Hi Fred I have a Rockwell AIM65 and book. I'll have to see if there is anything extra. Having worked on both 6800 and 6502 code, I can assure you that there is no code compatability. The 6502 traded depth in instructions for more page 0 accesses. For most applications, this worked well. Those who worked with Apples will tell you that the OS over used page 0 and didn't leave enough for the users. As was mentioned, there was a 6501 that was pin compatable with the 6800. It was also not code compatable. Rockwell also made a number of embedded 6502 application processors. These are a pain because they are P-MOS and have non-ttl busses. I have these in my old Gottlieb pinball machine ( what we pinheads call spider chips ). Dwight