Some Aftermarket tuners use these, its imply a hardware and software simulator of the real deal. Developers use these all the time, or sometimes the actual hardware hacked up and interfaced with a PC (Playstation developers, etc).
This is what allows the real time changes, since the actual PCM cannot do this, it has to be flashed from front to back which takes 3 minutes. The $EE PCM has two flash chips, the T and M chip, thats the only PCM I know because I have a 94 Z28. 93 and previous was a removable PROM, similar to most older cars.