Friday 22 July 2011

EARLY HISTORY

2500BC- THE ABACUS

     Abacus is the first known calculating machine used for counting. It is made of beads strung on cords and is used for simple arithmetic calculations. The cords correspond to positions of decimal digits. The beads represents digits. Numbers are represented by beads close to the crossbar. Abacus was mainly used for addition and subtraction and later for division and multiplication.

1 comment:

  1. Have you ever wondered why the Chinese abacus is the type of abacus most often pointed out as the ancestor of digital computer?

    The answer to the question may lie in the fact that the Chinese abacus has two heaven beads and five earth beads along each rod, and thus that makes the difference from other types of abaci.

    The Chinese abacus is commonly used for working in decimal, but it may be used as well for hexadecimal numbers. Note that when all beads along a rod are set then the sum of bead values would exactly be equal to 15 or F.

    Hexadecimal numerals are widely used by computer system designers and programmers because they provide a human-friendly representation of binary-coded values.

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