Lightweight microkernel.

Green Hills Software, USA

Early machine capable of distributing computing.

Lincoln Lab, USA

Early machine capable of distributing computing.

National Bureau of Standards, USA

Very early operating system developed by General Motors for the IBM 701. Unnamed.

General Motors, USA

Unix-like OS for IBM System/360 and sucessors.

IBM, USA

Operating system for IBM mainframes.

IBM, USA

Monitor and Operating system for the PDP-8/S computer system.

United States Naval Postgraduate School, USA

Xerox 1100 series of Lisp machines used an operating system also written in Interlisp, and was also ported to a virtual machine called "Medley".

Xerox, USA

Texas Instruments' Explorer Lisp machine workstations also had systems code written in Lisp Machine Lisp.

Texas Instruments, USA

Unnamed NetBSD variant for Airport Extreme and Time Capsule.

Apple, USA

Operating system designed around idiomatic C++ concepts such as RAII, iterators, and streams.

Bregmasoft

CP/M 2.2 with ZSDOS as BDOS replacement.

USA

Operating System for the Z8000.

Zilog, USA

Small free OS with a GUI.

Version of UNIX.

Zilog, USA

Small open-source Linux distribution for servers and embedded systems which aims to provide network services.

Fulvio Ricciardi

Small real-time operating system for connected, resource-constrained devices supporting multiple architectures and released under the Apache License 2.0.

Linux Foundation, Wind River Systems

Zenith Unix.

Zenith, USA

based on the original by Richard Conn.

Richard Conn, USA

Z-System based on CP/M 3.

USA

Virtual Storage Extended. 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.

IBM, USA

z/Architecture version of the VM OS with 64-bit addressing.

IBM, USA

z/Architecture extension.

IBM, USA

OS/390 supported z/Architecture, 64-bit addressing.

IBM, USA

Linux on IBM Z (or Linux on z for short, and previously Linux on z Systems) is the collective term for the Linux operating system compiled to run on IBM mainframes, especially IBM Z and IBM LinuxONE servers.

IBM, USA

Mobile operating system.

Alibaba Group, China

Yet Another Small OS. Free real-time OS especially dedicated to ARM Cortex-M3 micro-controllers.

Operating system for the Cedar Multiprocessor, a high-speed, floating point, shared memory. Based on version 4.2 of Unix.

University of Illinois, USA

Teaching operating system developed in the summer of 2006 for MIT's operating systems course.

MIT, USA

Multilevel secure computer operating system.

BAE Systems, UK

Transitioned from proprietary, mini-computer hardware to COTS, Intel x86 hardware.

BAE Systems, UK

Designed as a general-purpose operating system supporting a Unix-like application and user environment.

BAE Systems, UK

X Operating System.

Jascha Wetzel

Operating System for the experimental X-Tree Computer Architecture.

University of California at Berkelely, USA

Batch Processing OS for the Xerox Data Systems SIGMA Computers.

USA

Free Micro-Kernel Based Open Source Operating System.

Frank Anemaet, Daniel Pischl, Netherlands

Newest research exokernel to date. XOK is able to compile most UNIX programs (perl, gcc, emacs, etc.) with little or no change, and has equal to or greater speed than FreeBSD when using standard libOS's.

MIT, USA

Hard real-time operating system (HRTOS), deployed for high-end mechatronic products control. The goal of XOberon is about providing a framework for non-computer-scientists, looking for a rapid application development (RAD) tool for programming embedded applications.

ETH Zurich, Switzerland

Industrial RTOS based on Oberon. Object-oriented, hard-real time system software and framework, designed for safety, extensibility and abstraction.

ETH Zurich, Switzerland

eXtreme Minimal Kernel. Real-time operating system that is designed for minimal RAM/ROM use.

Shift-Right Technologies, USA

Limited Unix lookalike developed for educational purposes, for use with a text by Comer "XINU Is Not Unix.

Purdue University, USA

Real-time development framework cooperating with the Linux kernel, to provide a pervasive, interface-agnostic, hard real-time support to user space applications, seamlessly integrated into the Linux environment.

Xenix 386, Unix System V Release 2 based distribution for the Intel 80386 architecture.

SCO Group, USA

Xenix 286, Unix System V Release 2 based distribution for the Intel 80286 architecture.

SCO Group, USA

Last stable release.

Licensed version of Unix. Licensed to SCO in 1987.

Microsoft, SCO, USA

Virtualisation kernel to which Linux has been ported, NetBSD and XP are being ported, such that you can run as many of each of these OSs (and others if they are ported or written) on a single box.

University of Cambridge, UK

Operating system for the eighth-generation home video game console, Xbox One. It is a Windows-based operating system using the Hyper-V virtual machine monitor.

Microsoft, USA

Udateable software and operating system for the Xbox 360.

Microsoft, USA

X-OS - French OS Project

AlAdDiN

Operating system for the IBM System/360.

Stanford University, USA

Wang Word Processing System. Micro-code based system.

Wang Laboratories, USA

Microkernel based operating system including OS/2, developed and canceled in the 1990s.

IBM, USA

High-performance virtualized Linux. microkernel OS; usually a real time embedded OS.

National ICT Australia, Australia

Small OS for the M6800.

Wintek, USA

32-bit operating system with a primitive shell implemented.

University of Madras, India

Aka Windows NT 5.1

Microsoft, USA

Aka Windows NT 6.0

Microsoft, USA

Brand name for a group of server operating systems released by Microsoft.

Microsoft, USA

Windows Phone mobile client operating system.

Microsoft, USA

First Windows NT kernel public release.

Full 32-bit or 64-bit kernel, not dependent on MS-DOS. Part of Windows Server Family.

Microsoft, USA

Based on Windows CE, but for a smaller form factor.

Microsoft, USA

Aka Windows ME (Windows 4.9). Familial version of Windows 2000.

Microsoft, USA

Based on Windows Server 2008 R2.

Microsoft, USA

Based on Windows Server 2003.

Microsoft, USA

Thin client operating system based on Windows XP Embedded and is optimized for older, less powerful hardware.

Microsoft, USA

See Windows 3.11.

See Windows 3.1.

Extension that allowed users to share their resources and to request those of others without a centralized authentication server. Originally codenamed Winball and later Sparta.

Microsoft, USA

Brand of Windows Embedded operating systems designed to provide enterprises and device manufacturers the freedom to choose which capabilities will be part of their industry devices and intelligent system solutions.

First version of Windows Embedded Industry to be based on the Windows 7 Platform.

Released in 1999 as Windows NT Embedded 4.0. See IoT.

Microsoft, USA

Operating system for handhelds, embedded devices, and real-time applications that is similar to other versions of Windows.

Microsoft, USA

Microsoft Azure (formerly Windows Azure). Cloud computing service created by Microsoft for building, testing, deploying, and managing applications and services through a global network of Microsoft-managed data centers.

Microsoft, USA

Aka Windows 4.1. Codename Memphis. Like its predecessor, Windows 98 is a hybrid 16-bit and 32-bit monolithic product with the boot stage based on MS-DOS.

Microsoft, USA

Aka Windows 4.0. Codename Chicago. Windows 95 merged Microsoft's formerly separate MS-DOS and Windows products, and featured significant improvements over its predecessor, most notably in the graphical user interface (GUI) and in its simplified "plug-and-play" features.

Microsoft, USA

Aka Windows NT 6.3. Free update of Windows 8.

Microsoft, USA

Aka Windows NT 6.2. Windows 8 introduced major changes to the operating system's platform and user interface to improve its user experience on tablets.

Microsoft, USA

Aka Windows NT 6.1. Code name Blackcomb and Vienna.

Microsoft, USA

Chinese-only release of Windows 3.

Microsoft, USA

Improved version of Windows 3.1.

Microsoft, USA

Same as Windows 3.0 except required a minimum of a 286 PC with 1 MB of RAM to run, removed CGA support, TrueType font support, Ehanced Mode support.

Microsoft, USA

Second version of Microsoft Windows including a significantly revamped user interface as well as technical improvements to make better use of the memory management capabilities of Intel's 80286 and 80386 processors.

Microsoft, USA

Aka Windows NT 5.0. Four editions of Windows 2000 were released: Professional, Server, Advanced Server, and Datacenter Server.

Microsoft, USA

Separate version for i386 processor.

Second version of Microsoft Windows.

Microsoft, USA

Aka Windows NT 10. Series of personal computer operating systems produced by Microsoft as part of its Windows NT family of operating systems.

Microsoft, USA

First version of Microsoft Windows.

Microsoft, USA

16-bit and 32-bit preemptive and cooperative multitasking, running atop MS-DOS.

Microsoft, USA

MC-68K multiuser OS for their proprietary microcomputers, used mainly for CBT systems.

WICAT, USA

Simple share file system for distributed environment.

USA

See LG webOS.

Palm, USA

PC-DOS version.

Waterloo Microsystems, USA

Mobile operating system of the Apple Watch.

Apple, USA

Used on the VS line of minicomputer systems.

Wang Laboratories, USA

SAIL, Stanford Artificial Intelligence Laboratory. Time-sharing system for DEC PDP-6 and PDP-10, later TOPS-10.

DEC, USA

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

Wind River Systems, USA

Operating System for Harris computers.

USA

Virtual Technology’s Operating System. The second TRS‑80 Model I operating system.

Randy Cook, Virtual Technology, USA

Valencia's Simple Tasker. Was an operating system with a microkernel architecture, with all device drivers and file systems residing in userspace mode.

Andy Valencia

Virtual Storage Operating System. Operating system for the Cyber 205 pipelined processor.

USA

Program product replacing DOS/VSE and VSE/AF.

IBM, USA

DOS/VSE extended virtual memory support to 32-bit addresses (Extended System Architecture).

IBM, USA

Successor to RCA TSOS. Discontinued computer operating system available for the UNIVAC Series 90 mainframes during the late 1960s through 1980s.

Sperry UNIVAC, USA

IBM Virtual Storage OS. See OS/VS2.

IBM, USA

IBM Virtual Storage OS. See OS/VS1.

IBM, USA

Operating system for Wang VS series systems.

Wang Laboratories, USA

Virtual Resource eXecutive. Proprietary operating system on the NCR Criterion series, and later the V-8000 series of mainframe computers manufactured by NCR during the 1970s and 1980s. It replaced the B3 Operating System.

NCR, USA

Versatile Real-Time Executive. Real-time operating system suitable for both traditional board-based embedded systems and SoC architectures. It has been superseded by the Nucleus RTOS.

Mentor Graphics, USA

Virtual Processing System/Virtual Machine. Was an operating system that ran on IBM System/370 – IBM 3090 computers at Boston University in general use from 1977 to around 1990, and in limited use until at least 1993.

IBM, USA

Replaced the department computer operating system VOSK, was developed as a mid-range total management server with the features of a database server, a computing server, and a management server.

Hitachi, Japan

Small/medium OS for M-620, M-630 and M-640.

Hitachi, Japan

Operating system for HITAC M series computers.

Upgraded operating system over VOS3/AS, which supported the MP5800, which was the world’s fastest single-processor machine in 1995, and its smaller sister models, including the MP5500.

Multiple virtual storage system that provided an independent 16-MB virtual storage to each job.

Operating system for HITAC M computers.

Virtual-storage Operating System 3. For its IBM-compatible mainframes, based on IBM's MVS.

Hitachi, Japan

Was the first OS for the HITAC M series, which was a series of Hitachi's general-purpose computers

Hitachi, Japan

Upgraded operating system over VOS1/ES2.

General-purpose medium OS suitable for departmental distributed processing.

Operating system for HITAC L series distributed processing computers.

Operating system for lower models in Hitachi's HITAC M series of general-purpose computers, was the second OS in the M series following VOS2.

Hitachi, Japan

Operating system for HITAC L series distributed processing computers.

Hitachi, Japan

Virtual Operating System. Proprietary operating system running on Stratus Technologies fault-tolerant computer systems. With strong influence from Multics.

Stratus Technologies, USA

Operating System for Harris 600, 700, 800 computers.

USA

Virtual machine OS running on the Michigan Terminal System.

USA

Omnitasking realtime executive for Varian minicomputers.

USA

Last version. Succeeded by OpenVMS 6.0.

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.

DEC, USA

Virtual Memory Operating System. Timesharing OS for the RCA Spectra 70.

RCA, USA

DOS extender that adds Unix like multi-user capabilities. Version 3.0 will be DPMI compliant and will use a new portable microkernel named 'BABy'.

Tony Borras

New Version of this Multiuser DOS, originally introduced in 1984, The design of VMiX has changed to allow it to migrate from IA32 architectures to the newer AMD64 and IA64 environments.

SysDev, USA

Merger of VME/B and VME/K, it was in reality the VME/B base with a few selected features from VME/K grafted on.

Never actually launched.

Targeted at the mid-range systems such as the 2960.

Targeted at large processors such as the 2970/2980.

Virtual Machine Environment. Mainframe operating system. Implementation language S3 (ALGOL 68).

ICL, UK

Hypervisor from Fujitsu (formerly Siemens Nixdorf Informationssysteme) designed specifically for use with the BS2000 operating system. It is an EBCDIC-based operating system.

Siemens, Germany

Virtual Machine/Extended Architecture System Product.

IBM, USA

Virtual Machine/Extended Architecture System Facility. Allow the machine to provide execution in the virtual-machine environment of most of the instructions (including many privileged instructions) and most of the facilities (such as dynamic address translation) of both the System/370 and the 370-XA architectures.

IBM, USA

Virtual Machine/Extended Architecture Migration Assistance. Tool to assist in migration from MVS/370 to MVS/XA.

IBM, USA

VM/eXtended Architecture for System/370 with extended virtual memory.

IBM, USA

Virtual Machine/System Product.

IBM, USA

Virtual Machine/Extended Product. Functional ehancement to VM/370.

IBM, USA

Version of VM/370 for the PC/370.

IBM, USA

Virtual Machine / Extended System Architecture, added 31-bit addressing to VM series.

IBM, USA

Virtual Machine/Basic Extended Product. Functional ehancement to VM/370.

IBM, USA

Virtual Machine Facility/370. Virtual memory operating system. To assist customers in migration from OS/360 to OS/VS.

IBM, USA

Visual Operating System. The operating system is licensed under the GNU GPL.

Andy McLaughlin, Canada

First GUI for early PC machines. Not commercially successful.

VisiCorp, USA

DEC's proprietary operating system originally produced for its VAX minicomputer. Renamed "OpenVMS" around version 5.5.

DEC, USA

Operating system built of reusable, replacable components that can be organized by the end-user, even code running in kernel mode.

Harvard University, USA

MS-DOS compatible system for 68000.

Motorola, USA

Platform release of EOS that is supported on Amazon Web Service (AWS), Microsoft Azure and other public clouds.

Arista, USA

Experimental OS for a modified Interdata minicomputer, based on matching the computer architecture to the operating system.

Barbara Liskov, USA

Last version. Based on UNIX System V Release 4.2 (UnixWare).

Based on System V.

Like the original Venix/86, it included a C compiler, a Basic interpreter and added a Fortran 77 compiler as an option.

Discontinued version of the Unix operating system for low-end computers.

VenturCom, USA

Real-time operating system.

Green Hills Software, USA

Realtime object-oriented OS for the MicroVAX.

USA

Standard operating system for DEC VAX. Based on RSX-11.

USA

Virtual-machine monitor. TCSEC A1-class, VMM for VAX computers.

DEC, USA

Project to build out a Lisp-based OS based on a persistent object store and has quite a few other interesting principles.

Australia

Operating system focused on speed for projects like real-time video serving, etc.

V2 Lab, Netherlands

Discontinued microkernel operating system that was developed by faculty and students in the distributed systems group at Stanford University.

Stanford University, USA

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.

Gould CSD, USA

Operating system for Mitsubishi COSMO mainframes.

Mitsubishi, Japan

Discontinued implementation of the UNIX operating system for IBM mainframe (and compatible) computers.

Amdahl, USA

Universal Time-Sharing System. Time Sharing Operating System for Xerox SIGMA computers.

Xerox, USA

Universal Time-sharing Monitor. Operating system for a large-scale system capable of simultaneously performing batch processing, remote batch processing, real-time processing and time-sharing processing.

Mitsubishi, Japan

Real-time development system for 8086, 68000.

United States Software, USA

Non-preemptive, multitasking, priority based RTOS.

Marko Panger

Operating system for embedded microcontrollers.

Russia

Aka Uuu, "operating engine" is "a highly componentized system, where each component can be dynamically loaded, unloaded, replaced at runtime.

Dave Poirier, International

First, now discontinued, 32-bit Unix-like real-time operating system (RTOS) with real-time extensions.

Charles River Data Systems, USA

UnixWare 2 kernel plus parts of 3.2v5 (UnixWare 2 + OpenServer 5 = UnixWare 7). Referred to by SCO as SVR5.

Based on AT&T System V Release 4.2MP.

Unix operating system. It was originally released by Univel, a jointly owned venture of AT&T's Unix System Laboratories (USL) and Novell.

Univel, Novell, SCO, Caldera Systems, Caldera International, The SCO Group, Xinuos, USA

Early version of the Unix operating system. 32V was a direct port of the Seventh Edition Unix to the DEC VAX architecture.

Bell Labs, USA

See DMERT.

Bell Labs, USA

It is from Version 7 Unix that almost all Unix-based and Unix-like operating systems descend.

"Ken's new system," for its creator (Ken Thompson), officially Unics and then Unix, the prototypic operating system eated in Bell Labs in 1969 that formed the basis for the Unix family of operating systems.

Bell Labs, USA

The first version of AT&T System V UNIX on the IBM 286 and 386 PCs, ported and sold by Microport.

Discontinued version of the Unix operating system released by AT&T's Unix Support Group (USG).

Early version of the Unix operating system.

Family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix.

Bell Labs, USA

Server operating system derived from Debian GNU/Linux with an integrated management system for the central and cross-platform administration of servers, services, clients, desktops and users as well as virtualized computers operated in UCS.

Univention, Germany

Version of UNIX for the PDP-11 and VAX.

Human Computing Resources, USA

Operating system for the Unisys ClearPath Dorado family of mainframe systems.

Unisys, USA

Master Control Program. Proprietary operating system of the Burroughs small, medium and large systems, including the Unisys Clearpath/MCP systems.

Unisys, USA

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.

RoweBots, USA

Pretty standard, kernel based OS.

Michael Gerhards, Germany

Version of UNIX for PDP-11.

Uniq Digital Technologies, USA

Discontinued commercial version of the Unix System III and System V operating systems for the 68000.

Unisoft Systems, USA

For large machines. Upgrade to the UNIOS/F4.

For large machines.

For medium-sized machines.

For small machines.

Operating system for the FACOM V series, developed jointly by Fujitsu, USAC Electronic Industrial and Uchida Yoko.

Fujitsu, Japan

Unix-like OS from TSC for DMA-capable, extended addresses, Motorola 6809 based computers; e.g. SWTPC, GIMIX and others.

Technical Systems Consultants (TSC), USA

Uniplexed Information and Computing Service. Later Unix. AT&T, initially on DEC computers.

AT&T, USA

Name of a range of Unix-like operating system variants developed by Cray for its supercomputers. UNICOS is the successor of the Cray Operating System (COS).

Cray, USA

Network OS for the 8086, 68000, & 16032 families. Multitasking with transparent remote file access, load balancing, and multiple windows. UNIX and PC-DOS compatible.

Lantech Systems, USA

Virtual machine system for the IBM 360/67.

USA

Also known as UMIPS/V, UMIPS_V, or UMIPS (System V) was a port of AT&T UNIX System V Release 3.

MIPS Computers' first operating system, a port of Berkeley's BSD4.3 version of UNIX.

MIPS Computer Systems, USA

University of Michigan Executive System. Batch operating system.

IBM, USA

Operating system for 8080, 6800, 68000, Z8000 series, and others.

Boston Systems Office, USA

Last major release.

Brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX and DECstations.

DEC, USA

Originally called Level IV DOS. Operating system for the Tandy TRS-80 Level IV Products.

Vernon Hester, USA

Version of PICK.

The Ultimate Corp., USA

Multi-tasking OS suitable for small embedded µController systems.

Edo Franzi, Switzerland

Micro disk operating system for PC/AT compatibles with legacy floppy drive.

K. Gondow and M. Ohba, Japan

Free operating system built on the FreeDOS kernel with DJGPP.

B. Decker

Portable complete programming environment/operating system/virtual machine developed by a long running student project at UCSD.

University of California San Diego, USA

Virtual machine system developed at UCLA for modified PDP-11/45 for data security studies.

UCLA, USA

Early secure UNIX OS based on security kernel.

UCLA, USA

Also known as Ubuntu Phone. Mobile version of the Ubuntu operating system that was originally developed by Canonical and is now being developed by the UBports community.

Canonical, UK

Canonical agreement with the Ministry of Industry and Information Technology of the People's Republic of China to release an Ubuntu-based Linux OS.

Canonical, UK

Free and open-source operating system and Linux distribution based on Debian.

Canonical, Ubuntu community, UK

Family of real-time operating systems.

Green Hills Software, USA

Operating system for the Tymnet network.

Tymes, USA

Terminal Executive Development System. Proprietary operating systems for TI-990 minicomputers.

Texas Instruments, USA

Time Warp Operating System. OS developed for the Mark III Hypercube multiprocessor, primarily to support asynchronous discrete event simulation. Synchronizes events by unlimited process rollback.

Caltech Jet Propulsion Laboratory, USA

Operating system developed by Apple for the fourth-generation and later Apple TV digital media player.

Apple, USA

Enhanced multitasking version of CP/M for Z80 and 8086.

Software 2000, USA

Multi user CP/M like operating system for the Z80 and 8086 CPUs.

Software 2000, USA

One of the primitive operating systems for BK-0010 and BK-0010-01, ideologically close to KMON . File system is not compatible with anything.

Russia

Toronto University System. Unix-like operating system. TUNIS was a portable operating system compatible with Unix V7, but with a completely redesigned kernel, written in Concurrent Euclid.

University of Toronto, Canada

TU Dresden Research Operating System.

TU Dresden, Germany

Operating System with many unique, innovative features including Pre-emptive Timeslicing, and Dynamic Multitasking. See Raven.

PiSig Innovations Lab., USA

RT-11 compatible multitasking, multiprocessing OS for PDP-11 family.

S&H Computer Systems, USA

General purpose 32-bit multi-user multitasking operating system for x86 architecture platform, with a command line user interface. It is compatible with some 16-bit DOS applications and supports file systems FAT16 and FAT32.

S&H Computer Systems, USA

Time Sharing eXecutive.

IBM, USA

IBM's Time-sharing System for the S/360-67. Never officially released, canceled in 1969 and again in 1971.

IBM, USA

Discontinued time-sharing operating system. DEC also referred to it as Timeshared-8 and EduSystem 50.

DEC, USA

Timesharing OS for General Automation System 18/30.

USA

Early timesharing system for the AN/FSQ-32.

USA

Time Sharing Operating System. First OS supporting virtual addressing of the main storage and support for both timeshare and batch interface. Renamed VMOS.

RCA, USA

Time Sharing Monitor. Early timesharing OS for the 7090.

IBM, USA

Timesharing OS for the DEC PDP-8.

USA

Unix-like OS of the BSD family which provides a set of trusted operating system extensions to the FreeBSD operating system, targeting the Common Criteria for Information Technology Security Evaluation (CC).

Robert Watson, USA

Solaris with kernel and other enhancements to support multilevel security.

Sun Microsystems, USA

Previously known as PC-BSD. Unix-like, server-oriented operating system built upon the most recent releases of FreeBSD-CURRENT.

iXsystems, USA

Tandy

Tandy

Most widely used version of TRSDOS.

Tandy

First version of TRSDOS created by Radio Shack programmers.

Tandy

First version of Model I TRSDOS to be released to the public. All earlier versions had been used for testing within Radio Shack only.

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.

Randy Cook, Tandy, USA

The Real-Time Operating System Nucleus. Specification for a family of real-time operating systems and an associated CPU architecture.

TRON Project, University of Tokyo, Japan

Network oriented OS.

USA

TRIvial Portable Operating System.

University of Cambridge, University of Bath, MetaComCo, UK

Portable OS for Minicomputers. PDP-11, 68000 series, 32000 series.

USA

Operating system for three users, written in Concurrent Pascal, based on SOLO.

Per Brinch Hansen, USA

Static RTOS for small embedded systems. Its API is aligned with OSEK/VDX OS and AUTOSAR OS 4.2 standards.

LS2N (ex-IRCCyN) Laboratory, France

Disk operating system for the ZX Spectrum with Beta Disc and Beta 128 disc interfaces.

Technology Research, UK

Transaction Processing Facility. IBM real-time operating system for mainframe computers descended from the IBM System/360 family, including zSeries and System z9.

IBM, USA

Version of CP/M for the Epson QX-10.

Epson, Japan

Graphical OS called Towns OS, based on MS-DOS and the Phar Lap DOS extender.

Fujitsu, Japan

Operating Systems for the TOSBAC Q Series.

Toshiba, Japan

POS operating system based on IBM 4690 OS and FlexOS.

Digital Research, USA

First-Generation Operating Systems for the TOSBAC-1350.

Toshiba, Japan

First-Generation Operating Systems for the TOSBAC-1150 office computer.

Toshiba, Japan

First-Generation Operating Systems for the TOSBAC-1100E office computer.

Toshiba, Japan

IBM's Tape Operating System. Similar to BOS above and more fleeting, able to boot and run from 2x00 series tape drives.

IBM, USA

Teradata Operating System.

Teradata, USA

Operating system for the Atari 520ST and 1040ST. Derived from Concurrent 68K.

USA

Tape Operating System. Early operating system for the RCA Spectra 70.

USA

Teletype Operating System for the Microdata 1600 & 3200 minicomputers.

USA

Tape OS.

Hitachi, Japan

Single address-space (SAS) OS with orthogonal persistence

Dan Helfman

Eucational OS. It is a small multi-threaded message-based microkernel written in ANSI C and running on a R3000 simulator written in Java.

ETH Zurich, Switzerland

Proprietary OS used on some of DEC's 36-bit mainframe computers.

DEC, USA

Last stable release.

Last stable release.

Last stable release.

Timesharing/Total Operating System-10. Discontinued operating system from DEC for the PDP-10 (or DECsystem-10) computer family.

DEC, USA

Embedded operating system designed for running multiple concurrent, mutually distrustful applications on low-memory and low-power microcontrollers.

Japanese roughly equivalent to 'a certain'. Hobby operating system and kernel developed largely independently (notably contrary to most modern OSes.

Kevin Lange

compact and very fast real-time kernel for the embedded 32/16/8 bits microprocessors.

Yuri Tiomkin, Russia

Compact and fast real-time kernel for embedded 32/16 bits microprocessors.

Russia

Transaction Management eXecutive. NCR Corporation's proprietary transaction processing system running on NCR Tower 5000-series systems which were based on Motorola 680xx CPUs.

NCR, USA

Magnetic tape operation system based on 4K disk monitor system (DMS), but reconfigured to improve speed and performance on a magnetic tape.

DEC, USA

New Transaction Processing System TME-TP was introduced for the ME29, with a subset of the facilities of TPMS.

Transaction Machine Environment. was the operating system on the ME29 and required CL (Control Language) to run jobs - 'manual' operation being discouraged.

ICL, UK

South Korean OS based on Windows.

TmaxSoft, Korea

Lightweight RTOS-based platform to support low-end IoT devices.

Earlier called LiMo Platform. Operating system based on the Linux kernel, a project within the Linux Foundation and is governed by a Technical Steering Group (TSG) while controlled by Samsung and backed by Intel. Tizen works on a wide range of Samsung devices including smartphones, tablets, smart TVs, PCs and wearable.

Samsung Electronics, The Linux Foundation, Korea

Early time-sharing system.

Queen's University of Belfast, UK

Timesharing operating system for the Titan.

Cambridge University, UK

Embedded, component-based operating system and platform for low-power wireless devices, such as those used in wireless sensor networks (WSNs), smartdust, ubiquitous computing, personal area networks, building automation, and smart meters.

TinyOS Alliance

Small, multipurpose OS that could be used as a learning tool for the author and anyone else that cared to use it.

Bart Sekura

Used in routers from Alcatel-Lucent.

Alcatel-Lucent, France

Project to develop an OS and framework for the construction of a family of distributed object-oriented platforms.

Trinity College Dublin, Ireland

Real-time operating system for TI's embedded devices.

Texas Instruments, USA

Highly deterministic, embedded real-time operating system.

Express Logic, USA

Real-time operating system which is designed to be portable over a large set of machines.

University of Waterloo, Canada

Deceased project of a Unix OS implementation written from scratch for the purpose of learning.

Tudor Hulubei, USA

Operating system which started out as OASIS, a microcomputer operating system for small computers that use the Z80 processor.

Phase One Systems, USA

Multiprogramming system by Dijkstra. Introduced the first form of software-based memory segmentation, freeing programmers from being forced to use actual physical locations.

Eindhoven University of Technology, Netherlands

Ancestor of TOPS-20 from BBN, for the PDP-10.

DEC, USA

Algebraically specified abstract machine. Successor of Flex machine.

Royal Signals and Radar Establishment, Malvern, UK

Formerly J Operating System, SparrowOS and LoseThos. Biblical-themed lightweight operating system designed to be the Third Temple prophesied in the Bible.

Terry A. Davis

Tape and Disk Operating System.

Based on oCos. See Lepton.

Philippe Le Boulanger, France

Modern version of IS-DOS.

NedoPC, Russia

Full-featured real-time operating system designed specifically for embedded applications.

Blunk Microsystems, USA

Tape based OS derived from SCOPE for the CDC System 17.

USA

Now called Elate.

Suite of five POSIX Compliant Real Time Operating Systems that are individually optimized for each TI DSP family.

Blackhawk, USA

Uniprocessor operating system.

Uniprocessor operating system.

Uniprocessor operating system.

Multiprocessor operating system.

Uniprocessor operating system.

Object-oriented operating system. Initially started as a project within Apple to provide a replacement for the classic Mac OS, it was later spun off into a joint venture with IBM as part of the AIM alliance, with the purpose of building a competing platform to Microsoft Cairo and NeXTSTEP. Replaced by Copland and IBM CommonPoint.

Apple, USA

TAJ is India's first object oriented operating system. Its developed in C++. The code is well modularised & maintain. TAJ is a multitasking, multithreading and multiuser operating system.

Viral Patel, India

Tabos is a new operating system based on a modular monolithic kernel with module loading support, using the x86 platform features.

Jan-Michael Brummer, Germany

Research OS developed by Edsgar Dijkstra. Named for the Technische Hoogeschool at Eindhoven, where it was developed. Early exploration of program verification techniques. Early layered system design. First implementation of semaphores.

Technische Hoogeschoo, Netherlands

Open source real-time operating system designed for 32-bit microcontrollers. It is standardized by the T-Engine Forum, which distributes it under a "T-License" license agreement.

T-Engine

IBM version of Stratus/32 OS.

IBM, Stratus Computer, USA

Microkernel based multiprocessor, multitasking, multithreading operating system for the IBM-PC Intel i386 systems. It is developed in Department of Computer Science of Bahahuddin Zakariya University, Multan Pakistan.

Bahahuddin Zakariya University, Multan, Pakistan

System Executive. A time-sharing monitor for SIGMA/2 and small IBM S/360 computers.

USA

Operating system for the Philco-2000 computer.

Philco, USA

OGI's Synthetix project of fine-grained incremental partial evaluation in OS kernels, using a combination of highly isolated system components, and dynamic code generation. Sponsored by ARPA, Intel, and Hewlett-Packard.

OGI School of Science and Engineering, USA

The first of the modern OS that dynamically generated code at runtime. Although it was written in MC68000 assembly, it opened the path to projects like Aegis and Synthetix.

Henry Massalin, USA

SYstem for MOBIle applications. proprietary modern and mobile real-time operating system. Designed for the area of embedded and mobile systems.

Miray Software, Germany

SYmbiosis Multitasking Based Operating System. GUI based modern micro-kernel OS for x86, ARM and PowerPC processors. Used and developed further at Technical University of Munich.

Miray Software, UK

Successor to Symbian OS.

Symbian, UK

Discontinued mobile operating system and computing platform designed for smartphones.

Symbian, UK

Modern, independently originated OS. See AtheOS.

K. Van Der Vliet, K. de Vos, R. Caudill, A. Klenke, H. Isaksson, UK

Complete SDN operating system based on Open Network Linux (ONL), an open source effort within the Open Compute Project.

Big Switch Networks, USA

Pretty standard, kernel based OS, but that actually boots and works to some extent.

Single Virtual Storage. Refers to Release 1 of Operating System/Virtual Storage 2 (OS/VS2); it is the successor system to the MVT option of Operating System/360.

IBM, USA

Added RIAD-3 support.

Added Russian language capability.

Sistema Virtual'nykh Mashin. IBM VM/370 clone.

Russia

Designed for servers, mainframes, and workstations but can be installed on desktop computers for testing as well.

SUSE, Germany