List of operating systems

• CTSS (The Compatible TimeShare System, made at MIT by Corbato and others)
• Incompatible Timesharing System (The Incompatible Timeshare System, made at MIT)
• Multics (project by Bell Labs, GE, and MIT)
• Master programme for Leo Computers, Leo III in 1962
• THE operating system (by Dijkstra and others)

• Apple Computer (first version was firmware with Integer BASIC; later versions had Microsoft BASIC)
• Business Operating System (BOS) - cross platform, text-based
• Commodore PET, Commodore 64, and Commodore VIC-20,
• First IBM-PC had 3 OSes to start, UCSD P-system, CPM-86, PC-DOS
• Flex (by Technical Systems Consultants for Motorola 6800 based computers: SWTPC, Tano, Smoke Signal Broadcasting, Gimix, etc.)
• FLEX9 (by TSC for Motorola 6809 based micros)
• mini-FLEX (by TSC for 5.25" disks on 6800 based machines)
• Sinclair Micro and QX, etc.
• TRS-DOS, ROM OS's (largely Microsoft BASIC implementations with file system extensions)
• TI99-4

• AIX (Unix from IBM)
• Amoeba (research OS by Andrew S. Tanenbaum)
• AtheOS (continued with the Syllable code-fork)
• A/UX (Unix Apple OS from start of 1990s)
• BSD (Berkeley Software Distribution, a type of Unix)
• Cromix (Unix-emulating OS from Cromemco)
• Coherent (Unix-emulating OS from Mark Williams Co.)
• DNIX
• Digital UNIX (later, HP's Tru64 for Digital's AXP 64-bit computers)
• FreeBSD (Version of abandoned BSD with free source code)
• GNU/Hurd
• Haiku (operating system)
• HP-UX from HP
• Idris from Whitesmiths
• IRIX from SGI
• LainOS (FreeBSD project, a tried version of "Navi" GUI from Serial Experiments Lain)
• Linux (free Unix-like kernel)
• Minix (educational OS by Andrew S. Tanenbaum in the Netherlands)
• NetBSD (post-CSRG open source type of BSD)
• NeXTSTEP (foundation for OS X)
• OS-9 (not to be confused with Mac OS 9)
• OS-9/68k
• OS-9000 (OS-9 written in C)
• OS/360
• OSF/1
• OS X from Apple Inc.
• OpenBSD (post-CSRG open source type of BSD)
• OPENSTEP NeXTSTEP on Intel x86, HP PA-RISC, and different architectures.
• Plan 9 (by Bell Labs)
• QNX (POSIX, microkernel OS)
• Rhapsody
• RiscOS
• SCO UNIX (from SCO, purchased by Caldera)
• Solaris from Sun Microsystems
• SunOS from Sun Microsystems (became Solaris)
• System V (a release of AT&T Unix, 'SVr4' was the 4th minor release)
• UNIX (OS developed at Bell Labs in 1970 first by Ken Thompson)
• UNIflex (Unix emulating OS by TSC)
• Ultrix (DEC's first version of Unix for VAX, PDP-11, MIPS, and Decstation computers)
• UniCOS from Cray
• Xenix (Microsoft's version of Unix)
• z/OS (IBM mainframe OS)

• AOS, now called Bluebottle(update to Oberon operating system)
• AROS (Amiga Research Operating System)
• Bluebottle (see AOS)
• BS2000 by Siemens AG
• Control Program/Monitor-80 (CPM operating system)
• CP/M-86 (by Digital Research)
• DESQView (windowing GUI for MS-DOS,1985)
• DR-DOS (MS-DOS compatible OS from Digital Research)
• FLEX9 (by TSC)
• FreeDOS (open source, free MS-DOS alternative)
• GEM (GUI for MS-DOS by Digital Research)
• GEOS
• MS-DOS (Microsoft purchased from Seattle Computer)
• MorphOS (by Genesi)
• NetWare (by Novell)
• NeXTStep (Foundation for OS X)
• PC-DOS (IBM's version of MS-DOS)
• Pick
• Plan 9, Inferno (networked OS by Bell Labs)
• Primos by Prime Computer
• Mach (kernel by CMU, used in NeXTStep and OS X)
• MP/M-80 (by Digital Research)
• NewOS
• Oberon operating system (developed at ETH-Zürich by Niklaus Wirth)
• OS/2 Windows/MS-DOS compatible operating system made in a Microsoft and IBM project, but later Microsoft stopped when they wanted to work on Windows NT more; which was better than early Windows versions and MS-DOS.
• OS-9 (Unix emulating OS from Microware)
• OS-9/68k (Unix emulating OS from Microware)
• OS-9000 (portable Unix emulating OS from Microware)
• SSB-DOS (by TSC for Smoke Signal Broadcasting; a variant of FLEX)
• TripOS
• TUNES
• QDOS (made at Seattle Computer Products by Tim Paterson for new Intel 808x CPUs. Given to Microsoft—soon became MS-DOS)
• UCSD P-system (OS by a student project at the University of California, San Diego; directed by Prof Ken Bowles)
• VisiOn (first GUI for early PC machines, not successful)
• Visopsys (hobby OS for PCs)
• VME by International Computers Limited (ICL)
• Randolf by United Computer inc,
• Vision (first GUI for early PC machines, not successful, by Microware)

Operating systems written for a hobby.

• ReactOS (an open source OS that runs Windows NT applications natively)
• Panalix
• MenuetOS
• SkyOS

• Arthur
• ARX
• RISC OS (was later open sourced under a fully free/open source license)
• RISCiX

• AmigaOS
• AmigaOS 4

• MultiTOS
• MiNT
• TOS

• Apple DOS
• A/UX
• Darwin
• GS/OS
• iOS
• Macintosh/Mac OS classic
• macOS
• Newton OS
• ProDOS

• BeOS
• BeIA
• Zeta

• AIS
• ITS (for the PDP-6 and PDP-10)
• OS-8
• RSTS/E (ran on several machines, chiefly PDP-11s)
• RSX-11 (multi-user, multitasking OS for PDP-11s)
• RT-11 (single user OS for PDP-11)
• TENEX (from BBN)
• TOPS-10 (for the PDP-10)
• TOPS-20 (for the PDP-10)
• VMS (by DEC for the VAX mini-computer type; later renamed OpenVMS)
• WAITS

• AIX (a version of Unix)
• ALCS
• Basic Operating System (first system released for the System 360, as an interim)
• DOS/VSE
• MFT (later called OV/VS1)
• MVS (latest variant of MVT)
• MVT (later called OV/VS2)
• OS/2
• OS/360 (first OS planned for the System 360 architecture)
• OS/390
• OS/400
• PC-DOS (IBM's version of DOS)
• SVS
• TPF
• VM/CMS
• z/OS

• Xenix
• MS-DOS
• Microsoft Windows
  • Windows 1.0x (Mostly text interface organised into windows, because graphical hardware was expensive at the time)
  • Windows 2.X
  • Windows 3.X
  • Windows NT
  • Windows NT 4.0
  • Windows 9x
  • Windows Me
  • Windows 2000
  • Windows XP (based on code of Windows 2000, was first "non-business" version of Windows NT)
  • Windows Server 2003
  • Windows Vista
  • Windows Server 2008
  • Windows 7
  • Windows Server 2008 R2
  • Windows 8
  • Windows Server 2012
  • Windows 8.1
  • Windows Server 2012 R2
  • Windows 10
  • Windows Server 2016
  • Windows Server 2019
  • Windows 11
• Xenix

• EPOC, today is named Symbian OS
• iOS from Apple
• Newton OS from Apple, for Apple Newton MessagePad
• Palm OS from Palm Inc
• Pocket PC from Microsoft
• Windows CE (Windows Compact Edition, from Microsoft)

Little operating systems that run on small devices.

• Contiki
• INTEGRITY
• ITRON
• Nucleus RTOS
• OSEK
• QNX
• ThreadX
• TRON OS by Ken Sakamura
• VxWorks
• µCLinux
• eCos

Operating systems that have only appeared in fiction or as jokes.

• Lcars - From Star Trek
• ALTIMIT OS - From .hack
• Digitronix - From The Hacker Files
• Hyper OS - From the movie Patlabor
• Penix - Funny word formed from Microsoft Xenix and a not great word
• Wheatonix - April fool's joke.
• GLADOS - Genetic Lifeform and Disk Operating System
• Lex/OS - From DCEU/DCU

• Computer software
• Disk operating system