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
See also: Operating systems timeline
Early, proprietary microcomputer OS
Burroughs (later Unisys)
Later acquired by Unisys
Green Hills Software
- 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)
- 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
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)
- DOS based Windows
- Windows 9x family
- OS/2 (developed jointly with IBM)
- Windows NT
- 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
- 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
- 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
Lisp-based operating systems
- LISP machine Operating Systems ran on specialized processors with support for execution of Lisp code
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)
- DNIX from DIAB
- 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)
SDS (Scientific Data Systems)
- CP Control Program. SDS later acquired by Xerox, then Honeywell.
UNIVAC (later Unisys)
- TUNIS (University of Toronto)
Research Unix-like and other POSIX-compliant
- 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
- 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
Open source non-Unix-like
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)
- Multi-tasking user interfaces and environments for DOS
Web operating systems
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)
- 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 JNode.org'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
- 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
Personal digital assistants (PDAs)
- KeyKOS nanokernel
- MONADS designed to support the MONADS hardware projects.
- SPEEDOS builds on MONADS ideas
- V from Stanford, early 1980s