Reverse-engineering precision op amps from a 1969 analog computer
> We are restoring a vintage1 computer that CuriousMarc recently obtained. Analog computers were formerly popular for fast scientific computation, but pretty much died out in the 1970s. They are interesting, though, as a completely different computing paradigm from digital computers. In this blog post, I’m going to focus on the op amps used in Marc’s analog computer, a Simulators Inc. model 240.
> An analog computer performs computations using physical, continuously changeable values such as voltages. This is in contrast to a digital computer that uses discrete binary values. Analog computers have a long history including gear mechanisms, slide rules, wheel-and-disk integrators, tide computers, and mechanical gun targeting systems. The “classic” analog computers of the 1950s and 1960s, however, used op amps and integrators to solve differential equations. They were typically programmed by plugging cables into a patch panel, yielding a spaghetti-like tangle of wires.
Plus some good references to more about analog computers.
Ken Thompson did some of his early programming on an early analog computer, although I’m unsure of which model.