I installed a GRS trackball.
The trackball works in Windows 11 as a mouse (although it's slow).
The trackball works in MAME UI menu as a mouse (although it too is slow).
Set my MAME 0.225 mame.ini file to:
trackball_device, mouse
dial_device, mouse
multimouse, 1
I start Centipede, go into the MAME menu, change the input for general machine, and try to change the "Track X Analog" and "Track Y Analog" settings. But it does NOT change the input settings when I move the trackball. It only changes the input when I move the mouse. What is weird though is the MAME UI cursor moves correctly when I move the trackball, even when trying to change the input, so clearly MAME is understanding the input of the trackball.
What is even MORE odd, is when I use my mouse to set the inputs, the X axis (left and right) work just fine with the trackball (???), but the Y axis (forward and backward) only work with the mouse.
Attached is the mame.ini and the centipede.cfg files for your review.
mame.ini centiped.cfg