HELP: Trying 3 trackballs w/OptiPac

[clockworkman]

I have 2 trackballs (for the sides of my control panel) hooked up to an OptiPac which work great for games like Cabal, but am trying to hook up a Happ USB/PS2 trackball in the center of my control panel. The OptiPac is connected to the computer via the 2 serial connections and I am running AdvanceMame in DOS. I cannot get the trackball to work at all when hooked up to the mouse port in DOS. I am never going to be using all 3 trackballs at once, just the outside 2, or the center (Happ) one.

Does anyone have any ideas, maybe a software setting in mame or something?

I've also tried hooking up the Happ trackball directly to the OptiPac (same connection as trackball 1) instead of the PS2 port or USB port on the computer, but the optical reader PCBs for this USB/PS2 trackball are different from the norm and, according to Happ tech support, do not have the necessary X1,X2,Y1,Y2 connections suitable for the OptiPac.

Your help is greatly appreciated