Here are a couple of other related links that I've encountered in my travels - RTEMS, A GPL'd real time OS with support for Motorola PowerPC, M683x0, M680x0, Coldfire, Intel ix86, i960, MIPS R46x0, SPARC, Hitachi SH, AMD 29K, HP PA-RISC: http://www.oarcorp.com/rtems/rtems.html Upcoming release of Flux OSKit and Fluke Kernal (Don't know if this is free software, but looks interesting): http://www.cs.utah.edu/projects/flux/