Invention Of Calculator

For more than 300 years Blaise Pascal was credited with inventing the mechanical calculator. But in 1957 a German historian proved that Wilhelm Schickard had beaten Pascal to it by 18 years, with his invention of a so-called "calculator clock" in 1624.
In the 17th century John Napier (Scotland) had paved the way for the invention of mechanical calculating machines with his proposal that multiplication and division could be calculated as a series of additions and subtractions. Then, for more that three centuries, historians believed that Blaise Pascal (France) had invented the calculator in 1642, but this was disproved in the mid-20th century when historian Franz Hammer (Germany) discovered papers proving that in 1624, fully 18 years before Pascal, Wilhelm Schickard (Germany) had inventer something called a "calculator clock".

Schickard's machine not only predated Pascal's, it was also far more sophisticated and was capable of performing all four arithmetic operation of addition, subtraction, multiplication and division. Having discovered Schickard's papers in 1935, Hammer published them in 1957 and Schickard was finally acknowledged as the inventor of the mechanical calculator.

The first commercially successful calculator was invented in 1820 by Charles Xavier Thomas de Colmar (France), but the evolution of calculators as we know them came when Jack Kilby (USA), inventor of the microchip, began developing miniature electronic calculators as a means of exploiting the microchip. In 1967 Kilby, together with Jerry Merryman and James van Tassel (both USA) of Texas Instruments (TI), produced the first hand-held electronic calculator and three years later TI and Canon Inc. (Japan) launched the first commercial electronic pocket calculator, the Pocketronic.

Some historians cite the Sinclair Executive, invented in 1972 by Clive Sinclair (England), as the first pocket calculator, but that depends on the size of one's pocket. The Sinclair Executive was 9.5.. thick and 140mm long and used LED's (light-emitting diodes) to display its results, while the Pocketronic, which had a terminal paper print-out for results, was large enough to stretch the definition as well as the fabric of a pocket.

Source - The Book Of Inventions by Ian Harrison