Image:Wilhelm_Schickard.jpg '''Wilhelm Schickard''' (born 1592 in Herrenberg - died 1635 in Tübingen) built the first Automatic_calculator in 1623. Contemporaries called this machine the ''Calculating Clock.'' It precedes the less versatile ''Pascaline'' of Blaise_Pascal and the calculator of Gottfried_Leibniz by twenty years. Schickard's letters to Johannes_Kepler show how to use the machine for calculating astronomical tables. The machine could add and subtract six-digit numbers, and indicated an overflow of this capacity by ringing a bell; to aid more complex calculations, a set of Napier's_bones were mounted on it. The designs were lost until the twentieth century; a working replica was finally constructed in 1960. Schickard's machine, however, was not programmable. The first ''design'' of a programmable computer came roughly 200 years later (Charles_Babbage). And the first ''working'' program-controlled machine was completed more than 300 years later (Konrad_Zuse's Z3, 1941). The Schickard_crater on the moon is named after Schickard. ==External links== *Biography of Wilhelm Schickard by J J O'Connor and E F Robertson at MacTutor *Wilhelm Schickard, father of the computer age by Juergen_Schmidhuber *Computer history speedup since 1623 *Schickard moon crater Schickard, Wilhelm Schickard, Wilhelm Schickard, Wilhelm De:Wilhelm_Schickard Es:Wilhelm_Schickard Fr:Wilhelm_Schickard He:ולהלם_שיקארד Ja:ウィルヘルム・シッカート Pl:Wilhelm_Schickard Fi:Wilhelm_Schickard