List of operating systems

List of operating systems

Operating systems can be categorized by technology, ownership, licensing, working state, usage, and by many other characteristics. In practice, many of these groupings may overlap.

Early, and historically important

*CTSS (The Compatible Timeshare System, developed at MIT by Corbato, et al)
*Incompatible Timesharing System (ITS, developed at MIT for the Digital Equipment Corporation PDP-6 and PDP-10 mainframes)
*THE multiprogramming system (by Dijkstra "et al.")
*Multics (joint OS development project by Bell Labs, GE, and MIT)
*MCP (developed for Leo Computers, Leo III in 1962)Fact|date=January 2008
*The Master Program: multi-tasking OS able to run 16 programs simultaneously, used by LEO computers in the early to mid 1960s.Fact|date=January 2008
*RC 4000 Multiprogramming System (developed by Regnecentralen in 1969)

See also: Operating systems timeline

Early, proprietary microcomputer OS

*Apple Computer Apple DOS (initial version was Read-only memory firmware together with Integer BASIC; later versions included a Microsoft BASIC)
*Business Operating System (BOS) - cross platform, command-line based
*KERNAL, Tano, Smoke Signal Broadcasting, Gimix, etc)



*MOS (on the BBC Micro and BBC Master)
*RISC iX (based on 4.3BSD)


* Amiga Unix, a.k.a. Amix


*AEGIS/Domain/OS One of the first network-based systems. Ran on Apollo/Domain hardware. Later bought by Hewlett-Packard.


*Apple II
**Apple DOS
*Apple III
**SOS (Sophisticated Operating System)
*Lisa OS
**Mac OS
***System Software 1
***System Software 2
***System Software 3
***System Software 4
***System Software 5
***System Software 6
***System 7 (code-named "Big Bang")
***Mac OS 8
***Mac OS 9
***Mac OS X
****Mac OS X v10.0 (aka Mac OS X 10.0 "Cheetah")
****Mac OS X v10.1 (aka Mac OS X 10.1 "Puma")
****Mac OS X v10.2 (aka Mac OS X 10.2 "Jaguar")
****Mac OS X v10.3 (aka Mac OS X 10.3 "Panther")
****Mac OS X v10.4 (aka Mac OS X 10.4 "Tiger")
****Mac OS X v10.5 (aka Mac OS X 10.5 "Leopard")
****Mac OS X v10.6 (aka Mac OS X 10.6 "Snow Leopard")
****Mac OS X Server
***Darwin (open source underpinnings of Mac OS X, based on FreeBSD and NextStep)
***iPhone OS
***Apple Newton
****Newton OS


*Atari DOS (for 8-bit computers)
*Atari TOS
*Atari MultiTOS

BAE Systems

* XTS-400

Be Incorporated

*ZETA (Illegal copy of BeOS developed by yellowTAB and discontinued by Magnussoft)

Burroughs (later Unisys)

*MCP (Burroughs Large Systems)

Convergent Technologies

Later acquired by Unisys.

Digital/Tandem Computers/Compaq/HP

*ITS (for the PDP-6 and PDP-10)
*Multi-Programming Executive (from HP)
*TOPS-10 (for the PDP-10)
*WAITS (for the PDP-6 and PDP-10)
*TENEX (from BBN, for the PDP-10)
*TOPS-20 (for the PDP-10)
*RSTS/E (multi-user time-sharing OS for PDP-11s)
*RSX-11 (multiuser, multitasking OS for PDP-11s)
*RT-11 (single user OS for PDP-11)
*VMS (originally by DEC, now by HP) for the VAX mini-computer range, Alpha and Intel Itanium 2; later renamed OpenVMS)
*Domain/OS (originally "Aegis", from Apollo Computer who were bought by HP)
*RTE HP's Real Time Executive (ran on the HP 1000)
*TSB HP's Time Share Basic (yes, it was an operating system, ran on the HP 2000 series)
**Digital UNIX (derived from OSF/1, became HP's Tru64 UNIX)
*NonStop Kernel (Originally from Tandem Computers for their line of fault-tolerant platforms; originally called Guardian). It supports concurrent execution of:
**OSS (POSIX-compliant Open System Services)


*Towns OS

Green Hills Software

*INTEGRITY Reliable Operating system
*INTEGRITY-178B A DO-178B certified version of INTEGRITY.
*"µ-velOSity" A lightweight microkernel.


* RTE Real-time Environment; ran on HP1000 series computers.
*MPE Multi-programming Executive; ran on HP3000 mini-computers.
*HP-UX HP-UX; runs on HP9000 and Itanium servers - from small to mainframe-class computers.


*iRMX real-time operating system originally created to support the Intel 8080 and 8086 processor families in embedded applications


*IBM 7090/94 IBSYS
*SYSTEM 1400/1800 IJMON A Bootable serial I/O monitor for loading programs.
*BOS/360 Early interim version of DOS/360, briefly available at a few Alpha & Beta System 360 sites.
*TOS/360 Similar to BOS above and more fleeting, able to boot and run from 2x00 series tape drives.
*DOS/360 Disk Operating System. First commonly available OS for System/360 due to problems in the OS/360 Project. Multi-programming system with up to 3 partitions.
*DOS/360/RJE DOS/360 with a control program extension that provided for the monitoring of Remote Job Entry hardware (Card Reader & Printer) connected by dedicated phone lines.
*DOS/VSE First DOS offered on System/370 systems, provided Virtual Storage Extensions, and SNA. Still had fixed size processing partitions, but up to 14 partitions.
*DOS/VSE/ESA DOS/VSE extended virtual memory support to 32 bit addresses (Extended System Architecture).
*z/VSE Latest version of the four decades old DOS lineage. Now supports 64 bit addresses, Multiprocessing, Multiprogramming, SNA, TCP/IP, and some virtual machine features in support of Linux workloads. (All DOS ref. IBM website)
*OS/360 First official OS targeted for the System/360 architecture, saw customer installations of the following variations:
**PCP Primary Control Program, a kernel and a ground breaking automatic space allocating file system.
**MFT Multi-Programming Fixed Tasks, had 15 fixed size partitions defined at boot time.
**MVT Multi-Programming Variable Tasks, had up to 15 partitions defined dynamically.
*RTOS Real Time Operating System, run on 5 NASA custom System/360/75s. A mash up by the Federal Systems Division of the MFT system management, PCP basic kernel and file system, with MVT task management and FSD custom real time kernel extensions and error management. The pinnacle of OS/360 development.
*OS/370 The official port of OS/360 targeted for the System/370 virtual memory architecture. Customer installations in the following variations:
*OS/VS1 Virtual-memory version of OS/MFT
*OS/VS2 Virtual-memory version of OS/MVT
**SVS Single Virtual Storage (both VS1 & VS2 began as SVS systems)
**MVS Multiple Virtual Storage (eliminated any need for VS1)
*MUSIC/SP Mainframe operating system for IBM hardware, developed by McGill University
*OS/390 Upgrade to MVS, with an additional Unix-like environment.
*z/OS z/Architecture version of OS/390.
*TPF z/OS extension
*CP/CMS Control Program / Cambridge Monitor System, Virtual Machine operating System for System/360 Model 44 and 67
*VM/CMS Virtual Machine / Conversational Monitor System, VM (operating system) for System/370 with Virtual Memory.
*VM/XA VM (operating system) eXtended Architecture for System/370 with extended Virtual Memory.
*VM/ESA Virtual Machine /Extended System Architecture, added 32 bit addressing to VM series.
*z/VM z/Architecture version of the VM OS (64 bit addressing).
*IBM System/34, 36 System Support Program, or SSP
*OS/400 descendant of System/38 CPF
*i5/OS extends OS/400 with significant interoperability features.
**AIX (a System V Unix version)
**AOS (a BSD Unix version)
**GNU/Linux (IBM has contributed much code to this open source operating system, listed below)
*PC-DOS IBM supported, documented, and licensed copies of Microsoft MS-DOS
*OS/2 (developed jointly with Microsoft)
**OS/2 Warp
**eComStation (Warp 4.5/Workspace on Demand, rebundled by Serenity Systems International)
*IBM 8100 DPCX
*IBM 8100 DPPX
*K42 PowerPC or Intel x86 based cache-coherent multiprocessor systems (IBM Website)
*IBM EDX Event Driven Executive for the IBM/Series 1 minicomputers
*IBM RPS Realtime Programming System for the IBM/Series 1 minicomputers

ICL (formerly ICT)

*GEORGE 2/3/4 GEneral ORGanisational Environment, used by ICL 1900 series mainframes
*VME by International Computers Limited (ICL), particularly appearing on the ICL 2900 Series

LynuxWorks (originally Lynx Real-time Systems)



*MicroC/OS-II (Small pre-emptive priority based multi-tasking kernel)


*Xenix (licensed version of Unix; licensed to SCO in 1987)
*MSX-DOS (developed by MS Japan for the MSX 8-bit computer)
*MS-DOS (developed jointly with IBM, versions 1.0–6.22)
*Windows CE (OS for handhelds, embedded devices, and real-time applications that is similar to other versions of Windows)
**Windows CE 3.0
**Windows Mobile (based on Windows CE, but for a smaller form factor)
**Windows CE 5.0
*DOS based Windows
**Windows 1.0
**Windows 2.0
**Windows 3.0 (the first version to make substantial commercial impact)
**Windows 3.1x
**Windows 3.2 (Chinese-only release)
*Windows 9x family
**Windows 95 (aka Windows 4.0)
**Windows 98 (aka Windows 4.1) (codename: Memphis)
**Windows Millennium Edition (often shortened to Windows Me) (aka Windows 4.9)
*OS/2 (developed jointly with IBM)
*Windows NT
**Windows NT 3.1
**Windows NT 3.5
**Windows NT 3.51
**Windows NT 4.0
**Windows 2000 (aka Windows NT 5.0)
**Windows XP (aka Windows NT 5.1) (codename: Whistler)
**Windows Server 2003 (aka Windows NT 5.2) (codename: Whistler Server)
**Windows Fundamentals for Legacy PCs (aka Windows NT 5.1)
**Windows Vista (aka Windows NT 6.0) (codename: Longhorn)
**Windows Home Server
**Windows Server 2008 (aka Windows NT 6.0) (codename: Longhorn Server)
**Windows 7 (previously codenamed Blackcomb, then Vienna)
**Windows Preinstallation Environment (WinPE)
*Singularity - A research operating system written mostly in managed code (C#)
*Midori - A managed code operating system


*NetWare network operating system providing high-performance network services. Has been superseded by Open Enterprise Server line, which can be based on NetWare or Linux to provide the same set of services.
*SUSE Linux acquired by Novell which has adopted it as its core infrastructure. Novell now is a prime contributor to open-source projects based on Linux.


*BEST - Business Executive System for Timesharing


*TSOS, first OS supporting virtual addressing of the main storage and support for both timeshare and batch interface

=SCO / The SCO Group=

*Xenix, Unix System III based distribution for the Intel 8086/8088 architecture
*Xenix 286, Unix System V Release 2 based distribution for the Intel 80286 architecture
*Xenix 386, Unix System V Release 2 based distribution for the Intel 80386 architecture
*SCO Unix, SCO UNIX System V/386 was the first volume commercial product licensed by AT&T to use the UNIX System trademark (1989). Derived from AT&T System V Release 3.2 with an infusion of Xenix device drivers and utilities plus most of the SVR4 features
*SCO Open Desktop, the first 32-bit graphical user interface for UNIX Systems running on Intel processor-based computers. Based on SCO Unix
*SCO OpenServer 5, AT&T UNIX System V Release 3 based
*UnixWare 2.x, based on AT&T System V Release 4.2MP
*UnixWare 7, UnixWare 2 kernel plus parts of 3.2v5 (UnixWare 2 + OpenServer 5 = UnixWare 7). Referred to by SCO as SVR5
*SCO OpenServer 6, SVR5 (UnixWare 7) based kernel with SCO OpenServer 5 application and binary compatibility, system administration, and user environments [ cite web
url =
title = SCO History by William Bader
accessdate = 2008-04-02
] [ cite web
url =
title = Milestones in The History of The SCO Group
accessdate = 2008-04-02

Unicoi Systems

*Fusion RTOS highly prolific, license free Real-time operating system.
*DSPOS was the original project which would become the royalty free Fusion RTOS.

Wind River Systems

*VxWorks Small footprint, scalable, high-performance RTOS

Non-Standard languages

*The Mesa programming language was used to implement the Pilot operating system, used in Xerox Star workstations.
*PERQ Operating System (POS) was written in PERQ Pascal.

Lisp-based operating systems

*LISP machine Operating Systems ran on specialized processors with support for execution of Lisp code
**Symbolics Genera written in a systems dialect of the Lisp programming language called ZetaLisp and Symbolics Common Lisp. Genera was ported to a virtual machine for the DEC Alpha line of computers.
**Texas Instruments' Explorer Lisp machine workstations also had systems code written in Lisp Machine Lisp.
**The Xerox 1100 series of Lisp machines ran an operating system written in Interlisp that was also ported to virtual machine called "Medley."
**Lisp Machines, Inc. also known as LMI, also ran an operating system based on MIT's Lisp Machine Lisp.


*EOS (Operating System), developed by ETA Systems for use in their ETA-10 line of supercomputers
*EMBOS, developed by Elxsi for use on their mini-supercomputers
*GCOS is a proprietary Operating System originally developed by General Electric
*PC-MOS/386 - DOS-like, but multiuser/multitasking
*SINTRAN III - an operating system used with Norsk Data computers.
*TRS-DOS A floppy-disk-oriented OS supplied by Tandy/Radio Shack for their Z80-based line of personal computers.
*TX990/TXDS, DX10 and DNOS - proprietary operating systems for TI-990 minicomputers
*MAI Basic Four - An OS implementing Business Basic from MAI Systems.
*Michigan Terminal System - Developed by a group of American universities for IBM 360 series mainframes
*MUSIC/SP (an operating system developed for the S/370, running normally under VM)
*TSX-32, a 32-bit operating system for x86 platform.
*OS ES An operating system for ES EVM
*Prolog-Dispatcher - used to control Soviet Buran space ship.

Other proprietary Unix-like and POSIX-compliant

*Aegis (Apollo Computer)
*Amiga Unix (Amiga ports of Unix System V release 3.2 with Amiga A2500UX and SVR4 with Amiga A3000UX. Started in 1989, last version was in 1992)
*Clix (Intergraph's System V implementation)
*Coherent (Unix-like OS from Mark Williams Co. for PC class computers)
*DC/OSx (DataCenter/OSx was an operating system for MIPS based systems developed by Pyramid Technology)
*DG/UX (Data General Corp)
*DSPnano RTOS (POSIX nanokernel, DSP Optimized, Open Source)
*"Idris" workalike from Whitesmiths
*INTERACTIVE UNIX (a port of the UNIX System V operating system for Intel x86 by INTERACTIVE Systems Corporation)
*IRIX from SGI
*NeXTSTEP (developed by NeXT; a Unix-based OS based on the Mach microkernel)
*OS-9 Unix-like RTOS. (OS from Microware for Motorola 6809 based microcomputers)
*OS9/68K Unix-like RTOS. (OS from Microware for Motorola 680x0 based microcomputers; based on OS-9)
*OS-9000 Unix-like RTOS. (OS from Microware for Intel x86 based microcomputers; based on OS-9, written in C)
*OSF/1 (developed into a commercial offering by Digital Equipment Corporation)
*QNX (POSIX, microkernel OS; usually a real time embedded OS)
*Pardus (Turkish Linux)
*Rhapsody (an early form of Mac OS X)
*RISC/os (a port by MIPS of 4.3BSD to the RISC MIPS architecture)
*SCO UNIX (from SCO, bought by Caldera who renamed themselves SCO Group)
*SINIX (a port by SNI of Unix to the RISC MIPS architecture)
*Solaris (Sun's System V-based replacement for SunOS)
*SunOS (BSD-based Unix system used on early Sun hardware)
*SUPER-UX (a port of System V Release 4.2MP with features adopted from BSD and Linux for NEC SX architecture supercomputers)
*System V (a release of AT&T Unix, 'SVR4' was the 4th minor release)
*System V/AT, 386 (The first version of AT&T System V UNIX on the IBM 286 and 386 PCs, ported and sold by Microport)
*Trusted Solaris (Solaris with kernel and other enhancements to support multilevel security)
*UniFlex (Unix-like OS from TSC for DMA-capable, extended addresses, Motorola 6809 based computers; e.g. SWTPC, GIMIX, …)
*Unicos (the version of Unix designed for Cray Supercomputers, mainly geared to vector calculations)
*Unison RTOS (Multicore RTOS with DSP Optimization)

DS (Scientific Data Systems)

*CP Control Program. SDS later acquired by Xerox, then Honeywell.

TRON Project

*TRON (an open real-time operating system kernel)

UNIVAC (later Unisys)

*EXEC 8 Ran on 1100 series.
*VS/9, successor to RCA TSOS


*Open AT OS

Nonproprietary Unix-like

*TUNIS (University of Toronto)

Research Unix-like and other POSIX-compliant

*Minix (study OS developed by Andrew S. Tanenbaum in the Netherlands)
*Plan 9 (distributed OS developed at Bell Labs, based on original Unix design principles yet functionally different and going much further)
**Inferno (distributed OS derived from Plan 9, originally from Bell Labs)
**Plan B (distributed OS derived from Plan 9 and Off++ microkernel)
*Solaris, contains original Unix (SVR4) code (code now open source via OpenSolaris project)
*Unix (OS developed at Bell Labs ca 1970 initially by Ken Thompson)
*Xinu, (Study OS developed by Douglas E. Comer in the USA)

=Free Unix-like (aka open source)=

*BSD (Berkeley Software Distribution, a variant of Unix for DEC VAX hardware)
**FreeBSD (one of the outgrowths of UC Regents' abandonment of CSRG's 'BSD Unix')
***DesktopBSD FreeBSD distribution for desktop use
***PC-BSD FreeBSD distribution for desktop use
***DragonFly BSD forked from FreeBSD
**NetBSD (one of the outgrowths of UC Regents' abandonment of CSRG's 'BSD Unix')
***OpenBSD forked from NetBSD
*OpenSolaris, contains original Unix (SVR4) code
*SSS-PC Developed at Tokyo University

Nonproprietary non-Unix-like

Research non-Unix-like

*Amoeba (research OS by Andrew S. Tanenbaum)
*House Haskell User's Operating System and Environment, research OS written in Haskell and C.
*ILIOS Research OS designed for routing
*EROS microkernel, capability-based
**CapROS microkernel EROS successor.
**Coyotos microkernel EROS successor, goal: be first formally verified OS.
*L4 Second generation microkernel
*Mach (from OS kernel research at Carnegie Mellon University; see NeXTSTEP)
*MONADS capability-based OS designed to support the MONADS hardware projects
**SPEEDOS (Secure Persistent Execution Environment for Distributed Object Systems) builds on MONADS ideas
*Nemesis Cambridge University research OS - detailed quality of service abilities.
*Singularity - A research operating system written mostly in managed code (C#) by Microsoft.
*Spring (research OS from Sun Microsystems)
*V from Stanford, early 1980s [ Capability-Based Computer Systems] ]

Open source non-Unix-like

*FullPliant (programming language based)
*FreeDOS (open source DOS variant)
*FreeVMS (open source VMS variant)
*Haiku (open source inspired by BeOS, under development)
*ReactOS (free software Windows NT compatible OS, in early development since 2001)
*osFree (open source OS/2 implementation)

Disk Operating System

*DR-DOS (Digital Research's [later Novell, Caldera, ...] DOS variant)
**Concurrent DOS (Digital Research's first multiuser DOS variant)
**Multiuser DOS (Digital Research's [later CCI's. Real's/...] multiuser DOS variant)
*FreeDOS (open source DOS variant)
*ProDOS (operating system for the Apple II series computers)
*PTS-DOS (DOS variant by Russian company Phystechsoft)
*86-DOS (developed at Seattle Computer Products by Tim Paterson for the new Intel 808x CPUs; licensed to Microsoft, became MS-DOS/PC-DOS. Also known by its working title QDOS.)
**MS-DOS (Microsoft's now abandoned DOS variant)
**PC-DOS (IBM's DOS variant)
*RDOS (Data General Corp)
**TurboDOS (Software 2000, Inc.)
*Multi-tasking user interfaces and environments for DOS
** DESQview+ QEMM 386 multi-tasking user interface for DOS
** DESQView/X (X-windowing GUI for DOS)


*Cambridge Ring
*CTOS (Convergent Technologies, later acquired by Unisys)
*Data ONTAP by NetApp
*SAN-OS by Cisco
*Fabric OS by Brocade
*NetWare (networking OS by Novell)
*NOS (developed by CDC for use in their Cyber line of supercomputers)
*Novell Open Enterprise Server (Open Source networking OS by Novell. Can incorporate either SUSE Linux or Novell NetWare as its kernel).
*Plan 9 (distributed OS developed at Bell Labs, based on Unix design principles but not functionally identical)
**Inferno (distributed OS derived from Plan 9, originally from Bell Labs)
**Plan B (distributed OS derived from Plan 9 and Off++ microkernel)
**TurboDOS (Software 2000, Inc.)

Web operating systems

*Browser OS

Generic/commodity, non-Unix, and other

*Bluebottle also known as AOS (a concurrent and active object update to the Oberon operating system)
*BS1000 by Siemens AG
*BS2000 by Siemens AG, now BS2000/OSD from Fujitsu-Siemens Computers (formerly Siemens Nixdorf Informationssysteme)
*BS3000 by Siemens AG (functionally similar to OS-IV and MSP from Fujitsu)
*Control Program/Monitor (CP/M)
**CP/M-80 (CP/M for Intel 8080/8085 and Zilog Z80 from Digital Research)
**CP/M-86 (CP/M for Intel 8088/86 from Digital Research)
**CP/M-68k (CP/M for Motorola 68000 from Digital Research)
**CP/M-8000 (CP/M for Zilog Z8000 from Digital Research)
**MP/M-80 (Multi programming version of CP/M-80 from Digital Research)
**MP/M-86 (Multi programming version of CP/M-86 from Digital Research)
*FLEX9 (by TSC for Motorola 6809 based machines; successor to FLEX, which was for Motorola 6800 CPUs)
*FutureOS (for Amstrad/Schneider CPC6128 and CPCPlus machines)
*GEM (windowing GUI for CP/M, DOS, and Atari TOS)
*GEOS (popular windowing GUI for PC, Commodore, Apple computers)
*JNode's OS written 99% in Java (native compiled), provides own JVM and JIT compiler. Based on GNU Classpath
*JX Java operating system that focuses on a flexible and robust operating system architecture developed as an open source system by the University of Erlangen.
*KERNAL (default OS on Commodore 64)
*MERLIN for the Corvus Concept
*MorphOS (by Genesi)
*MSP by Fujitsu (successor to OS-IV), now MSP/EX for 31-bit mode
*nSystem by Luis Mateu at DCC, Universidad de Chile
*NetWare (networking OS by Novell)
*Oberon operating system (developed at ETH-Zürich by Niklaus Wirth et al) for the Ceres and Chameleon workstation projects. see also Oberon programming language
*OSD/XC by Fujitsu-Siemens (BS2000 ported to an emulation on a Sun SPARC platform)
*OS-IV by Fujitsu (based on early versions of IBM's MVS)
*Pick (often licensed and renamed)
*PRIMOS by Prime Computer (sometimes spelled PR1MOS and PR1ME)
*Sinclair QDOS (multitasking for the Sinclair QL computer)
*SkyOS (Commercial desktop OS for PCs)
*SSB-DOS (by TSC for Smoke Signal Broadcasting; a variant of FLEX in most respects)
*SymbOS (GUI based multitasking operating system for Z80 computers)
*Symobi (GUI based modern micro-kernel OS for x86, ARM and PowerPC processors, used and developed further at Technical University of Munich)
*TripOS, 1978
**TurboDOS (Software 2000, Inc.)
*UCSD p-System (portable complete programming environment/operating system/virtual machine developed by a long running student project at the Univ Calif/San Diego; directed by Prof Ken Bowles; written in Pascal)
*UMIX, made for the ICFP Programming Contest 2006.
*VOS by Stratus Technologies with strong influence from Multics
*VOS by Hitachi for its IBM-compatible mainframes, based on IBM's MVS
*VM2000 by Siemens AG
*VisiOn (first GUI for early PC machines; not commercially successful)
*VPS/VM (IBM based, main operating system at Boston University for over 10 years.)
*aceos under GPL
*Miraculix Russian OS, under unknown license.

For Elektronika BK Soviet personal computer

* DOSB10
* MicroDOS
* PascalDOS
* RT-11
** ROM embedded
** RT-11SJ
** OS BK-11 (RT-11 version)
* Turbo-DOS


*AROS (AROS Research Operating System, formerly known as Amiga Research Operating System)
*AtheOS branched to become Syllable
*DexOS, (Game console-like operating system for 32-bit x86 computers)
*FAMOS Foremost Advanced Memory Operating System (webpage: )
*KolibriOS (fork of MenuetOS)
*MenuetOS (extremely compact OS with GUI, written entirely in FASM assembly language)
*Syllable (a modern, independently originated OS; see AtheOS)


*Embedded Linux
*Inferno (distributed OS originally from Bell Labs)
*.NET Micro Framework
*Open AT OS
*polyBSD (embedded NetBSD)
*RTXC Quadros RTOS by Quadros Systems
*Windows XP Embedded
*Windows CE

Personal digital assistants (PDAs)

*Inferno (distributed OS originally from Bell Labs)
*Palm OS from Palm Inc; now spun off as PalmSource
*EPOC originally from Psion (UK), now from Symbian, preferred name now is Symbian OS
*Windows CE, from Microsoft
**Pocket PC from Microsoft, a variant of Windows CE.
**Windows Mobile from Microsoft, a variant of Windows CE.
*Linux on Sharp Zaurus and Ipaq
*DOS on Poqet PC
*Newton OS on Apple Newton Messagepad
*VT-OS for the Vtech Helio
*Internet Tablet OS based on Debian Linux and deployed on Nokia's Nokia 770, N800 and N810 Internet Tablets.
* Magic Cap

Music players



*BlackBerry OS
*Embedded Linux
**Openmoko Linux
**LiMo Platform
*iPhone OS
*JavaFX Mobile
*Palm OS
*Symbian OS
*Windows CE
**Windows Mobile


* AirOS by Ubiquiti networks
* CatOS by Cisco Systems
* Cisco IOS (originally Internetwork Operating System) by Cisco Systems
* CyROS by Cyclades
* DD-WRT by NewMedia-NET
* Inferno (distributed OS originally from Bell Labs)
* IOS-XR by Cisco Systems
* JunOS by Juniper Networks
* RouterOS by Mikrotik
* ROX by Ruggedcom
* ScreenOS by Juniper Networks originally from Netscreen

Microcontroller, Real-time

*ChibiOS/RT GPL licensed RTOS
*Contiki written in C
* DSPnano RTOS (POSIX nanokernel, DSP Optimizations, Open Source)
*embOS (Segger)
*Fusion RTOS
*INtime RTOS for Windows, an evolutionary variant of iRMX for Windows designed for 32-bit Windows platforms
*iRMX (originally developed by Intel)
*Inferno (distributed OS originally from Bell Labs)
*LUnix written in 6502
*MontaVista Linux (see also Embedded Linux)
*OS-9 by Microware
*Operating System Embedded: OSE
*RTEMS (Real-Time Executive for Multiprocessor Systems)
*RTLinux by Wind River Systems
*RTXC Quadros RTOS by Quadros Systems
*TRON Project and ITRON Project (related to BTRON, CTRON, MTRON, etc.)
*µOS++ (micro OS plus plus)
*Unison Operating System / Unison DSP Operating System (RTOS) / Unison RTOS (Multicore DSP Operating System)
*VRTX / Versatile Real-Time Executive
*VxWorks by Wind River Systems
*XMK (eXtreme Minimal Kernel)


*KeyKOS nanokernel
**EROS microkernel
***CapROS EROS successor
***Coyotos EROS successor, goal: be first formally verified OS
*MONADS designed to support the MONADS hardware projects.
**SPEEDOS builds on MONADS ideas
*V from Stanford, early 1980s

LEGO Mindstorms

*BrickOS operating system
*leJOS operating system
*ChyanOS operating system

ee also

* Comparison of operating systems
* List of Real-time operating systems


External links

* [ A catalog of operating systems]
* [ Google directory of Operating Systems]

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