History of Computers

                History of Computer



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.

This picture shows what were known as "counting tables" [photo courtesy IBM]

A typical computer operation back when computers were people.

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).

A very old abacus

A more modern abacus. Note how the abacus is really just a representation of the human fingers: the 

5 lower rings on each rod represent the 5 fingers and the 2 upper rings represent the 2 hands.

In 1617 an eccentric (some say mad) Scotsman named
 John Napier invented logarithms, which are a technology
 that allows multiplication to be performed via addition. The
 magic ingredient is the logarithm of each operand, which
 was originally obtained from a printed table. But Napier
 also invented an alternative to tables, where the logarithm
 values were carved on ivory sticks which are now called Napier's Bones.

An original set of Napier's Bones [photo courtesy IBM]

A more modern set of Napier's Bones

Napier's invention led directly to the slide rule, first built in
 England in 1632 and still in use in the 1960's by the NASA
 engineers of the Mercury, Gemini, and Apollo programs which
 landed men on the moon.

A slide rule

Leonardo da Vinci (1452-1519) made drawings of gear-driven
calculating machines but apparently never built any.

    A Leonardo da Vinci drawing showing gears arranged for computingThe first gear-driven calculating machine to actually be built was
 probably the calculating clock, so named by its inventor, the
 German professor Wilhelm Schickard in 1623. This device got
 little publicity because Schickard died soon afterward in the
 bubonic plague.

Schickard's Calculating Clock

In 1642 Blaise Pascal, at age 19, invented the Pascaline as
 an aid for his father who was a tax collector. Pascal built 50
 of this gear-driven one-function calculator (it could only add
) but couldn't sell many because of their exorbitant cost and
because they really weren't that accurate (at that time it was
 not possible to fabricate gears with the required precision).
Up until the present age when car dashboards went digital,
the odometer portion of a car's speedometer used the very
 same mechanism as the Pascaline to increment the next wheel
 after each full revolution of the prior wheel. Pascal was a child
 prodigy. At the age of 12, he was discovered doing his version o
f Euclid's thirty-second proposition on the kitchen floor. Pascal
 went on to invent probability theory, the hydraulic press, and the
 syringe. Shown below is an 8 digit version of the Pascaline, and
 two views of a 6 digit version:

Pascal's Pascaline [photo © 2002 IEEE]

A 6 digit model for those who couldn't afford the 8 digit model

A Pascaline opened up so you can observe the gears and cylinders which rotated to display the numerical result

Click on the "Next" hyperlink below to read about the punched
 card system that was developed for looms for later applied to
 the U.S. census and then to computers...