The standard JAMMA connector configuration provides the obvious audio and video throughputs, a joystick and three buttons for each of the two players, and a Start button. All JAMMA boards, even those with JAMMA+ functionality, should work with this configuration; you’ll just be missing extra button controls.

Here’s a diagram of those standard JAMMA pins:

 PARTS SIDE     SOLDER SIDE
  ---------------|---------------
       GRD  1|A GRD
       GRD  2|B GRD
       +5V  3|C +5V
       +5V  4|D +5V
       -5V  5|E -5V
      +12V  6|F +12V
       KEY  7|H KEY
 COUNTER 1  8|J COUNTER 
C LOCKOUT 1 9|K C LOCKOUT 2
 SPEAKER + 10|L SPEAKER -
       N/C 11|M N/C
       RED 12|N GREEN
      BLUE 13|P SYNC
       GRD 14|R SERVICE SW
   TEST SW 15|S SLAM SW
    COIN 1 16|T COIN 2
  1P START 17|U 2P START
     1P UP 18|V 2P UP
   1P DOWN 19|W 2P DOWN
   1P LEFT 20|X 2P LEFT
  1P RIGHT 21|Y 2P RIGHT
 1P FIRE 1 22|Z 2P FIRE 1
 1P FIRE 2 23|z 2P FIRE 2
 1P FIRE 3 24|b 2P FIRE 3
       N/C 25|c N/C
       N/C 26|d N/C
       GRD 27|e GRD
       GRD 28|f GRD

The setup for SNK’s wonderful Neo Geo cartridge system is almost identical to the JAMMA setup, except that the unused Pins 25/c handles 1P FIRE 4 and 2P FIRE 4, respectively. This is the fourth D button for each player. Few of the basic and classic Neo Geo games, such as Metal Slug, use it, but all of the system’s fighting titles, including the King Of Fighters and Samurai Shodown series, do.

If you have a two-, four-, or even six-slot Neo Geo MVS system in which you can plug in multiple cartridges at once, there’s also a Select button to wire in. This button switches control between the different cartridges.

Keep in mind that Neo Geo games expect a specific control setup—some have the A and B buttons on top and the C and D buttons directly below them. Many of the fighting games make attacks and combos out of pressing A+B together or C+D together. If you’re rewiring a six-button Capcom-style cabinet to play Neo Geo games, make sure to use this button configuration and leave the two end buttons alone. Otherwise, you’ll end up playing finger-Twister to pull off your attacks. Unfortunately, other Neo Geo button layouts put buttons A through D in a row, left to right, which is even less compatible with the Capcom layout.

The famous Capcom CPS2 cartridge system, which has all the decent Capcom fighting games (Street Fighter Alpha, Vampire Savior, X-Men, Marvel Super Heroes) from the early and mid ’90s on it, uses the Street Fighter II button-layout scheme, with a grand total of six buttons per player. There’s no way to squeeze the extra buttons for these games onto the existing JAMMA harness, so there’s a custom Capcom wiring harness for those extra buttons.

The games will still boot without those buttons connected,^[11] but you’ll need all the buttons connected to play properly. Unfortunately, the original versions of Street Fighter II used a different wiring scheme from the CPS2 harness, so bear this in mind if you happen to pick up a reasonably common Street Fighter II cabinet from somewhere. You can buy CPS2 wiring harnesses on eBay and rewire them fairly easily, however.

Of course, if you want to play Neo Geo games on a CPS2 system, remember that 1P FIRE 4 is now wired into your custom harness, not the JAMMA connector. D’oh.

This system is an extra custom button connector with all the connections for the third and fourth player; it doesn’t touch the JAMMA connector at all. This is relatively rare, but games such as Konami’s excellent Teenage Mutant Ninja Turtles, the X-Men side-scrolling beat-em-ups, and Midway’s classic NBA Jam all have this ability. Fortunately, they all still play through the normal JAMMA connector as two-player games.

In reality, you’ll probably never build two extra controllers onto your machine if you don’t have them. Four-player games are sometimes no fun to play with one player; the first controller is so far to the left of the control panel, it’s difficult to see the screen. If you already have a JAMMA-compatible NBA Jam cabinet, however, this information may be useful.

What’s the solution for all of this kerfuffle? If you have a six-button CPS2-style cabinet, the extra button connector also includes the wiring for the fourth button, which some Neo Geo MVS and Sega ST-V games need. This is a major issue, because you theoretically need to rewire every time you switch between the games.

One idea is to use an easily detachable bridging connector with the offending common wires connected. Again, the excellent Solvalou site has something along these lines with its Egret setup (http://www.solvalou.com/arcade_egret.php), using an Atari-type joystick connector as a mediator.

Of course, you can always just stick to the one game type you like.

For further reading on this subject, especially for the more exotic controllers such as trackballs and steering wheels, check out the excellent Arcade Controls page (http://www.arcadecontrols.com/arcade_controls.shtml). Bear in mind that many older games with exotic controllers don’t support JAMMA natively, however. Those recent JAMMA titles that do use exotic controls often have such specific controls that they support only a few compatible games after installing them. I still recommend joysticks if you want to play many high-quality, low-cost JAMMA titles.