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 core store, and used five-hole paper tape for input and output, and magnetic tape for data storage. The world's first transistorised computer was the Manchester Transistor Computer, operational in 1953. The 1955 Harwell CADET is a contender for the title of first fully transistorised computer. Many of the early transistorised computers used valves for non-computing elements such as the power supply and clock. RREAC used ALGOL 60 as its programming language - the first computer language to use nested functions, and the ancestor of some of today's main programming languages. Royal Radar Establishment Automatic Computer The Royal Radar Establishment Automatic