Appendix B: Versions of DOS Version 1.0 This is the version released with the IBM PC computer in August 1981. The program had 4,000 lines of code and reguired 136K bytes of storage when fully installed. Versions 1.1 and 1.25 Version 1.1 was released in May 1982 for PC computers with two disk drives and to enable writing on both sides of the diskette. This doubled the diskette capacity from 160K to 320K bytes. Microsoft released MS DOS Version 1.25 for IBM compatible computers. Version 2. Was released in March 1983 for the IBM PC XT computer. Initially IBM only wanted an upgrade to accommodate a hard disk on the new PC XT computer. However Paul Allen decided to enhance the software and add additional features. Some of those new features were hierarchical directories, a limited form of multitasking for printing and certain UNIX features . The floppy disk format was also changed from 8 sectors per track to 9 sectors that increased the storage capacity to 360 K bytes. The program now had 20,000 lines of code. Version 2.1 (PC-DOS) Was introduced in November 1983 for the IBM PC Junior . Version 2.11 Was released in March 1984 for international customers. It supported the variations in date format and comma instead of a period for decimal point notation. The program was translated into many languages and sold worldwide. By June 1984, Microsoft had licensed MS-DOS to 200 manufacturers. AB/1 AB/2 A History of the Personal Computer Version 3. Was released in August 198 4 for the IBM PC AT computer. It accommodated high-density 1.2 megabyte diskettes. It also added features such as: RAM disk, volume names and the ATTRIB command. The program now consisted of 40,000 lines of code. Version 3.1 Was released in March 1985 to add networking capabilities for IBM PC Network and Microsoft MS-Net. Version 3.2 Was released in December 1985 to accommodate 3 1/2 inch disk drives. Version 3.3 Was released in April 1987 to accommodate multiple partitions, improved foreign character support, support for a 32 megabyte hard disk and the IBM PS/2 series of computers . Version 4.0 Was released in June 1988. It had a graphical user interface or DOS shell for use with a mouse, EMS support and support for hard disk partitions over 32 megabytes. The program required 1.1 MB of storage. Version 5.0 Was released in June 1991. It featured a MS-DOS kernel which loaded into HMA (high memory), 80386 memory management, a new shell, improved multitasking capabilities, limited switching capabilities, on-line help and a full-screen editor. Version 6.0 Was released in March 1993. The new features added were: DoubleSpace disk compression, improved memory management, backup and defrag utilities licensed from Appendix B: Versions of DOS AB/3 Symantec Corporation, anti-virus and undelete utilities licensed from Central Point Software Inc., Multi- configuration support on start-up, an improved SmartDrive, three new commands (Move, Deltree and Choice) and a file transfer utility called Interlink. The program required 8.4 MB of storage. Version 6.2 Was released in November 1993. DoubleGuard that is a part of DoubleSpace is added to verify data integrity before writing to disk. Versions 6.21 and 6.22 Version 6.21 was released in February 1994 to delete DoubleSpace after litigation with Stac Electronics. Version 6.22 was released in June 1994 to add a new disk compression program called DriveSpace. MS-DOS was essentially made obsolete with the introduction of Microsoft Windows 95 in August 1995. Windows 95 integrates the functionality of MS-DOS and the previous Windows graphical interface.