From: "Eckhard Stolberg" > Which Trakball does your program read, the CX-22 or the CX-80? > And how often do you sample new data? In my experiments with the > Trakball on the 2600 I found that you'd need at least 20 values > per frame for a smoothly moving cursor. > The driving controller works the same way as the CX-80 Trakball > (wich is the same as the ST mouse, BTW). But it only has one axis > and a much lower resolution. So, if your demo is programmed for > the CX-80, it should work with the driving controller too. The zones are 8 lines high, so the DLI gets called 31 times per NTSC frame (37 times PAL). I think it's the CX-22 (don't have one myself) which has one direction signal per axis (increment or decrement) and one movement signal (change 0<->1). Hmm, if the CX-80 woks like the driving controller (grey code), then I'll just make my driving controller code read all 4 axes. I do have a driving controller, so that I can test. Unfortunately, I don't have a light gun; and that would be much harder to develop without testing.