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

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

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

Uniprocessor operating system.

Multiprocessor operating system.

Uniprocessor operating system.

Uniprocessor operating system.

Uniprocessor operating system.

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

Blackhawk, USA

Operating system for Tandem NonStop servers.

Hewlett-Packard, USA

Now called Elate.

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

USA

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

Blunk Microsystems, USA

Modern version of IS-DOS.

NedoPC, Russia

Based on oCos. See Lepton.

Philippe Le Boulanger, France

CDC computers OS based on NASA/LANGLEY. Replaced by SCOPE 3.3.

Control Data, USA

Tape and Disk Operating System.

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

Algebraically specified abstract machine. Successor of Flex machine.

Royal Signals and Radar Establishment, Malvern, UK

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

DEC, 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

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

Phase One Systems, USA

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

Tudor Hulubei, USA

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

University of Waterloo, Canada

Highly deterministic, embedded real-time operating system.

Express Logic, USA

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

Trinity College Dublin, Ireland

See TSS-8.

DEC, USA

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

Used in routers from Alcatel-Lucent.

Alcatel-Lucent, France

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.

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

Texas Instruments, USA

Timesharing operating system for the Titan.

Cambridge University, UK

Early time-sharing system.

Queen's University of Belfast, UK

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

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

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.

South Korean OS based on Windows.

TmaxSoft, Korea

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

ICL, UK

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

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

DEC, USA

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

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

Russia

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

Yuri Tiomkin, Russia

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

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

Semi-distributed OS for DEC Firefly workstation written in Modula-2+ and garbage collected. Consisted of multiple components such as the Taos operating system that used a microkernel named the Nub and the Trestle window system.

DEC, USA

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

DEC, USA

Last stable release.

Last stable release.

Last stable release.

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

DEC, USA

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

Single address-space (SAS) OS with orthogonal persistence.

Tape OS.

Hitachi, Japan

Teletype Operating System for the Microdata 1600 & 3200 minicomputers.

USA

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

USA

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

USA

Teradata Operating System.

Teradata, USA

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

IBM, USA

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

Toshiba, Japan

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

Toshiba, Japan

First-Generation Operating Systems for the TOSBAC-1350.

Toshiba, Japan

POS operating system based on IBM 4690 OS and FlexOS.

Digital Research, USA

Operating Systems for the TOSBAC Q Series.

Toshiba, Japan

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

Fujitsu, Japan

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

Epson, Japan

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

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

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

Per Brinch Hansen, USA

TRIvial Portable Operating System.

University of Cambridge, University of Bath, MetaComCo, UK

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

USA

Network oriented OS.

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

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

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

First version of TRSDOS created by Radio Shack programmers.

Most widely used version of TRSDOS.

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

iXsystems, USA

Solaris with kernel and other enhancements to support multilevel security.

Sun Microsystems, USA

Variant initially developed by IBM, under the name Secure Xenix; later versions, under the Trusted Xenix name, were developed by Trusted Information Systems.

IBM, 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

Timesharing OS for the DEC PDP-8.

USA

Time Sharing Monitor. Early timesharing OS for the 7090.

IBM, 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

Early timesharing system for the AN/FSQ-32.

USA

Timesharing OS for General Automation System 18/30.

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

Time Sharing eXecutive.

IBM, 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

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

S&H Computer Systems, USA

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

PiSig Innovations Lab., USA

TU Dresden Research Operating System.

TU Dresden, Germany

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

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

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

Apple, 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

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

Texas Instruments, USA

Operating system for the Tymnet network.

Tymes, USA