Hi Chuck, thanks for the suggestion. I did try the card in J8 but it didn't work. Reviewing
this old thread it's pretty apparent why; as it needs to generate the card select signal - which, it seems, would happen to be interchangeable with the /NOWS signal I'm looking at for ATs, if I'm understanding things correctlly
So by including a switchable output on that line from the address decoders (in the logic) the board
should work in slot 8 on the XT as well as running faster in an AT? Unfortunately I need to order new prototype boards to test any of this properly, as I grounded the unused CPLD pins in the current board and I think they're too small to cut into (by me, anyway).