Microsoft DOS history
Listed below are the important events in history relating to MS-DOS, including release dates for each of its versions and related events.
For a history of Microsoft Windows, see: Microsoft Windows history.
1981
Microsoft licensed the operating system 86-DOS from SCP (Seattle Computer Products) for $25,000 on July 27, 1981.
Microsoft PC-DOS 1.0, the first official version, was released in August 1981. It was designed to operate on the IBM PC.
1982
Microsoft PC-DOS 1.1 was released in May 1982, with support for double-sided disks.
MS-DOS 1.25 was released in August 1982. It was the first version titled "MS-DOS."
1983
MS-DOS 2.0 was released in March 1983, designed for the IBM PC XT (extended technology). It introduced support for hard disk drives.
MS-DOS 2.1 was released in November 1983, designed for the IBM PCjr. It introduced support for half-height disk drives and ROM cartridges.
1984
MS-DOS 3.0 was released in August 1984, designed for the IBM PC AT (advanced technology).
1985
MS-DOS 3.1 was released in April 1985. Marketed as "MS-DOS for networks," it was the first version of DOS that supported local area networks.
1986
MS-DOS 3.2 was released in April 1986, featuring support for 3 1/2 inch, 720 KB floppy disk drives.
1987
MS-DOS 3.3 was released in April 1987, designed for the IBM PS/2. It featured support for 3 1/2 inch, 1.44 MB floppy disk drives, and extended (non-primary) disk partitions.
MS-DOS 3.31 was released in November 1987, designed for Compaq computers. It added support for hard disk partitions larger than 32 MB.
1988
MS-DOS 4.0 was released in July 1988, featuring multitasking. It was used primarily in Europe and was sometimes called European MS-DOS 4.0.
MS-DOS 4.01 was released in November 1988, introducing support for volume serial numbers. Unlike MS-DOS 4.0, version 4.01 did not feature support for multitasking.
1991
MS-DOS 5.0 was released in June 1991. It featured support for 3.5 inch 2.88 MB floppy disks and a full-screen text editor, "edit." It was the first version of MS-DOS to include himem.sys, which loaded part of the operating system into the UMA (Upper Memory Area).
1993
MS-DOS 6.0 was released in August 1993. It featured a help system in QBasic, disk compression (via the dblspace utility), UMA optimization, and antivirus software msav.
MS-DOS 6.2 was released in November 1993. It featured critical bug fixes to dblspace, and ScanDisk, a replacement for the chkdsk utility.
1994
MS-DOS 6.21 was released in March 1994. It removed the DBLSPACE utility, which legally infringed on the third-party disk compression software STACKER.
MS-DOS 6.22 was released in April 1994. It included DRVSPACE, a compression utility that replaced DBLSPACE. It was the last stand-alone version of MS-DOS to be released.
1995
Windows 95 was released on August 24, 1995. In the Windows 95 command line, the operating system version number was listed as MS-DOS version 7.0.