https://retropie.org.uk/docs/RetroArch-Core-Options/
\\centipede\configs\all
retroarch-core-options.cfg
mame2003_dialsharexy = "enabled"
Does nothing, ignore.
\\centipede\configs\all
Added
input_player1_mouse_index = 1
Just under
# input_player8_joypad_index = 7
and sure enough spinner works now.
I think mouse_index 0 is track ball.
I could not find it in RGUI but now I realize there are two different Port 1 Controls Menu Screens.
You have to go into Main Menu, Settings, the Port 1 Controls.
if you go straight in to Port 1 Controls it's not there.
I see Mouse Index and can change it from RGUI.
Basically when you first bring up RGUI, it brings you into something called quick menu, which only has some settings.
You have to back out of quick menu by pressing BACK (b) to get into Main Menu.
From here we can see everything.
Personally I find this insanely confusing.
Perhaps there is a way to make RGUI launch main menu?
Speed is a problem. Need to figure out how to control speed.
This can be controlled from Mame Menu NOT RGUI. There is yet another menu.
Where are the mame binary options saved?
Mame configured options are stored in roms dir under mame2003 subdir.
\\centipede\roms\am\mame-libretro\trackball\mame2003\cfg