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The history of computer science began long before the modern discipline of computer science that emerged in the 20th century, and was hinted at in the centuries prior. The progression, from mechanical inventions and mathematical theories towards modern computer concepts and machines, led to a major academic field and the basis of a massive worldwide industry.〔(【引用サイトリンク】title=History of Computer Science )〕 The earliest known tool for use in computation was the abacus, developed in the period between 2700–2300 BCE in Sumer. The Sumerians' abacus consisted of a table of successive columns which delimited the successive orders of magnitude of their sexagesimal number system. Its original style of usage was by lines drawn in sand with pebbles . Abaci of a more modern design are still used as calculation tools today. The Antikythera mechanism is believed to be the earliest known mechanical analog computer.〔(''The Antikythera Mechanism Research Project'' ), The Antikythera Mechanism Research Project. Retrieved 2007-07-01〕 It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to c. 100 BCE. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe.〔In search of lost time, Jo Marchant, ''Nature'' 444, #7119 (November 30, 2006), pp. 534–538, PMID 17136067.〕 When John Napier discovered logarithms for computational purposes in the early 17th century, there followed a period of considerable progress by inventors and scientists in making calculating tools. In 1623 Wilhelm Schickard designed a calculating machine, but abandoned the project, when the prototype he had started building was destroyed by a fire in 1624 . Around 1640, Blaise Pascal, a leading French mathematician, constructed a mechanical adding device based on a design described by Greek mathematician Hero of Alexandria.〔(【引用サイトリンク】title=History of Computing Science: The First Mechanical Calculator )〕 Then in 1672 Gottfried Wilhelm Leibnitz invented the Stepped Reckoner which he completed in 1694.〔, p.38-42, translated and edited from 〕 In 1837 Charles Babbage first described his Analytical Engine which is accepted as the first design for a modern computer. The analytical engine had expandable memory, an arithmetic unit, and logic processing capabilities able to interpret a programming language with loops and conditional branching. Although never built, the design has been studied extensively and is understood to be Turing equivalent. The analytical engine would have had a memory capacity of less than 1 kilobyte of memory and a clock speed of less than 10 Hertz . Considerable advancement in mathematics and electronics theory was required before the first modern computers could be designed. == Binary logic == In 1702, Gottfried Wilhelm Leibnitz developed logic in a formal, mathematical sense with his writings on the binary numeral system. In his system, the ones and zeros also represent ''true'' and ''false'' values or ''on'' and ''off'' states. But it took more than a century before George Boole published his Boolean algebra in 1854 with a complete system that allowed computational processes to be mathematically modeled . By this time, the first mechanical devices driven by a binary pattern had been invented. The industrial revolution had driven forward the mechanization of many tasks, and this included weaving. Punched cards controlled Joseph Marie Jacquard's loom in 1801, where a hole punched in the card indicated a binary ''one'' and an unpunched spot indicated a binary ''zero''. Jacquard's loom was far from being a computer, but it did illustrate that machines could be driven by binary systems .〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「history of computer science」の詳細全文を読む スポンサード リンク
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