When you read the following text, you will probably meet words and expressions that are new to you. First try to understand their meaning from the context - read the same passage a few times. When you have read the whole text, check new words in a dictionary. Most of the words in boldtypeface are explained in the Glossary at the end of this book.
 Let us take a look at the history of the computers that we know today. 1 The very first calculating device used was the ten fingers of a man's hands. This, in fact, is why today History of computers we still count in tens and multiples of tens. Then the abacuswas invented, a bead frame in which the beads are moved from left to right. People went on using some form of abacus 5 well into the 16th century, and it is still being used in some parts of the world because it can be understood without knowing how to read.
 During the 17th and 18th centuries many people tried to find easy ways
of calculating. J. Napier, a Scotsman, devised a mechanical way of
multiplying and dividing, which is how the modern slide ruleworks. 10
Henry Briggs used Napier's History of computers ideas to produce logarithm tableswhich all mathematicians use today. Calculus,another branch of mathematics, was independently invented by both.Sir Isaac Newton, an Englishman, and Leibnitz, a German mathematician.
 The first real calculating machine appeared in 1820 as the result of 15
several people's experiments. This type of machine, which saves a great deal of time and reduces the possibility of making mistakes, depends on a series of ten-toothed gear wheels. In 1830 Charles Babbage, an Englishman, designed a machine that was called 'The Analytical Engine'. This machine, which Babbage showed at the Paris Exhibition 20 in 1855, was an attempt to cut out the History of computers human being altogether, except for providing the machine with the necessary facts about the problem to be solved. He never finished this work, but many of his ideas were the basis for building today's computers.
 In 1930, the first analogcomputer was built by an American named 25
Vannevar Bush. This device was used in World War II to help aim guns. Mark I, the name given to the first digitalcomputer, was completed in 1944. The men responsible for this invention were Professor Howard Aiken and some people from IBM. This was the first
machine that could figure out long History of computers lists of mathematical problems, all at 30 a very fast rate. In 1946 two engineers at the University of Pennsylvania, J. Eckert and J. Mauchly, built the first digital computer using parts called vacuum tubes.They named their new invention ENIAC. Another important advancement in computers came in 1947, when John von Newmann developed the idea of keeping instructions for 35 the computer inside the computer's memory.
 The first generation of computers, which used vacuum tubes, came out in 1950. Univac I is an example of these computers which could perform thousands of calculations per second. In 1960, the second generation of computers was History of computers developed and these could perform work 40 ten times faster than their predecessors. The reason for this extra speed was the use of transistorsinstead of vacuum tubes. Second-generation computers were smaller, faster and more dependable than first-generation computers. The third-generation computers appeared on the market in 1965. These computers could do a million calculations 45 a second, which is 1000 times as many as first-generation computers. Unlike second-generation computers, these are controlled by tiny integrated circuits and are consequently smaller and more dependable. Fourth-generation computers have now arrived, and the integrated circuits that are being developed have been greatly History of computers reduced in size. This 50 is due to microminiaturization,which means that the circuits are much smaller than before; as many as 1000 tiny circuits now fit onto a single chip.A chip is a square or rectangular piece of silicon, usually from w to 4 inch, upon which several layers of an integrated circuit are etched or imprinted, after which the circuit is encapsulated in plastic, ceramic 55 or metal. Fourth-generation computers are 50 times faster than third-generation computers and can complete approximately 1,000,000 instructions per second.
 At the rate computer technology is growing, today's computers might
be obsolete by 1988 and History of computers most certainly by 1990. It has been said that if 60 transport technology had developed as rapidly as computer technology, a trip across the Atlantic Ocean today would take a few seconds.
Which statement best expresses the main idea of the text? Why did you eliminate the other choices?
EH 1. Computers, as we know them today, have gone through many changes.
I I 2. Today's computer probably won't be around for long. I I 3. Computers have had a very short history.