The JAMMA, short for the Japan Arcade Machine Manufacturers' Association, refers to the standardized pinout of most arcade games made after 1986. With this standard arcade game boards could be changed easily and would not require any rewiring. The adopted standard used a 56-pin harness and designated which wires would carry the power input, video output, audio output, and user input signals. JAMMA was used on most arcade games in the late 1980s and early 1990s; however, Nintendo, Sega, and sometimes Atari continued to use their own pinouts until about 1990.

Since the JAMMA standard only specified the location of three buttons for each player, games that used more than three buttons would either require a separate harness for the addition button input signals or use the two unassigned pins for the additional button input signals. Other games that had three or for players also required and additional harness since the JAMMA harness only had enough room for two players. Some unique games such as those that used a trackball, optical joysticks, or steering wheels mapped the user input signals to a separate harness rather than the JAMMA harness. All of these games are often referred to as “JAMMA Plus” since they used the JAMMA harness plus another smaller harness. There was no standardization of these additional harnesses so not all JAMMA Plus games are fully plug and play compatible with JAMMA or even other JAMMA Plus games. Generally you can hook up any JAMMA or JAMMA Plus game in any JAMMA or JAMMA Plus cabinet but the ability to actually play the game may be limited by the types of directional controls or number of buttons used for each game.

I have two JAMMA cabinets in my collection, a converted Defender cabinet with two buttons and a Buster Bros. marquee and a generic Grand Products, Inc three button cabinet that has ESWAT Cyber Police artwork. The KLOV and System 16 are two great sites to find information about JAMMA games.