Computer History

The first computers were people! That is, electronic computers (and the earlier mechanical computers) were given this name because they performed the work that had previously
been assigned to people. "Computer" was originally a job title: it was used to describe
those human beings (predominantly women) whose job it was to perform the repetitive 
calculations required to compute such things as navigational tables, tide charts, and
planetary positions for astronomical almanacs. Imagine you had a job where hour after
hour, day after day, you were to do nothing but compute multiplications. Boredom would
quickly set in, leading to carelessness, leading to mistakes. And even on your best days
you wouldn't be producing answers very fast. Therefore, inventors have been searching
for hundreds of years for a way to mechanize (that is, find a mechanism that can perform)
this task.

The abacus was an early aid for mathematical computations. Its only value is that it aids the memory of the human performing the calculation. A skilled abacus operator can work on addition and subtraction problems at the speed of a person equipped with a hand calculator (multiplication and division are slower). The abacus is often wrongly attributed to China. In fact, the oldest surviving abacus was used in 300 B.C. by the Babylonians. The abacus is still in use today, principally in the far east. A modern abacus consists of rings that slide over rods, but the older one pictured below dates from the time when pebbles were used for counting (the word "calculus" comes from the Latin word for pebble).