Stumbled across a head scratcher.
Working on an A500 rev. 6a I installed a UU ROM switch with 1.3 and 3.1. 3.1 works perfectly in the default position.
Put the 1.3 ROM in the default position and nothing. Black screen, no signs of life.
Try to switch over to the 1.3 with the recommended keystrokes and same thing. Dead computer.
I've tried 1.3 and even an old 1.2. Both work without the switch.
I've used these before with a 1.3 so I'm at a loss as to what the heck is going on here.
Any suggestions?