Coin counter
The coin counter is an internal electromechanical device used to count inserted coins in MVS cabs. It could be a law-imposed device.
The counter has typically one pin hardwired to +12V, and the other one connected to the MVS board. It is operated by the MVS board, not directly by the coin chutes.
When writing to REG_SETCC1 or REG_SETCC2, current flows through the counter, it's incremented. When REG_RESETCC1 or REG_RESETCC2 are written to, current flow is stopped.