Coin counter

Not to be confused with the credits display.

Coin counters are internal electromechanical devices used to count inserted coins in arcade cabs. They can only count up and should be made hard to reset.

The counters typically have one pin hardwired to +12V, and the other one connected to the MVS board by JAMMA pins 8 and J. They are operated by software, not directly by the coin chutes.

Control

Writing to REG_SETCC1 or REG_SETCC2 causes current to flow to the counters, writing to REG_RESETCC1 or REG_RESETCC2 stops it.

Incrementing a counter is done by sending power to it and then interrupting it, both during a long enough time for the mechanism to work properly.

Even if game software is free to access the control registers, only the system ROM should use them.