Precise and accurate processor simulation dating
This computer was used to solve differential equations and is currently housed at the Cambridge Museum of Technology. Typically, as the input voltage increases, progressively more diodes conduct.
One disc was a face cam, and a follower on the block in the face cam's groove set the radius. The majority of op amps in a representative setup are summing amplifiers, which add and subtract analog voltages, providing the result at their output jacks.
A special type of integrator, used at a point where only moderate accuracy was needed, was based on a steel ball, instead of a disc.