Experimental microkernel used to construct flexible embedded systems inspired by famous L4 microkernel.

Firmware for Brocade Communications Systems's Fibre Channel switches and Fibre Channel directors. It is also known as FOS and Fabos.

Brocade Communications Systems, USA

Operating System for the Fast Amsterdam Multiprocessor (FAMP). A distributed, Real-time OS based on a network of M68000s with a UNIX host.

USA

Linux distribution for iPAQ machines and other personal digital assistants (PDAs), intended as a replacement for Windows CE on these machines.

Multitasking 8080 OS.

MVT Microcomputer Systems, USA

Secured operating for the ARCANE smartphone.

Fantome, Hong-Kong

Facebook Open Switching System. Linux-based operating system for Wedge switch.

Facebook, USA

Uses only 30K code.

Frizzz, Germany

Desktop, workstation, server, cloud OS.

Very concise portable real time - preemptive operating system (RTOS) for embedded microcontrollers.

Open-source operating system – made for smartphones, tablet computers and smart TVs. Designed by Mozilla and external contributors.

Mozilla, USA

32-Bit Realtime Operating System.

Single-tasking operating system.

Technical Systems Consultants (TSC), USA

Multi-computer OS.

Navy Signals and Radar Est. (RSRE), USA

Tagged, capability machine with OS and other software written in ALGOL 68RS.

Royal Signals and Radar Establishment, Malvern, UK

Successor to FLEX, which was for Motorola 6800 CPUs.

Technical Systems Consultants (TSC), USA

Derivative of Concurrent DOS 286.

Digital Research, USA

Variant of FlexOS for hosts.

Derivative of Concurrent DOS 68K.

Variant of FlexOS for terminals.

Later variant of FlexOS for hosts.

Flexible Microkernel Infrastructure/Operating System. Successor of VSTa.

FORTRAN Monitor system.

North American Aviation, USA

Single-user background operating system basic operating system. Soviet RT-11 clone.

Russia

Single-user background operating system basic operating system. Soviet RT-11 clone.

Russia

Soviet RT-11 clone.

Russia

Experimental Foreground/Background OS for the PDP-8.

USA

No-kernel systems group of OS. See BootOS, colorForth, ZOG, SOL, ForthOS, Diesel, Aha, JPB Forth, herkforth, COLDFORTH, 4os, etc..

CMU project to write an OS using (an extension to) the programming language Standard ML.

Carnegie-Mellon University, USA

One of the outgrowths of UC Regents' abandonment of CSRG's 'BSD Unix.

Formerly Free-DOS and PD-DOS. Free operating system for IBM PC compatible computers.

Open-source attempt at creating a Windows clone for x86 platforms.

Scalable RTOS for embedded systems. Based on OSEK RTOS specification (OSEK-VDX).

Argentina ?

Real-time operating system kernel for embedded devices that has been ported to 35 microcontroller platforms. It is distributed under the MIT License.

Real Time Engineers, UK

Live CD based on the FreeBSD.

Real-Time Operating System provides real-time performance within a small, configurable footprint. The RTOS is tightly integrated with the latest 32-bit MCUs and MPUs from Freescale. See MQX.

NXP Semiconductors, Netherlands

FreeBSD based operating system for system administrators. It contains software for hardware tests, file system check, security check and network setup and analysis.

Ukraine

Free Operating Systems for Tiny Embedded Devices.

Free Standing Operating System. Basic memory-resident OS for General Automation SPC-16 mini.

General Automation, USA

Force10 Operating System. Firmware family used on Force10 Ethernet switches.

Capability-based, real-time, operating system (RTOS) scalable to universal devices, in early development, from the tiniest embedded hardware, wristwatches, tablets to the largest personal computers. Unlike Chrome OS and Android, it is not based on the Linux kernel, but instead began on a new microkernel called "Zircon", derived from "Little Kernel".

Google, USA

Real-time operating system developed for a variety of microcontroller architectures.

Mostly-functional OS, written in Scheme.

Dave Mason, Canada

Priority-based, preemptive, multitasking, real-time operating system designed and optimized for high performance DSPs and media-centric microprocessors.

Unicoi Systems, USA

Expanded OS for Amstrad computers optimized for speeed.

Future Soft, Germany

Operating system and applications library designed for the PDP-11 family of computers. It was intended as a development platform and research pipewrench for the DARPA/NSF Internet.

David Mills, USA

Real-time operating system for embedded applications.

Eremex, Russia