MenuetOS
Graphical realtime OS written in all 32-bit assembly, for x86 i386+, fits on one floppy, protected memory, 44 kHz sound soon, GUI, DOS loader download; advancing well. [Open Source, GPL]
NicheTask
A multitasking embedded operating system with a proven track record, expressly designed for embedded devices with limited resources.
Nilsen Elektronikk AS
Makes 2 very small, open source realtime OSs for embedded systems, written in C: proc Real-Time Kernel, preemptive, mature; nesos Finite State Machine Operating System (FSMOS), modular, use concurrent programming methods in little time and space. Also: nemon Boot and Debug Monitor; Embedded Web Servers.
RET & COM Research
Makes RadiOS, Radiant Operating System; realtime, multitasking, multiuser, for i386+, written in all assembly in NASM. Goal: create OS that combines all advantages of OS/2 and Unix; ftp downloads. [Public Domain]
Roadrunner
One-user, general purpose OS built on a protected memory, POSIX threads RT kernel; full kernel, device drivers, file systems, and network protocols runs in about 200 K RAM; now runs on x86 CPUs but designed for easy portability. [GPL]
rtmk
Realtime microkernel: preemptive, fully re-entrant, multithreaded, SMP, continuations, full locking primitives; shares many ideas with Mach, developed by CMU in late 1980's, early 1990's, stopped in 1994. [GPL]
RTMX, Inc.
Makes RTMX O/S: IEEE POSIX realtime extensions to OpenBSD, with vendor specific ports for embedded, dedicated systems, application specific Internet/intranet servers. Many fine features. North Carolina, USA.
S.Ha.R.K.
Dynamic configurable kernel architecture to support hard/soft/non realtime use with interchangeable scheduling algorithms: fully modular in scheduling policies, aperiodic servers, concurrency control protocols; all not modular in most traditional OSs. Derived from HARTIK: HArd Real TIme Kernel. [GPL]
Linux Journal: Open Source Software for Real-Time Solutions
Compares 2 open source OSs for embedded uses: RTLinux, eCOS by Cygnus. (October, 1999)
EE Times: Open source code smooths RTOS design
Benefits of open source compared to other RTOS licensing models. (July 26, 1999)
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