Operating system expansion for the Commodore 64 that gives it a whole new set of sophisticated tools with a powerful and unified user interface.

OpCoders, Canada

Memory-based real-time UNIX-like executive for the PDP-11 or VAX. Runs multiple C or Pascal Tasks.

JMI Software Consultants, USA

Privileged-mode portion of V++, a scalable multiprocessor OS.

Kenneth Duda, USA

Research OS for the CDC 6400.

USA

Latest stable version.

DR DOS acquired by Caldera in 1996. See DR-DOS.

Digital Research, USA

MS-DOS compatible operating system, the descendant of DR DOS and Novell DOS.

Digital Research, USA

All operating system procedures written in ALGOL 68C, with some closely associated protected procedures in BCPL.

Cambridge University, UK

Experimental local area network architecture.

Cambridge University, UK

Capital is an Object Oriented Operating System being developed for iPAX386+ processors. It features a multithreading tasking model. The kernel itself is multithreaded and is fully preemptible giving support for Real Time processes.

Nippun Goel, India

Capability-based Reliable Operating System. Open source operating system. Microkernel EROS successor.

Strawberry Development Group, USA

Cassette Monitor System for the DEC PDP-11.

DEC, USA

Cassette Monitor system for the DEC PDP-8.

DEC, USA

Open-source operating system, based on FreeDOS kernel. CarbonOS is a successor of discontinued LightDOS. Compaible with MS-DOS.

Corbin Davenport, USA

Catalyst Operating System. Discontinued operating system for many of the Catalyst brand of legacy network switches. It was originally called XDI by the switching company Crescendo Communications, Inc. Cisco renamed it to CatOS when they acquired Crescendo in late 1993.

Cisco Systems, USA

Variant of the UNIX operating system used internally at Bell Labs for administrative databases and transaction processing.

Bell Labs, USA

Real-time multi-user multi-tasking operating system.

Concurrent Controls, USA

Communications Control Program. Limited OS for the IBM System/3.

IBM, USA

Disk Operating system compatible with CP/M.

Cromemco, USA

Linux distribution that provides a free, enterprise-class, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux.

Like OpenBLT is a cleanroom implementation of an OS based on a microkernel (codenamed Storm), announced over the summer; there is both code and documentation available on the site, as well as a downloadable and bootable demo floppy that will let you try your hand at it in no time.

Henrik Hallin and Per Lundberg, Sweden

Simple 32bit operating with simple code. Perfect to teach basics. In future it will be using 4 rings of CPU.

Fixa, Poland

Distributed OS for the Crystal Multicomputer project. Explores coarse-grained parallelism without shared memory for computationally intensive tasks.

University of Wisconsin, USA

Nano-kernel OS aimed at the support of Orthogonal Persistence.

Compact and fast real-time operating system supporting multiple architectures and released under the GPL3 license.

Giovanni Di Sirio, Italy

Operaing system for the UNIVAC 1108 in a service bureau environment.

Case Western Reserve, USA

Operating system for the CDC 6600 supercomputer. Original name of SCOPE.

Control Data, USA

Object-oriented operating system.

University of Illinois, U. of Idaho ?, USA

Proprietary microkernel OS, rival of Mach and a RTOS, (now acquired by Sun Microsystems) for telecommunication devices (cellphones, etc.) and network appliances (webphones, set top boxes, etc...).

INRIA, France

Designed to work exclusively with web applications. The Chrome OS source code was released in 2009, under the BSD license as Chromium OS.

Google, USA

Open source operating system development version of Chrome OS. Both operating systems are based on the Linux kernel.

Google, USA

Real-time Linux patch.

Virginia Tech, USA

Batch oriented disk operating system for the Cincinnati Milacron CIP/2200.

USA

Free Common Lisp development and deployment platform for Linux-based GNU systems.

Originally Internetwork Operating System. Family of software used on most Cisco Systems routers and current Cisco network switches.

Cisco Systems, USA

Colloquial term used to describe a series of operating systems developed for the Macintosh family of personal computers by Apple.

Apple, USA

Operating system written in Python with the Python VM as a micro-kernel on top of a minimal C/asm layer.

Live CD of FreeBSD.

Microkernel-based system for x86 hardware. It's based on modular architecture and already supports preemptive multithreading + user-level processes.

Pype & the Clicker Development Team, Belgium

Multilevel secured operating system.

ANSSI, France

Distributed object-based operating system.

Georgia Institute of Technology, USA

Cambridge Multiple Access System.

University of Cambridge, UK

Cambridge Model Distributed System. Sets out to provide, by means of a number of interconnected mini- and microcomputers, facilities that are similar to those provided by a time-sharing system.

University of Cambridge, UK

Cambridge Monitor System or Conversational Monitor System. Single User Interactive OS developed in conjunction with the Virtual Machine Control Program CP-40 at IBM Cambridge Laboratories. Later adapted for CP-67 and VM/370.

IBM, USA

Cloud Network Operating System.

Lenovo, China

Now Stratify OS.

Stratify Labs, USA

Local network operating system based on UNIX, developed for the COCANET local area network.

U.C. Berkeley, USA

Free, open source, cooperative task scheduler, based on coroutines targeted for embedded microcontrollers like AVR, MSP430 and STM32.

Coherent Unix-like OS from Mark Williams Co. for PC class computers.

Mark Williams Corp., USA

ROM-based OS created by Microsoft for the TRS-80 Color Computer.

Tandy, USA

Disk operating system used with Commodore's 8-bit computers.

Commodore, USA

Object-oriented application development environment. Commercial version of Apple/Taligent operating system.

Taligent, USA

Network operating system for Comware switches.

Hewlett-Packard, USA

Dual-processor variant of Concurrent CP/M for 8086 and 8080 CPUs.

Variant for the 68000.

BDOS 3.1 with PC-MODE (Digital Research's successor of CP/M-86 and MP/M-86).

Adaptation of Concurrent CP/M-86 for the LSI-M4, LSI Octopus and CAL PC computers.

Successor of CP/M-86 and MP/M-86 supporting limited multitasking.

Successor of CP/M-80 and MP/M-80.

Digital Research, USA

Concurrent DOS 386 variant with advanced graphics terminal capabilities.

Port of Concurrent DOS to Motorola 68000 CPUs with DOS source code portability capabilities.

Successor of Concurrent CP/M-86 with PC-MODE.

Digital Research, USA

Dual-processor variant of Concurrent DOS for 8086 and 8080 CPUs.

Real-mode variant of Concurrent DOS with EEMS support.

Concurrent DOS variant for IBM compatible PCs.

Digital Research, USA

Replaced in 1986 by Concurrent DOS XM.

Distributed OS described as a "hunter of idle workstations," which distributes large computationally intensive jobs among available processors in a workstation pool. Renamed HTCondor.

University of Wisconsin, USA

Small romable embedded operating system for ARM processors.

Nexus, USA

Operating system for networked, memory-constrained systems with a focus on low-power wireless Internet of Things devices.

Also known variously as CTOS, BTOS and STARSYS, was a modular, message-passing, multiprocess-based operating system. Later acquired by Unisys.

Convergent Technologies, USA

Operating system for the CDC 1604 computer.

Control Data, USA

Customer-Oriented Optimum Language. Decimal machine language and operating system for the Melcom 81 computers.

Mitsubishi, Japan

Embedded real-time multi-task OS specially for ARM Cortex M series. Originally a project launched by Embest Info. Tech. Co. along with Wuhan University of Technology

CooCox, China

Unreleased operating system prototype for Apple Macintosh computers of the late 1990s, intended to be released as the modern System 8 successor.

Apple, USA

Comprehensive Operating Supervisor.

General Electric, USA

Cassette OS for Computer Automation Alpha LSI and Naked Mini LSI.

USA

Commercial Operating System. Early OS for the PDP.

USA

Commercial data management system for the PDP-8.

Operating system for the PDP-11.

Commercial data management system for the PDP-8.

Commercial data management system for the PDP-11.

Concurrent Operating System. Provided limited multiprogramming for Univac 9200, 9300.

USA

Operating System for GEC Computers.

USA

Cray Operating System. OS for the Cray-1 Pipelined Supercomputer.

USA

Core Operating System. For diskless real-time systems.

GEC Computers, UK

China Operating System. Linux kernel-based mobile operating system developed in China mainly targeting mobile devices, tablets and set top boxes. Developed by the Institute of Software at the Chinese Academy of Sciences (ISCAS) together with Shanghai Liantong Network Communications Technology to compete with foreign operating systems like iOS and Android.

Liantong Network Communications Technology, China

Operating system for TOSBAC-5100/30.

Toshiba, Japan

Operating system for TOSBAC-5100/20. Was capable of continuously executing batch jobs using a magnetic tape.

Toshiba, Japan

Operating system for TOSBAC-5100/10. Was capable of continuously executing batch jobs using a magnetic tape.

Toshiba, Japan

Un OS en fran?ais enti?rment en ASM. Le site traite aussi de la prog des OS.

cos2000, France

Open Source Managed Operating System a toolkit for building operating systems written in C.

Aka Borealis. Small OS built with NASM and DJGPP.

Culham Online Task Activation Network. Multiaccess on-line system for a KDF9 computer connected to a small PDP-8 computer.

UKAEA Culham, UK

Microkernel EROS successor, goal: be first formally verified OS.

University Johns-Hopkins, The Éros Group, USA

Control Program. A component of VM/370 for the IBM/370. CP is the kernel which implements the virtual machine.

USA

Control Program/Cambridge Monitor System.

IBM, USA

Originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created for Intel 8080/85-based microcomputers.

Digital Research, USA

Combined version of CP/M 2.2 and CP/M-86.

CompuPro, USA

First CP/M available for the Amstrad CPC.

CPM For Motorola 68000.

Popular operating system for 8080 and Z80 microcomputers. Each release was customized by OEMs specifically for their hardware.

CPM For Zilog Z8000.

The last 8-bit version of CP/M was version 3, often called CP/M Plus.

UK

Version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. The system commands are the same as in CP/M-80

Digital Research, USA

Released for the Apricot PC. Based on the multitasking Concurrent CP/M-86 kernel.

Released for the Apricot PC. Based on the multitasking Concurrent CP/M-86 kernel.

Networking version of CP/M. Enables microcomputers to access common resources via a network. CP/NET allows microcomputers to share and transfer disk files, to share printers and consoles, and to share programs and data bases.

Digital Research, USA

Memory-resident, diskless version of CP/NET.

Digital Research, USA

Predecessor to CP-67 on modified IBM System/360 Model 40.

IBM, USA

Discontinued computer operating system developed by Honeywell. It was a backward-compatible work-alike of the Xerox CP-V fully rewritten for Honeywell Level/66 hardware.

Honeywell, USA

Also known as CP/CMS. Virtual machine control program for the IBM 360/67. Successor to CP-40. See also CMS.

IBM, USA

Control Program for Real-Time. Realtime operating system for Xerox 550 and Sigma 9 computer systems.

Xerox, USA

Compatible successor to UTS. It supported the same CPUs as UTS plus the Xerox 560.

Xerox, USA

Control Program Facility.

IBM, USA

Card/Paper Tape Programming System for the IBM 1130.

IBM, USA

Early OS for DEC minicomputers.

USA

Control Programming Support, subset of RPS.

IBM, USA

Operating System for FACOM System 80 office computer. Derived from BMOS.

Fujitsu, Japan

Free operating system based on the Cpcdos OSx kernel, written only with CpcdosC+ language.

Sebastien Favier, France

Operating system for Cray supercomputers. New name for UNICOS/lc.

USA

New name for UNICOS.

USA

Multi-tasking, multi-user, Unix-like OS. first Unix-like operating system for microcomputers.

Cromemco, USA

Object-oriented distributed computing system for heterogenous environments.

Software development kit (SDK) for use in developing collaborative virtual world applications.

Alan Kay, Julian Lombardi, Mark P. McCahill, Andreas Raab, David P. Reed, David A. Smith, USA

Conversation Real-time Oriented System. Floppy Disk Operating system for OKITAC System 9 series.

Oki, Japan

Conversation Real-time Oriented System. Hard-disk Operating system for OKITAC System 9 series.

Oki, Japan

Operating system, created in Samara, for the Soviet Elektronika BK-0011M and Elektronika BK-0011 microcomputers.

Russia

Operating system for the CSIRONET ?

CSIRO, Australia

Customer-oriented System Products. Operating system developed jointly by Fujitsu and USAC Electronic Industrial (which later became PFU) for the FACOM K series of office computers.

Fujitsu, Japan

For small machines.

For medium-sized machines.

For large machines.

Merge between CSP/F3 and CSP/F5.

Cassette Tape OS for Datapoint 1100, 2200, 5500.

Datapoint, USA

Cassette Tape Operating System for early desktop systems. Capable of up to 8 simultaneous users. Replaced by OS.

Real time, multitasking, multiprocessing OS for 8086 family.

Convergent Technologies, USA

Central and Communication TRON. Mainframe computers and telecommunications TRON.

NTT, Japan

Commercial single or multiuser OS for small PDP-11 systems.

DEC, USA

Commercial single or multiuser OS for small PDP-11 systems.

DEC, USA

Compatible Time-Sharing System. Developed at MIT's Computation Center for use on a modified IBM 7094.

MIT, USA

Cray Timesharing System. Successor to LTSS.

Lawrence Livermore Labs, USA

Operating system for Harris Night Hawk series.

USA

OS for Cybiko PDA.

Operating system for Harris Night Hawk series.

USA