> I hope that somebody may be able to help me with a problem that I have
>with an Atari Asteroids board. The PCB passes selftest OK, and I have
>verified that ROM, RAM and all I/O is working correctly. However, the PCB
>when switched into game mode, displays a diagonal line on the monitor and
>then resets? Anybody seen this before? Is there any hardware that the game
>uses but the self test doesn't i.e. all levels of the vector jump stack ?
May be a bad PROM at location C8. This is not part of the program ROM; it's
sorta/kinda an address-decoding circuit. I ran into this very same problem
a few months ago and, sure enough, that chip was bad. Replacing it cured
the problem.
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