JAMMA (Japan Arcade Machine Manufacturers' Association) is a standard 56-way connector used on many arcade boards to simplify conversion of cabinets from one game to another. The majority of newer games use a subset of this pinout. Some games (i.e., Street Fighter) which need extra buttons have extra connectors for these additional controls. The JAMMA connector has a .156" pin spacing edge connector (male on the game board). The JAMMA standard was invented in 1985; any game older than this will not be JAMMA.
To connect older non-JAMMA games to a standard JAMMA cabinet a custom wiring harness is needed. In some cases a pre-made convertor harness could be used (the Namco2Jamma convertor shown is available from mikesarcade.com).
The easiest way to connect a PC to an arcade cabinet that is JAMMA ready is to use a J-PAC keyboard encoder (by Ultimarc).
A printable JAMMA pinout label is available here on the forums.
- What To Do With Your JAMMA Harness by Bob Roberts
- Getting Familiar With The JAMMA Standard Basic primer, including video, for JAMMA
- JAMMA at Wikipedia