Tate who changed the name to dBASE II in 1981.

Other early database programs were Condor, FMS 80
and Selector.

7/10 Part II 1970's-TheAltair/Appleera
7.6 ... Miscellaneous

Games

Various games had been developed for use on larger
computers in the 1950' s and 1960's as described in
Sections 1.4 and 2.6. Then in the early 1970's video
games that used dedicated processors were introduced and
became very popular. Most of these video games used high
resolution graphics and sound effects that would
subseguently be implemented on more powerful
microcomputers .

Nolan K. Bushnell developed the first commercial
video game called Computer Space in 1970. It evolved
from his interest in games and his previous exposure to
the Space Wars game at the University of Utah. Bushnell
subseguently founded Atari Corporation (see Section
4.6) . This led to Stephen Wozniak developing an Apple
Computer version of a game called Breakout that he and
Steven Jobs had worked on for Atari. Also released at
Apple Computer was a program called Lunar Lander
developed by Bob Bishop. Bill Budge also developed a
number of game programs, such as Penny Arcade, that he
sold to Apple Computer in 1979.

In the early 1970' s, Will Crowther developed a
non-graphic fantasy game that was set in a cavern world
with hidden treasure and challenging features such as
dragons, flying horses and trolls. Crowther released the
game on the ARPANET. The program was then refined by Don
Woods and became known as the Adventure game. It became
highly popular and formed the basis for personal
computer Adventure games by Adventureland International
and Microsoft.

Adventure Land was one of the earliest text
adventure games for personal computers. Scott Adams
developed the program for the Radio Shack TRS-80
computer in 1978 . Adventure Land reguired a player to
search through a magic realm that had wild animals,
perils and mysteries to locate treasures . Adams founded
Adventure International in 1978 to produce, be a
distributor and publisher of other computer games . The
game was adapted for the Apple II and other games such

Other Software m the 1 970 ' s 7/11

as Laser Ball, Fire Copter and Pirate Adventure
followed .

Peter R. Jennings developed Microchess initially,
for the MOS Technology KIM-1 microcomputer in 197 6.
Jennings sold the source code for $15. Shortly after,
Daniel Fylstra and Jennings founded Personal Software,
Inc. to market Microchess and other game programs.

Another chess playing program was SARGON, that was
released around 1978. It was developed by Dan and Kathe
Spracklen.

Toru Iwatani designed the Pac-Man game at a
Japanese company called Namco Limited. It was first
introduced in Japan in the late 1970 ' s. Atari licensed
the rights for Pac-Man and it became very successful in
North America.

Other Software

Radio Shack issued a variety of software in the
late 1970' s for their TRS-80 systems. Some of the
programs were: General Ledger, Inventory Control System,
Real Estate, Statistical Analysis and various computer
games. The programs were provided on cassettes and 5-
inch floppy disks.

Stephen Wozniak developed SWEET16 in 1977 as an
interpreter program that was contained in the initial
Apple II ROM memory chip. Wozniak called it a 16-bit
"metaprocessor " [402] . It was used to manipulate 16-bit
pointer data and its arithmetic on the 8-bit Apple II
computer .

Mitchell Kapor developed Tiny Troll in 1978/79
with help from Eric Rosenfeld of MIT. The program
displayed line charts, multiple regressions, statistical
analysis information and had a text editor. The software
formed the basis for the later development of VisiPlot
and VisiTrend programs .

7/12 Part II 1970's-TheAltair/Appleera

Conclusion

In the 1970' s, software had developed in
conjunction with personal computer technology. Initially
it had focused on programming languages such as BASIC,
and operating systems such as CP/M to support disk drive
technology. However in the late 1970' s a change in user
orientation from the technical enthusiast to the mass
market consumer occurred. This was supported by the
release of application software such as the VisiCalc
spreadsheet .