Quote:
Originally Posted by Mark1960
There is also my misunderstanding of the chip select behaviour on the PET. I expected a separate chip select pulse for each memory access, but thats not the case.
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Actually, I think it is as you understood it to be. Although there are two chip selects on each PROM, the active high CS3 is tied directly to +5V so the only one being used is the active low _CS1 (pin 20).
The relevant diagram section is:-
http://www.zimmers.net/anonftp/pub/c...N/320349-4.gif
Or in case you are having trouble viewing that, here's a screen grab.