This article details versions of MS-DOS, IBM PC DOS, and at least partially compatible disk operating systems. It does not include the many other operating systems called "DOS" which are unrelated to IBM PC compatibles.

Historical and licensing information Originally MS-DOS was designed to be an operating system that could run on any computer with a 8086-family microprocessor. It competed with other operating systems written for such computers, such as CP/M-86 and UCSD Pascal. Each computer would have its own distinct hardware and its own version of MS-DOS, a situation similar to the one that existed for CP/M, with MS-DOS emulating the same solution as CP/M to adapt for different hardware platforms. So there were many different original equipment manufacturer (OEM) versions of MS-DOS for different hardware. But the greater speed attainable by direct control of hardware was of particular importance, especially when running computer games. So very soon an IBM-compatible architecture became the goal, and before long all 8086-family computers closely emulated IBM hardware, and only a single version of MS-DOS for a fixed hardware platform was all that was needed for the market. This specific version of MS-DOS is the version that is discussed here, as all other versions of MS-DOS died out with their respective systems. One version of such a generic MS-DOS (Z-DOS) is mentioned here, but there were dozens more. All these were for personal computers that used an 8086-family microprocessor, but which were not fully IBM PC compatible.

Name First public release date Creator Owner or maintainer License 86-DOS 1.00 Seattle Computer Products rowspan="2" , MIT License PC DOS 1.0 Microsoft (for IBM) rowspan="13" PC DOS 1.1 rowspan="13" PC DOS 2.0 PC DOS 2.1 PC DOS 3.0 PC DOS 3.1 PC DOS 3.2 PC DOS 3.3 IBM DOS 4.0(called PC DOS 4.0) IBM DOS 5.0(called PC DOS 5.0) PC DOS 6.1, PC DOS 6.3 IBM PC DOS 7.0 (revision 0) PC DOS 2000(PC DOS 7.0 revision 1) PC DOS 7.10 MS-DOS 1.25 (first version named "MS-DOS") Microsoft rowspan="16" , MIT License Z-DOS 1.25 OEM Zenith Data Systems MS-DOS 2.0 Microsoft , MIT License MS-DOS 2.11 rowspan="5" MS-DOS 3.0 MS-DOS 3.1 MS-DOS 3.2 MS-DOS 3.3 MS-DOS 4.0 , MIT License MS-DOS 5.0 rowspan="15" MS-DOS 6.0 MS-DOS 6.20 MS-DOS 6.21 MS-DOS 6.22 MS-DOS 7.0 (Windows 95A) MS-DOS 7.10 (Windows , 98, ) MS-DOS 8.0 (Windows Me and later)MS-DOS 8.0 has most of the functionality of prior versions, but with significant losses of usability, e.g., the loss of FORMAT /S command, that can be substituted by formatting HDD/FDD and then copying IO.SYS from CD-ROM boot A: image, as first ever file onto drive; loss of SYS A: (or SYS B:) command for floppies, that can be substituted too in the same way as FORMAT /S; inability to boot to a command prompt without substitution/modification of IO.SYS (other than CD-ROM boot version) and COMMAND.COM. For purpose of booting from C: drive, an unmodified IO.SYS from simulated A: boot diskette image, that is placed on Windows Me OEM CD-ROM, from which that CD boots, can be used, and English COMMAND.COM can be modified by replacing in this file at hex offset byte by byte , or substituted by (now freeware) 4DOS http://www.jpsoft.com/download.htm While Windows ME support ended, a version of its underlying DOS is included with . When one formats a floppy in Windows XP and selects "Create an MS-DOS startup disk", the floppy is formatted with a DOS version that identifies itself as "Windows Millennium Version 4.90.3000". DOS Plus 1.1, 1.2/1.2a Digital Research rowspan="7" DOS Plus 2.1 DR DOS 3.31-3.35 DR DOS 3.40-3.41 DR DOS 5.0 DR DOS 6.0 Novell DOS 7 Novell Caldera OpenDOS 7.01 Caldera, Inc.;Caldera UK, Ltd. officially;a derivative, Enhanced DR-DOS, wasmaintained by Udo Kuhnt until 2011 rowspan="2" , free non-commercial use Caldera DR-OpenDOS 7.02 rowspan="2" Caldera DR-DOS 7.02 rowspan="4" Caldera DR-DOS 7.03 1999, 1998 prereleased Caldera Thin Clients, Inc.;Caldera UK, Ltd;Lineo, Inc. DR-DOS 8.0 DeviceLogics rowspan="2" DR-DOS 8.1DR-DOS 8.1 was pulled from the market after it was discovered that 8.1 code had been copied from FreeDOS in violation of the GPL license. DRDOS, Inc. FreeDOS 1.0 Jim Hall, et al. rowspan="4" rowspan="4" , GPL FreeDOS 1.1 FreeDOS 1.2 FreeDOS 1.3 PTS-DOS 6.4 PhysTechSoft rowspan="5" rowspan="11" PTS-DOS 6.5 ? PTS-DOS 6.6 PTS-DOS 2000 (6.7) PTS-DOS 32 (7.0) PTS-DOS 6.51 ca. Paragon Technology Systems rowspan="2" Paragon DOS 2000 Pro ? ROM-DOS 6.22 Datalight rowspan="2" ROM-DOS 7.1 Embedded DOS General Software DIP DOS 2.11 DIP Research, Atari Corporation RxDOS 6.2 Michael Podanoffsky rowspan="2" , GPL RxDOS 7.20-7.24 C. Masloch SISNE plus ? Itautec, Scopus Tecnologia

Technical specifications