An Illustrated History of Computers

Part 1

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Table of Contents

John Kopplin © 2002

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.

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

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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).

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A very old abacus

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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]

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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.

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A slide rule

Leonardo da Vinci (1452-1519) made drawings of gear-driven calculating machines

but apparently never built any.

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A Leonardo da Vinci drawing showing gears arranged for computing

The 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.

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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 of 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:

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Pascal’s Pascaline [photo © 2002 IEEE]

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

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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…