I have been doing just that, the server has 4 independent computers in there each with cpu's and roms, all running independently and together at the same time.
these standoff work with these back plate / use m3x16 for the board and the original backplate will self tap into them.
https://www.digikey.ca/en/products/detail/essentra-components/DLSP-1-30M-01/3811816
im going to need to dig into the select logic as i am not 100% on the reverse engineering of the serial card. also the nabu that i received has the -12 power rail for the serial card neutered at the board, although the ones that i have seen with serial cards have been modified to to get the -12...
Yes using cp/m contin conout I shifted the option card over a slot so fdc in 1 and serial in 2. I've got it hooked up to real term to monitor any activity. The one thing I have found is the fdc works in slot 0 and 1
I was just reading through the thread, the interrupt line is connected. here is the schematic as best as can can tell , but might not be 100% accurate , it is not working with my preliminary tests .