An operating system based on the best Windows NT design principles
AO RTOS is small real time OS based on Active Object concurrency model
Software development for 4Mb portable, using Z80 CPU and AA batteries
C-BIOS is an open source BIOS for MSX computers.
OS-9/6809 compatible operating system for Tandy CoCo and Dragon
Simplest kernel for cooperative multithreading
OS bootable from Linux,Windows and others partitions as auxiliary OS
Message passing microkernel-based Operating System for ZX Spectrum +3e
Real time preemptive embedded multi-thread kernel
Real-Time Embedded Operating System
FreeDOS is an open source DOS-compatible operating system
Reductively Architected Breviloquently Built Information Environment
FreeMiNT is a free alternative OS kernel for Atari systems & clones
Written in pure ASM and Exode with cloud computing in mind.
A multiplatform, DOS-like operating system
64-BIt Operating System with Compiler