...of course, shortly after starting with FORTRAN IV and IITRAN, I took a lab course involving analogue computers. No vacuum tubes – these were the 70's – but jumpers, potentiometers, and op amps. Programming involved correctly setting the potentiometers, plugging in the right jumpers to the right places, etc. Output was usually by a strip chart recorder.

After all, it was a good way to solve problems involving ∂ and ∇ or even f(x) = x″ + ax′ + x