This is probably answered somewhere here, but I couldn't find it. If I swap the logic board from an HP-45 into an HP-80 of the same vintage, is it compatible with the mating display/keypad board?
Yes, you could put a 45 mainboard in an 80, but then it would act like a 45. The keyboard/display PCB is common between the 35, 45 and 80.
Thanks.