The JAMMA (Japan Amusement Machine and Marketing Association) wiring standard was established in the mid-1980s to allow arcade operators to swap game PCBs between cabinets without rewiring. The connector is a 56-pin card-edge type with 3.96 mm (0.156 inch) pitch — 28 pins per side — providing +5 V, +12 V, and −5 V power rails alongside TTL-level joystick and button inputs for two players, analogue RGB video with composite sync, mono amplified audio output, and coin-mechanism signals. All control inputs are active-low (grounded to activate). The standard was never published as an open IEEE or ANSI specification; documentation survives through game service manuals and arcade-industry technician references.
| Jamma connector chart |
|---|
| Solder |
| Ground |
| Ground |
| +5V |
| +5V |
| -5V |
| +12V |
| Key |
| Meter 2 |
| Lockout 2 |
| Speaker - |
| Audio Ground |
| Video Green |
| Video Sync |
| Service Switch |
| Tilt Switch |
| Coin 2 |
| 2 Player start |
| Player 2 Up |
| Player 2 Down |
| Player 2 Left |
| Player 2 Right |
| Player 2 Button 1 |
| Player 2 Button 2 |
| Player 2 Button 3 |
| (Player 2 Button 4) |
| Not used |
| Ground |
| Ground |
Notes
- All input pins need ground to be activated (active low).
- Key 7/H says no connection because there is usually a piece of plastic placed in to this spot which will line up with a slot cut in the PCB. This is to prevent any chance of the connector being put on upside-down.
- Coin counter 1 “8” and coin counter 2 “J” are outputs. This is a mechanical style counter that increments every time a coin is inserted.
- Coin Lockout 9/K are outputs. This delivers power to a plunger activated by a solenoid which, when engaged into the coin path of the coin mech, will prevent a valid coin from tripping the coin switch and send it to the coin return slot. When power is fed to the coin door, an electromagnet retracts the plunger so that the coin path becomes open. Few games have coin lockout software in them.
- Service Switch “R” puts 1 credit onto the game but does not increment the coin meter.
- Test “15” enables the test mode, if the PCB supports it and triggers the test mode software of the game.
- Tilt “S” like in pinball games AKA “Slam” switch. The switch is found on almost all coin doors and is a leaf switch with a weight on the tip of one of them. If you slam the game hard enough, the leaf switch will close. Almost no games have tilt software in them. Behaviour ranges from a screeching tone for a few seconds to resetting the entire game.
- Coin Switch 1 “16” and coin Switch 2 “T” are inputs. When coin is inserted, a Ground pulse is sent to this pin and credits the game.
- Speaker +/- “10/L” is mono. It does not need an external amp. The speaker +/- is for post-amp output directly to the speaker.
- Audio +/- “11/M” is for pre-amp outputs but is hardly ever used.