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Text B. Computer System

A computer system is made up of five fundamental units. The central part of a computer is the Central Processing Unit (CPU). The CPU includes 2 units: the Control Unit (CU), and the Arithmetic-Logical Unit (ALU).

The Arithmetic-Logical Unit is the "brain" of the computer system. It performs the most important operations of a computer system - arithmetic and logical operations on the data.

On the other hand, the Control Unit functions more like a "house master". It decides the sequence of operations for the system. It generates and manages all control signals to streamlining the operations and flow of data within the ALU.

Memory module is the next part of a computer system. 'The memory of the computer is used to store information. Several types of memories are normally present in a computer system. These two basic types of memories are respectively known as ROM (Read Only Memory) or RAM (Random Access Memory). Secondary memories can reside externally to the computer. A typical example would be diskettes.

The last part of a computer system is the input /output - module. The input - module supplies data to the ALU. It can be, for example, a keyboard. The output - module on the other hand displaysto the outside world the data exiting from the ALU. A familiar example is the video display unit (VDU).

Personal computer systems are used now on a wide scale.

The basic components of a personal computer consist of the system unit, the keyboard, the video display unit, the printer and optionally the mouse. They can be easily connected and ready to be used in a matter of minutes.

The system unit contains a 16 / 24 / 32 - bit microprocessor, the two diskette drives housed in a single table - top unit. The system unit is powered from a standard 230 - volt ac grounded wall outlet.

The computer system has two modes: alphanumeric (A / N) or text mode and graphics mode.

A few words about A / N mode.

In text mode, it supports either a 40 / 25 or an 80 / 25 display format. Each character is format in an 8 / 8 character box. Characters can be black or white or displayed in colour with 8 background colours and 16 foreground colours. Multiple pages of text may also be stored in the adapter.

The display adapter card contains ROM character generator that provides 256 characters for displaying on the screen. In addition to the standard 96 ASCII characters, there are special characters for supporting games and text processing, plus international character and symbols, line graphics, scientific notations and Greek characters.

Each display character position is defined by two bytes in the adapter 16K RAM. One byte is for the display character code byte, which is the ASCII character code and the second byte is the attribute.

Thus, for the 80 column per 25 rows display, it's required 4000 bytes.

The second possible mode is a graphics mode. The adapter card has two graphics modes - a 320 / 200 four colour mode and a 640 / 200 monochrome mode. In the 320 / 200 mode, each dot on the screen can be programmed with any of the four colours.

The 320 / 200 medium resolution mode uses 16000 bytes of memory, organised in 4 pixels horizontally per byte. The screen is divided into two buffers, the first 8K buffer holding data for the even lines and the second hold data for the odd lines. Each pixel on the screen is defined by two bits

The 640 / 200 high resolution mode requires 16Kb. Every bit is mapped to a pixel on the screen. So, one byte will represent 8 pixels on the screen.

The personal computer can be connected to either 84-keys or 101-keys keyboard.

The 84-keys keyboard is a AT / XT compatible keyboard. It is changeable to the AT or XT by selective switch at the back of the keyboard.

Various languages keyboards are available: English, German, Russian and others.

The 101-keys keyboard with an outside is to select XT or AT mode. It is basically an intelligent and detachable keyboard.

Vocabulary

1. Read the following international words from the text. Guess their meanings:
   

computer, system, byte, fundamental, central, process, control, arithmetic, logical, operation, function, master, generate (-or), signal, module, information, type, diskettes, familiar, video, personal, printer, contain, microprocessor, volt, text, graphic, character, format, adapter, position, game, international, symbol, line, notation, bit, attribute, column, monochrome, program, organize, horizontally, selective.

1. Read and remember the following abbreviations:

1. Produce definitions to the following:

CPU, character, computer, data, access, instruction, magnetic tape, word, byte, bit, capacity, address, code, chip.

Use the sentences below:

1.А basic unit of a data in a computer memory. It consists of a predetermined number of characters or bits to be processed. The word “bit” is formed from the letter ”b” in the word “binary” and two letters in the word “digit”. 2.The process of acquiring information from a computer register, memory or peripheral unit. 3. One of the elementary operations which can be performed by a computer. 4.The mechanical, magnetic, electronic and electrical devices or components of a computer. 5.The part of a computing system which obtains instructions from the memory and interprets them as well as performs the actual operations. 6.A collection of numeric, alphabetic or special characters denoting facts and information. 7.Any device capable of accepting information, applying prescribed processes to the information and supplying the results of these processes, in other words, a device for performing sequences of arithmetic and logic operations. 8.One of a set of elementary symbols which may be arranged in groups to express information. The symbols may include the decimal digits 0 through 9, letters A through Z, punctuation marks and operation symbols which a computer may read, store and rite. 9.A tape with a magnetic surface on which data can be stored by selective magnetisation of portions of the surface. 10.A system of characters and rules for representing information in a language capable of being understood and used by a computer. 11.A small piece of silicon on which an integrated circuit is fabricated. 12.A unique label, name, or number that identifies a memory location. 13.The number of bits or words or bytes that can be stored. 14.The smallest unit of information within a character which can assume the values of 0 and 1.

1. Translate the following word combinations. Pay attention to the left-hand attributes:
   

control unit functions, memory module, input/output module, personal computer systems, video display unit, standard 230-volt ac grounded wall outlet, each display character position, adapter card, 320/200 medium resolution mode, first 8K buffer, 640/200 high resolution mode, 101 – keys keyboard, at/xt compatible keyboard, various languages keyboard.

1. Fill in the table according to the pattern:

1. 
   
2. Translate the sentences below. Pay attention to the meanings of the following words:
   a) a result - результат, следствие
   as a result - в результате
   to result in - приводить к
   to result from -вытекать из....; являться результатом

1.After performing computations a computer displays the results. 2.The development of cybernetics has resulted in growing application of various computers. 3.These data result from the comparison operation. 4.As a result, solving such problems will save human lives. 5.He reported the results of the experiment made by means of a general-purpose computer. 6.The importance of computing machines results from their ability to process information in an extremely short time.

b) rather - довольно, до некоторой степени, скорее
rather than -а не..., вместо того, чтобы; скорее чем

1. These measurements require rather high accuracy. 2.The speedometer reads the instantaneous velocity of a car rather than the average one. 3.This graph is plotted rather for an object moving with uniform velocity. 4.In case of varying values an analog computer rather than a digital one should be used.

c) way - путь, способ
way out -выход (из положения)
in this way -таким образом
by the way -между прочим
the other way round -наоборот

1. The only way of solving this complicated problem is to use a computer. 2. In this way, the difference in the design of these computing machines is the difference in their functions. 3. It should be always remembered that the machine serves man, and not the other way round. 4. By the way, some decades ago the principle use of computers was in the area of applied mathematics. 5. There is no better way of raising productivity than by applying modern electronic computers. 6. In this way, the crystal acts as a switch and “remembers” the light impulses. 7. One of th e ways of storing information in a computer is storing by using a set of small magnetically polarised spots (пятна) on a magnetic surface. 8. The only possible way out is to simulate the situation by means of a computer.

d) term - термин; срок; семестр
to term - называть
in terms of - с точки зрения; на языке; в терминах

1.Technically, the term microprocessor has come to mean the central processing unit of a small computer system. 2.A code can be written in terms of automatic language for then it is easy to make changes in it. 5.A program may be termed a routine or code as they are synonyms. 4.If the language being described is called simply "the language", then the language in terms of which the description is being made is called "metalanguage”. 5.Computers are best understood in terms of their real capabilities.

e) a number -число; количество; номер
to number - насчитывать
a number of - pяд, множество

1.If the code for number 3 is stored in register R, the operation will be perfomed by the computer 3 times. 2.A number of computing devices were arranged in our laboratory. 5.An instruction word looks like a number and there is no way to tell from the word itself whether it is a quantity or an instruction.

f) consideration -рассмотрение, обсуждение; соображение
to take into consideration - принимать во внимание
under consideration - рассматриваемый, обсуждаемый
in consideration of - принимая во внимание

1. In view of these considerations one can foresee the development of cryoelectronic memories with extremely high component densities. 2. The prime consideration in choosing this type of a computer is its lower price. 3. It should be taken into consideration that CAD reduces drafting time and effort. 4. The problem under consideration is connected with hardware of the supercomputer. 5. In consideration of advantages in speed, reliability and capacity a great deal of attention will be given to this computing machine.

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