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.

--
WB
..........


"Jim Stewart" wrote in message
...

Much of this stuff was still around in the
70's and 80's. I can't speak for the Navy,
but the Army's Pershing I and Nike Herc missiles
used extensive mechanical computation devices
to solve ballistic flight and intercept equations.

The centerpiece of the Pershing I guidance
computer was a beautifully crafted ball-and
disk integrator.