Trackball



Special controller only used in The Irritating Maze cabs.

Works the same way as an upside-down mechanical mouse. Uses two optical encoders for X and Y movement, handled by the SIT board.

A special system ROM is used (236-bios.sp1).

The counter values are read from :


 * The X counter value when bit 0 of is 0.
 * The Y counter value when bit 0 of is 1.

Speed and direction are computed from the counter deltas.