Tag Archives: Operating Systems

Comparison of Operating Systems

From Wikipedia, the free encyclopedia

These tables provide a comparison of operating systems, of computer devices, as listing general and technical information for a number of widely used and currently available PC or handheld (including smartphone and tablet computer) operating systems. The article “Usage share of operating systems” provides a broader, and more general, comparison of operating systems that includes servers, mainframes and supercomputers.

Because of the large number and variety of available Linux distributions, they are all grouped under a single entry; see comparison of Linux distributions for a detailed comparison. There is also a variety of BSD and DOS operating systems, covered in comparison of BSD operating systems and comparison of DOS operating systems. For information on views of each operating system, see operating system advocacy.

General Information

General Information

Technical Information

Technical information




For POSIX compliant (or partly compliant) systems like FreeBSD, Linux, macOS or Solaris, the basic commands are the same because they are standardized.



History of Operating Systems

From Wikipedia, the free encyclopedia

Computer operating systems (OSes) provide a set of functions needed and used by most application programs on a computer, and the links needed to control and synchronize computer hardware. On the first computers, with no operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for peripheral devices like printers and punched paper card readers. The growing complexity of hardware and application programs eventually made operating systems a necessity for everyday use.

1 Background
2 Mainframes
2.1 Systems on IBM hardware
2.2 Other mainframe operating systems
3 Minicomputers
4 Microcomputers
4.1 Home computers
4.2 Operating systems in video games and consoles
4.3 Personal computer era
4.4 Mobile operating systems
5 Rise of virtualization


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The earliest computers were mainframes that lacked any form of operating system. Each user had sole use of the machine for a scheduled period of time and would arrive at the computer with program and data, often on punched paper cards and magnetic or paper tape. The program would be loaded into the machine, and the machine would be set to work until the program completed or crashed. Programs could generally be debugged via a control panel using dials, toggle switches and panel lights.

Symbolic languages, assemblers, and compilers were developed for programmers to translate symbolic program-code into machine code that previously would have been hand-encoded. Later machines came with libraries of support code on punched cards or magnetic tape, which would be linked to the user’s program to assist in operations such as input and output. This was the genesis of the modern-day operating system; however, machines still ran a single job at a time. At Cambridge University in England the job queue was at one time a washing line from which tapes were hung with different colored clothes-pegs to indicate job-priority.

As machines became more powerful the time to run programs diminished, and the time to hand off the equipment to the next user became large by comparison. Accounting for and paying for machine usage moved on from checking the wall clock to automatic logging by the computer. Run queues evolved from a literal queue of people at the door, to a heap of media on a jobs-waiting table, or batches of punch-cards stacked one on top of the other in the reader, until the machine itself was able to select and sequence which magnetic tape drives processed which tapes. Where program developers had originally had access to run their own jobs on the machine, they were supplanted by dedicated machine operators who looked after the machine and were less and less concerned with implementing tasks manually. When commercially available computer centers were faced with the implications of data lost through tampering or operational errors, equipment vendors were put under pressure to enhance the runtime libraries to prevent misuse of system resources. Automated monitoring was needed not just for CPU usage but for counting pages printed, cards punched, cards read, disk storage used and for signaling when operator intervention was required by jobs such as changing magnetic tapes and paper forms. Security features were added to operating systems to record audit trails of which programs were accessing which files and to prevent access to a production payroll file by an engineering program, for example.

All these features were building up towards the repertoire of a fully capable operating system. Eventually the runtime libraries became an amalgamated program that was started before the first customer job and could read in the customer job, control its execution, record its usage, reassign hardware resources after the job ended, and immediately go on to process the next job. These resident background programs, capable of managing multistep processes, were often called monitors or monitor-programs before the term “operating system” established itself.

An underlying program offering basic hardware-management, software-scheduling and resource-monitoring may seem a remote ancestor to the user-oriented OSes of the personal computing era. But there has been a shift in the meaning of OS. Just as early automobiles lacked speedometers, radios, and air-conditioners which later became standard, more and more optional software features became standard features in every OS package, although some applications such as database management systems and spreadsheets remain optional and separately priced. This has led to the perception of an OS as a complete user-system with an integrated graphical user interface, utilities, some applications such as text editors and file managers, and configuration tools.

The true descendant of the early operating systems is what is now called the “kernel”. In technical and development circles the old restricted sense of an OS persists because of the continued active development of embedded operating systems for all kinds of devices with a data-processing component, from hand-held gadgets up to industrial robots and real-time control-systems, which do not run user applications at the front-end. An embedded OS in a device today is not so far removed as one might think from its ancestor of the 1950s.

The broader categories of systems and application software are discussed in the computer software article.


The first operating system used for real work was GM-NAA I/O, produced in 1956 by General Motors’ Research division for its IBM 704. Most other early operating systems for IBM mainframes were also produced by customers.

Early operating systems were very diverse, with each vendor or customer producing one or more operating systems specific to their particular mainframe computer. Every operating system, even from the same vendor, could have radically different models of commands, operating procedures, and such facilities as debugging aids. Typically, each time the manufacturer brought out a new machine, there would be a new operating system, and most applications would have to be manually adjusted, recompiled, and retested.

Systems on IBM Hardware

The state of affairs continued until the 1960s when IBM, already a leading hardware vendor, stopped work on existing systems and put all its effort into developing the System/360 series of machines, all of which used the same instruction and input/output architecture. IBM intended to develop a single operating system for the new hardware, the OS/360. The problems encountered in the development of the OS/360 are legendary, and are described by Fred Brooks in The Mythical Man-Month—a book that has become a classic of software engineering. Because of performance differences across the hardware range and delays with software development, a whole family of operating systems was introduced instead of a single OS/360.

IBM wound up releasing a series of stop-gaps followed by two longer-lived operating systems:

  • OS/360 for mid-range and large systems. This was available in three system generation options:
    • PCP for early users and for those without the resources for multiprogramming.
    • MFT for mid-range systems, replaced by MFT-II in OS/360 Release 15/16. This had one successor, OS/VS1, which was discontinued in the 1980s.
    • MVT for large systems. This was similar in most ways to PCP and MFT (most programs could be ported among the three without being re-compiled), but has more sophisticated memory management and a time-sharing facility, TSO. MVT had several successors including the current z/OS.
  • DOS/360 for small System/360 models had several successors including the current z/VSE. It was significantly different from OS/360.

IBM maintained full compatibility with the past, so that programs developed in the sixties can still run under z/VSE (if developed for DOS/360) or z/OS (if developed for MFT or MVT) with no change.

IBM also developed TSS/360, a time-sharing system for the System/360 Model 67. Overcompensating for their perceived importance of developing a timeshare system, they set hundreds of developers to work on the project. They ended up with a bloated, buggy project that took as long to boot as it did to crash, and ended the project without releasing it.

Several operating systems for the IBM S/360 and S/370 architectures were developed by third parties, including the Michigan Terminal System (MTS) and MUSIC/SP.

Other Mainframe Operating Systems

Control Data Corporation developed the SCOPE operating systems] in the 1960s, for batch processing and later developed the MACE operating system for time sharing, which was the basis for the later Kronos. In cooperation with the University of Minnesota, the Kronos and later the NOS operating systems were developed during the 1970s, which supported simultaneous batch and timesharing use. Like many commercial timesharing systems, its interface was an extension of the DTSS time sharing system, one of the pioneering efforts in timesharing and programming languages.

In the late 1970s, Control Data and the University of Illinois developed the PLATO system, which used plasma panel displays and long-distance time sharing networks. PLATO was remarkably innovative for its time; the shared memory model of PLATO’s TUTOR programming language allowed applications such as real-time chat and multi-user graphical games.

For the UNIVAC 1107, UNIVAC, the first commercial computer manufacturer, produced the EXEC I operating system, and Computer Sciences Corporation developed the EXEC II operating system and delivered it to UNIVAC. EXEC II was ported to the UNIVAC 1108. Later, UNIVAC developed the EXEC 8 operating system for the 1108; it was the basis for operating systems for later members of the family. Like all early mainframe systems, EXEC I and EXEC II were a batch-oriented system that managed magnetic drums, disks, card readers and line printers; EXEC 8 supported both batch processing and on-line transaction processing. In the 1970s, UNIVAC produced the Real-Time Basic (RTB) system to support large-scale time sharing, also patterned after the Dartmouth BASIC system.

Burroughs Corporation introduced the B5000 in 1961 with the MCP (Master Control Program) operating system. The B5000 was a stack machine designed to exclusively support high-level languages, with no software, not even at the lowest level of the operating system, being written directly in machine language or assembly language; the MCP was the first OS to be written entirely in a high-level language – ESPOL, a dialect of ALGOL 60 – although ESPOL had specialized statements for each “syllable” in the B5000 instruction set. MCP also introduced many other ground-breaking innovations, such as being one of the first commercial implementations of virtual memory. The rewrite of MCP for the B6500 is still in use today in the Unisys ClearPath/MCP line of computers.

GE introduced the GE-600 series with the General Electric Comprehensive Operating Supervisor (GECOS) operating system in 1962. After Honeywell acquired GE’s computer business, it was renamed to General Comprehensive Operating System (GCOS). Honeywell expanded the use of the GCOS name to cover all its operating systems in the 1970s, though many of its computers had nothing in common with the earlier GE 600 series and their operating systems were not derived from the original GECOS.

Project MAC at MIT, working with GE and Bell Labs, developed Multics, which introduced the concept of ringed security privilege levels.

Digital Equipment Corporation developed TOPS-10 for its PDP-10 line of 36-bit computers in 1967. Before the widespread use of Unix, TOPS-10 was a particularly popular system in universities, and in the early ARPANET community. Bolt, Beranek, and Newman developed TENEX for a modified PDP-10 that supported demand paging; this was another popular system in the research and ARPANET communities, and was later developed by DEC into TOPS-20.

Scientific Data Systems/Xerox Data Systems developed several operating systems for the Sigma series of computers, such as the Basic Control Monitor (BCM), Batch Processing Monitor (BPM), and Basic Time-Sharing Monitor (BTM). Later, BPM and BTM were succeeded by the Universal Time-Sharing System (UTS); it was designed to provide multi-programming services for online (interactive) user programs in addition to batch-mode production jobs, It was succeeded by the CP-V operating system, which combined UTS with the heavily batch-oriented Xerox Operating System (XOS).


Digital Equipment Corporation created several operating systems for its 16-bit PDP-11 machines, including the simple RT-11 system, the time-sharing RSTS operating systems, and the RSX-11 family of real-time operating systems, as well as the VMS system for the 32-bit VAX machines.

Several competitors of Digital Equipment Corporation such as Data General, Hewlett-Packard, and Computer Automation created their own operating systems. One such, “MAX III”, was developed for Modular Computer Systems Modcomp II and Modcomp III computers. It was characterised by its target market being the industrial control market. The Fortran libraries included one that enabled access to measurement and control devices.

IBM’s key innovation in operating systems in this class (which they call “mid-range”), was their “CPF” for the System/38. This had capability-based addressing, used a machine interface architecture to isolate the application software and most of the operating system from hardware dependencies (including even such details as address size and register size) and included an integrated RDBMS. The succeeding OS/400 for the AS/400 has no files, only objects of different types and these objects persist in very large, flat virtual memory, called a single-level store. i5/OS and later IBM i for the iSeries continue this line of operating system.

The Unix operating system was developed at AT&T Bell Laboratories in the late 1960s, originally for the PDP-7, and later for the PDP-11. Because it was essentially free in early editions, easily obtainable, and easily modified, it achieved wide acceptance. It also became a requirement within the Bell systems operating companies. Since it was written in the C language, when that language was ported to a new machine architecture, Unix was also able to be ported. This portability permitted it to become the choice for a second generation of minicomputers and the first generation of workstations. By widespread use it exemplified the idea of an operating system that was conceptually the same across various hardware platforms, and later became one of the roots of the free software and open source including GNU, Linux, and the Berkeley Software Distribution. Apple’s macOS is also based on Unix via NeXTSTEP and FreeBSD.

The Pick operating system was another operating system available on a wide variety of hardware brands. Commercially released in 1973 its core was a BASIC-like language called Data/BASIC and a SQL-style database manipulation language called ENGLISH. Licensed to a large variety of manufacturers and vendors, by the early 1980s observers saw the Pick operating system as a strong competitor to Unix.


Beginning in the mid-1970s, a new class of small computers came onto the marketplace. Featuring 8-bit processors, typically the MOS Technology 6502, Intel 8080, Motorola 6800 or the Zilog Z80, along with rudimentary input and output interfaces and as much RAM as practical, these systems started out as kit-based hobbyist computers but soon evolved into an essential business tool.

Home computers
While many eight-bit home computers of the 1980s, such as the BBC Micro, Commodore 64, Apple II series, the Atari 8-bit, the Amstrad CPC, ZX Spectrum series and others could load a third-party disk-loading operating system, such as CP/M or GEOS, they were generally used without one. Their built-in operating systems were designed in an era when floppy disk drives were very expensive and not expected to be used by most users, so the standard storage device on most was a tape drive using standard compact cassettes. Most, if not all, of these computers shipped with a built-in BASIC interpreter on ROM, which also served as a crude command line interface, allowing the user to load a separate disk operating system to perform file management commands and load and save to disk. The most popular home computer, the Commodore 64, was a notable exception, as its DOS was on ROM in the disk drive hardware, and the drive was addressed identically to printers, modems, and other external devices.

More elaborate operating systems were not needed in part because most such machines were used for entertainment and education, and seldom used for more serious business or science purposes.

Another reason is that the hardware they used was (largely) fixed and a need for an operating system to abstract away differences was thus not needed. They shipped with minimal amounts of computer memory—4-8 kilobytes was standard on early home computers—as well as 8-bit processors without specialized support circuitry like a MMU or even a dedicated real-time clock. On this hardware, a complex operating system’s overhead supporting multiple tasks and users would likely compromise the performance of the machine without really being needed.

Video games and even the available spreadsheet, database and word processors for home computers were mostly self-contained programs that took over the machine completely. Although integrated software existed for these computers, they usually lacked features compared to their standalone equivalents, largely due to memory limitations. Data exchange was mostly performed through standard formats like ASCII text or CSV, or through specialized file conversion programs.

Operating Systems in video games and consoles

Since virtually all video game consoles and arcade cabinets designed and built after 1980 were true digital machines based on microprocessors (unlike the earlier Pong clones and derivatives), some of them carried a minimal form of BIOS or built-in game, such as the ColecoVision, the Sega Master System and the SNK Neo Geo.

Modern-day game consoles and videogames, starting with the PC-Engine, all have a minimal BIOS that also provides some interactive utilities such as memory card management, audio or video CD playback, copy protection and sometimes carry libraries for developers to use etc. Few of these cases, however, would qualify as a true operating system.

The most notable exceptions are probably the Dreamcast game console which includes a minimal BIOS, like the PlayStation, but can load the Windows CE operating system from the game disk allowing easily porting of games from the PC world, and the Xbox game console, which is little more than a disguised Intel-based PC running a secret, modified version of Microsoft Windows in the background. Furthermore, there are Linux versions that will run on a Dreamcast and later game consoles as well.

Long before that, Sony had released a kind of development kit called the Net Yaroze for its first PlayStation platform, which provided a series of programming and developing tools to be used with a normal PC and a specially modified “Black PlayStation” that could be interfaced with a PC and download programs from it. These operations require in general a functional OS on both platforms involved.

In general, it can be said that videogame consoles and arcade coin-operated machines used at most a built-in BIOS during the 1970s, 1980s and most of the 1990s, while from the PlayStation era and beyond they started getting more and more sophisticated, to the point of requiring a generic or custom-built OS for aiding in development and expandability.

Personal Computer Era

The development of microprocessors made inexpensive computing available for the small business and hobbyist, which in turn led to the widespread use of interchangeable hardware components using a common interconnection (such as the S-100, SS-50, Apple II, ISA, and PCI buses), and an increasing need for “standard” operating systems to control them. The most important of the early OSes on these machines was Digital Research’s CP/M-80 for the 8080 / 8085 / Z-80 CPUs. It was based on several Digital Equipment Corporation operating systems, mostly for the PDP-11 architecture. Microsoft’s first operating system, MDOS/MIDAS, was designed along many of the PDP-11 features, but for microprocessor based systems. MS-DOS, or PC DOS when supplied by IBM, was based originally on CP/M-80. Each of these machines had a small boot program in ROM which loaded the OS itself from disk. The BIOS on the IBM-PC class machines was an extension of this idea and has accreted more features and functions in the 20 years since the first IBM-PC was introduced in 1981.

The decreasing cost of display equipment and processors made it practical to provide graphical user interfaces for many operating systems, such as the generic X Window System that is provided with many Unix systems, or other graphical systems such as Microsoft Windows, the Radio Shack Color Computer’s OS-9 Level II/MultiVue, Commodore’s AmigaOS, Atari TOS, Apple’s classic Mac OS, and macOS, or even IBM’s OS/2. The original GUI was developed on the Xerox Alto computer system at Xerox Palo Alto Research Center in the early 1970s and commercialized by many vendors throughout the 1980s and 1990s.

Since the late 1990s, there have been three operating systems in widespread use on personal computers: Microsoft Windows, Apple Inc.’s Mac OS X, and the open source Linux. Since 2005 and Apple’s transition to Intel processors, all have been developed mainly on the x86 platform, although Mac OS X retained PowerPC support until 2009 and Linux remains ported to a multitude of architectures including ones such as 68k, PA-RISC, and DEC Alpha, which have been long superseded and out of production, and SPARC and MIPS, which are used in servers or embedded systems but no longer for desktop computers. Other operating systems such as AmigaOS and OS/2 remain in use, if at all, mainly by retrocomputing enthusiasts or for specialized embedded applications.

Mobile Operating Systems

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In the early 1990s, Psion released the Psion Series 3 PDA, a small mobile computing device. It supported user-written applications running on an operating system called EPOC. Later versions of EPOC became Symbian, an operating system used for mobile phones from Ericsson, Motorola, and Nokia. In 1996, Palm Computing released the Pilot 1000 and Pilot 5000, running Palm OS. Microsoft Windows CE was the base for PocketPC 2000, renamed Windows Mobile in 2003, which at its peak in 2007 was the most common operating system for smartphones in the U.S.

In 2007 Apple introduced the iPhone and its operating system, iOS, which, like Mac OS X, is based on the Unix-like Darwin. In addition to these underpinnings, it also introduces a powerful and innovative graphic user interface – later also used for the tablet computer iPad. A year later, Android was introduced, based on a modified Linux kernel, and its own graphical user interface, and Microsoft re-entered this market with Windows Phone in 2010, due to be replaced by Windows 10 Mobile in 2015.

In addition to these, a wide range of other mobile operating systems are contending in this area.

Rise of Virtualization

Operating systems originally ran directly on the hardware itself and provided services to applications, but with virtualization, the operating system itself runs under the control of a hypervisor, instead of being in direct control of the hardware.

On mainframes IBM introduced the notion of a virtual machine in 1968 with CP/CMS on the IBM System/360 Model 67, and extended this later in 1972 with Virtual Machine Facility/370 (VM/370) on System/370.

On x86-based personal computers, VMware popularized this technology with their 1999 product, VMware Workstation, and their 2001 VMware GSX Server and VMware ESX Server products. Later, a wide range of products from others, including Xen, KVM and Hyper-V meant that by 2010 it was reported that more than 80 percent of enterprises had a virtualization program or project in place, and that 25 percent of all server workloads would be in a virtual machine.

Over time, the line between virtual machines, monitors, and operating systems was blurred:

  • Hypervisors grew more complex, gaining their own application programming interface, memory management or file system.
  • Virtualization becomes a key feature of operating systems, as exemplified by KVM and LXC in Linux, Hyper-V in Windows Server 2008 or HP Integrity Virtual Machines in HP-UX.
  • In some systems, such as POWER5 and POWER6-based servers from IBM, the hypervisor is no longer optional.
  • Radically simplified operating systems, such as CoreOS have been designed to run only on virtual systems.
  • Applications have been re-designed to run directly on a virtual machine monitor.

In many ways, virtual machine software today plays the role formerly held by the operating system, including managing the hardware resources (processor, memory, I/O devices), applying scheduling policies, or allowing system administrators to manage system.

List of Operating Systems

From Wikipedia, the free encyclopedia

This is a list of operating systems. Computer 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. Criteria for inclusion is notability, as shown either through an existing Wikipedia article or citation to a reliable source.


Acorn Computers

  • Arthur
  • ARX
  • MOS
  • RISC iX

Amiga Inc.

  • AmigaOS
    • AmigaOS 1.0-3.9 (Motorola 68000)
    • AmigaOS 4 (PowerPC)
  • Amiga Unix (a.k.a. Amix)

Apple Inc.

  • Apple II family
  • Apple DOS
  • Apple Pascal
  • ProDOS
  • GS/OS
  • GNO/ME

Apple III

  • Apple SOS

Apple Lisa

  • Lisa Workshop
  • Lisa Operating System

Apple Macintosh

  • Classic Mac OS
  • A/UX (UNIX System V with BSD extensions)
  • Copland
  • MkLinux
  • Pink
  • Rhapsody
  • macOS (formerly Mac OS X and OS X)
  • macOS Server (formerly Mac OS X Server and OS X Server)

Apple Network Server

  • IBM AIX (Apple-customized)

Apple Message

  • PadNewton OS

iPhone, iPod Touch, iPad

  • iOS

Apple Watch

  • watchOS

Apple TV

  • tvOS

Embedded operating systems

  • A/ROSE
  • iPod software (unnamed embedded OS for iPod)
  • Unnamed NetBSD variant for Airport Extreme and Time Capsule

Apollo Computer

  • Domain/OS : One of the first network-based systems. Run on Apollo/Domain hardware. Later bought by Hewlett-Packard.


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

BAE Systems

  • XTS-400

Be Inc.

  • BeOSBeIA
  • BeOS r5.1d0
  • magnussoft ZETA (based on BeOS r5.1d0 source code, developed by yellowTAB)

Bell Labs

Unix (“Ken’s new system,” for its creator (Ken Thompson), officially Unics and then Unix, the prototypic operating system created in Bell Labs in 1969 that formed the basis for the Unix family of operating systems)UNIX Time-Sharing System v1

  • UNIX Time-Sharing System v2
  • UNIX Time-Sharing System v3
  • UNIX Time-Sharing System v4
  • UNIX Time-Sharing System v5
  • UNIX Time-Sharing System v6
    • PWB/UNIX
      • USG
      • CB Unix
  • UNIX Time-Sharing System v7 (It is from Version 7 Unix (and, to an extent, its descendants listed below) that almost all Unix-based and Unix-like operating systems descend.)
    • Unix System III
    • Unix System IV
  • Unix System V
  • Unix System V Releases 2.0, 3.0, 3.2, 4.0, and 4.2
  • UNIX Time-Sharing System v8
  • UNIX TIme-Sharing System v9
  • UNIX Time-Sharing System v10

Non-Unix Operating Systems:

  • Plan 9 from Bell Labs

Bull SAS

  • General Comprehensive Operating System (GCOS)
  • Burroughs Corporation, Unisys[edit]
  • Burroughs MCP

Control Data Corporation

  • Chippewa Operating System (COS)
    • MACE (Mansfield and Cahlander Executive)
      • Kronos (Kronographic OS)
      • NOS (Network Operating System)
        • NOS/BE NOS Batch Environment
        • NOS/VE NOS Virtual Environment
    • SCOPE (Supervisory Control Of Program Execution)
    • SIPROS (for Simultaneous Processing Operating System)
  • EP/IX (Enhanced Performance Unix)

Convergent Technologies

  • Convergent Technologies Operating System (later acquired by Unisys)

Data General

  • AOS for 16-bit Data General Eclipse computers and AOS/VS for 32-bit (MV series) Eclipses, MP/AOS for microNOVA-based computers
  • DG/UX
  • RDOS Real-time Disk Operating System, with variants: RTOS and DOS (not related to PC DOS, MS-DOS etc.)


  • CTOS Z-80 based, Cassette Tape Operating System for early desktop systems. Capable of up to 8 simultaneous users. Replaced by DataPoint DOS.
  • DOS Intel 808x/80×86-based, Disk Operating Systems for desktop systems. Capable of up to 32 users per node. Supported a sophisticated network of nodes that were often purpose-built. The name DOS was used in these products login screens before it was popularized by IBM, Microsoft and others.

DDC-I, Inc.

  • Deos Time & Space Partitioned RTOS, Certified to DO-178B, Level A since 1998
  • HeartOS Posix-based Hard Real-Time Operating System

Digital Research, Inc.

  • CP/M
    • CP/M CP/M for Intel 8080/8085 and Zilog Z80
      • Personal CP/M, a refinement of
      • CP/M
    • CP/M Plus with BDOS 3.0
    • CP/M-68K CP/M for Motorola 68000
    • CP/M-8000 CP/M for Zilog Z8000
      • CP/M-86 CP/M for Intel 8088/8086CP/M-86 Plus
      • Personal CP/M-86
    • MP/M Multi-user version of CP/M-80MP/M II
    • MP/M-86 Multi-user version of CP/M-86
      • MP/M 8-16, a dual-processor variant of MP/M for 8086 and 8080 CPUs.
    • Concurrent CP/M, the successor of CP/M-80 and MP/M-80
    • Concurrent CP/M-86, the successor of CP/M-86 and MP/M-86
      • Concurrent CP/M 8-16, a dual-processor variant of Concurrent CP/M for 8086 and 8080 CPUs.
    • Concurrent CP/M-68K, a variant for the 68000
  • DOS
    • Concurrent DOS, the successor of Concurrent CP/M-86 with PC-MODEConcurrent PC DOS, a Concurrent DOS variant for IBM compatible PCs
      Concurrent DOS 8-16, a dual-processor variant of Concurrent DOS for 8086 and 8080 CPUs

      • Concurrent DOS 286
      • Concurrent DOS XM, a real-mode variant of Concurrent DOS with EEMS support
      • Concurrent DOS 386Concurrent DOS 386/MGE, a Concurrent DOS 386 variant with advanced graphics terminal capabilities
    • Concurrent DOS 68K, a port of Concurrent DOS to Motorola 68000 CPUs with DOS source code portability capabilities
    • FlexOS 1.0 – 2.34, a derivative of Concurrent DOS 286
      • FlexOS 186, a variant of FlexOS for terminals
      • FlexOS 286, a variant of FlexOS for hosts
        • Siemens S5-DOS/MT, an industrial control system based on FlexOS
        • IBM 4680 OS, a POS operating system based on FlexOS
        • IBM 4690 OS, a POS operating system based on FlexOSToshiba 4690 OS, a POS operating system based on IBM 4690 OS and FlexOS
      • FlexOS 386, a later variant of FlexOS for hosts
        • IBM 4690 OS, a POS operating system based on FlexOS
          • Toshiba 4690 OS, a POS operating system based on IBM 4690 OS and FlexOS
      • FlexOS 68K, a derivative of Concurrent DOS 68K
    • Multiuser DOS, the successor of Concurrent DOS 386
      • CCI Multiuser DOS
      • Datapac Multiuser DOS
        • Datapac System Manager, a derivative of Datapac Multiuser DOS
    • IMS Multiuser DOS
      • IMS REAL/32, a derivative of Multiuser DOS
      • IMS REAL/NG, the successor of REAL/32
    • DOS Plus 1.1 – 2.1, a single-user, multi-tasking system derived from Concurrent DOS 4.1 – 5.0
    • DR-DOS 3.31 – 6.0, a single-user, single-tasking native DOS derived from Concurrent DOS 6.0Novell PalmDOS 1.0
      • Novell “Star Trek”
      • Novell DOS 7, a single-user, multi-tasking system derived from DR DOS
      • Caldera OpenDOS 7.01
      • Caldera DR-DOS 7.02 and higher

Digital Equipment Corporation, Tandem Computers, Compaq, Hewlett-Packard

  • Batch-11/DOS-11
  • Domain/OS (originally Aegis, from Apollo Computer who were bought by HP)
  • Multi-Programming Executive (from HP)
  • NonStop
  • OS/8
  • 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)
  • TOPS-10 (for the PDP-10)
  • TENEX (an ancestor of TOPS-20 from BBN, for the PDP-10)
  • TOPS-20 (for the PDP-10)
  • Digital UNIX (derived from OSF/1, became HP’s Tru64 UNIX)
  • Ultrix
  • VMS (originally by DEC and HP now by VMS Software Inc.) for the VAX mini-computer range, Alpha and Intel Itanium i2 and i4; later renamed OpenVMS)
  • WAITS (for the PDP-6 and PDP-10)


  • OSE Flexible, small footprint, high-performance RTOS for control processors


  • Towns OS

General Electric

  • Real-Time Multiprogramming Operating System


  • Chrome OS is designed to work exclusively with web applications. Announced on July 7, 2009, Chrome OS is currently publicly available and was released summer 2011. The Chrome OS source code was released on November 19, 2009, under the BSD license as Chromium OS.
    • Chromium OS is an open source operating system development version of Chrome OS. Both operating systems are based on the Linux kernel.
  • Android is an operating system for mobile devices. It consists of Android Runtime (userland) with Linux (kernel), with its Linux kernel modified to add drivers for mobile device hardware and to remove unused Vanilla Linux drivers.

Green Hills Software

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

Heathkit, Zenith Data Systems

  • HDOS; ran on the H8 and Heath/Zenith Z-89 series
  • HT-11 (a modified version of RT-11) ran on the Heathkit H11


  • HP Multi-Programming Executive (MPE, MPE/XL, and MPE/iX) runs on HP 3000 and HP e3000 mini-computers
  • HP-UX; runs on HP9000 and Itanium servers – from small to mainframe-class computers
  • NonStop OS; runs on HP’s NonStop line of Itanium servers


  • Multics
  • GCOS
  • CP-6

Intel Corporation

  • iRMX; real-time operating system originally created to support the Intel 8080 and 8086 processor families in embedded applications.
  • ISIS, ISIS-II; “Intel Systems Implementation Supervisor” was an environment for development of software within the Intel microprocessor family in the early 1980s on their Intellec Microcomputer Development System and clones. ISIS-II worked with 8 inch floppy disks and had an editor, cross-assemblers, a linker, an object locator, debugger, compilers for PL/M, a BASIC interpreter, etc. and allowed file management through a console.


On early Mainframes: 1400, 1800, 701, 704, 709, 7090, 7094

  • BESYS (for the IBM 7090)
  • CTSS (The Compatible Time-Sharing System, developed at MIT’s Computation Center for use on a modified IBM 7094)
  • GM OS & GM-NAA I/O (for the IBM 704)
  • IBSYS (tape based operating system for IBM 7090 and IBM 7094)
  • IJMON (A bootable serial I/O monitor for loading programs for IBM 1400 and IBM 1800)
  • SOS (SHARE Operating System, for the IBM 704 and 709)
  • UMES (University of Michigan Executive System, for the IBM 704, 709, and 7090)

On S/360, S/370, and Successor Mainframes

  • OS/360 and successors on IBM S/360, S/370, and successor mainframes
    • 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 (original Multi-programming with a Fixed number of Tasks, replaced by MFT II)
      • MFT II (Multi-Programming with a Fixed number of Tasks, had up to 15 fixed size application partitions, plus partitions for system tasks, initially defined at boot time but redefinable by operator command)
      • MVT (Multi-Programming Variable Tasks, had up to 15 application regions defined dynamically, plus additional regions for system tasks)
    • OS/VS (port of OS/360 targeted for the System/370 virtual memory architecture, “OS/370” is not correct name for OS/VS1 and OS/VS2, but rather refers to OS/VS2 MVS and MVS/SP Version 1),Customer installations in the following variations:
      • SVS (Single Virtual Storage, both VS1 & VS2 began as SVS systems)
      • OS/VS1 (Operating System/Virtual Storage 1, Virtual-memory version of MFT II)
      • OS/VS2 (Operating System/Virtual Storage 2, Virtual-memory version of OS/MVT but without multiprocessing support)OS/VS2 R2 (called Multiple Virtual Storage, MVS, eliminated most need for VS1)
    • MVS/SE (MVS System Extensions)
    • MVS/SP (MVS System Product)
    • MVS/XA (MVS/SP V2. MVS supported eXtended Architecture, 31-bit addressing)
    • MVS/ESA (MVS supported Enterprise System Architecture, horizontal addressing extensions: data only address spaces called Dataspaces; a Unix environment was available starting with MVS/ESA V4R3)
    • OS/390 (Upgrade from MVS, with an additional Unix environment)
    • z/OS (OS/390 supported z/Architecture, 64-bit addressing)
  • DOS/360 and successors on IBM S/360, S/370, and successor mainframes
    • 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 2×00 series tape drives)
    • DOS/360 (Disk Operating System (DOS), multi-programming system with up to 3 partitions, first commonly available OS for System/360)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/VS (First DOS offered on System/370 systems, provided virtual storage)
    • DOS/VSE (also known as VSE, upgrade of DOS/VS, up to 14 fixed size processing partitions )
    • VSE/SP (program product replacing DOS/VSE and VSE/AF)
    • 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, supports 64-bit addresses, multiprocessing, multiprogramming, SNA, TCP/IP, and some virtual machine features in support of Linux workloads)
  • CP/CMS (Control Program/Cambridge Monitor System) and successors on IBM S/360, S/370, and successor mainframes
    • CP-40/CMS (for System/360 Model 40)
    • CP-67/CMS (for System/360 Model 67)
    • VM/370 (Virtual Machine / Conversational Monitor System, virtual memory operating system for System/370)
    • VM/XA (VM/eXtended Architecture for System/370 with extended virtual memory)
    • VM/ESA (Virtual Machine / Extended System Architecture, added 31-bit addressing to VM series)
    • z/VM (z/Architecture version of the VM OS with 64-bit addressing)
  • TPF Line (Transaction Processing Facility) on IBM S/360, S/370, and successor mainframes (largely used by airlines)
    • ACP (Airline Control Program)
    • TPF (Transaction Processing Facility)
    • z/TPF (z/Architecture extension)
  • Unix-like on IBM S/360, S/370, and successor mainframesAIX/370 (IBM’s Advanced Interactive eXecutive, a System V Unix version)
    • AIX/ESA (IBM’s Advanced Interactive eXecutive, a System V Unix version)
    • OpenSolaris for IBM System z
    • UTS (developed by Amdahl)
    • z/Linux
  • Others on IBM S/360, S/370, and successor mainframes:BOS/360 (Basic Operating System)
    • MTS (Michigan Terminal System, developed by a group of universities in the US, Canada, and the UK for the IBM System/360 Model 67, System/370 series, and compatible mainframes)
    • RTOS/360 (IBM’s Real Time Operating System, ran on 5 NASA custom System/360-75s)[3]
    • TOS/360 (Tape Operating System)
    • TSS/360 (IBM’s Time Sharing System)
    • MUSIC/SP (developed by McGill University for IBM System/370)
    • ORVYL and WYLBUR (developed by Stanford University for IBM System/360)

On PC and Intel x86 based Architectures

    • PC DOS 1.x, 2.x, 3.x (developed jointly with Microsoft)
    • IBM DOS 4.x, 5.0 (developed jointly with Microsoft)
    • PC DOS 6.1, 6.3, 7, 2000, 7.10OS/2OS/2 1.x (developed jointly with Microsoft)
  • OS/2 2.x
    • OS/2 Warp 3 (ported to PPC via Workplace OS)
    • OS/2 Warp 4
    • eComStation (Warp 4.5/Workspace on Demand, rebundled by Serenity Systems International)
  • IBM 4680 OS version 1 to 4, a POS operating system based on Digital Research’s Concurrent DOS 286 and FlexOS 286 1.xx
    • IBM 4690 OS version 1 to 6.3, a successor to 4680 OS based on Novell’s FlexOS 286/FlexOS 386 2.3x
      • Toshiba 4690 OS version 6.4, a successor to 4690 OS 6.3

On other hardware platforms

  • IBM Series/1
    • EDX (Event Driven Executive)
    • RPS (Realtime Programming System)
    • CPS (Control Programming Support, subset of RPS)
    • SerIX (Unix on Series/1)
  • IBM 1130
    • DMS (Disk Monitor System)
  • IBM 1800
    • TSX (Time Sharing eXecutive)
    • MPX (Multi Programming eXecutive)
  • IBM 8100
    • DPCX (Distributed Processing Control eXecutive)
    • DPPX (Distributed Processing Programming Executive)
  • IBM System/3
    • DMS (Disk Management System)
  • IBM System/34, IBM System/36
    • SSP (System Support Program)
  • IBM System/38
    • CPF (Control Program Facility)
  • IBM System/88
    • Stratus VOS (developed by Stratus, and used for IBM System/88, Original equipment manufacturer from Stratus)
  • AS/400, iSeries, System i, Power Systems i Edition
    • OS/400 (descendant of System/38 CPF, include System/36 SSP environment)
    • i5/OS (extends OS/400 with significant interoperability features)
    • IBM i (extends i5/OS)
    • AIX (Advanced Interactive eXecutive, a System V Unix version)
    • AOS (a BSD Unix version, not related to Data General AOS)
  • Others
    • Workplace OS (a Microkernel based operating system including OS/2, developed and canceled in the 1990s)
    • K42 (open-source research operating system on PowerPC or x86 based cache-coherent multiprocessor systems)
    • Dynix (developed by Sequent, and used for IBM NUMA-Q too)

International Computers Limited[edit]

  • J and MultiJob for the System 4 series mainframes
  • GEORGE 2/3/4 GEneral ORGanisational Environment, used by ICL 1900 series mainframes
  • Executive, used on the 1900 and 290x range of minicomputers. A modified version of Executive was also used as part of GEORGE 3 and 4.
  • TME, used on the ME29 minicomputer
  • ICL VME, including early variants VME/B and VME/2900, appearing on the ICL 2900 Series and Series 39 mainframes, implemented in S3
  • VME/K on early smaller 2900s


  • Remix OS

Lynx Real-time Systems, LynuxWorks, Lynx Software Technologies

  • LynxOS

Micrium Inc.

  • MicroC/OS-II (small pre-emptive priority based multi-tasking kernel)
  • MicroC/OS-III (small pre-emptive priority based multi-tasking kernel, with unlimited number of tasks and priorities, and round robin scheduling)

Microsoft Corporation

  • 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 (16-bit and 32-bit preemptive and cooperative multitasking, running atop
    • MS-DOS)Windows 1.0 (Windows 1)
    • Windows 2.0 (Windows 2 – separate version for i386 processor)
    • Windows 3.0 (Windows 3)
    • Windows 3.1x (Windows 3.1)
    • Windows for Workgroups 3.1 (Codename Snowball)
    • Windows 3.2 (Chinese-only release)
    • Windows for Workgroups 3.11
    • Windows 95 (codename Chicago – Windows 4.0)
    • Windows 98 (codename Memphis – Windows 4.1)
    • Windows Millennium Edition (Windows ME – Windows 4.9)
  • Windows NT (Full 32-bit or 64-bit kernel, not dependent on MS-DOS)Windows NT 3.1
    • Windows NT 3.5
    • Windows NT 3.51
    • Windows NT 4.0
    • Windows 2000 (Windows NT 5.0)
    • Windows XP (Windows NT 5.1)
    • Windows Server 2003 (Windows NT 5.2)
    • Windows Fundamentals for Legacy PCs (based on Windows XP)
    • Windows Vista (Windows NT 6.0)
    • Windows Azure (Cloud OS Platform) 2009
    • Windows Home Server (based on Windows Server 2003)
    • Windows Server 2008 (based on Windows Vista)
    • Windows 7 (Windows NT 6.1)
    • Windows Server 2008 R2 (based on Windows 7)
    • Windows Home Server 2011 (based on Windows Server 2008 R2)
    • Windows Server 2012 (based on Windows 8)
    • Windows 8 (Windows NT 6.2)
    • Windows Phone 8
    • Windows 8.1 (Windows NT 6.3)
    • Windows Server 2012 R2 (based on Windows 8.1)
    • Xbox One system software
    • Windows Phone 8.1
    • Windows 10 (Windows NT 10.0)
    • Windows 10 Mobile
    • Windows Server 2016
  • Windows CE (OS for handhelds, embedded devices, and real-time applications that is similar to other versions of Windows)Windows CE 3.0
    • Windows CE 5.0
    • Windows CE 6.0
    • Windows Mobile (based on Windows CE, but for a smaller form factor)
    • Windows Phone 7
  • Singularity – A research operating system written mostly in managed code (C#)
  • Midori – A managed code operating system
  • Xbox 360 system software
  • Xbox One system software
  • MontaVista[edit]
  • MontaVista Mobilinux

NCR Corporation

  • TMX – Transaction Management eXecutive
  • IMOS – Interactive Multiprogramming Operating System (circa 1978), for the NCR
  • Century 8200 series minicomputers
  • VRX – Virtual Resource eXecutive


  • es is a computer operating system developed originally by Nintendo and since 2008 by Esrille. It is open source and runs natively on x86 platforms.


  • 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.
  • UnixWareNovell “SuperNOS”, a never released merge of NetWare and UnixWare
    Novell “Corsair”Novell “Exposé”
  • Open Enterprise Server, the successor to NetWare.

Quadros Systems

  • RTXC Quadros RTOS proprietary C-based RTOS used in embedded systems


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


  • DSPnano RTOS 8/16 Bit Ultra Tiny Embedded Linux Compatible RTOS
  • Unison RTOS 32 Bit Open Standards, Linux Compatible, Ultra Tiny Size, Modularity, POSIX-compliant RTOS that supports a variety of wireless modules and provides a complete set of security protocols

Samsung Electronics

  • Bada
  • Tizen

SCO, 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
  • SCO OpenServer 6, SVR5 (UnixWare 7) based kernel with SCO OpenServer 5 application and binary compatibility, system administration, and user environments
  • UnixWare
    • 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

Scientific Data Systems (SDS)

  • Berkeley Timesharing System for the SDS 940

Sciopta Systems GmbH

  • SCIOPTA Pre-emptive, priority-based real-time kernel (IEC61508 certified)


  • PikeOS is a certified real time operating system for safety and security critical embedded systems

Tandy Corporation

  • TRSDOS; A floppy-disk-oriented OS supplied by Tandy/Radio Shack for their TRS-80 Z80-based line of personal computers. Eventually renamed as LS-DOS or LDOS.
    Color BASIC; A ROM-based OS created by Microsoft for the TRS-80 Color Computer.
  • NewDos/80; A third-party OS for Tandy’s TRS-80 personal computers.
  • DeskMate; Operating system created by Tandy Corporation and introduced with the Tandy 1000 computer.

TCSC (later NCSC)

  • Edos – enhanced version of IBM’s DOS/360 (and later DOS/VS and DOS/VSE) operating system for System/360 and System/370 IBM mainframes

Texas Instruments

  • TI-RTOS Kernel; Real-time operating system for TI’s embedded devices.

TRON Project

  • TRON (open real-time operating system kernel)
  • T-Kernel


  • Unisys MCP
  • Unisys OS 2200 operating system

UNIVAC, Unisys

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

Wang Laboratories

  • WPS Wang Word Processing System. Micro-code based system.
  • OIS Wang Office Information System. Successor to the WPS. Combined the WPS and VP/MVP systems.
  • Wang VS Operating System (VSOS) – used on the VS line of minicomputer systems.


  • WICAT Multiuser Computer System (WMCS). MC-68K multiuser O/S for their proprietary microcomputers, used mainly for CBT systems

Wind River Systems

  • VxWorks Small footprint, scalable, high-performance RTOS for embedded microprocessor based systems.



  • Lisp Machines, Inc. (also known as LMI) used an operating system written in MIT’s Lisp Machine Lisp.
  • 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.
  • Xerox 1100 series of Lisp machines used an operating system also written in Interlisp, and was also ported to a virtual machine called “Medley.”
  • PilOS Stand alone operating system. It is a full blown 64-bit PicoLisp runs directly on a standard x86-64 PC hardware.

Non-standard Language-based

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

Other Proprietary Non-Unix-like

  • Эльбрус-1 (Elbrus-1) and Эльбрус-2 used for application, job control, system programming,[6] implemented in uЭль-76 (AL-76).
  • EOS; 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
  • MAI Basic Four; An OS implementing Business Basic from MAI Systems.
  • Michigan Terminal System; Developed by a group of universities in the US, Canada, and the UK for use on the IBM System/360 Model 67, the System/370 series, and compatible mainframes
  • MUSIC/SP; an operating system developed for the S/370, running normally under
  • VM
  • OS ES; an operating system for ES EVM
  • PC-MOS/386; DOS-like, but multiuser/multitasking
  • Prolog-Dispatcher; used to control Soviet Buran space ship.
  • SINTRAN III; an operating system used with Norsk Data computers.
  • SkyOS; commercial desktop OS for PCs
  • TSX-32; a 32-bit operating system for x86 platform.
  • TX990/TXDS, DX10 and DNOS; proprietary operating systems for TI-990 minicomputers

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 1990, last version was in 1992)
  • Coherent (Unix-like OS from Mark Williams Co. for PC class computers)
  • DC/OSx (DataCenter/OSx—an operating system developed by Pyramid Technology for its MIPS-based systems)
  • DG/UX (Data General Corp)
  • DNIX from DIAB
  • DSPnano RTOS (POSIX nanokernel, DSP Optimized, Open Source)
  • HeliOS developed and sold by Perihelion Software mainly for transputer based systems
  • Interactive Unix (a port of the UNIX System V operating system for Intel x86 by Interactive Systems Corporation)
  • IRIX from SGI
  • MeikOS
  • 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 680×0 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)
  • Rhapsody (an early form of Mac OS X)
  • RISC iX – derived from BSD 4.3, by Acorn computers, for their ARM family of machines
  • RISC/os (a port by MIPS Technologies of 4.3BSD for its MIPS-based computers)
  • RMX
  • SCO UNIX (from SCO, bought by Caldera who renamed themselves SCO Group)
  • SINIX (a port by SNI of Unix to the MIPS architecture)
  • Solaris (from Sun, bought by Oracle; a 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 and others)
  • Unicos (the version of Unix designed for Cray Supercomputers, mainly geared to vector calculations)
  • UTX-32 (Developed by Gould CSD (Computer System Division), a Unix-based OS that included both BSD and System V characteristics. It was one of the first Unix based systems to receive NSA’s C2 security level certification.)
  • Zenix, Zenith corporations Unix (a popular USA electronics maker at the time)



Research and other POSIX-compliant

  • MINIX (study OS developed by Andrew S. Tanenbaum in the Netherlands)
  • Plan 9 from Bell Labs (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)
  • Unix (OS developed at Bell Labs ca 1970 initially by Ken Thompson)
  • Xinu (Study OS developed by Douglas E. Comer in the United States)

Free and 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’)
      • DragonFlyBSD, forked from FreeBSD 4.8
    • MidnightBSD, forked from FreeBSD 6.1
    • Darwin, created by Apple using FreeBSD and NeXTSTEP
    • GhostBSD
    • TrueOS (previously known as PC-BSD)
  • NetBSD (an embedded device BSD variant)
    • OpenBSD forked from
      • NetBSDBitrig forked from OpenBSD
  • GNU Hurd
  • GNU Linux (or simply Linux)
  • Android x86
  • Cray Linux Environment
  • illumos, contains original Unix (SVR4) code derived from the OpenSolaris (discontinued by Oracle in favor of Solaris 11
    • Express)OpenIndiana, operates under the illumos Foundation. Uses the illumos kernel, which is a derivative of OS/Net, which is basically an OpenSolaris/Solaris kernel with the bulk of the drivers, core libraries, and basic utilities.
    • Nexenta OS, based on the illumos kernel with Ubuntu packages
    • SmartOS, an illumos distribution for cloud computing with Kernel-based Virtual Machine integration.
  • RTEMS (Real-Time Executive for Multiprocessor Systems)
  • Haiku (open source inspired by BeOS, under development)
  • Syllable Desktop
  • Univention Corporate Server
  • VSTa
    • FMI/OS, successor of VSTa


  • Plurix
  • TUNIS (University of Toronto)



  • Amoeba (research OS by Andrew S. Tanenbaum)
  • Croquet
  • EROS microkernel, capability-based
    • CapROS microkernel EROS successor.
    • Coyotos microkernel EROS successor, goal: be first formally verified OS.
  • HelenOS research and experimental operating system
  • House – Haskell User’s Operating System and Environment, research OS written in Haskell and C
  • ILIOS Research OS designed for routing
  • L4 second generation microkernel
  • Mach (from OS kernel research at Carnegie Mellon University; see NeXTSTEP)
  • Nemesis Cambridge University research OS – detailed quality of service abilities
    Spring (research OS from Sun Microsystems)
  • THE multiprogramming system by Dijkstra in 1968, at the Eindhoven University of Technology in the Netherlands, introduced the first form of software-based memory segmentation, freeing programmers from being forced to use actual physical locations
  • V from Stanford, early 1980s

Free and Open Source

  • Cosmos (written in C#)
  • FreeDOS (open source DOS variant)
  • Ghost OS (written in Assembly, C/C++)
  • ITS written by MIT students (for the PDP-6 and PDP-10) (written in MIDAS)
    osFree OS/2 Warp open source clone.
  • OSv (written in C++)
  • Phantom OS (persistent object oriented)
  • ReactOS, open source OS designed to be binary compatible with Windows NT and its variants (Windows XP, Windows 2000, etc.); currently in development phase
  • SharpOS (written in .NET C#)
  • TempleOS (written in HolyC)
  • Redox OS (written in Rust)

Disk Operating Systems (DOS)

  • 86-DOS (developed at Seattle Computer Products by Tim Paterson for the new Intel
  • 808x CPUs; licensed to Microsoft, became PC DOS/MS-DOS. Also known by its working title QDOS.)
    • PC DOS (IBM’s DOS variant, developed jointly with Microsoft, versions 1.0–7.0, 2000, 7.10)
    • MS-DOS (Microsoft’s DOS variant for OEM, developed jointly with IBM, versions 1.x–6.22 Microsoft’s now abandoned DOS variant)
  • Concurrent CP/M-86 3.1 (BDOS 3.1) with PC-MODE (Digital Research’s successor of CP/M-86 and MP/M-86)Concurrent DOS 3.1-4.1 (BDOS 3.1-4.1)
    • Concurrent PC DOS 3.2 (BDOS 3.2) (Concurrent DOS variant for IBM compatible PCs)
      • DOS Plus 1.1, 1.2 (BDOS 4.1), 2.1 (BDOS 5.0) (single-user, multi-tasking system derived from Concurrent DOS 4.1-5.0)
    • Concurrent DOS 8-16 (dual-processor variant of Concurrent DOS for 8086 and 8080 CPUs)
    • Concurrent DOS 286 1.x
      • FlexOS 1.00-2.34 (derivative of Concurrent DOS 286)FlexOS 186 (variant of FlexOS for terminals)
      • FlexOS 286 (variant of FlexOS for hosts)
        • Siemens S5-DOS/MT (industrial control system based on FlexOS)
      • IBM 4680 OS (POS operating system based on FlexOS)
      • IBM 4690 OS (POS operating system based on FlexOS)Toshiba 4690 OS (POS operating system based on IBM 4690 OS and FlexOS)
    • FlexOS 386 (later variant of FlexOS for hosts)
      • IBM 4690 OS (POS operating system based on FlexOS)
        • Toshiba 4690 OS (POS operating system based on IBM 4690 OS and FlexOS)
    • Concurrent DOS 386 1.0, 1.1, 2.0, 3.0 (BDOS 5.0-6.2)
      • Concurrent DOS 386/MGE (Concurrent DOS 386 variant with advanced graphics terminal capabilities)
      • Multiuser DOS 5.0, 5.01, 5.1 (BDOS 6.3-6.6) (successor of Concurrent DOS 386)
        • CCI Multiuser DOS 5.0-7.22 (up to BDOS 6.6)
          • Datapac Multiuser DOSDatapac System Manager 7 (derivative of Datapac Multiuser DOS)
    • IMS Multiuser DOS 5.1, 7.0, 7.1 (BDOS 6.6-6.7)
      • IMS REAL/32 7.50, 7.51, 7.52, 7.53, 7.54, 7.60, 7.61, 7.62, 7.63, 7.70, 7.71, 7.72, 7.73, 7.74, 7.80, 7.81, 7.82, 7.83, 7.90, 7.91, 7.92, 7.93, 7.94, 7.95 (BDOS 6.8 and higher) (derivative of Multiuser DOS)
        • IMS REAL/NG (successor of REAL/32)
    • Concurrent DOS XM 5.0, 5.2, 6.0, 6.2 (BDOS 5.0-6.2) (real-mode variant of Concurrent DOS with EEMS support)
      • DR DOS 3.31, 3.32, 3.33, 3.34, 3.35, 5.0, 6.0 (BDOS 6.0-7.1) single-user, single-tasking native DOS derived from Concurrent DOS 6.0)
        • Novell PalmDOS 1 (BDOS 7.0)
        • Novell DR DOS “StarTrek”
        • Novell DOS 7 (single-user, multi-tasking system derived from DR DOS, BDOS 7.2)
          • Novell DOS 7 updates 1-10 (BDOS 7.2)
            • Caldera OpenDOS 7.01 (BDOS 7.2)
              • Enhanced DR-DOS 7.01.0x (BDOS 7.2)
                • Dell Real Mode Kernel (DRMK)
    • Novell DOS 7 updates 11-15.2 (BDOS 7.2)
      • Caldera DR-DOS 7.02-7.03 (BDOS 7.3)
        • DR-DOS “WinBolt”
        • OEM DR-DOS 7.04-7.05 (BDOS 7.3)
        • OEM DR-DOS 7.06 (PQDOS)
        • OEM DR-DOS 7.07 (BDOS 7.4/7.7)
  • FreeDOS (open source DOS variant)
  • ProDOS (operating system for the Apple II series computers)
  • PTS-DOS (DOS variant by Russian company Phystechsoft)
  • TurboDOS (Software 2000, Inc.) for Z80 and Intel 8086 processor-based systems
  • Multi-tasking user interfaces and environments for DOS
    • DESQview + QEMM 386 multi-tasking user interface for DOS
    • DESQView/X (X-windowing GUI for DOS)

Network Operating Systems

  • Banyan VINES (Banyan Systems)
  • Cambridge Ring
  • Cisco IOS by Cisco Systems
  • CTOS (Convergent Technologies, later acquired by Unisys)
  • Data ONTAP by NetApp
  • Enterprise OS by McDATA
  • ExtremeWare by Extreme Networks
  • ExtremeXOS by Extreme Networks
  • Fabric OS by Brocade
  • JunOS by Juniper
  • 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)
  • SAN-OS by Cisco (now NX-OS)
  • TurboDOS (Software 2000, Inc.)

Generic, Commodity, 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)
  • FLEX9 (by TSC for Motorola 6809 based machines; successor to FLEX, which was for Motorola 6800 CPUs)
  • GEM (windowing GUI for CP/M, DOS, and Atari TOS)
  • GEOS (popular windowing GUI for PC, Commodore, Apple computers)
  • JNode (Java New Operating System Design Effort), 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 (Amiga compatible)
  • MSP by Fujitsu (successor to OS-IV), now MSP/EX, also known as Extended System Architecture (EXA), for 31-bit mode
  • NetWare (networking OS by Novell)
  • Oberon (operating system) (developed at ETH-Zürich by Niklaus Wirth et al.) for the
  • Ceres and Chameleon workstation projects
  • 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)
  • 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, developed by Miray Software; 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 UCSD; directed by Prof Kenneth Bowles; written in Pascal)
  • VOS by Stratus Technologies with strong influence from Multics
  • VOS3 by Hitachi for its IBM-compatible mainframes, based on IBM’s MVS
  • VM2000 by Siemens AG
  • Visi On (first GUI for early PC machines; not commercially successful)
  • VPS/VM (IBM based, main operating system at Boston University for over 10 years.)

For Elektronika BK

  • KMON
  • MK-DOS


  • AROS (AROS Research Operating System, formerly known as Amiga Research Operating System)
  • AtheOS (branched to become Syllable Desktop)
  • Syllable Desktop (a modern, independently originated OS; see AtheOS)
  • BareMetal
  • DexOS – 32-bit operating system written in x86 assembly
  • DSPnano RTOS
  • EmuTOS
  • EROS (Extremely Reliable Operating System)
  • HelenOS, based on a preemptible microkernel design
  • LSE/OS
  • MenuetOS (extremely compact OS with GUI, written entirely in FASM assembly language)
  • KolibriOS (a fork of MenuetOS)
  • S-OS (a minimal DOS for Z80 machines)
  • ToaruOSPonyOS


Personal Digital Assistants (PDAs)

  • DIP DOS on Atari Portfolio
  • Embedded LinuxAndroid
  • Firefox OS
  • Ångström distribution
  • Familiar Linux
  • Mæmo based on Debian deployed on Nokia’s Nokia 770, N800 and N810 Internet Tablets.
  • MeeGo merger of Moblin and Maemo
  • OpenZaurus
  • webOS from Palm, Inc., later Hewlett-Packard via acquisition, and most recently at LG Electronics through acquisition from Hewlett-Packard[12]
  • Inferno (distributed OS originally from Bell Labs)
  • iOS
  • Magic Cap
  • MS-DOS on Poqet PC, HP 95LX, HP 100LX, HP 200LX, HP 1000CX, HP OmniGo 700LX
  • NetBSD
  • Newton OS on Apple MessagePad
  • Palm OS from Palm, Inc; now spun off as PalmSource
  • PEN/GEOS on HP OmniGo 100 and 120
  • PenPoint OS
  • Plan 9 from Bell Labs
  • PVOS
  • Symbian OSEPOC
  • Windows CE, from MicrosoftPocket PC from Microsoft, a variant of Windows CE
  • Windows Mobile from Microsoft, a variant of Windows CE
  • Windows Phone from Microsoft
  • Digital media players[edit]
  • DSPnano RTOS
  • iOS
  • iPod software
  • iPodLinux
  • iriver clix OS
  • RockBox

Mobile Phones and Smartphones

  • BlackBerry OS
  • Embedded LinuxAccess Linux Platform
    • Android
    • bada
    • Firefox OS (project name: Boot to Gecko)
    • Openmoko Linux
    • OPhone
    • MeeGo (from merger of Maemo & Moblin)
    • Mobilinux
    • MotoMagx
    • Qt Extended
    • Sailfish OS
    • Tizen (earlier called LiMo Platform)
    • Ubuntu Touch
    • webOS
  • iOS
  • Palm OS
  • Symbian platform (successor to Symbian OS)
  • Windows Mobile (superseded by Windows Phone)
  • BlackBerry 10


  • AlliedWare by Allied Telesis (a.k.a. Allied Telesyn)
  • AirOS by Ubiquiti Networks
  • CatOS by Cisco Systems
  • Cisco IOS (originally Internetwork Operating System) by Cisco Systems
  • DD-WRT by NewMedia-NET
  • Inferno (distributed OS originally from Bell Labs)
  • IOS-XR by Cisco Systems
  • IronWare by Foundry Networks
  • JunOS by Juniper Networks
  • LibreWRT GNU/Linux-libre
  • OpenWrt
  • RouterOS by Mikrotik
  • ScreenOS by Juniper Networks, originally from Netscreen
  • Timos by Alcatel-Lucent
  • FTOS by Force10 Networks
  • RTOS by Force10 Networks
  • List of wireless router firmware projects

Other embedded

  • Apache Mynewt
  • ChibiOS/RT
  • Contiki
  • ERIKA Enterprise
  • eCos
  • NetBSD
  • uClinux
  • NCOS
  • freeRTOS, openRTOS and safeRTOS
  • OpenEmbedded (or Yocto Project)
  • pSOS (Portable Software On Silicon)
  • QNX Unix-like real-time operating system, aimed primarily at the embedded systems market.
  • REX OS (microkernel OS; usually an embedded cell phone OS)
  • RIOT
  • TinyOS
  • ThreadX
  • DSPnano RTOS
  • Windows Embedded
    • Windows CE
    • Windows Embedded Standard
    • Windows Embedded Enterprise
    • Windows Embedded POSReady
  • Wind River VxWorks Small footprint, scalable, high-performance RTOS for
  • embedded microprocessor based systems.
  • Wombat OS (microkernel OS; usually a real time embedded OS)
  • Zephyr

LEGO Mindstorms

  • brickOS
  • leJOS


  • Cambridge CAP computer operating system demonstrated the use of security capabilities, both in hardware and software, also a useful fileserver, implemented in ALGOL 68C
  • Flex machine – Custom microprogrammable hardware, with an operating system, (modular) compiler, editor, * garbage collector and filing system all written in ALGOL 68.
  • HYDRA – Running on the C.mmp computer at Carnegie Mellon University, implemented in the programming language BLISS
  • KeyKOS nanokernel
    • EROS microkernelCapROS EROS successor
    • Coyotos EROS successor, goal: be first formally verified OS
  • V from Stanford, early 1980s