Ms pacman board hack?

sandmanx

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I finally got around to giving my cab a good look around inside and changing all the fuses tonight, and noticed that the board has been hacked to add a chip in. The chip is labeled HD74LS00P. It's soldered to a pin on chips 8C(pin 9 I think) and 9C(pin 2) and looks like it's pulling power from C2. It's also soldered to a pin on a daughtercard (a socket next to CP16).

I was wondering if anybody maybe knew why this was done. I'm going to pull the board in a couple of days and get a better look. I thought the ghost behavior was a little off for Sue on this machine, and I'm wondering if this has something to do with it. Ms. pacman is also getting caught by the red ghost up near the top of the board on the attract mode, which differs from the result I see in MAME.
mspac1.jpg
mspac2.jpg
 

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if you knew what part of the circuit this nand gate is on you might have a better chance to see what the logic is doing. Is it hooked to another chip? If so which one and what pin
 
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