This is a list of disk operating systems in which the acronym DOS is used to form their names. Many of these are simply referred to as "DOS" within their respective communities.

MS-DOS / IBM PC DOS compatible systems

Main article: DOS

MS-DOS (since 1981), Microsoft operating system based on 86-DOS for x86-based personal computers
IBM PC DOS (since 1981), rebranded OEM version of MS-DOS sold by IBM. Identical or almost identical to MS-DOS until PC DOS version 6
DR-DOS (since 1988), MS-DOS-compatible operating system originally developed by Digital Research
ROM-DOS (1989), MS-DOS clone by Datalight
PTS-DOS (since 1993), MS-DOS clone developed in Russia by PhysTechSoft
FreeDOS (since 1998), open source MS-DOS clone

Other x86 disk operating systems with "DOS" in the name

86-DOS (a.k.a. QDOS, created 1980), an operating system developed by Seattle Computer Products for its 8086-based S-100 computer kit, heavily inspired by CP/M
Concurrent DOS (a.k.a. CDOS, Concurrent PC DOS and CPCDOS) (since 1983), a CP/M-86 and MS-DOS 2.11 compatible multiuser, multitasking DOS, based on Concurrent CP/M-86 developed by Digital Research
DOS Plus (since 1985), a PC DOS and CP/M-86 compatible multitasking operating system for early x86-based personal computers, based on Concurrent PC DOS 4.1/5.0 by Digital Research
Multiuser DOS (a.k.a. MDOS), a PC DOS and CP/M-86 compatible multiuser multitasking operating system based on Concurrent DOS by Digital Research
NetWare PalmDOS, a successor of DR DOS 6.0 specifically tailored for early mobile and palmtop PCs by Novell
Novell DOS, a multitasking successor of DR DOS 6.0 by Novell
OpenDOS, a successor of Novell DOS by Caldera

Disk operating systems for the Atari 8-bit family

Disk operating systems for other platforms

AmigaDOS, disk operating system portion of AmigaOS
AMSDOS, for Amstrad CPC compatibles
ANDOS, operating system for the Russian Electronika BK
Apple DOS, operating system for the Apple II series from late 1978 through early 1983
Apple ProDOS, name for both ProDOS 8 for the Apple II and ProDOS 16 for the Apple IIGS
Commodore DOS, for Commodore's 8-bit computers
Cromemco DOS (CDOS), a CP/M-like operating system
CSI-DOS, for the Soviet Elektronika BK computers
DOS (Diskette Operating System), a small OS for 16-bit Data General Nova computers, a cut-down version of their RDOS.
DEC BATCH-11/DOS-11, the first operating system to run on the PDP-11 minicomputer
Delta DOS, third party option from Premier Microsystems for the Dragon 32/64
DIP DOS, the operating system of the Atari Portfolio
DOS/360, 1966 IBM System/360 mainframe computer Disk Operating System
DragonDOS, for the Dragon 32/64
GEMDOS, one of the components of Atari TOS
IS-DOS, for Russian ZX Spectrum clones, developed in 1990 or 1991
IMDOS, for IMSAI 8080
MasterDOS, replacement DOS for the SAM Coupé
MDOS (Micropolis DOS) for S-100
MDOS, Myarc Disk Operating System for the Geneve 9640
MSX-DOS, a cross between MS-DOS 1.0 and CP/M developed by Microsoft for the MSX computer standard
NewDos/80, third-party option for the TRS-80
Oric DOS, for the Oric-1 home computer
PTDOS,^[2] for the 1970s Sol-20 from Processor Technology
SAMDOS, original DOS for the SAM Coupé
SDOS, for the SWTPC 6800 from the Southwest Technical Products Corporation
Sinclair QDOS, for the Sinclair QL
RDOS, a real-time operating system released in 1972 for the Data General Nova and Eclipse minicomputers
SK*DOS,^[3] for Motorola 68000-based systems
TR-DOS, for the ZX Spectrum
TRSDOS, for the Tandy TRS-80 line of 8-bit Zilog Z80 microcomputers
Xtal DOS for the Tatung Einstein

References

^ ^a ^b ^c Clausen, Eric (July 1985). "Everything You Wanted to Know About Every D.O.S.". Antic. 4 (3).
^ "PTDOS User's Manual" (PDF). Sol-20.org. Processor Technology Corporation. 1978.
^ "SK*DOS 68K User's Manual" (PDF). textfiles.org.