DanBoris' Tech Blog - Game Control

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I am hoping that I can get a little help figuring this section out. I am pretty good with digital analysis, but my transistor theory is a little (ok a lot) rusty. The purpose of this section is to control the game state. Here are the things that I do know about this circuit:

 

- When either /STOPG1 or /STOPG2 goes low, indicating that one of the score counters has reached the game ending score, the output of B3 (STOP G) will go high which stops the game. The high on STOP G will also set /ATRACT low, putting the game into Attract mode.

 

- When a coin is inserted, COIN SW is momentarily closed which takes /SRST low, resetting the score counters.

 

- Antenna is an external input that is used to detect a static shock to the machine. In theory is should prevent someone from shocking the machine into giving them a free game.

 

I would appreciate any help deciphering how the rest of this circuit works.

 

 

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