Is this online anywhere to anyone's knowledge? I assume it's in the techrefs
[1] (which I don't have, unfortunately), but I'm sure I've seen the schematic
online somewhere in the last few years.
IIRC it's only a handful of latches, buffers and address decoding - so not a
complex bit of hardware.
[1] The circuit on the MDA card is probably the same... if someone could
confirm that then I could at least trace it from a real MDA card here :)
cheers
Jules