writes: "LEON, the open-source CPU developed for the European Space Agency, has been successfully manufactured and tested by Atmel on an Atmel ATC35. Gaisler Research, whose CEO Jiri Gaisler wrote the VHDL model of LEON, also offers a real time kernel, simulator, a cross-compiler, etc. for this SPARC-family processor designed for space applications. Check it out."
You can find more good information on the LEON
processor on the Gaisler site, including diagrams and further reading. Open Source hardware running Free software -- wheee!