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

See also: Operating systems timeline

Early, proprietary microcomputer OS







BAE Systems

Be Incorporated

Burroughs (later Unisys)

Convergent Technologies

Later acquired by Unisys.

Digital/Tandem Computers/Compaq/HP


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.
  • Unix-like
    • 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

ICL (formerly ICT)

LynuxWorks (originally Lynx Real-time Systems)


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



  • 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

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

Lisp-based operating systems


Other proprietary Unix-like and POSIX-compliant

SDS (Scientific Data Systems)

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

TRON Project

UNIVAC (later Unisys)


Nonproprietary Unix-like

  • TUNIS (University of Toronto)

Research Unix-like and other POSIX-compliant

Free Unix-like (aka open source)

Nonproprietary non-Unix-like

Research non-Unix-like

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

For Elektronika BK Soviet personal computer



Personal digital assistants (PDAs)

Music players



Microcontroller, Real-time


LEGO Mindstorms

See also


External links

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