Coin lockout

The coin lockout mechanism is a common cab device, which isn't specific to MVS cabs.


 * When powered, it allows an inserted coin to hit the coin switch and go in the coin box.
 * When not powered, it defaults to a "safe" position which makes the coin take the return path.

This mechanism and the watchdog system were devised as failsafe measures to prevent users from losing an inserted coin when the cab isn't operating (properly).

Coin lockouts are typically hardwired to 12V only. It's the game PCB's job to power them by grounding their second terminal, then closing the circuit.

On MVS hardware, the coin lockout outputs are driven by through an  power transistor array, providing open-collector outputs.

They are software controlled by registers, , , and.