Wild_Bill wrote:
A factor that's been mentioned before, wrt electronic circuits used for
defense or critical missions, is immunity to an EMP event.

Mechanisms have high immunity levels, but I suppose that instruments
that rely on magnets could be affected.

Not a factor. Mechanical computation devices
were used, but there was still plenty of
semiconductors in the design. And in 1972
we were doing a major change program to EMP
harden the equipment.

Mechanical computation equipment was used because
it worked, was accurate enough, and fit within
the space and power availability for the mission.