On 09/18/2018 07:11 PM, D. Hugh Redelmeier via talk wrote: > The PDP-8i was meant to be part of a hybrid computer (analogue + > digital). I never used the analogue part (what's an op amp?).
As far as I know, the PDP-8i I worked on didn't have any analog hardware, though it might have been available as an option. Many years ago, analog computers were often used in science and engineering, as digital computers weren't fast enough. Of course an analog computer was useless for business use, where you need accurate results and not just so much precision. Op amps are high performance amplifiers, with characteristics primarily controlled by components in the feed back loop. For example, it possible to determine exponents or logs, just by adding a diode to the feedback loop, in the appropriate manner. It's also easy to create a summing circuit, by using multiple input resistors. Op amps are still commonly used in instrumentation, servos, etc.. Incidentally, those mini-computers, from DEC, Data General, etc. often had prototyping boards available, which could be used to build any custom interface that might be needed in a lab, factory, etc.. --- Talk Mailing List talk@gtalug.org https://gtalug.org/mailman/listinfo/talk
