Hi Raghunathan,

Thanks. I've downloaded the document and added it to my "stash." I found myself wondering how many people understand why they are called Op(erational) Amplifiers.

These circuits were the Flip-Flops of the analog computer. They are called Op Amps because they are designed to carry out mathematical operations. They can produce the sum or difference of two inputs. They can also produce the integral or derivative of an input (hence the "I" and "D" in "PID). Yes, they are still popular in applications of instrumentation and process control, but in the time before digital gates and µ-controllers, these were the only technology available.

I wonder how many of us could do the things we do today, with 8052s, if all we had were op-amps. I don't think that my mass spectrometer would be practical without a µ-controller. It would be possible, but it would require a prohibitively large number of analog circuits and their quantity would always be a fundamental limitation (for any finite number).