History of Computing

SOME ASPECTS OF THE HISTORY OF COMPUTING

When someone uses the word "computer", we immediately think of an electronic device such as the one you are using to read this. But the word has a much more general meaning. The entry in Collins English Dictionary for "compute" is -

compute (kom-put') v.t. to count; to calculate; to estimate. - comput'able a. - comput'er n. - computation n. calculation; reckoning; estimate. - computator n. [L. con-; putare, to reckon].

So stricly speaking, we should call this device an "electronic computer", but for the rest of this page, we will just say "computer" as in common usage.

What is a computer?

If you ask ten computer "experts" this question, you are likely to get ten different answers! Here is one definition -

A computer is an electronic device, operating under the control of instructions stored in its own memory unit, which can accept and store data, perform arithmetic and logical operations on those data without human intervention, and produce output from the processing.

(Shelly and Cashman, p1.1)

Now that we know what a computer is, we can have a bit of a look at some aspects of its history.

Three Ways of Computing

There are three common ways of computing - they are mental, mechanical and electronic. This thing we now call a computer belongs to the third of those categories, and before we look at that, we will have a look at the first two.

A. MENTAL COMPUTING

The earliest computing was carried out mentally, even if some form of counting aid was used. An interesting example of this is the way the Sibiller tribesmen of New Guinea counted. Because of the particular parts of the body they used as an aid, they were only able to count to twenty seven.

CLICK ON THE PICTURE TO SEE MORE PICTURES

Of course, we use mental computing every day. We mentally compute the total cost of a pie and a packet of chips when we buy them. It would be a little embarrasing to have to carry a computer around to do computations like this one!

B. MECHANICAL COMPUTING

1. The Abacus

Mechanical devices of various kinds have been used for computing for many centuries. Perhaps the best known of these is the abacus. Although most people associate the abucus with the orient, it was also used throughout most of Europe's history. Today it is still very common in Asia. Some abacus operators there can compute faster than clerks with fairly modern adding machines.

An Abacus
CLICK ON THE ABACUS TO FIND OUT MORE ABOUT IT!

2. Babbage's Multiplier

Charles Babbage, a nineteenth century English inventor, designed his "Difference Engine" to calculate and print mathematical tables. Although it would theoretically do what it was meant to, it failed because parts could not be machined precisely. The picture below shows part of the computing element for multiplying. It was a series of toothed wheels on shafts, and they worked rather like a modern distance meter.

Babbage's Difference Engine

CLICK ON THE PICTURE TO FIND OUT MORE ABOUT BABBAGE AND HIS INVENTIONS

3. The Differential Analyser

The differential analyser, shown below with its inventor, Dr Vanevar Bush, is a giant modern mechanical computer built in 1930 in the USA to solve differential equations. A later model, a transition to the electronics age, replaced many of the gears and shafts with electrical switches. Bush's machine was used to calculate artillery trajectories during World War II.

CLICK ON THE PICTURE TO FIND OUT MORE ABOUT THIS DIFFERENTIAL ANALYSER.

CLICK HERE TO FIND OUT ABOUT A DIFFERENTIAL ANALYSER IN GREAT BRITAIN.

4. Weaving by Card

In 1728 a French engineer invented this automatic loom. An endless chain of punched cards was set to rotate past the needles of the loom. As the cards moved past, only the needles which matched the holes were able to penetrate, and their threads determined the pattern. The punched cards used in early computers for data input evolved from these.

5. Punching by Machine

By 1890, Herman Hollerith, an American engineer, had perfected the first data-processing machine to use punched cards. The holes had to be punched one by one, but by 1916 the device on the right had been patented to solve this problem, punching nine holes in the card at once.

CLICK ON THE PICTURE TO SEE MORE ABOUT HOLLERITH.

6. Input by Card

The use of punched cards in computing really belongs in the third section of this page, C. ELECTRONIC COMPUTING, but it seems logical to mention them here. As the card moved through the card reader, small brushes could make an electric contact through the holes, thus providing input to the computer. Later, light beams and tiny photo-electric cells replaced the brush contacts. The keyboard has now replaced this rather slow and cumbersome way of inputting.

CLICK ON THE CARD TO SEE SOME OTHER PUNCHED CARDS.

7. The Slide Rule

The slide rule was widely used by mathematicians and other scientists before the invention of the eletronic calculator. As Dave Van Domelen, of Ohio State University puts it -

"Few things in history have become so completely and quickly obsolete as the slide rule, replaced by the electronic calculator and portable computer. Even abacuses are still used in some circles, but everyone who would have used a slide rule now uses an electronic calculator instead." (Quote from his web site.)

To check out Dave's slide rule page, CLICK HERE

Here is a picture of a slide rule. Click on it to read a bit more detail about slide rules. The page you will get to is from Hewlett-Packard's very interesting history of calculators site.

C. ELECTRONIC COMPUTING

1. Decimal and Binary Systems

We are familiar with the decimal system of counting which uses just ten symbols - 0 and the digits 1 to 9. But the computer uses the binary system which has only two symbols - 0 and 1. To find out more about the binary system, click on the "byte" below.

00101101

2. An Early Electronic Memory

One early type of memory was made up of many units like the one above. Each unit was made up of many wires in the form of a grid with tiny, circular core magnets strung at each intersection. Data were stored by sending current through the core magnets in different directions.

Counter-clockwise field - 0, clockwise field - 1.

3. The Sinclair ZX80

The SINCLAIR ZX80 was one of the first home computers, and was released in England in 1980. It used the TV as a monitor, and cassette tape for storage. It had 1K of memory, which could be expanded up to 4K with a plug-in ROM! Only 70,000 of them were sold world-wide. The picture below is of the one the writer of this article bought as his first computer!!!

CLICK ON THE PICTURE TO FIND OUT MORE ABOUT SINCLAIR COMPUTERS.

You can still buy ZX80s (and other historic Sinclairs)! Click HERE.

4. The Apple Macintosh

This photo was taken in 1990 to show what was then the very latest in desktop computers. It was one of the latest versions of the "Mac", the IIcx, and it had 2 Mbytes of RAM, expandable to 8 Mb, and 256 k of ROM. It was regarded as having a very large memory and one of the first WIMP machines. WIMP stands for "Windows, Icons, Mouse Pointer". (No - the word "Windows" doesn't belong to Microsoft and PCs!) The first APPLE computer appeared in 1976, and the MACINTOSH in the early eighties. The "Mac" provided a new type of interface with its menus shown in windows on the screen, and menu selections, as well as other input, could be carried out by keyboard or by mouse.

CLICK ON THE PICTURE TO FIND OUT MORE ABOUT
THE HISTORYOF APPLE COMPUTERS.

And another APPLE history site - click HERE.

AND TO FINISH OFF, HERE IS ANOTHER GREAT HISTORY OF COMPUTING SITE!

Bibliography

Shelley, Gary B. & Thomas J. Cashman (1984). Computer Fundamentals for an Information Age. Anaheim Publishing Company, Inc., Brea, CA.

This page was prepared by Robert Tanner, March, 1999. Last update 3 November, 2002.
All material is copyrighted by the author. The picture of the slide rule used with kind permissin of David Van Domelen. All other illustrations are either owned by the author or in the public domain.