Neil Cherry
Would analog computers have be used in control systems where feed back would be used?
Possibly. Generally analog computers in "physical plants" would be used to simulate the plant's operation. For instance, an oil refinery. The computer would not control the plant, but various controls and valves might be adjusted based on the model's response, when set-up to model the production of some chemical or distillation product. Most analog computers solve the same problem over and over again, to produce an oscillograph or paper-graph - not for real-time operations. Real-time may run faster or slower than the simulation. But, some labs (psychology labs testing human or animal responses) might use an analog computer to perform the test and record results. Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT retrotechnology DOT info