Asteroids state machine??

From: <MKDUD_at_aol.com>
Date: Sun Mar 23 2003 - 18:35:51 EST

     
Hello,
     I'm still trying to fix the Asteroids board with the "sonic"
daughtercard on it.
     I'm sure it is a speedmod, but I wasn't sure exactly how it worked - the
IC's on the card have been scratched so you can't read them. I'm guessing the
8 dip has to be a 555 timer, but I'm not sure about the other IC.
     Any ideas about how to debug the state machine? When I lift pin 1 of the
LS42 @ L6, the watchdog stops, and the game plays blind & passes self test
with no errors. Obviously, there is no picture with /DMAGO disconnected.
     With the machine in test mode, /DMAGO connected and WD disabled, I'm
getting what look like reset (or WD) pulses on pin 23 of the 6502A (A13). Pin
34 (R//W) of the 6502A is doing the same thing with the WD disabled.
Obviously, this is is screwing up lots of stuff associated with the address
decoder. I have already replaced L6 (LS42), B2 (LS244), and all rams. I don't
know what else I should be checking. Any help would be appreciated.

Thanks,
MK

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Received on Sun Mar 23 15:36:04 2003

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