The history of MS-DOS is surprisingly long. It started off as QDOS (Quick and Dirty Operating System) which was developed by Seattle Computer Products to run on IBM's new PC. This list is fairly comprehensive, although a number of the more obscure versions of DOS have been omitted.
| Version | Date | Comments |
| 1.0 | 1981 | The original version of MS-DOS. This was a renamed version of QDOS which had been purchased by an upstart company called Microsoft. |
| 1.25 | 1982 | This added support for double-sided disks. Previously the disk had to be turned over to use the other side |
| 2.0 | 1983 | This added support for IBM's 10 MB hard disk, directories and double-density 5.25" floppy disks with capacities of 360 KB |
| 2.11 | 1983 | Support for foreign and extended characters was added. |
| 3.0 | 1984 | Support for high-density (1.2 MB) floppy disks and 32 MB hard disks was added. |
| 3.1 | 1984 | Network support was added. |
| 3.3 | 1987 | This release was written to take advantage of IBM's PS/2 computer range. It added support for high density 3.5" floppy disks, more than one partition on hard disks (allowing use of disks bigger than 32 MB) and code pages. |
| 4.0 | 1988 | This version provided XMS support, support for partitions on hard disks up to 2 GB and a graphical shell. It also contained a large number of bugs and many programs refused to run on it. |
| 4.01 | 1989 | The bugs in version 4.0 were fixed. |
| 5.0 | 1991 | This was a major upgrade. It allowed parts of DOS to load itself in the high memory area and certain device drivers and TSRs to run in the unused parts of the upper memory area between 640K and 1024K. This version also added support for IBM's new 2.88 MB floppy disks. An improved BASIC interpreter and text editor were included, as was a disk cache, an undelete utility and a hard-disk partition-table backup program . After the problems with MS-DOS 4, it also provided a utility to make programs think they were running on a different version of MS-DOS. |
| 5.0a | 1992-1993 | This was a minor bug fix which dealt with possibly catastrophic problems with UNDELETE and CHKDSK. |
| 6.0 | 1993 | This was a catch-up with Novell's DR-DOS 6. It added a disk-compression utility called DoubleSpace, a basic anti-virus program and a disk defragmenter. It also finally included a MOVE command, an improved backup program, MSBACKUP and multiple boot configurations. Memory management was also improved by the addition of MEMMAKER. A number of older utilities, such as JOIN and RECOVER were removed. The DOS Shell was released separately as Microsoft felt that there were too many disks. |
| 6.2 | 1993 | Extra security was built into DoubleSpace following complaints of data loss. A new disk checker, SCANDISK, was also introduced, as well as improvements to DISKCOPY and SmartDrive . |
| 6.21 | 1993 | Following legal action by Stac Electronics, Microsoft released this version which had DoubleSpace removed. It came with a voucher for an alternative disk compression program. |
| 6.22 | 1994 | Microsoft licenced a disk-compression package called DoubleDisk from VertiSoft Systems and renamed it DriveSpace, which was included in this version. |
| 7.0 | 1995 | This version is part of the original version of Windows 95. It provides support for long filenames when Windows is running, but removes a large number of utilities, some of which are on the Windows 95 CD in the \other\oldmsdos directory. |
| 7.1 | 1997 | This version is part of OEM Service Release 2 and later of Windows 95. The main change is support for FAT 32 hard disks, a more efficient and robust way of storing data on large drives. |