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INSIDE those OLD pinball machines
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this post was submitted on 08 Dec 2023
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Analog computers are pretty cool, yet underrated tech. Although they aren't very flexible compared to digital computers in the range of what they can do, they do their specific use case very well.
Need to solve a partial differential equation in real time? Don't bother with iterative algorithms, that's fool's math, playa. Just hook it up to an analog computer specifically designed to solve that PDE type, rig up some wires for the input and output to your oscilloscope for real time mathz.
The old firing computers from WW2 are cool as hell.
Not just analog, but mechanical analog.
They take 25 inputs, some of which come directly from the spotter scope things, some from the ship itself, and then controls the guns directly.
It's all cams, gears, reciprocating whatsits and stuff.
And because it's analog, there is no quantisation, rounding errors, floating point errors. It's continuously and instantly calculated.
Very cool stuff.
https://youtu.be/s1i-dnAH9Y4
Very pretty stuff. I particularly recommend Ken Shirriff's Reverse-engineering the mechanical Bendix Central Air Data Computer:
He goes into detail about how non-linear equations are implemented using shaped cam gears (and how such functions can be difference-encoded against linear forms). It's insane.
Eh, I'd say that runout and stiction are their own demons with potentially more bias than those error types :) Not to mention temperature sensitivity -- hot days will give different answers to the equations!
Ha, oh yeh. Good point.
A bit of dirt throwing off the calculations.