6502 CPU schematics

Roy J. Tellason wrote: Well, I'm short of a 6520 PIA! Have you any of those left? If so, please contact me off list. When I was 13 (1980. Ouch!) I was given a PET for my birthday. A few years later I blew up an output buffer in one of the 6520s trying to use the Cassette 2 motor output as a controlled power supply. We connected one of those two-tone doobells that uses the back emf from the "ding" solenoid when you open the switch to sound the "dong". Said back emf killed the output buffer on that pin of the 6520. It managed to do so without any noticeable damage to the intervening circuitry, too! I have other PETs, but (a) I want to preserve my "original" one and (b) it goes against the grain to scavenge chips from another working system. My PET is useable, but I have to swap the 6520s around depending on what I/O function I need... Philip.