The only commercial company that I know of, but I don't know much, who has explored using one of his CPUs is BMW.

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If you want to try it out you can use their emulator: http://greenarraychips.com/home/documents/greg/cf-intro.htm softsim is an instruction level simulator for GreenArrays chips, using code you compile for ROM and/or RAM, and with provision for adding testbeds to simulate I/O.extend softsim to allow you to define and simulate external peripherals to interact with using I/O pins.