Allows you to use your Irem classic pre-JAMMA game, in a JAMMA cabinet or a supergun device.

Irem or International Rental Electronics Machines started producing arcade games in the late 1970s. In the early, to mid-1980s they released a number of arcade games on similar hardware which consisted of a sandwich of three or fours boards stacked together.

The pinout used by this hardware remained mostly unchanged throughout the years with one small exception. The exception is a small variation in how the coin counters are wired. The adapter provides a jumper to handle the variation, but unless you really need to have working coin counters, you can just simply ignore this feature.