Remember the Paradise EGA card that didn't work properly? Turns out the 14.3 MHz signal (which drives the pixelclock for the 320x200 modes) on the 286 board looks like this. I think 7 Vpp is NOT a good signal. This is measured on B30 on the ISA bus. There is massive undershoot.
Excellent video about counterfeit chips that also haunt the retro scene. I just wish the recyclers wouldn't relabel salvaged chips... and I wish we had a way to reproduce vintage ICs with modern technology.
