操作系统：时间轴和家族树

本文译自：Operating Systems: Timeline and Family Tree

摘要：各操作系统出现的时间轴，各操作系统之间的关系、操作系统家族关系，如常见的：Unix、FreeBSD、iOS、Mac OS、OpenBSD、类 Unix、Linux、Android、CentOS、Debian、Fedora、Oracle、Red Hat、SuSE、Ubuntu、CP/M、DOS、VMS、Windows、AmigaOS、RISC、IBM大型机、L4、OSEK等。

到目前为止包括大约 850 个操作系统

上次更新时间：2022 年 1 月

在这篇文章中，您将找到操作系统的家谱和时间表。我试图包括所有操作系统，无论多旧或晦涩难懂。当然，一个完整的列表几乎是不可能的，因为没有办法对所有可能存在的微小爱好和嵌入式系统进行编目。

另请注意，我只收录了几个选定的 Linux/BSD/Solaris 发行版（这些发行版是否应该单独算作操作系统是有争议的）。

目前，家谱包括 800 到 900 种不同的操作系统。提示：使用 Ctrl+F（在 Mac 上为 Cmd+F）搜索系统。

单击此处在新选项卡中打开图片

此图中的操作系统包括：

（图中仅显示原始/名字，后来的重命名，但不显示在列表中）

Unix
- 3BSD
- 4.4BSD
- A/UX [Apple]
- airyxOS
- AIX [IBM]
- Amiga Unix [Amiga]
- AOS [IBM]
- Atari Unix [Atari]
- audioOS [Apple]
- BKUNIX
- BRL Unix
- BSD
- BSD Net/1 [Acorn]
- BSD Net/2
- BSD/OS
- CB UNIX
- CellOS [Sony Playstation 3]
- Concentrix [Alliant]
- ConvexOS [Convex]
- COSIX [CS&S]
- CTIX [Convergent]
- CXOs [Cray]
- Darwin [Apple]
- DC/OSx [Pyramid]
- DEC OSF/1 [DEC]
- Dell Unix [Dell]
- DG/UX [Data General]
- DragonFlyBSD
- Dynix [Sequent Computer Systems]
- Eurix/Generics Unix [Generics]
- FreeBSD
- Genix [National Semiconductor]
- GhostBSD
- GNU/Hurd
- HardenedBSD
- HeliOS [Perihelion]
- HelloSystem
- HEP-UPX [Denelcor]
- Hitachi OSF/1-MJ [Hitachi]
- HI-UX [Hitachi]
- HP OSF/1 [HP]
- HPBSD [HP]
- HP-UX [HP]
- Idris [Whitesmiths]
- Illumos
- iOS [Apple]
- IRIS GL2 [SGI]
- IRIX [SGI]
- IS/1 [Interactive]
- JunOS [Juniper]
- Lites
- LSX
- Mac OS X Server 10 [Apple]
- Mach (kernel)
- Mach386 [mt Xinu]
- MachTen [Tenon]
- MacMach
- macOS X [Apple] (now macOS)
- MAXION/OS [Concurrent]
- MERT
- Micronix [Morrow]
- Microport Unix
- MidnightBSD
- Mini Unix
- MkLinux
- Monterey
- more/BSD [mt Xinu]
- MP-RAS Unix [NCR]
- Munix [Generics]
- NDIX [Norsk Data]
- NetBSD
- News-OS [Sony]
- NeXTSTEP [NeXT Computer]
- NonStop-UX [HP]
- OpenBSD
- OpenDarwin
- OpenIndiana
- OpenSolaris
- OS/MP [Solbourne]
- OSF/1
- OSF/1 AD [Locus Computing]
- Paragon OSF/1 [Paragon]
- PC-BSD [iXsystems]
- PC-IX [Interactive Systems Corp]
- PWB/Unix
- Real Time UNIX [Concurrent]
- RetroBSD
- Rhapsody
- RISC Unix [Acorn]
- RISC/OS [MIPS]
- RT PC AOS [IBM]
- Sinix [Siemens]
- SmartOS
- Solaris [Sun]
- SPIX [Bull Computers]
- SPP-UX [Convex]
- SunOS [Sun]
- SUPER-UX [NEC]
- TI System V [Texas Instruments]
- TNIX [Tektronix]
- Trusted IRIX/B [SGI]
- Trusted Solaris [Sun]
- Trusted Xenix [SCO]
- TS
- tvOS [Apple]
- UCLA Locus
- UCLA Secure Unix
- Ultrix 32M [DEC]
- UMAX 4.3 [Encore]
- Unicos MAX [Cray]
- Unicos/mk [Cray]
- Unicos/mp [Cray]
- UNICS [AT&T/Bell Labs]
- UniPlus System V [UniSoft]
- UNIX 32V
- UNIX System III [AT&T]
- Unix/NS [NCR]
- UNSW
- Unleashed
- USG
- UTEK [Tektronix]
- UTS [Amdahl]
- UTS/M [Fujitsu]
- UTX/32(S) [Gould]
- UXP/DS [Fujitsu]
- V/386
- V7M [DEC]
- V7/x86
- Venix [VenturCom]
- watchOS [Apple]
- WEGA [East Germany]
- Xenix [Microsoft]
- xMach
类 Unix，但不是遗传 Unix
- 9atom
- 9front
- ABCenix [Luxor]
- AFROS (based on EmuTOS)
- ANALIX
- BlackBerry 10 [BlackBerry]
- Blackberry PlayBook OS [RIM]
- C Executive [JMI Software]
- Chorus [Chorus Systemes]
- Coherent [MWC]
- Cromix [Cromemco]
- Data ONTAP [NetApp]
- DCC-IX
- Digix [Digirede]
- DNIX [Dataindustrier]
- Domain/OS [Apollo]
- DRM System [NV Philips]
- EDIX
- Escape
- GNO/ME [Procyon]
- Harvey OS
- Inferno
- IOS-XR [Cisco]
- LUnix
- LynxOS
- MeikOS [Meiko Scientific]
- MERLIN [Silicon Valley Software]
- MINIX
- Minix-VMD
- MiNT/MultiTOS
- MSS
- Mulplix
- Multics
- NachOS
- Nix
- Oasis [Phase One Systems]
- Onyx
- OS 9 [Microware]
- OSv [Clodius Systems]
- Pintos
- Plan 9 [AT&T/Bell Labs]
- Plan B
- Plurix
- Punix
- QNX Neutrino [QNX Software]
- QUNIX [QNX Software]
- REAL
- Redox OS
- SeaOS
- SerenityOS
- SIDIX
- Sortix
- SOX [Cobra Tecnologia]
- Sprite
- System/88 OS [IBM]
- TC/IX [Control Data]
- Thix
- Thoroughbred/OS [Omega]
- TUNIS
- UNOS [Charles River Data Systems]
- USIX [System Six]
- UZIX
- VirtualLogix C5 [Jaluna]
- VMEexec [Motorola]
- VOS [Stratus Technologies]
- VSTa
- XDI [Crescendo Communications]
- Xinu
- 基于类dos系统的类unix系统
  - INOS [Introl]
  - PCUNIX/PCNX [Wendin]
  - UniFLEX [TSC]
- Linux
  - Android [Google]
  - Android Hardening
  - Arch Linux
  - Bada [Samsung]
  - CalyxOS
  - CentOS
  - ChromeOS [Google]
  - Copperhead OS
  - CyanogenMod
  - Debian GNU/Linux
  - elementary OS
  - Eelo
  - Enoch Linux
  - Fedora Core
  - Fire OS [Amazon]
  - Firefox OS [Mozilla]
  - KaiOS [KaiOS Technologies]
  - KDE Neon
  - Linux Mint
  - Mageia Linux
  - Mandrake Linux [MandrakeSoft]
  - MeeGo
  - MEPIS
  - mer
  - MX Linux
  - My Home Screen [Panasonic]
  - Oracle Linux [Oracle]
  - OS2005 [Nokia]
  - Palm webOS [Palm]
  - PCLinuxOS
  - Pop!_OS [System76]
  - Red Hat Linux [Red Hat]
  - ROSA Linux
  - Sailfish OS [Jolla]
  - Scientific Linux
  - Slackware Linux
  - SuSE Linux [SuSE]
  - SUSE Linux Enterprise [SuSE]
  - Tizen [Samsung]
  - Ubuntu [Canonical]
  - Ubuntu Touch
被同名的unix版本所取代的非unix系统
- BlackBerry OS [RIM]
- System [Apple]
类 CP/M
- 4860 OS [IBM]
- Apple CP/M [Apple]
- BCU880 [Robotron]
- CCI Multiuser DOS [Concurrent Controls]
- Compaq DOS [Compaq]
- Concurrent CP/M-68k [Digital Research]
- Concurrent CPM-80 [Digital Research]
- COS-PSA [Robotron]
- CP/A [Robotron]
- CP/K [Robotron]
- CP/KC [Robotron]
- CP/L [Robotron]
- CP/M [Digital Research]
- CP/M 80 [Digital Research]
- CP/Z [Robotron]
- CPM-FDE [Robotron]
- CSOC [Robotron]
- CSOS [Robotron]
- DAC [Robotron]
- DataPac Multiuser DOS [DataPac]
- DCP [Robotron]
- DIP DOS [Atari]
- doesmu
- DOS Plus [Digital Research]
- DOS-PSA [Robotron]
- DR PalmDOS [Digital Research]
- DR-DOS/OpenDOS [Digital Research]
- FlexOS [Digital Research]
- IMS Multiuser DOS
- K8918-OS [Robotron]
- MFA-CPA [Robotron]
- MicroDOS [Robotron]
- MicroOS
- MP/M-80 [Digital Research]
- MP/M-86 [Digital Research]
- MS-DOS [Microsoft]
- MSX-DOS [Microsoft]
- OS/M [Robotron]
- PD-DOS
- QDOS/86-DOS [SCP]
- S5-DOS/MT [Siemens]
- SCP [Robotron]
- SCP/M [Robotron]
- SCP-IBE [Robotron]
- TOS/M [Robotron]
- Towns OS [Fujitsu]
- Wendin-DOS [Wendin]
- XDOS
- Z-DOS [Microsoft]
其他DOS系统
- Altair DOS [MITS]
- AMSDOS [Amstrad]
- ANDOS
- AOS [Data General]
- AOS/RT32 [Data General]
- AOS/VS [Data General]
- AOS/VS II [Data General]
- Apple DOS [Apple]
- Apple SOS [Apple]
- Atari DOS [Atari]
- Batch-11/DOS-11 [DEC]
- BonnyDOS/286
- CDOS [Cromemco]
- CMB DOS [Commodore]
- CSI-DOS
- DG SOS [Data General]
- DOS XL [Optimized Systems]
- Embedded DOS [General Software]
- GDOS [Miles Gordon Technology]
- GS/OS [Apple]
- HDOS [Heath Company]
- ICOS
- IS-DOS
- MDOS/MIDAS [Microsoft]
- MiniDOS
- MK-DOS
- MP/AOS [Data General]
- MP/OS [Data General]
- NewDOS/80 [Apparat]
- Oric DOS [Tangerine]
- Paragon DOS [Paragon]
- PC-MOS/386 [Software Link]
- ProDOS [Apple]
- PTS-DOS [PhysTechSoft]
- ROM-DOS [Datalight]
- RxDOS
- Sinclair QDOS
- SMSQ/E
- SpartaDOS X [ICD Inc]
- SSB-DOS (Smoke Signal DOS) [TSC]
- SuperDOS
- TASiS
- TR-DOS [Technology Research]
- TRSDOS [Tandy]
- TurboDOS [Software 2000]
RSX-11 或类 VMS
- ArcaOS
- DOS/RV (OCPBM) [Soviet Union]
- eComStation [Serenity Systems]
- FreeVMS
- IAS [DEC]
- Micro/RSX [DEC]
- MicroVMS [DEC]
- MOOS [Robotron]
- OMOS [Robotron]
- OS/2 [IBM/Microsoft]
- OS/RW [Soviet Union]
- osFree
- PCVMS [Wendin]
- ReactOS
- RSX-11M [DEC]
- RSX-11M+ [DEC]
- RSX-11S [DEC]
- RSX-15 [DEC]
- RSX180
- RSX-20F [DEC]
- SM-EVM [Soviet Union]
- VAX-11/VMS [DEC]
- VAXELN [DEC]
- Windows 10 Mobile [Microsoft]
- Windows NT 3.x [Microsoft] and successor (up to Windows 11 today)
- Windows Phone 8 [Microsoft]
- Windows RT [Microsoft]
其他微软系统
- Midori
- Pocket PC and Windows Mobile
- Singularity
- Windows CE
- Windows Phone 7
类 AmigaOS
- AROS
- AspireOS
- AtheOS
- CDTV
- BeOS [Be Inc]
- MorphOS
- NewOS
- OpenBeOS
- PhOS/PhosphurOS
- pOS [ProDAD]
- TripOS [Commodore]
- VMWAros
类 RISC OS
- Arthur [Acorn]
- NCOS [Element 15]
- RISC OS
IBM大型机系统，由IBM开发
- BOS/360 [IBM]
- BSEPP (VM/BSE) [IBM]
- CP/CMS [IBM]
- CP-50/CP-67 [IBM]
- CPF [IBM]
- CTSS [IBM]
- Fortran Monitor System (FMS) [IBM]
- IBM 1410/7010 OS [IBM]
- IBSYS [IBM]
- IM/370 [IBM]
- OS/400 [IBM]
- OS/MVT [IBM]
- OS/PCP [IBM]
- SABER [IBM]
- SABRE [IBM]
- SEPP (VM/SE) [IBM]
- SRTOS [IBM]
- SSP [IBM]
- System/3
- System/32
- TOS/360 [IBM]
- TSS/360 [IBM]
- VM/CMS [IBM]
- VM/IS
- VM/IX [Interactive/IBM]
- VP/CSS [IBM]
用于IBM大型机的系统，而不是IBM开发的系统
- BOS [Fujitsu]
- BS3000 [Siemens]
- DOS/ES [Robotron]
- Edos [TSCS]
- OS ES [Soviet Union]
- OSIV/ESPIII [Fujitsu]
- OSIV/F2 [Fujitsu]
- OSIV/F4 [Fujitsu]
- OSIV/X8 [Fujitsu]
- OSIV/XSP [Fujitsu]
- VOS2 [Hitachi]
L4微内核家族
- CodeZero
- E1 Distributed OS
- Fiasco
- Fiasco.OC/L4Re
- Gnuppix GNU/Hurd-L4
- Iguana/Wombat OS
- L2/Eumel
- L4/Alpha
- L4/MIPS
- L4Ka::Pistachio (X.2)
- NICTA::L4-embedded
- NOVA
- OKL4
- Osker
- P4
- REX OS
- seL4
- TUD:OS
- WrmOS
OSEK 兼容系统
- ERIKA Enterprise
- ERCOS [ETAS]
- osCAN [Vector Informatik]
- MICROSAR OS [Vector Informatik]
- ProOSEK [3SOFT/Elektrobit]
- ProOSEK/time [3SOFT Elektrobit]
- RTA-OSEK [ETAS]
- RTA-OS [ETAS]
- tresos [3SOFT/Elektrobit]
- TTP-OS [TTTech]
- Arctic Core
- FreeOSEK
- nxtOSEK
- ev3OSEK
- openOSEK
- TOPPERS-OSEK
- Trampoline
- OSEKturbo [Metrowerks]
- Trioz OSEK RTOS [Trioztech]
- PICOS18 [Pragmatic]
- mKernel
不属于任何其他类别的其他系统和小型家族
- (Open)Genera [Genera]
- 3DS system software [Nintendo]
- A/ROSE [Apple]
- Accent (kernel)
- Admiral
- AL/1
- Aleph (kernel)
- AlliedWare [Allies Telesis]
- AMBOSS [Siemens]
- AMIGOD
- Amoeba
- AMOS [Alpha Microsystems]
- AMOS 32 [Alpha Microsystems]
- AMOS/L [Alpha Microsystems]
- AN/FSQ-32
- AOS [Burroughs]
- Apache Mynewt
- Apple II Pascal [Apple]
- ARX [Acorn]
- Atari TOS [Atari]
- Atlas I Supervisor
- AuraOS
- AVM/EF [Fujitsu]
- B1/B2/B3/B4 [NCR]
- Baget RTOS (OS2000)
- Banyan VINES [Banyan Systems]
- BareMetal [Return Infinity]
- Barrelfish [Microsoft]
- Basic Executive System
- Berkeley Timesharing System
- BESYS [Bell Labs/AT&T]
- BKY
- BLIS/COBOL [Information Processing Inc]
- Bluebottle
- BOS1810 [Robotron]
- brickOS
- BROS [Robotron]
- BS2000 [Siemens]
- BS600 [Robotron]
- BS-M [Siemens]
- CAL
- Cambridge CAP OS
- Cambridge Ring
- CapROS
- CAPS-11 [DEC]
- CAPS-8 [DEC]
- CCOS [Corvus Systems]
- CD-RTOS
- ChibiOS/RT
- Chios
- Chippewa Operating System [Cray]
- ChrysaLisp
- clix OS [iriver]
- CNK OS [IBM]
- Color BASIC [Microsoft]
- CombOS [Trueb AG/Winter AG]
- Contiki
- Copland [Apple]
- COQOS [OpenSynergy]
- COS-310/350 [DEC]
- Cosmos
- Coyotos
- CP-6 [Honeywell]
- CPC-OS [Amstrad]
- CPS (IBM Series/1) [IBM]
- Cray Operating System [Cray]
- Croquet
- CSIRONET
- CTOS [Convergent Technologies]
- Dartmouth Time Sharing System (DTSS)
- David [Microware]
- DawnOS
- DECtape Library System [DEC]
- Deos [DDC-I]
- DexOS
- DIPOS [Nixdorf]
- DiscOS
- DMS (IBM 1130) [IBM]
- DMS (IBM Series/3) [IBM]
- DNOS [Dell]
- DNOS [Texas Instruments]
- DPCX (IBM 8100) [IBM]
- DPPX (IBM 8100) [IBM]
- Dragon Slayer
- DRYOS [Canon]
- DSi system software [Nintendo]
- DSPnano RTOS [RowerBots]
- DX10 [Texas Instruments]
- DYSEAC
- eCos
- EDX (IBM Series/1) [IBM]
- EIEX [Robotron]
- Elbrus-1
- EMAS
- embOS [Segger]
- EmuTOS
- Enterprise OS [McDATA]
- EOS [ETA Systems]
- es [Nintendo]
- Essence
- ETOS
- EUROS RTOS [EUROS]
- EXEC [Unisys]
- Exec 8 [Unisys]
- Executive [ICL]
- ExtremeWare [Extreme Networks]
- Fabric OS [Brocade]
- Fontac Monitor [Fujitsu]
- FreeRTOS
- Fuchsia [Google]
- Future OS
- Galileo [Acorn]
- GAMMA-11 [DEC]
- GECOS/GCOS [General Electric]
- GeekOS
- Genode
- GEORGE [ICL]
- GEOS [Berkeley Softworks]
- Ghost OS
- GMOS [General Motors]
- Gnosis
- Harmony OS [Huawei]
- GRiD-OS
- HeartOS [DDC-I]
- HelenOS
- HEP/OS [Denelcor]
- House
- HP-1000/RTE [HP]
- HT-11 [Heathkit]
- Hubris [Oxide]
- Hurricane
- HYDRA
- IDA
- IJMON [IBM]
- ILIOS
- IMOS [NCR]
- INTEGRITY [Green Hills Software]
- INTEGRITY-178B [Green Hills Software]
- Interim OS
- IOS [Cisco]
- IronWare [Foundry Networks]
- IOP OS [Broad On] (Nintendo Wii)
- IOS U [Nintendo] (Wii U)
- IS/M [Robotron]
- ISIS [Intel]
- ITOS [CTM Computer]
- ITS
- J Operating System/LoseThos
- J/MultiJob [ICL]
- JAMB [Robotron]
- JavaOS [Sun Microsystems]
- JNode
- JOSS (on JOHNNIAC)
- JX
- K42 [IBM]
- KasperskyOS [Kaspersky]
- KDF9 Timesharing Director [English Electric]
- KERNAL [Commodore]
- KI-TELNEX
- Kitten [Sandia]
- KMON
- Knight OS
- KOBRA [Robotron]
- KolibriOS
- KRONOS [Control Data]
- LAP6-DIAL
- LCOS [Lancom Systems]
- leJOS
- LEO I OS [J. Lyons and Co.]
- Lisa OS [Apple]
- LOS
- LSE/OS
- Lua RTOS
- MACE [Control Data]
- Machine Operating System (MOS) [Acorn]
- Magic Cap [General Magic]
- MAI Basic Four
- MaRTE OS
- MARTOS [AEG]
- MARTOS-K [AEG]
- MCP [Burroughs]
- MDOS [Micropolis]
- Meetix OS
- MenuetOS
- MEOS [Robotron]
- Michigan Terminal System (MTS)
- Micro/RSTS [DEC]
- MicroC/OS [Micrium]
- MicroMore [Access]
- MicroMPX [Encore]
- micro-velOSity [Green Hills Software]
- MikeOS
- MonaOS
- MuditaOS
- MPE-A [HP]
- MPX (IBM 1800) [IBM]
- MPX-32 [Systems Engineering Labs]
- MS/8 [DEC]]
- MULTI-8 [DEC]
- MULTOS [DEC]
- MultOS/8 [DEC]
- MUMPS
- MUSIC/SP
- MZOS [Micropolis]
- Nanos
- Nemesis
- Netware [Novell]
- Newton OS [Apple]
- NitrOS-9
- NLTSS
- NonStop [Tandem]
- NOS [Control Data]
- Nucleus RTOS [Accelerated]
- Nut/OS
- NuttX
- Oberon
- Octa OS
- On Time RTOS-32 [On Time Informatik]
- OpenCatamount [Sandia]
- OpenComRTOS/Virtuoso Next [Altreonic]
- OpenRTOS [Wittenstein]
- ORVYL
- OS/78 [DEC]
- OS-9 RTOS [Microware]
- OS-9000 [Microware]
- OSC245 [Ferranti]
- OSD/BC [Fujitsu]
- OSD/XC [Fujitsu]
- OSE & OS80 [ENEA AB]
- Palm OS [Palm]
- PANOS [Acorn]
- PAPL [Robotron]
- PBS (Plattenbetriebssystem) [Siemens]
- PC-BLIS
- PDP-1 OS [DEC]
- PDP-6 Monitor [DEC]
- PEARL Operating System (POS) [Brown, Boverie & Cie]
- PenPoint OS [GO Corp]
- PERQ [Three Rivers]
- Phantom OS
- Pick
- PilOS
- PlayStation Portable system software [Sony]
- PlayStation Vita system software [Sony]
- PRIMOS [Prime]
- PS/8 [DEC]
- pSOS [Software Components Group]
- p-System
- RACS
- Rainbow
- RBASIC [Robotron]
- RC 4000 MS [Regnecentralen]
- RIOT
- RMOS [Siemens]
- RMX/iRMX [Intel]
- RockBox
- RPS (IBM Series/1) [IBM]
- RSTS-11 [DEC]
- RT-11 [DEC]
- RTEMS
- RTMOS [General Electric]
- RTOS-UH
- RTXC Quadros
- SafeRTOS [Wittenstein]
- SAGE [IBM]
- SCIOPTA RTOS
- SCOMP [BAE Systems]
- SCOPE [Control Data]
- ScreenOS [Juniper]
- SECOS
- SEPIA [Kolter Electronic]
- SeriX (IBM Series/1) [IBM]
- SHARE Operating System (SOS)
- Share/43 [Remington]
- Share/7 [Remington]
- SharpOS
- SIBO OS [Psion]
- Simultaneous Operating System (SIOS) [Control Data]
- SINTRAN I [Norsk Data]
- SIOS [Robotron]
- SIPROS [Control Data]
- SkyOS
- Solar OS
- S-OS
- Spring [Sun Microsystems]
- SPSYS
- SRT8 [DEC]
- STSS
- SUNMOS [Sandia]
- Switch system software [Nintendo]
- SymbOS
- Symobi [Miray Software]
- SYSMIC [R2E]
- SYS-PSA [Robotron]
- Taligent [Apple]
- Tape Director (WHIRLWIND I)
- TCOS [T-Systems]
- TDOS
- TENEX [DEC]
- THE multiprogramming system
- Thoth
- ThreadX [Express Logic]
- TiMOS [Alcatel-Lucent]
- TinyOS
- TI-RTOS [Texas Instruments]
- Titan Supervisor
- T-Kernel
- TME [ICL]
- TMX [NCR]
- ToaruOS
- Topaz/Taos
- TOPS-20 [DEC]
- TOPSY
- Tornado
- TriangleOS
- TRON (BTRON, CTRON, eTRON, ITRON, JTRON, microITRON
- TSOS [RCA]
- TSS-8 [DEC]
- TSX (IBM 1800) [IBM]
- TSX-32 [S&H Computer Systems]
- TX990/TXDS [Texas Instruments]
- UDOS [Robotron]
- UMES (University of Michigan Executive System)
- Unison RTOS [RoweBots]
- Urbit
- V
- Verex
- VersaDOS
- Viewpoint/GlobalView [Xerox]
- Vinix
- Virtuoso RTOS (a.k.a. Rocket)
- Visopsys
- VM2000 [Siemens]
- VME/B [ICL]
- VME/K [ICL]
- VRTX [Wind River Systems]
- VRX [NCR]
- VSOS [Wang]
- VSPWorks
- VxWorks AE [Wind River Systems]
- WAITS
- WMCS [WICAT]
- WPS [Wang]
- Xerox Alto OS [Xerox]
- Zephyr