open source analogue of IBM OS/2 operating system
Free operating system for Atari computers, and more.
EmuTOS is a TOS compatible operating system for Atari ST series computers, and more. It is made from Digital Research's GPLed original sources and is a free and open source alternative to Atari proprietary ROMs.
CMAKE build enviroment for LPC2000 and LPC17xx Cortex MCUs
The goal of project is to build CMSIS like environment for LPC2000 series MCU and to write RTOS for LPC2000 and Cortex Microcontrollers
Tesoro is an open source operating system project fully written in x86 Assembler language. The architecture is partially based on some QNX ideas and some fresh ideas. It combines low level assembler coding (e.g. microkernel with extremely fast task switch
FreeDOS-64 is 64-bit Disk Operating System under development for the AMD64 platform.
FOS - open source 32-bit microkernel operating system.
GrindarsOS - 32bit protect-mode one-task operating system.