history of computer

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 mathematicaltheories towards modern computer concepts and machines, led to a major academic field and the basis of a massive worldwide industry.

The earliest known tool for use in computation was the abacus, developed in the period between 2700–2300 BCE inSumer.The Sumerians' abacus consisted of a table of successive columns which delimited the successive orders of magnitude of their sexagesimal number system.^:11 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.It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greekisland 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 inEurope.

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 1623Wilhelm 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 byGreek mathematician Hero of Alexandria.Then in 1672 Gottfried Wilhelm Leibnizinvented the Stepped Reckoner which he completed in 1694.

In 1837 Charles Babbage first described hisAnalytical 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.