# Comparison of DOS operating systems

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 as of 2021 | License |
| 86-DOS 0.42 | 1981-02-25 | Seattle Computer Products | Support ended | Proprietary |
| 86-DOS 1.00 | 1981-04-28 | Seattle Computer Products | Support ended | Proprietary |
| PC DOS 1.0 | 1981-08-12 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 1.1 | 1982-05-?? | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 2.0 | 1983-03-?? | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 2.1 | 1983-10-?? | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 3.0 | 1984-08-?? | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 3.1 | 1985 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 3.2 | 1986 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 3.3 | 1987 | Microsoft (for IBM) | Support ended | Proprietary |
| IBM DOS 4.0 (called PC DOS 4.0) | 1988 | Microsoft (for IBM) | Support ended | Proprietary |
| IBM DOS 5.0 (called PC DOS 5.0) | 1991 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 6.1, PC DOS 6.3 | 1993 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 7.0 (revision 0) | 1995 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 2000 (PC DOS 7.0 revision 1) | 1998 | Microsoft (for IBM) | Support ended | Proprietary |
| PC DOS 7.10 | 2003 | Microsoft (for IBM) | Support ended by IBM | Proprietary |
| MS-DOS 1.25 (first version named "MS-DOS") | 1982 | Microsoft | Support ended | Open source, MIT License |
| Z-DOS 1.25 | 1982-05-?? | OEM Zenith Data Systems | Support ended | Proprietary |
| MS-DOS 2.0 | 1983-03-?? | Microsoft | Support ended | Open source, MIT License |
| MS-DOS 2.11 | 1983-12-?? | Microsoft | Support ended | Proprietary |
| MS-DOS 3.0 | 1984 | Microsoft | Support ended | Proprietary |
| MS-DOS 3.1 | 1984 | Microsoft | Support ended | Proprietary |
| MS-DOS 3.2 | 1986 | Microsoft | Support ended | Proprietary |
| MS-DOS 3.3 | 1987 | Microsoft | Support ended | Proprietary |
| MS-DOS 4.0 | 1988 | Microsoft | Support ended | Open source, MIT License |
| MS-DOS 5.0 | 1991 | Microsoft | Support ended | Proprietary |
| MS-DOS 6.0 | 1993 | Microsoft | Support ended | Proprietary |
| MS-DOS 6.20 | 1993 | Microsoft | Support ended | Proprietary |
| MS-DOS 6.21 | March 1994 | Microsoft | Support ended | Proprietary |
| MS-DOS 6.22 | April 1994 | Microsoft | Support ended | Proprietary |
| MS-DOS 7.0 (Windows 95A) | 1995 | Microsoft | Support ended | Proprietary |
| MS-DOS 7.10 (Windows 95 OSRs 2 and 2.5, 98, 98 SE) | 1996 | Microsoft | Support ended | Proprietary |
| MS-DOS 8.0 (Windows Me and later) | 2000 | Microsoft | Support ended by Microsoft | Proprietary |
| DOS Plus 1.1, 1.2/1.2a | 1985 | Digital Research | Support ended | Proprietary |
| DOS Plus 2.1 | 1986 | Digital Research | Support ended | Proprietary |
| DR DOS 3.31-3.35 | 1988 | Digital Research | Support ended | Proprietary |
| DR DOS 3.40-3.41 | 1989 | Digital Research | Support ended | Proprietary |
| DR DOS 5.0 | 1990 | Digital Research | Support ended | Proprietary |
| DR DOS 6.0 | 1991 | Digital Research | Support ended | Proprietary |
| Novell DOS 7 | 1993 | Novell | Support ended | Proprietary |
| Caldera OpenDOS 7.01 | 1997 | Caldera, Inc.; Caldera UK, Ltd. | Support ended officially; a derivative, Enhanced DR-DOS, was maintained by Udo Kuhnt until 2011 | Partial, free non-commercial use |
| Caldera DR-OpenDOS 7.02 | 1997 | Caldera, Inc.; Caldera UK, Ltd. | Support ended | Partial, free non-commercial use |
| Caldera DR-DOS 7.02 | 1998 | Caldera, Inc.; Caldera UK, Ltd. | Support ended | Proprietary |
| Caldera DR-DOS 7.03 | 1999, 1998 prereleased | Caldera Thin Clients, Inc.; Caldera UK, Ltd; Lineo, Inc. | DRDOS, Inc. | Proprietary |
| DR-DOS 8.0 | 2004 | DeviceLogics | Support ended | Proprietary |
| DR-DOS 8.1 | 2005 | DRDOS, Inc. | Support ended | Proprietary |
| FreeDOS 1.0 | 2006-09-03 | Jim Hall, et al. | The FreeDOS Project | Open source, GPL |
| FreeDOS 1.1 | 2012-01-02 | Jim Hall, et al. | The FreeDOS Project | Open source, GPL |
| FreeDOS 1.2 | 2016-12-25 | Jim Hall, et al. | The FreeDOS Project | Open source, GPL |
| FreeDOS 1.3 | 2021-12-14 | Jim Hall, et al. | The FreeDOS Project | Open source, GPL |
| PTS-DOS 6.4 | 1993 | PhysTechSoft | PhysTechSoft | Proprietary |
| PTS-DOS 6.5 | ? | PhysTechSoft | PhysTechSoft | Proprietary |
| PTS-DOS 6.6 | ? | PhysTechSoft | PhysTechSoft | Proprietary |
| PTS-DOS 2000 (6.7) | ? | PhysTechSoft | PhysTechSoft | Proprietary |
| PTS-DOS 32 (7.0) | ? | PhysTechSoft | PhysTechSoft | Proprietary |
| PTS-DOS 6.51 | ca. 1995 | Paragon Technology Systems | Paragon Technology Systems | Proprietary |
| Paragon DOS 2000 Pro | ? | Paragon Technology Systems | Paragon Technology Systems | Proprietary |
| ROM-DOS 6.22 | ? | Datalight | Datalight | Proprietary |
| ROM-DOS 7.1 | ? | Datalight | Datalight | Proprietary |
| Embedded DOS | ? | General Software | General Software | Proprietary |
| DIP DOS 2.11 | 1989 | DIP Research, Atari Corporation | Support ended | Proprietary |
| RxDOS 6.2 | 1999 | Michael Podanoffsky | Support ended | Open source, GPL |
| RxDOS 7.20-7.24 | 2018 | C. Masloch | C. Masloch | Open source, GPL |
| SISNE plus | ? | Itautec, Scopus Tecnologia | Support ended | Proprietary |

## Technical specifications

| Name | Hard drive: partition size max | Native support: File systems | Native support: floppy capacities 3.5" | Native support: floppy capacities 5.25" | Native support: floppy capacities 8.0" | Integrated disk compression utility | Native support: long file names |
| 86-DOS 0.42-1.00 | — | FAT12; (CP/M 2 through RDCPM) | — | NorthStar 87.5 KB; Cromemco 90 KB | Cromemco/Tarbell 250.25 KB; Tarbell 616 KB; Tarbell 1232 KB | No | No |
| MS-DOS 1.25 | — | FAT12 | — | 160 KB; 320 KB | 250.25 KB | No | No |
| MS-DOS 2.0-2.11 | 16 MB (32 MB with third-party FORMAT) | FAT12 | — | 160 KB; 180 KB; 320 KB; 360 KB | 250.25 KB; 500.5 KB; 616 KB; 1232 KB | No | No |
| MS-DOS 3.0 | 32 MB | FAT12, FAT16 | — | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 3.1 | 32 MB | FAT12, FAT16 | — | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 3.2 | 32 MB | FAT12, FAT16 | 720 KB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 3.3 | 32 MB | FAT12, FAT16 | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 3.31 | 512 MB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 4.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 5.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB, 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 6.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | DoubleSpace | No |
| MS-DOS 6.20 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | DoubleSpace | No |
| MS-DOS 6.21 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| MS-DOS 6.22 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | DriveSpace | No |
| MS-DOS 7.0 (Windows 95A) | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | DriveSpace | No |
| MS-DOS 7.1 (Windows 95B/OSR2, Windows 95C/OSR2.5, Windows 98, and Windows 98SE) | 124.55 GB with FAT32 | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | DriveSpace for Windows 95, none for Windows 98 | No |
| MS-DOS 8.0 (Windows Me and later Windows versions) | 124.55 GB with FAT32 | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| PC DOS 1.0 | — | FAT12 | — | 160 KB | — | No | No |
| PC DOS 1.1 | — | FAT12 | — | 160 KB; 320 KB (double-sided) | — | No | No |
| PC DOS 2.0-2.1 | 16 MB (32 MB with third-party FORMAT) | FAT12 | — | 160 KB; 180 KB; 320 KB; 360 KB | — | No | No |
| PC DOS 3.0 | 32 MB | FAT12, FAT16 | — | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| PC DOS 3.1 | 32 MB | FAT12, FAT16 | — | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| PC DOS 3.2 | 32 MB | FAT12, FAT16 | 720 KB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| PC DOS 3.3 | 32 MB | FAT12, FAT16 | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| IBM DOS 4.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| IBM DOS 5.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB, 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| PC DOS 6.1 (early version) | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| PC DOS 6.1 with Compression / PC DOS 6.3 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | SuperStor | No |
| PC DOS 7.0 / PC DOS 2000 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 1.86 MB (XDF), 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB, 1.54 MB (XDF) | — | Stacker | No |
| PC DOS 7.10 | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 1.86 MB (XDF), 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB, 1.54 MB (XDF) | — | Stacker, not on FAT32 | No |
| DOS Plus 1.1 | 32 MB | FAT12, FAT16, CP/M-86 | 315 KB; 720 KB; CP/M 315 KB; CP/M 720 KB; MSX-DOS 360 KB; MSX-DOS 720 KB | 160 KB; 180 KB; 320 KB; 360 KB; 800 KB; 1.2 MB; CP/M 160 KB; CP/M 320 KB | — | No | No |
| DOS Plus 1.2-2.1 | 32 MB | FAT12, FAT16, CP/M-86 | Apricot 315 KB; (720 KB) | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB; Acorn 640 KB; Acorn 800 KB; CP/M 320 KB | — | No | No |
| DR DOS 3.31-3.35 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | — | No | No |
| DR DOS 3.40-3.41 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | No | No |
| DR DOS 5.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | No | No |
| DR DOS 6.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | SuperStor | No |
| PalmDOS 1.0 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | SuperStor | No |
| Novell DOS 7 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker | No |
| OpenDOS 7.01 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker | No |
| DR-OpenDOS 7.02 | 2 GB | FAT12, FAT16, FAT16B | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker | No |
| DR-DOS 7.02 | 2 GB | FAT12, FAT16, FAT16B, (FAT32 in FDISK only) | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker | Partial, COMMAND.COM and LONGNAME only |
| DR-DOS 7.03 | 2 GB | FAT12, FAT16, FAT16B, (FAT32 in FDISK only) | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker | Partial, COMMAND.COM and LONGNAME only |
| DR-DOS 7.04-7.05 | ? | FAT12, FAT16, FAT16B, FAT32 (non-bootable) | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker, not on FAT32 | Partial, COMMAND.COM and LONGNAME only |
| DR-DOS 7.06-7.07 | ? | FAT12, FAT16, FAT16B, FAT32 (bootable) | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Stacker, not on FAT32 | Partial, COMMAND.COM and LONGNAME only |
| DR-DOS 8.0 | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 160 KB; 180 KB; 320 KB; 360 KB; 1.2 MB | (250.25 KB) | Supported, not on FAT32 | Partial, COMMAND.COM only |
| DR-DOS 8.1 | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | No | No |
| FreeDOS 1.0 | 2 TB | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | ? | No |
| FreeDOS 1.1-1.3 | 2 TB | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | No | Yes |
| PTS-DOS 32 | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | No | No |
| PTS-DOS 2000 | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | No | No |
| PTS-DOS 2000 PRO | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | No | No |
| Datalight ROM-DOS | ? | FAT12, FAT16, FAT16B, FAT32 | 720 KB; 1.44 MB, 2.88 MB | 360 KB; 1.2 MB | — | No | Yes |
| DIP DOS | — | FAT12 | — | — | — | No | No |