From counting to computer *Why is the decimal system so widely used ? As traders , the Babylonians needed a quick and easy way of working with high numbers , and s they developed a decimal system of writing numerals. They were also the first to use a symbole of zero .The decimal system depends on the position of each digit . Ten was taken as the basis of the system because men used to count on their fingers . Not all ancient peoples used a decimal system , however , and there are still some primitive tribes who can count no further than three . Even the Romans , who were so advanced in many ways , were poor mathematicians . They were held back by their inefficient system of writing numbers , which included no symbol for zero . *Have you ever used one of these ? In these days of pocket computers , manual aids to calculating like abacus seem slow and dated . Yet it is still use in many parts of the world , notably in China .Many mechanical calculating machines have been produced since Pascal , the French mathematician , made his in 1642 , but the great breakthrough did not come until the 1940s when the first electronic computer was made . *Why is the decimal system not suitable for computers ? The circuits in n electronic computer can either be on or off , according to the impulse they receive . Thus a binary , or ‘two-based’ , system of counting is needed to suit the on/off pulses .This is why binary mathematics is now taught in many schools . *What is inside a computer ? Mistakes in bank accounts , railway bookings and tax calculations are frequently blamed on computers . people now have a machine to blame , but , in fact , computers very seldom make mistakes and a human error in programming and presenting the information is a much more likely source . The compuer consists of an input unit , control unit , output unit , memory unit and arithmetic unit . The input unit ‘digests’ the program as it is received and passes it on to the store in the form of a magnetic recordings . The store can supply information , or data , a either to the arithmetic unit , the control unit or directly to the output unit , as it is needed . All the calculations are done in the arithmetic unit . The control unit , which is the ‘nerve centre, of the computer , carries out the instructions which are received in a program . The arithmetic unit and the control unit each have small stores of information called registers . The output unit presents the results of each computer operation , usually as a printout . Digital computers are really counting machines . You use them for high speed mathematical calculations . You can mutiply , divide , add , or subtract numbers with them . You can operate the smaller ones manually like typewriters . Your programme larger digital computers with punched cards , punched tape or magnetic tape . A unit called the reader reads the information which someone puts in . In this unit , something converts the data into a form which the computer can use . Someone bases these computers on very complex electrical circuits .
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