Do you have a
logic analyser? If so, then I would try looking at the 8080=
address bus. See what bit of the program it's
executing, see if it does
the right things when you press the keys, etc.
=
I have, it's a Biomation K100-D. When I first set it up Sunday afternoon,
Amazingly that's what I have... I didn't get the pods with mine, but a
bit of work and some 10124 TTL-ECL translators got the thing useable with
TTL level signals
[...]
That depends on the length of the instruction. Anyway,
I see the addresses
60-110 (octal) in the correct order and see the address jump at 101 to the
address 335 (a subroutine). I see the complete execution of the subroutine
and the return. Indeed going to address 105. That means the stackpointer
and the memory must be OK! ReturnPC stored in RAM, and retrieved correctly.=
Be careful!. I have in the back of my mind the idea that the 8008 has an
internal (8-ish level) return stack and doesn't use RAM for this. So you
could still have RAM problems.
-tony