button voltages

SuperSprint

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Judging from the wiring, all games hold the control panel inputs high and the button pulls them low. Are all/the majority TTL (5v) signals? Is +5V ubiquitous, or are some games -5v?
 
All the ones I've seen are pulled to +5V and the button sinks them low. Although I just learned that the buttons on Atari Stunt Cycle use the NC to hold them low and then when pressed they break open and the signal gets pulled high.
 
Judging from the wiring, all games hold the control panel inputs high and the button pulls them low. Are all/the majority TTL (5v) signals? Is +5V ubiquitous, or are some games -5v?

TTL chips are 5VDC. Negative 5VDC is used for some audio chips, some RAM, some (older) ROMs/PROMs, and ELC chips.

Edward
 
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