The Fingers
Look at your hands. Have you ever used your fingers to help you count? Perhaps you used them to help you to add two numbers. When you did this, you were using your fingers as a counting device. It was a very simple device which helped you to carry out / simple additions.
Stones
To start with, look at your fingers again. How many have you? You have ten if you include your thumbs. Because you have ten fingers, they are not very good for counting when the numbers are larger than 10. Because of this, primitive man started to use stones instead of fingers to help him to count. Suppose he wanted to count the number of animals he owned, He built a pile of stones with one stone for every animal. After he had finished building the pile he needed to look at it and see how many there were in it.
This was not easy if all the stones were in a single pile. So he put them into smaller piles of the same size. What size did he choose for each of these smaller piles? He decided that the size of each pile should be ten. He picked this number because he had ten fingers.
Suppose that after counting his animals the primitive man had three piles of ten stones and one smaller pile of four After looking at the piles he said,
"I have three tens and one four." He called the number thirty-four.
Even quite small numbers like 34 used a lot of stones. Using stones is no good for large numbers.
The next step was to use a different stone to mean ten animals. Perhaps our primitive man used black Stones to count up to 10. He used white stones to
Counting with stones
Count the number of tens. The number 34 only needed 7 stones, 3 white and 4 black. This method was also used to count larger numbers. Red stones could be used for hundreds. Then the number 154 used only ten stones. This simple way of counting was difficult to use because stones were very awkward.
ABACUS
The next idea was to use coloured beads threaded on a string. At first the beads were made of stone. Around about the year 1200 the Chinese used this 1 method to count. The beads were threaded on lines of wire frame. The beads on the first line counted the units. The beads on the second wire counted the tens. The bead on the third wire counted the hundreds and so on. By moving the beads back and Abacus with beads showing forth along wires, numbers could be added and the numbers could be subtracted. This device was called an ABACUS. The Abacus is a wooden frame with strings on which colourful beads are strung.
Early mechanical aids to counting
Calculating devices
Just over three hundred years ago, the first machines for helping with calculations were invented. These machines were mechanical. They had parts which moved. The power that caused the movement was provided by the person who was using the machine. Calculating machines like these were still used in the 1970s but they became out of date with the invention of electronic calculators.
PASCALINE
A Frenchman called Blaise Pascal invented the first machine which could do both addition and subtraction, in 1642. The machine was named PASCALINE.
It had a number of wheels with teeth on them. The first wheel counted units, the second the tens, the third the hundreds, and so on.
Every time the first wheel made one complete turn, the second wheel moved one position forward. Ten turns on the first wheel caused one complete turns the second wheel.
One hundred turns on the first wheel caused ten turns on the second wheel and one complete turn on the third wheel.
After a large number of turns, by looking at the position of each wheel you can read a number from them. This method is still used today in fuel and electricity meters.
Addition is done by moving the wheels forward. Subtraction by moving them backwards.
THE STEPPED RECKONER
The next step was to invent a machine called THE STEPPED RECKONER which was able to do multiplication and division. It could also calculate square roots.
This was done in 1671 by a German called Gottfried von Leibnitz. This machine also used wheels with teeth on them.
Information processing devices
The machines mentioned so far are only calculators. They are used to add, subtract, multiply and divide two or more numbers.
In the nineteenth century there was a new idea. This idea was to give a machine some information which was then used by it. We say that the machine is processing the information which it has been given.
Jacquard's Loom
An early example of a machine which processed information was used by a French An ea manufacturer, called Joseph Jacquard. In 1802 he built a machine to help weave complicated patterns. When a pattern is woven, each of a number of threads must be raised or lowered. When this has been done the weaving loom pulls mother thread between the raised and lowered threads. Then each of the threads is raised or lowered in a different way and the loom passes between them again.
This is done very many times when a length of cloth is woven.
Jacquard's loom used lines of holes on a card to represent the weaving pattern. If there were ten threads there was space in each line for ten holes.
The card was attached to a device on the loom which was able to look for holes in the card. The device looked at each line. If there was a hole in positions 3, 5, and 9 then the third, fifth and ninth threads were raised and the rest lowered. After this was done the loom would start to weave. Then the device would look at the next line of holes on the card. It would raise and lower the threads and start weaving again. The information on the card was processed by the loom. A loom operator used to do these before the invention and it was tedious and time consuming job.
Jacquard's invention emphasised three concepts:
* information could be coded on punched cards
* cards could be linked in a series of instructions and
* many programs could automate jobs.
Sir Charles Babbage's Difference Engine
In 1822, an Englishman called Sir Charles Babbage built a machine called a Difference Engine. In this, information on cards was supplied to the machine.
The machine then used wheels with teeth on them to do some mathematical calculations.
Babbage later designed another machine called an 'Analytical Engine'. He wanted to use this for more complicated calculations. Babbage died before he could complete this difficult task. He was the first to exploit the concepts from Jacquard's loom in a computing machine. Charles Babbage is known as the father of computers because of the ideas he introduced.
A friend of Babbage called Ada, Countess of Lovelace, showed how the 'Analytical Engine' could be used to do some particular calculations.
Sir Charles Babbage is often thought of as the inventor of the computer and Lady Lovelace is regarded as the first computer programmer. She is also one of the few women to have been involved in the early history of computing.
The Analytical Engine has four parts:
* a mill for calculating
* a store for holding instructions, intermediate and final results
* an OPERATOR (or system) for carrying out instructions
* a device for "reading" and "writing" data on punched cards.
Hermann Hollerith's Machine
During the rest of the nineteenth century more complicated mechanical devices were built. The most important was made by an American called Hermann Hollerith. He used it to process the information obtained in the census of the population carried out in the United States in 1890. With this machine, he was able to do in three years what would have taken very many people seven years to do by hand.
Hollerith formed a company to sell his machines. After a series of mergers with other companies, his company became part of the American Computer Company, International Business Machines (IBM. IBM is now one of the largest computer manufacturers in the world.
At this time a major change was about to take place. It was made possible by inventions in ELECTRONICS. We will look at these inventions in the next section.
Electronic systems used another important idea. You have always counted in a system based on tens. This is called a decimal system. You can also count in a system based on eights, sixes, twos or indeed in one based on any number.
Electronic computers count in a system based on twos. We will look at this and other number system later in this book.
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