This site is a free non-profit repository of materials from GAP/R George A Philbrick Researches, the company that launched the commercial use of the Operational Amplifier in 1952.
The first commercial Operational amplifier was the K2-W op-amp. It was based on the amplifier used in the Philbrick modular Analog-Computor "black boxes ".
That amplifier's basic circuit architecture, in turn, was probably inspired by an earlier amplifier designed by Loebe Julie (Dan Sheingold and Bob Pease, thanks for helping me with this information). The K2-W Operational Amplifier entered the commercial market in 1952.
