I wish you were a bit closer, as I certainly owe you a beer.
There is something about the W65C02S beyond just pins 1, 5 and 36 that is causing a problem with the S-100 6502 board. Pin 1 (Vector Pull) and Pin 5 (Memory Lock) aren't connected to anything (I bent them out of the socket to be sure) and pin 36 (Bus Enable) is tied to VDD (Pin 8) already. Interesting the board is able to access I/O ports fine - but can't read/write properly to RAM that is over the S-100 bus.
In any case, a Rockwell R65C02P4E fixed the problem (after 2 weeks of hair pulling) and seems rock stable at 4mhz.
If anyone else has had success with the W65C02S I'd be interested in hearing - otherwise it might be worth a mention on John's site so others can avoid this gotcha'.
Many thanks to John and Ian for the debugging help!
On Friday, August 29, 2014 11:15:09 AM UTC-4, Ian May wrote: