Computer science development of sophisticated computing equipment. Wilhelm Schickard designed and constructed the first working mechanical calculator in 1623. In 1673, Gottfried Leibniz demonstrated a digital mechanical calculator, called the Stepped Reckoner. He may be considered the first computer scientist and information theorist, for, among other reasons, documenting the binary number system. In 1820, Thomas de Colmar launched the mechanical calculator industry when he released his simplified arithmometer, which was the first calculating machine strong enough and reliable enough to be used daily in an office environment. Charles Babbage started the design of the first "automatic mechanical calculator", his Difference Engine, in
Royal Radar Establishment Automatic Computer Royal Radar Establishment Automatic Computer The Royal Radar Establishment Automatic Computer, or the RREAC, was an early solid-state computer in 1962. It was made with transistors; many of Britain's previous experimental computers used the thermionic valve, also known as a vacuum tube. Britain had built the world's first electronic computer, the Colossus computer, during the war at Bletchley Park in late 1943 and early 1944, and the world's first stored-program computer, the Manchester Baby, on 21 June 1948. The Germans had built the electro-mechanical Z3 in 1941 in Berlin, which used relays. The world's first digital computing device was the