RAM Addressing on Spy Hunter

I'm debugging a Spy Hunter game which won't boot. The watchdog timer
keeps resetting the board, so I disabled it. The game still doesn't
come up.

I'm using my 9010A for the first time, so I'm still learning...

I verified all of the ROMS on the CPU board against the MAME signatures
using the 9010A. I'm now trying to test the RAM, but I keep getting
random errors (e.g. decode errors and tied bit errors).

I tried using the probe in A and D sync modes to watch the RAM chip
select pin, but I can't seem to get it to indicate correctly - so I'm
suspecting a RAM decode problem. Unfortunately, I can't understand how
the RAM chip select circuitry works by reading the schematic. It's
pretty cryptic.

Does anyone know how the RAM select circuit works on a MCR III board?

Anything else I should try?

Thanks!

Rich

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Received on Sun Jan 3 22:59:28 2010