IC or integrated circuit was first performed by Jack Kilby of Texas Instruments in 1958 Integrating several transistors and other components in one semiconductor device. Integrated circuit started to be used in calculators from the mid 1960s. However, techniques were slowly developed for putting more and more transistors on a small chip, so that a single chip could perform more complex functions.

From about 1965 to about 1971 the development of integrated circuits for calculators was at the leading edge of electronics research, and took place almost exclusively in the U.S.A.

One of the pioneers was the Victor Comptometer Corporation. The journal “Electronics” of October 18th 1965 announced “The first commercial equipment to use metal-oxide-semiconductor (MOS) integrated circuits will be introduced at the Business Equipment Exposition in New York City next week when the Victor Comptometer Corp.’s Victor 3900 makes its debut. The desk-top calculator uses MOS ICs that contain 250 transistors each. The integrated circuits are made by General Micro-electronics, Inc.”
However, General Micro-electronics had great difficulties making the integrated circuits and the Victor 3900 only appeared in prototype form, its launch being dragged out over several years before being finally abandoned.

The first integrated circuit included only a small number of transistors in each package, and performed the function of a small number of logic gates. These are known as Small Scale Integration (SSI) integrated circuits, and were still required in dozens in calculators.

As today, with the race to put more and more transistors and functions into microprocessors in PCs, so then there was a race to put more and more of the calculator’s electronics onto the chips. Medium Scale Integration (MSI) integrated circuits put whole subsystems onto a single chip, so the number of chips required was greatly reduced.

In Large Scale Integration (LSI) integrated circuits, hundreds or thousands of transistors were manufactured on one chip, and calculators were produced using just three or four LSI chips.