Note: This Topic has its origins here
Well, as I mentioned in the other thread, Yovan and I have collaborated with the MAME/MESS development team in the emulation of several Fidelity chess computers. My main work has been the reverse engineering, where Yovan has also helped, but he has also contributed by analyzing the code, as he is an expert in 6502 assembler code, and he is extremely methodical, too. We've both learned a lot.
The Par Excellence program IMHO marked a turning point. The program of Fidelity computers after Par Excellence with 6502 microprocessor (e. g. Designer models) is basically the same! Depending on the Designer model, somewhat faster (6MHz instead of 5MHz), some changes in the opening book, incorporation of a Display, etc. But insignificant changes in the chess engine.
I don't remember the exact details now, but I'm going to try to get Yovan to come here in order to explain this subject in detail...