Hi Gerry,
Yes I did that, set 2 my buttons in Screen4 with "OEM Numbers" 1920and 1921, and Mach did not respond.
To check Pokeys was sending data, I changed Pokeys to be sending OEM LED instead, set to 1920. I then created LED 1920 in screen4 and it responded to the pokeys input.
Pity I cant write to OEM LED's 65, 66, 82 that would solve all my problems!
Jon