The Pi2JAMMA is a PCB that connects your RaspBerry to a JAMMA connector.
It allows a 15Khz audio / video output on a JAMMA connector.
The joysticks / buttons are also managed on the JAMMA port.
To do this, the Pi2JAMMA connects very simply to the GPIO interface of RaspBerry.
The sound is recovered from the headphone jack via an audio cable.
The Pi2JAMMA does not need extra power to operate.