Micrium, Inc. - Makes µC/OS, µC/OS-II (MicroC/OS, MicroC/OS-II), full source code, no royalty, free non-commercial use; other software for embedded use: Embedded Systems Building Blocks, µC/GUI for most 8- to 64-bit processors, µC/FS FAT filesystem.
MicroC/OS-II - Growing article, with links to many related topics. Wikipedia.
Simulation of uC/OS-II on Win32 Platform - Environment for uC/OS-II RTOS on Windows 32-bit platform; has 2 main modules, run as normal programs: module 1 (WCOS) runs RTOS with embedded program, module 2 (WSim) has functions to run and control full simulation with any hardware platform.