86

UNIT 6. LESSON 3

Read the text without a dictionary.

6B. THE DIGITAL COMPUTER'S WORK

There are five main units in a digital computer: an input unit which accepts the data, a memory unit for storing and holding the information until it is required, an arithmetical unit which carries out the arithmetical or logical operations with the data according to a set of coded instructions, an output unit for displaying the results of the arithmetical operations, and a control unit which coordinates the operations of the other units.

Most digital computers operate with numbers in the binary system. In the binary system of numbering there are only two ciphers: 0 and 1. The numbers 0 to 10 in the binary system are represented as follows:

Decimal	Binary	Decimal	Binary	Decimal	Binary
0	0	4	100	8	1000
1	1	5	101	9	1001
2	10	6	110	10	1010
3	11	7	111

The advantage of the binary system is that only two-state devices are required to represent any number. Two-state devices such as simple switch, relay, semiconductor transistor, which are either on or off, are the simplest, cheapest and fastest components available. This is why digital computers consist mainly of very large numbers of twostate devices and these devices go from one state to the other in ordered groups and chains.

In modern digital computers the memory or store is usually a collection of a large number of tiny magnets which have two distinct magnetic states, one of them represents zero and the other unity. One state is converted very rapidly into the other by an electrical pulse and each little magnet is identified by a number called the 'address'. The control unit, consisting of a collection of electronic switches, selects numbers from the store according to a set of instructions and manipulates them as required by the calculation. The skill in using the computer is mainly in devising the best and most economical program: i.e. setting up series of instructions in the language which the machine understands, which cause the computer to carry out all necessary operations in simple steps and each is a single arithmetic operation. An instruction may be: "Add number in address 615 to number in address 670", or "Repeat previous instructions". The instructions are carried out in the arithmetic unit, which is made up of a number of

87

electronic circuits which serve as registers and are called accumulators. Arithmetic units are capable of addition, multiplication, subtraction and division and elementary logical operations.

Data, or information, is supplied to the computer through the input unit and may take many forms. Formerly these included punched paper tapes, punched cards, magnetic tape, magnetic cards, signals from electric typewriters, magnetic discs, data transmitted by wire among others. Now these are laser discs. Whatever the form of the input data the input unit must translate the information into digital electronic signals when the program asks for it. Modern high-speed digital computers gave tremendous appetites for information and there has been much research and effort in devising ways of feeding in data quickly and accurately.

COMPREHENSION TEST

I.Fill in the blanks selecting the appropriate variant:

1.There are ... main units in a digital computer. 1) four; 2) five; 3) three.

2.An input unit ... the data. 1) displays; 2) stores; 3) accepts.

3.A memory unit is used for ... the information. 1) storing; 2) accepting; 3) displaying.

4.An arithmetical unit ... the arithmetical or logical operations. 1) does not carry out;

2)carries out.

5.An output unit is used for ... the results of the arithmetical operations. 1) accepting; 2) storing; 3) displaying.

6.Most digital computers operate with numbers in the ... system. 1) single; 2) binary;

3)third.

7.The advantage of the binary system is that only ... devices are required to represent any number. 1) one-state; 2) two-state.

8.Two-state devices are ... components available. 1) the simplest, cheapest and fastest; 2) the most complicated, expensive and slowest; 3) the most complex, dearest and not the fastest.

9.The process occurring in the two-state devices is ... changes from one state to the other. 1) slow; 2) rapid; 3) neither rapid nor slow.

10.The control unit ... numbers from the store. 1) selects no; 2) does not select; 3) chooses.

11.Data, or information is supplied to the computer through the ... . 1) output unit;

2)input unit.

12.Modern high-speed digital computers have ... for information. 1) few requirements; 2) enormous requirements; 3) little appetite.

88

13.There has been much research and effort in ... ways of feeding in data quickly and accurately. 1) reading; 2) writing; 3) devising.

Translate the text into English. Entitle the text.

TEXT 6C

Два основных типа компьютеров, аналоговые и цифровые, имеют большие отличия.

Аналоговые машины считаются моделью физической или математической

задачи. Их	обычно	конструируют для		конкретного использования. Работа
аналоговых	ЭВМ обычно ограничивается точностью. Задачи				решаются	с
помощью	сходства	с	процессом. Они	используются	для	решения

специализированных и технических задач.

Цифровой компьютер решает задачи вычислением. Все данные хранятся в памяти. Цифровая ЭВМ выполняет три основные функции. Она работает как вычислительная машина, используется для обработки данных и контролирует различные процессы. Цифровой компьютер используется в различных отраслях науки и техники, промышленности, бизнесе и образовании.

6D. THE CURRENT TECHNICAL REVOLUTION

There is a revolution going on, a technical revolution. Every day, there are new changes: changes in components, products, systems, materials; changes in processes, and even in whole technologies. We are constantly evaluating, developing, testing and applying new techniques.

Research and its applications is being promoted, supported and improved. That's the reason we're involved in so many different science areas. During the last two decades emphasis has been placed on highly specialized fields of science.

Many of the achievements of contemporary science have been won by the combined efforts of scientists working in various fields. For instance, a successful launching means not only the creation of the rocket itself, although this alone is an outstanding scientific achievement. Here we can find delicate electronics, and computer technology is also needed to define the parameters of the flight. But even this is not enough. The success of the space flight is impossible without the creation of the systems of remote control by which the sputnik can be guided from the Earth, from the flight control centre, and the apparatus on board the spaceship, which guarantees obtaining different kinds of scientific information.

89

The rapid progress of solid state physics which began in the 50s was connected with great achievements in the semiconductor industry, i.e. with the production of electronic elements (transistors) which phased out (replaced) electron valves in second generation computers.

Achievements in the field of solid-state physics research have caused a revolution in the radio-electronics industry which has long ago undergone a change from vacuum electronic devices to semiconductor devices.

The first electronic computers using electron tubes were bulky, not very reliable and consumed much energy. They were capable of performing no more than a few thousand operations per second and were used mainly as high-speed calculators. The use of microelectronic circuits has made it possible to increase computer operation speed to several billion operations per second.

I. Translate the text using the dictionary.

II. Give the main idea in 2-3 sentences.

III. Make up a short plan of the text.

LISTENING COMPREHENSION. TEXT 6E

Listen to the text and decide whether these sentences appear in the text.

1.We may divide electronic computers into two groups: machines that can measure and those that cannot.

2.Besides they must be able to combine many problems and take them in one order.

3.When a question is fed into the computer, it can actually reply in a voice.

4.Laser and new plastic units are spectacular features of a memory system for recently developed computers.

I.Give the main idea of the text.

II. Render the text into Russian.

III. Retell the text.