¡çáåêèñòîí àëîêà âà àõáîðîòëàøòèðèø àãåíòëèãè
Òîøêåíò àõáîðîò òåõíîëîãèÿëàðè óíèâåðñèòåòè
×åò òèëëàð êàôåäðàñè
ÌÅÒÎÄÈÊ ÊÓÐÑÀÒÌÀ
òåëåêîììóíèêàöèÿ ñîҳàñè á¢éè÷à
ñèðòêè á¢ëèì I, II, III êóðñ
òàëàáàëàðè ó÷óí
5140900,5521900,5522000,
5522100,5522200,5840200
Òàøêåíò 2003
Ñ¢ç áîøè.
Èëìèé-òåõíèêà òàðàққè¸òè õîçèðãè êóíäà ¡çáåêèñòîíãà îëèá áîðèëà¸òãàí èçëàíèøëàðíèíã íàòèæàëàðèíè êåéèí é¢ëãà қ¢éèø ñèñòåìàñèíè òàқîçî ýòìîқäà.
×åò òèëëàðèíè àìàëè¸òäà èøëàòà áèëìîқ õîçèðãè çàìîí èëìèé òåõíèê àõáîðîòëàðèíè êåíã ê¢ëàìäà қàáóë қèëèøãà ¸ðäàì áåðàäè.
×åò òèëèíè ¢ðãàíèø , àéíèқñè ñèðòêè á¢ëèìäà, ¢ç ¢ñòèäà òèíìàé èøëàøíè òàëàá қèëàäè.
Êóéèäàãè áåðèëãàí íàçîîðàò âàçèôàëàðè ÒÀÒÓ ñèðòқè á¢ëèì òàëàáàëàðèíè óíèâåðñèòåò ¢қóâ ðåæàñè àñîñèäà èíãëèç òèëèíè ìóñòàқèë ¢ðãàíèø âà íàçîðàò èøëàðèíè òóғðè áàæàðèøãà ¸ðäàì áåðàäè.
Control Work 1.
Variant 1
Task 1. Translate the text:
BASIS OF RADIO COMMUNICATION
1. Radio communication may be defined as the interchange of signals, symbols, intelligence, impressions between two or more points, employing electromagnetic waves as the medium of transmission. Engineering may be defined as the art and science by which natural forces and materials are utilized in structures, machines, or mechanisms for man's benefit. Radio engineering — that branch of engineering which deals with radio communication — may, therefore, be defined as the art science by which natural forces and materials are utilized for man's benefit in mechanisms intended to convey for interchange of intelligence between two or more points through the use of electromagnetic waves as the transmission medium.
2. Both in theory and in practical application, a very large part of radio engineering may be regarded as a broadened and generalized field of electrical engineering although, in addition, some phases of radio engineering include other branches of physics such as acoustics, optics, meteorology, crystallography, and similar fields. Radio engineering practice differs from electrical engineering practice primarily in two important aspects. The radio engineer is nearly always interested in transforming the maximum amount of power from the transmitting to the receiving ends of the system, whereas the electrical engineer is usually more interested in the transmission of power between two points with a maximum of efficiency. Radio engineering practice also differs from electrical engineering practice in the much greater range of frequencies employed and in the utilization of certain electrical phenomena whose effects are negligible at the comparatively low frequencies at which electric power is generated, distributed and utilized. Radio engineering requires a wide range of frequencies in order that electromagnetic waves may be produced practically and also in order that appreciable amounts of intelligence (considerable details) may be imparted to the electrical system in the communication process.
3. Modern radio communication rests on two fundamental bases: (1) the analysis, formulation, and manipulation of the intelligence to be conveyed, in a form suitable for transmission by radio means, and (2) the fundamentals of those branches of physics (primarily electromagnetism) by which electromagnetic waves maybe produced, modulated in accordance with the intelligence to be transmitted, propagated through space, and received at a distant point where the intelligence is extracted. The proper combination of both of these topics provides the foundations for radio communication engineering.
Task 2. Make up a summary of the text.
Task 3. Translate word combinations:
a) radio engineer, radio engineering, electrical engineering practice, transmission medium, wide range of frequencies, maximum amount of power, power transmission, radio engineering practice, frequency range;
b) to transmit power, to transmit signals; to employ electromagnetic waves, to employ electronic devices, to employ radio-receiving and radio-transmitting devices; to employ greater range of frequency, to be propagated through space, to achieve results through such measures.
Task 4. Answer the questions:
1. How may radio communication be defined? 2. What does radio engineering deal with? 3. What must be used to convey the interchange of intelligence between two or more points? 4. In what way may a very large part of radio engineering be regarded? 5. What is the difference between radio and electrical engineering? 6. What does radio engineering require a wide range of frequencies for? 7. What does modern radio communication rest on?
Task 5. Translate the following sentences:
1. In this case visual images are to be transmitted by electrical means. 2. Scientists had to make a great number of investigations to improve radar equipment. 3. The radio operator was able to determine the exact location of a distant object. 4. We shall be allowed to switch on a radio set in a few minutes. 5. This important information should be transmitted by wireless. 6. Every radio engineer ought to master the fundamentals of radio engineering. 7. You should have switched off the device in time. 8. You ought to have used these data in your experimental work. 9. They will have to listen to this lecture. 10. They were to obtain the necessary data in time.
Variant 2
Task 1. Translate the text:
FARADAY'S DISCOVERY
1. The important discovery on the way toward present day electrical machinery was that of the celebrated English experimenter, Faraday. He produced rotation of a wire carrying electrical current, around a magnetic pole. The experiment may be repeated by anyone who has a coil of wire, a bar magnet and a sensitive current indicator.
2.
Faraday's experiment was the
following: when the bar magnet, or the coil carrying the current, was
motionless, there was no motion of the needle. When a bar was thrust into the
coil the needle moved in one direction. The motion
of the bar being reversed, the needle reversed its motion too. There was no metallic connection between
the two coils, or between the coil and the bar magnet — and yet changing the
position of one with respect to the other, or changing the direction or
magnitude of current through one coil produced some electrical effect in the
other circuit.
3. The facts underlying Faraday’s experiment are these: an electric voltage was generated or induced in the coil when the bar magnet was trust into it. A voltage of opposite polarity was generated when the magnet was removed. This voltage sent a current through the coil and the galvanometer so that needle moved. The same explanation holds when two coils are used, one of them carrying a current, taking the place of the iron bar. Whenever lines of force are cut by a conductor, a voltage is generated in that conductor. As long as the conductor moves so that it cuts the lines, i.e., does not move parallel with them, a voltage is set up. The more lines per second, and the more it cuts the lines at right angels, the greater the voltage.
Task 2. Make up a summary of the text.
Task 3. Translate word combinations:
a) electrical machinery, bar magnet, metallic connection, electrical effect, lines of force, sensitive current indicator;
b) to induce a current, to generate a current, to send a current, to carry the current, to change the position, to change the direction, to change the polarity, to reverse the motion, to produce some electrical effect, to produce the rotation, to set up voltage.
Task 4. Answer the questions:
1. What was the Faraday famous for? 2. Was he an English or French scientist? 3. What is need for repeating Faraday’s experiment? 4. When was there no motion of the needle? 5. Was there any metallic connection between two coils? 6. What is generated in the conductor when lines of force are cut in it? 7. What does almost every application of electricity in modern life depend upon?
Task 5. Translate the sentences:
1. The larger the size of the electrodes, the more current capacity they supply. 2. The lower the voltage of one battery the greater the required number of batteries. 3. The closer are the positive and negative plates, the greater is the charge. 4. The higher the voltage used to charge the condenser, the more energy it will store.
Variant 3
Task 1. Translate the text.
TRANSISTORS
1. In vacuum tubes, the control of free electrons in vacuum is of primary interest. However, in transistors and semiconductors in general, the current may be carried by two distinguishable and distinctly different means — conduction by electrons and conduction by "holes". In intrinsic (pure) semiconductor materials, these two conduction mechanisms contribute mutually opposed particle flow. A voltage being applied, the current consists of the absolute sum of the electron and hole currents (different sign of charge cancels different direction of motion). However, in the commonly used doped (extrinsic) semiconductors such as germanium and silicon, conduction, in some cases, is caused by excess electrons or by excess holes. Transistor interaction occurs in the region where excess electrons control excess holes (or vice versa). Consequently, the semiconductor material (i.e. the medium in which transistor action takes place) is of basic concern in transistors.
In application, transistors are almost analogous to vacuum tubes. For instance, they are three-terminal, nonreciprocal, active devices. The attractiveness of the transistor lies in its small size and its amazingly small power consumption. On the other hand, today's transistors have an upper frequency limit that is lower than that of electron tubes.
Task 2. Make up a summary of the text.
Task 3. Translate the word combinations:
Different means, conduction by holes, mutually opposed particle flow, power consumption, upper frequency limit, conduction mechanism, excess holes, excess electrons, transistor interaction.
Task 4. Answer the questions:
1. What is of primary interest in vacuum tubes? 2. What does current consist of when voltage is applied? 3. Where does transistor interaction occur in semiconductors? 4. What are transistors analogous to in application? 5. What does the attractiveness of the transistor lie in?
Task 5. Translate the sentences:
1. Íå likes reading English scientific books. 2. They think of applying electronic devices in their laboratory. 3. This little girl likes being read to. 4. Flying into outer space has been man's age-old dream. 5. The Government takes great care of the development of science by providing our scientists with all the necessary things for their research work. 6. Before carrying out this experiment he carefully examined all the instruments. 7. Many Institutes have been established for training specialists for various branches of our national economy. 8. The idea of building artificial satellites belongs to K. Tsiolkovsky. 9. After introducing the electronic equipment we raised the efficiency of some processes. 10. In our country great progress has been achieved in developing all branches of science and engineering.
Variant 4
Task 1. Translate the text:
RADAR
Radar — the name was coined from Radio Detection and Ranging — was one of the main factors in the rapid growth of electronics during the last years.
The principle of radar is simple: a beam of energy in the .form of waves is directed at an object and the time required V/for the reflected waves to return to the sender is measured; if the speed of the waves is known the distance of the object can be calculated. By using more than one sender, or a beam whose direction can be precisely fixed, the position as well as the range of the object can be determined. This is all straight forward for a large fixed object like a cliff a few miles away from a ship. But if the target happens to be an aircraft traveling at, say, 500 m.p.h. and about 10 miles away, the use of sound waves is out of the question. It would require something like a volcanic eruption to produce a sound powerful enough to have a detectable echo from an aircraft 10 miles away, and the structure for focusing the sound so that the echoes were confined to those from the aircraft which would have to be several miles across. Even if some fantastic schemes along these lines were devised it would not be very useful for aircraft detection since there would be a delay of at least 100 seconds before the return of the echo, in which time the aircraft would have moved some 10 miles from its original position.
Task 2. Make up a summary of the text.
Task 3. Translate word combinations:
coherent radar, detection of moving targets, search and tracking in the atmosphere, frequency of the returns, velocity information, signal to noise ratio, volumetric search, fire control radars, microwave power amplifier tube, power handling ability, coded signals, matched radar system, noise pulse repetition periods, counter measure deception techniques, range velocity ambiguity restriction, jamming.
Task 4. Answer the questions:
1. What are coherent radars
used for? 2. What does the use of coherent radars show? 3. What is necessary to
determine by means of two operations? 4. What devices must radar use for
obtaining coherence? 5. In what way do these tubes surpass magnetrons? 6. Is
radar using a chain of these tubes simple or complicated? 7. What are primary
factors for application coherent radars? 8. How can the coding vary? 9. What
makes each radar transmission more unique? 10. What can be used to
overcome range velocity ambiguity
restriction?
Task 5. Translate the sentences:
1. Use is made of coherent radars in ground mapping, detection of moving targets, etc. 2. All the problems connected with the operational use of coherent radars are of great significance. 3. Research work in the field of coherent radars is under way. 4. Mention should be made that microwave power amplifier tubes are very expensive. 5. Provision is made of techniques for obtaining coherence with radars using magnetron transmitter rather than microwave power amplifier. 6. This problem is still under consideration. 7. Two operations which are necessary to determine the Doppler shifts in frequency of the returns are of great importance.
Variant 5
Task 1. Translate the text:
MESSAGES BY ELECTRICITY
Electricity completely changed communications. Once it was discovered that an electric current would flow along a wire, it seemed possible that it could be used for messages. As long as two places were connected by a wire electric currents could be sent along it. They could be sent with the speed of light. The question was how could electric current make words?
Real telegraphs were not possible until it was proved that electricity and magnetism were connected. It was found that needle of a compass moved when it was put near a wire with a current flowing through it. A compass needle is a magnet. If a wire carrying a current could move it, then the wire must be a magnet too.
A lot of people began to see how electro-magnets could be used to send messages. One of the most famous people of all in communication is Samuel Morse. He invented the Morse code. This code is still used in signaling all over the world.-His idea was simple. He thought of using time, sending current along a wire for a long time or a short time. Combining different sets of these "impulses", just using the long or short, he made a code for the whole alphabet, and the numbers from 0 to 9.
The Morse code simplified sending messages. It was also very fast. With practice, the Morse code can be read at 30 words a minute or more. It became the most widely used code because it was the easiest to understand and the fastest 1 transmit. The telegraph meant that at last people could send messages a long way at great speed. Soon people wanted to send messages even farther.
If two places on land, say, London and Manchester could be connected by wire, why could not the lands themselves — England and America, for instance, be connected by wires under the sea? This was a question quickly answered after the telegraph was proved to work. There were some problems about this, however. The main one was insulation, which means protecting the wire so that electric current does not leak away. Dry air is a good insulator, but sea water is not. If a wire was laid under water, the current would all leak away. In any case, all the insulating substances known up to then could be damaged by sea water. But in 1847 gutta-percha was introduced as an insulating material. Gutta-percha is a gummy substance obtained from trees, like rubber, and it does not allow electricity to flow through it easily.
After several unsuccessful attempts, in 1866 Britain and America were linked by the underwater cable by the famous cable-laying ship the Great Eastern. After that cables were laid all over the world, and nowadays it is possible to telegraph from almost everywhere.
Task 2. Make up a summary of the text.
Task 3. Fill in the blanks with the following words:
cables, connect, electricity, impulses, insulation, longer, magnets, simple
1. It was discovered that ... and
magnetism are connected. 2. A wire carrying an electric current can move a
compass needle because they are both... 3. The dots and dashes used in the
Morse code can be made by electric ... passing through a wire. 4. The impulse
used to send a dash is ... than that used
to send a dot. 5. The letters SOS are used in times of danger because they are
... letters to signal. 6. Telegraph lines ... telephone stations that are far
apart. 7. ... is used to protect telegraph wires. 8. Messages are carried under
the sea through
telegraph...
Task 4. Give equivalents for the following English word combinations:
change communications, real telegraph, the code is used in signaling all over the world, a long time or a short time, make a code for the whole alphabet, simplify sending messages, at great speed, the telegraph was proved to work.
Task 5. Answer the following questions:
1. At what speed can messages be sent by electricity? 2. At what speed can the Morse code messages be read? 3. Give two reasons why the Morse code was so widely used. 4. What was the main problem about sending messages by telegraph under the sea? 5. Give two reasons why telegraph cables must be insulated. 6. Why is gutta-percha a good material for insulating telegraph cables?
Control Work 2.
Variant 1
Task 1. Translate the text:
EDISON'S LIGHTING SYSTEM
Only at the end of the 19th century electricity began to play its part in modern civilization. The man who achieved more in this field of practical engineering than any of his contemporaries was the American inventor, Thomas Alva Edison. He became interested in the problem of electric lighting. He knew what had been done in the field of electric lighting before his time, and he had seen some devices of his contemporaries, such as arc-lamp illuminations, which had been installed here and there. Two sticks of carbon (óãîëüíûé ýëåêòðîä), nearly touching, can be made to produce an electric arc which closes the circuit. Many scientists and inventors working in this field knew that only incandescent (ðàñêàëåííûé) electric light — produced by some substance glowing (ñâåòÿùååñÿ) in a vacuum so that it cannot burn up — could be used instead of gas lighting.
Edison put his laboratories to the task of developing such a lamp. His first experimental lamp appeared in 1879. Its light was yellowish and it worked for forty hours; the incandescent electric lamp was born.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences:
Cables, connect, electricity, impulses, insulation, longer, magnets, simple
1. It was discovered that ... and magnetism are connected. 2. A wire carrying an electric current can move a compass needle because they are both ... . 3. The dots and dashes used in the Morse code can be made by electric ... passing through a wire. 4. The impulse used to send a dash is ... than that used to send a dot. 5. The letters SOS are used in times of danger because they are ... letters to signal. 6. Telegraph lines ... telephone stations that are far apart. 7. ... is used to protect telegraph wires. 8. Messages are carried under the sea through telegraph ... .
Task 4. Give the equivalents for the following English word combinations:
change communications, real telegraph, the code is used in signaling all over the world, a long time or a short time, make a code for the whole alphabet, simplify sending messages, at great speed, the telegraph was proved to work
Task 5. Answer the following questions:
1. At what speed can messages be sent by electricity? 2. At what speed can the Morse code messages be read? 3. Give two reasons why the Morse code was so widely used. 4. What was the main problem about sending messages by telegraph under the sea? 5. Give two reasons why telegraph cables must be insulated. 6. Why is gutta-percha a good material for insulating telegraph cables?
Variant 2
Task 1. Translate the text:
THE ELECTRIC TELEGRAPH
Modern telegraph systems are based upon the fact that electric current will flow through a wire which forms a circuit. The circuit can be broken to interrupt the flow of electricity and closed again for a short time by to send an electrical impulse through the circuit. Here the wire is not joined all the way round, but the circuit is complete because electricity will flow through the wire and back through the earth. This is called an "earth return". When the key is pressed the circuit is closed. Electricity from the battery flows through the wire and earth circuit and causes the buzzer to make a noise. Using the Morse code, or some other code, messages can be sent in this way.
Men wanted to increase the speed of sending messages. They knew that current flows very quickly along a wire, much more quickly than even the fastest operator can use a machine to send messages by hand. One way of getting higher speeds was to use the fact that current could flow one way round the circuit, or the other.
A flow in one direction could be the same as a dash in Morse, and a flow in the other could be the same as a dot. The system is called "double current working". It is faster than normal, or "single", current working. A dash or a dot is signaled for the same length of time, but in the ordinary Morse code a dash in signaled by an impulse lasting three times as long as a dot.
A machine was invented to receive messages by making a mark on a paper tape with dots on one side of a line and dashes on the other. Through the years other machines were invented, both to receive and transmit messages. These machines are called teleprinters. They use a code called the International 5-unit teleprinter code instead of the Morse code. It is called a "5-unit" code because a letter or a figure is made up of five impulses of electrical current, either positive or negative — three positive, two negative; one positive, four negative; and so on. All the letters are the same length in time. This is quite different from the Morse code, where E is the shortest and "naught" the longest.
A teleprinter is really a machine which sends a typewriter message over a telegraph circuit. In fact, it looks like a typewriter and has the same keyboard. Every time one of the keys on the keyboard is pressed it sends the five impulses that make one letter or figure. It also sends a "start" impulse. This sets the teleprinter (or any number of them that are connected) at a receiving station ready to print the letter that follows immediately. A "stop" impulse brings all the teleprinters to rest after each letter or figure.
In the early days of telegraphy direct current was used. This is current which flows along a line in one direction at a time. Most modern telegraph systems use alternating current. This is current which flows backwards and forwards along the wire. Alternating current is usually supplied to people's houses at 50 cycles per second. This means that every second the current reverses its direction 100 times. Alternating current used to send telegraph messages reverses its direction much more frequently than this, it works on much higher frequencies. These frequencies range from 420 cycles per second to 3,180 cycles per second.
As the number of people who wanted to send telegraph messages increased, more and more messages had to travel along the same telegraph line. Using alternating current, one line can be used to send many messages at the same time if each message is sent out at a different frequency. A transmitting machine sends a message at one of the high frequencies mentioned, say 420 cycles. A receiving machine also working on a current alternating at 420 cycles per second will get the message. But it will not get a message being transmitted at the next highest frequency (which is 540 cycles per second) by another machine, even though this message is traveling along the same line at the same time. To get this message another receiving machine, working on current alternating at 540 cycles, must be used.
Task 2. Make up a summary of the text.
Task 3. Fill in the blanks with the following words:
circuit, direct, direction, frequencies, increase, length, received, reverses, transmitted, transmitting
1. Electrical impulses will not flow through a wire if the ... is broken. 2. Electricity can flow in either ... around a circuit. 3. New codes were invented to ... the speed of sending telegraph messages. 4. In the International 5-unit teleprinter code all the letters take the same ... of time to transmit. 5. In the Morse code, E can be ... more quickly than "naught". 6. Current which travels along a line in one direction only is called ... current. 7. Alternating current supplied to people's houses usually ... its direction 100 times every second. 8. Current used in telegraphy alternates at much higher ... than current supplied to people's houses. 9. A message sent by a ... machine working on current alternating at 540 cycles per second can only be ... by a machine working on the same frequency.
Task 4. Answer the following questions:
1. How is a key used to send an electrical impulse through a circuit? 2. What is an "earth return"? 3. How can the circuit be closed? 4. Why could the Morse code be transmitted more quickly by "double current working" than by "single current working"? 5. Which sign takes the longest to transmit by the Morse code? 6. How is a teleprinter used to receive a message started? 7. What kind of current is mostly used in telegraphy nowadays? 8. What is the highest frequency to transmit messages by alternating current? 9. Why was it necessary to increase the number of messages that could be sent along one telegraph line? 10. Why are machines now used instead of human operators to transmit and receive telegraph messages?
Task 5. Open the brackets using the correct tense form:
1. The remarkable properties of transistor (to open) the doors to a new era in telephone switching. 2. Tremendous changes in telecommunication (to take place) in the last decade. 3. The scientists (to develop) these new units from the beginning of the year to the end of March. 4. Microelectronics (to take) a big leap forward with the development of silicon integrated circuits which (to find) already many uses in space projects. 5. They (to test) these new units for the repeaters for some weeks. 6. I suppose the laboratory (to develop) the new electronic telephone system for the whole year.
Variant 3
Task 1. Translate the text:
RADIO
In the early days of the telegraph and the telephone, men observed that signals sometimes jumped across the space between wires running next to each other, so that messages sent to one person went to another. They realized that electricity could pass through the air as well as along a wire.
Just as sound travels through the air in waves, so electricity travels2 through the air in what we call radio waves. A. S. Popov, a Russian inventor, had the idea of sending messages by radio waves, or "by wireless". He constructed a coherer detector for the study of lightning discharges and his receiver was described in 1895.
In fact, the radio waves travel in a straight line, but they are reflected from the sky back to the earth's surface. This is how radio waves travel around the world. You have heard on the radio of "long-wave transmissions" and "short-wave transmissions". In fact, there are two ceilings in the sky, not solid ceilings like the ceiling in a room, but more like nets which allow some radio waves to pass through them and reflect others. The lower ceiling is called "Heavyset layer". This reflects long waves. Short waves are reflected by the higher ceiling, called the "Appleton layer". Radio transmitters can also send out ultra-short waves. These waves pass through both layers in the sky but are useful for communicating with spaceships and can even be used to send sound to very long distances when they are reflected from satellites in space.
It was exciting to be able to communicate over long distances by signals sent by wireless, but soon men wanted to try to broadcast the sound of voices and even music in this way. A modern broadcast transmitting station has an aerial from which sound waves combined with carrier waves are transmitted. These waves are received on the radio sets in people's houses.
However, broadcasting like this would not be possible without the use of valves in the transmitting station and inside the radio sets. Radio waves are sent out by alternating current. Valves at the transmitting station are used to keep the electric circuits oscillating, that is, sending the current backwards and forwards in the aerial. The number of times the current alternates decides the frequency, or wave-length, on which the station is broadcasting.
Valves inside radio sets oscillate the current from the radio waves which are received. By turning a tuner you can arrange that the oscillations of the circuits in your radio set are the same as those at one of the broadcasting stations. We say, that you are "tuning in" to that broadcast.
Valves inside your radio set have two other uses. Firstly, they change alternating current into direct current, and it is direct current that goes to the loud speaker in the radio. It makes the centre of the loud speaker vibrate to produce the sound waves that you hear. Secondly, the valves amplify the very small amount of electrical energy received from the transmitter. This energy would be far too little to be any use if it were not amplified by a valve.
Task 2. Make up a summary of the text.
Task 3. Fill in the blanks with the following words:
air, alternating, amplify, Heavyset, higher, transmit, tune, wireless
1. Electricity passes along a wire, but it may also pass through the ... . 2. A. S. Popov was the first man to send messages by ... . 3. The Appleton layer is the name for the .. ceiling in the sky which reflects radio waves. 4. Long waves are reflected by the ... layer. 5. Ultra-short waves are used to ... messages to spaceships. 6. You can ... in to a broadcasting station by turning a tuner of your radio. 7. ... current is used to transmit radio waves. 8. Valves inside your radio ... the electrical energy received from the transmitter.
Task 4. Answer the following questions:
1. In the early days of telegraphy, why were messages sometimes sent to the wrong person? 2. What happens to radio waves when they go into the sky? 3. What is the Heavyset layer? 4. How can we send messages to spaceships? 5. How do satellites in space help us to broadcast? 6. From what part of a broadcasting station are sound waves transmitted? 7. What are valves used for at a broadcasting station? 8. What are the valves inside a radio set used for?
Task 5. Translate the following sentences paying attention to the functions of "it":
1. It is not the sound of the voice that travels over the wire when we talk over a telephone. 2. If the valve in the cylinder moves easily, it should be replaced immediately. 3. When a ray of any kind strikes an atom, it may knock an electron out of the atom. 4. It is to be noted that ocean cables are one of the most dependable means of transmission yet designed. 5. It is impossible to increase the number of telephone channels on open-wire lines without applying carrier equipment.
Variant 4
Task 1. Translate the text:
MICROELECTRONICS
Our present age is characterized by its exponentially growing complexity — almost any statistical measure demonstrates such behavior. The densities of men and machines are higher, and yet we go farther and faster away from each other. As a result, population density, transportation speed, telecommunications volume, and information-processing volume are growing exponentially. There is no indication that this growth is turning over; hence, we may expect the complexity of our existence to increase still further. Man's attempt to cope with this increasing complexity has been more through electronics, through complex computers, transmission methods, and automation. It is becoming a marvelous extension of man's senses and mind. It provides the essential instruments man needs to cope with the staggering amount of information he must process to control his complex world.
Early large-scale systems were primarily extensions of smaller simpler systems. This led to a detailed specification of the elemental components by the user. Very often these statements of requirements without knowledge of the component development possibilities led to unforeseen compatibility and interconnection difficulties when the components were assembled into systems. The component designer has often developed components only in terms of his own specialized technology and without knowledge of their eventual system function and environment or their compatibility with other specialized components of the future system application.
In the past microminiaturization in electronics has been largely a practical enterprise guided by experience, however, now fundamental relations in this field are emerging. It should first be made clear what the term "microelectronics" implies, since the name appears in many forms — microminiaturization, integrated electronics, microsystems electronics, molecular electronics, etc., and since the term is in notarization, integrated electronics, microsystems electronics, molecular electronics, etc., and since the term is in itself somewhat misleading. Microelectronics surrounds the entire body of the electronic art which is connected with, or applied to, the realization of electronic circuits, subsystems, or the entire systems from extremely small electronic parts (devices).
Task 2. Make up a summary of the text.
Task 3. Fill in the blanks with the following words and word combinations:
hybrid circuitry, distinguished, integrated, performance, substrate, value, low cost, reliability, to cope with, practical enterprise, large-scale, thin-film
1. Man’s attempt ... this complexity has been more and more through electronics. 2. Early ... systems were primarily extensions of smaller systems. 3. In the past microminiaturization has been largely ... . 4. The techniques used should ultimately lead to ... high ... and improved ... . 5. Small size is of extreme ... . 6. Component parts are ... into one single circuit. 7. Separate ... performs the function of a mechanical support. 8. Component parts in functional circuit cannot be ... from one another. 9. Many ... circuits use individually attached active semiconductor devices. 10. These combinations of various approaches are commonly referred to as ... .
Task 4. Answer the following questions:
1. Why is telecommunication volume growing exponentially? 2. What does the term "microelectronics" mean? 3. What fact does the primary interest in microelectronics stem from? 4. What component parts are used to assemble micro miniature electronic circuits? 5. How many technologies are there for integrating component parts into one single circuit? 6. What approaches are commonly referred to as hybrid circuitry?
Task 5. Translate the following sentences paying attention to the use of Perfect Tenses:
1. By the end of the previous term the students had mastered the necessary lab techniques. 2. By the end of the year they will have settled all the problems and will begin their tests. 3. They have developed the new waterproof cable which will help to solve all the problems relating to telephone service failures since water cannot enter the space between insulated conductors. 4. He has already returned to Moscow. 5. I have known him since 1980.
Variant 5
Task 1. Translate the text:
The Primary Interest in Microelectronics.
The primary interest in microelectronics stems not from the fact that small size can be achieved, but from the much more important fact that the techniques used should ultimately lead to low cost, high reliability, and improved performance Small size is of extreme value in many applications, such as in space or in portable equipment. However, in the overwhelming number of applications, small size is of only secondary interest, while low cost, high reliability and improved performance are of great importance. Glossary contains microelectronic definitions for commonly used terms, for example, active device; active substrate; component; device; electrical element; hybrid integrated circuit; integrated circuit; magnetic integrated circuit; microsystems electronics; module; packaging; packaging density; passive substrate; semiconductor integrated circuit; subsystem; substrate; transistance; thin-film integrated circuit; etc.
Scaled-down separate component parts such as resistors, capacitors, inductors, diodes, transistors and other separate electronic parts with random or uniform form factors are used to assemble microminiature electronic circuits. Component parts are integrated into one single circuit. This approach has been developed along two major technologies.
In film circuits the component parts are evaporated, electroplated and a separate substrate performs only the function of a mechanical support. Usually the component parts are interconnected in the process of their fabrication. In semiconductor integrated circuits the semiconductor material is used to fabricate component parts within a single piece of semiconductor, which then becomes an entire circuit or part of a circuit.
A monolithic piece of material is treated in such a way as to possess an electronic circuit function. Unlike previous categories, component parts in functional circuit cannot be distinguished from one another, and the structure itself cannot be divided without its stated electronic function being destroyed. It should be noted that there can be many instances where the microelectronic circuit may combine more than one of these approaches in a single structure. For example, many thin-film circuits use individually attached active semiconductor devices, such as diodes and transistors. There are also circuits which combine the semiconductor integrated circuits with thin-film component parts. These and similar combinations of various approaches are commonly referred to as hybrid approaches or hybrid circuitry.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences paying attention to the forms of the Participle:
l. A component designer developing components tries to increase their reliability. 2. When assembling an integrated circuit different approaches may be utilized. 3. The communication network is expanding rapidly. 4. When insulated the wire may be used as a conductor. 5. The device produced was powerful. 6. Being constructed in a new way the device has high reliability. 7. Having obtained the necessary data he stopped his work. 8. Having been given the wrong address I could not find his house. 9. Data estimated were used in designing the new system. 10. The increasing importance of radio broadcasting has resulted in both greater power transmitters and more efficient antennae.
Task 4. Translate the sentences paying attention to the Absolute Participle Construction:
1. A simple component having failed, the whole cable system was repaired. 2. The conductor having the form of a oil, the inductance increased. 3. The semiconductor material being used to fabricate component parts within a single voce of semiconductor, the latter becomes an entire circuit: part of a circuit. 4. Microelectronics surrounds the entire steady of the electronics, the term itself appearing in many forms - microminiaturization, microsystems, etc. 5. The evaporation increases with the temperature, other things being equal. 6. Reduced weight and size are particularly important, miniaturization becoming the necessity in order to reach the sigh speed. 7. The effect is highly dependent upon frequency, the lower frequencies showing less noise. 8. The construction if a high-power radio system completed, we can send both telephone conversation and television over a long distance.
Task 5. Translate the following sentences:
1. I have never been to Navoi. 2. Have you
ever been to Samarqand? 3. The scientists of our laboratory had been carrying
out experiments with a new type of
insulating material for several years before they got positive results. 4. Our
engineers had been testing the new device for some months before it was put
into service. 5. By the end of the year they will have been carrying out field
trials with
a new teleprinter for several months. 6. They will have been carrying out this
work until they get the necessary data.
Control Work 3.
Variant 1
Task 1. Translate the text:
Semiconductor.
The term "semiconductor" is formed by the prefix "semi-" which means «ïîëó» and the word "conductor" — «ïðîâîäíèê».
Semiconductor is an electric conductor with resistivity in the range between metals and insulators, in which the electric charge-carrier concentration increases with the increasing temperature range. There are semiconductor integrated circuits. They are the physical realization of a number of electric elements connected with each other on or within a substrate to perform the function of a circuit.
An integrated circuit is fabricated upon or within the supporting material, which is called substrate. Sometimes an integrated circuit is attached to it. Such a substrate which may serve as a physical support and heat-exchanger to a thin-film integrated circuit and exhibits no transistance is a passive substrate. Examples of a passive substrate are glass, ceramic, and similar materials. A substrate may be active, when parts of it display transistance. Examples of active substrates are single crystals of semiconductor materials within which transistors and diodes are formed.
Task 2. Make up a summary of the text.
Task 3. Translate the
sentences paying attention to the function of the
Participle:
1. Controlling equipment is set up in planes and rockets. 2. The filters reducing large noise level are used in satellites communication systems of various kind. 3. Integrated circuitry are widely used nowadays. 4. The article published in the scientific magazine will be discussed. 5. Due to reduced size and weight microelectronics may be used to increase the speed of the equipment. 6. Having computed the data the operator used the results obtained. 7. Electronics is being used more and more throughout the industry. 8. When reading the article he made some notes. 9. The applied device was very efficient. 10. Achieving small size the component designer reduced the cost of the whole system. 11. Integrated into one more single circuit, component parts are evaporated or electroplated. 12. Electronic systems are spreading widely all over the world.
Task 4. Fill in the blanks with the following words and word combinations:
High-speed, temporary, average, heat dissipation, failure rate, cooling, diminishing return, failures, value
1. Frequently the ... of reduced size and weight is estimate considering size as a variable parameter. 2. The time .ring which this extra capacity may be used is the ... serve life of such vehicles. 3. In ... logical circuits’ miniaturization of the circuits is desirable. 4. The problem of making. fill interconnections is no less difficult, particularly if disconnections are required. 5. One of the most difficult
problems in microelectronics is .... 6. The miniaturization the system to a size below that of its heat exchange is ... 7. Considerable attention must be given to ... One of the most important considerations in the design
integrated circuits is component ... in fabrication. 9. A very reliable device with low ... in use may be very difficult ... fabricate.
Task 5. Translate the following definitions and memorize the terms:
Cable. A transmission line or a group of transmission lines mechanically assembled into a complex flexible form.
Code. A plan for representing each of a finite number of symbols as a particular arrangement or sequence of discrete conditions.
Communication. The transmission of information from one point to another by means of electromagnetic waves.
Variant 2
Task 1. Translate the text:
Microelectronics.
It should first be made clear what the term "microelectronics" implies. Microelectronics embraces the entire body of the electronic art which is connected with, or applied to, the realization of I electronic circuits, subsystems, or the entire systems from extremely small electronic devices. The terms "microelectronics" and "integrated circuits" are sometimes used interchangeably, but j this is not correct.
Microelectronics is a name for extremely small electronic 1 components and circuit assemblies, made by thin-film, thick-film I or semiconductor techniques.
An integrated circuit (1C) is a special kind of microelectronics. It is a circuit that has been fabricated as an inseparable assembly of electronic elements in a single structure. It cannot be divided without destroying its intended electronic function. Thus, ICs come under the general category of microelectronics, but all microelectronic units are not necessarily ICs.
Task 2. Make up a summary of the text.
Task 3. Translate the following sentences:
1. With the invention of the transistor all essential circuit] functions could be carried out inside solid bodies. 2. Plasma etching results in large increase in etch rate. 3. The process is a chemical vapour reaction conducted under reduced pressure conditions. 4. The electrical resistance of a metal wire is a disruption of the orderly movement of electrons by interactions with the atomic structure of the material.
Task 4. Translate the text and explain: a) electronic industry; b) films.
Even before the invention of the transistor the electronics industry had studied the properties of thin films of metallic and insulating materials. Such films range in thickness from a fraction of a micron, or less than a wavelength of light, to several microns. (A micron is a millionth of a meter; the wavelength of red light is about 7 micron.)
Task 5. Translate the text and explain: a) resistor; b) zigzag pattern; c)capacitance.
A typical thin-film resistor consists of a fine metal line only a few thousandths of an inch wide and long enough to provide the desired value of resistance. If high precision is required laser trimming is used. If high values are desired, the line can be laid down in a zigzag pattern. To form a capacitance one can lay down a thin film of insulating material between two thin films of metal.
Variant 3
Task 1. Translate the text:
Integrated Electronics
Integrated electronics is a field so new and so fast changing I that many interested people have difficulty keeping up with its day-to-day developments. There is even some confusion concerning what integrated electronics is and what its significance is for the development of science and technology.
The essence of integrated electronics is batch (ïàðòèÿ; ãðóïïà) processing. Instead of making, protecting, testing and assembling individual (or discrete) components one at a time, large groupings of these components together with their interconnections are made now, all at a time. The resulting new entity, or "integrated component", therefore, is an assemblage of old-style components interconnected into circuits, networks, or even subsystems. Hence, for a given system functions the number of separate components have been greatly reduced, while system capability has been greatly increased.
Integrated electronics will develop further. First, the efforts are being made to get more and more circuit functions on slice of silicon which means cramming (ðàçìåùåíèå) even more circuit elements into still smaller areas. Second, integrated electronics will move not only towards more functions per slice, but toward new types of functions.
Task 2. Make up a summary of the text.
Task 3. Answer the questions:
1. What were the most important facts for the development of electronics? microelectronics? 2. Why could not early transistors satisfy the needs of the growing high-speed computers industry and microwave communication systems? 3. What is the major difference between electronic systems and microelectronic devices?
Task 4. Answer the questions:
1. What would you say about the steady reduction of 1C feature sizes? 2. What has allowed the integration of more and more devices on the same chip? 3. What does higher integration level , allow? 4. What are the dominant factors limiting device performance? 5. What limits the design of any machine? 6. Who has made a great contribution to the study of semiconductor physics? 7. What would you say about polycrystalline materials? 8. What is essential foundation for semiconductor products?
Task 5. Read the text. What have you known about silicon, active and passive elements?
1. far from being —äàëåêî îò; 2. at all —âîîáùå; 3. abundance — ìíîæåñòâî
All the components of the circuit must be fabricated in a crystal of silicon or on the surface of the crystal. Silicon is far from being ideal material for these functions and only modest values of resistance and capacitance can be achieved. Practical microelectronic inductors cannot be formed at all. On the other hand, silicon is a material without equal for the fabrication of transistors, and the abundance of these active components in microelectronic devices more than compensates for the shortcomings of the passive elements.
Variant 4
Task 1. Translate the text:
Semiconductor
A semiconductor is a material having a resistivity in the range between conductors and insulators and having a negative temperature coefficient. The conductivity increases not only with temperature but is also affected very considerably by the presence of impurities in the crystal lattice.
Types of semiconductor material commonly used are elements falling into group IV of the Periodic Table, such as silicon or germanium. The donor and acceptor impurities are group V and group III elements, respectively, differing in valency by only one electron.
Certain compounds such as gallium arsenide (Symbol: GaAs) which has a total of eight valence electrons, also make excellent semiconductors. GaAs is a direct-gap Ø-V semiconductor that has a relatively band gap and high carrier mobility. The relatively high carrier mobility allows the semiconductor to be used for high-speed and because of the large energy gap it has a high resistivity that allows easier isolation between different areas of the crystal The conduction band is a two-state conduction band; some electrons therefore are "hot" electrons, i.e. they have small effective mass and higher velocity, this resulting in the Gunn effect.
GaAs is difficult to work since diffusion of impurities into the material is extremely difficult. Epitaxy or ion implantation must therefore be used to produce areas of different conductivity type. The main uses for gallium arsenide have been as microwave de vices, such as Gunn diodes or IMPATT diodes, but lately it has been used as a MESFET (a GaAs junction field-effect transistor) for high speed logic circuits.
Task 2. Make up a summary of the text.
Task 3. Fill in the blanks with the following words and word combinations:
high-speed, temporary, average, heat dissipation, failure rate, cooling, diminishing return, failures, value
1. Frequently the ... of reduced size and weight is estimate considering size as a variable parameter. 2. The time ring which this extra capacity may be used is the ... serve life of such vehicles. 3. In ... logical circuits miniaturization of the circuits is desirable. 4. The problem of making ill interconnections is no less difficult, particularly if disconnections are required. 5. One of the most difficult problems in microelectronics is .... 6. The miniaturization the system to a size below that of its heat exchange is ... . 7. Considerable attention must be given to ... . One of the most important considerations in the design integrated circuits is component ... in fabrication. 9. A very reliable device with low ... in use may be very difficult. fabricate.
Task 4. Translate the following sentences paying attention to the non-finite forms of the verbs:
1. Heat exchangers and cooling power transistors should be taken into consideration when designing powerful „amplifiers of nowadays. 2. As a rule there is one simple on-and-off relay to be used for handling a unit information situation. The Bell System insisted on designing an experimental laser communication system for transmitting and receiving television signals. 4. The increasing demand for high-quality long-distance communication systems has resulted in the development of reliable radio equipment. 5. Special attention has to be paid to the quality of measuring instruments intended for satellites. 6. The new post-office-designed equipment for measuring signal attention in cables is being introduced in Great Britain. 7. To go hand in hand with the increased demand in communication services, communication equipment should be radically revised.
Task 5. Answer the question.
1. How is a key used to send an electrical impulse though a circuit? 2. What is an “earth return”? 3. How can the circuit be closed? 4. Why could the Morse code be transmitted more quickly by “double current working” than by “single current working”? 5. Which sing takes the longest to transmit by the Morse code? 6. How is a teleprinter used to receive a message started?
Variant 5
Task 1.Translate the text.
Microelectronics in Data-Processing
In many computer systems today a number of processors are connected together to form a distributed-processing network. Most commonly the network consists of a number of minicomputers, but mainframe computers and microcomputers can also be incorporated into it. Input-output ports and data-transmission hardware are considered an active part of the network only if they are able to process information. Parts of a task are distributed among the elements of the network. Each element works independently for some period of time, communicating as necessary with other elements.
Distributed-processing systems can be organized in several ways. A large distributed-processing system can be organized into a hierarchical structure. At the top of the hierarchy is a single mainframe computer that communicates with processors in the network at a secondary level, which in turn can communicate with other processors on a tertiary level and so on; In a pure hierarchy the processors on any particular level cannot communicate directly with one another. Instead communications must be routed through the next higher level.
Alternatively a distributed-processing system can be organized into a peer structure. All the computers are on the same level and communicate with one another on an equal footing. Except for very small networks, however, it seldom happens that every element in the network can communicate with every other element. Instead the hierarchical structure and peer structure can be combined into a hybrid system in which the processors on a particular level can communicate with one another and with processors on the next higher level.
Task 2. Make up a summary of the text.
Task 3.Translate paying attention to the Modal verbs:
1. Before discussing the patterns themselves it is necessary examine factors which are likely to interfere with the results. 2. In order to shorten the time required to perform instructions, it to is desirable to perform as many operations as possible in parallel 3. Provision is made to complete computers for all initial boundary conditions to be applied. 4. Human needs and conventions have to be identified first and then converted to programs in the best possible way. 5. Sometimes the microcomputer system is to be used as a general purpose computer. 6. Engineers must deal with the evolution of the existing systems as well as the design of new systems. 7. Properly designed information systems might be viewed as black boxes. 8. The computer has made it possible to mechanize much of the information interchange and processing that constitute the nervous system of our society. 9. Architectures should provide adequate flexibility to support the growing trend to distributed systems. 10. Information systems grow and new ones are continuously added. The architecture must support such growth.
Task 4. Answer the questions:
1. What is the function of the microprocessor? 2. What are the advantages of microcomputers in comparison with random-logic design? 3. What technology made the smaller size and lower cost of electronic devices possible? 4. What are the main factors resulting in greater cost savings of electronic devices? 5. What limits the numeric range of data the processor can handle? 6. What features of microprocessors are to be considered when dealing with their applications?
Task 5.Translate the following sentences:
1. The relationship must be set properly. 2. Industrial research in materials faces a different set of problems. 3. The microprocessor has a sophisticated instrument set. 4. This interface sets board dimensions. 5. Computing time was a little more than five times longer than that required for a single iteration of the gradient procedure.6.The problem of timing is very important as information is being read into and out of the flip-flops at the same time. 7. The complete photo resist process must be repeated each time the silicon oxide is selectively removed. 8. Although improvements will reduce the required computation times, emulation will nevertheless be restricted to real time systems having slow response times.
Control Work 4.
Variant 1
Task 1.Translate the text:
MICROPROCESSORS: A BRAIN TO THE HARDWARE
(Part 1)
The microprocessor forms the heart of a microcomputer.
The first microprocessors were developed in 1971 as an offshoot of pocket calculator development. Since then there has been a tremendous upsurge of work in this field and some years later there appeared dozens of different microprocessors commercially available.
The age of the microprocessor is not great. Yet, we have seen the evolution of the microprocessor as it progressed from early applications in simple hand-held calculators through 4- and 8-bit controller applications towards more sophisticated processing operations.
Microprocessors are used primarily to replace or upgrade random logic design.
By taking advantage of the knowledge and concepts gained in mainframe and minicomputer applications better and more sophisticated microprocessors are beginning to emerge. What we see are: larger and denser chips; higher resolution; higher speed; specially designed RAMs (random access memory) and ROMs (read-only memory); specially designed I/O and peripheral interface circuits; on-chips clock and timing circuits; more extensive and more powerful instruction sets and lower power dissipation.
With the enormous efforts now directed to MPs, performance will improve rapidly. A far larger number of bits (higher resolution), higher speeds, more extensive and more powerful instruction sets, and elimination of non-LSI components have come. In addition, software for these machine would also evolve into more standardized forms.
Microprocessors are now appearing in many types of equipment and their field of application will inevitably widen.
Since these devices are likely to be used by the million in the near future, it is reasonable to ask what a microprocessor is, how it can be used and what its future impact will be.
As mentioned before computer actually refers to a computing system including hardware (processor, I/O circuits, power supplies, control panel, etc.) and software (instruction manual, user's manual, assembler, and diagnostic and service routines). Processor is known to refer to the processing circuits: central processing unit, memory, interrupt unit, clock, and timing. Most processors also include computer software.
Task 2. Make up a summary of the text.
Task 3. Answer the questions.
1. What is a microprocessor? 2. When was the first microprocessor developed? 3. What are the advantages of microprocessors hi comparison with random-logic design? 4. What does a typical microprocessor consist of? 5. What are the current trends in the development of microprocessors? 6. What is programmability? 7. Why is the integration of more functions on a chip important?
Task 4. Translate the sentences:
1. Before discussing the patterns themselves it is necessary to examine factors which are likely to interfere with the results. 2. In order to shorten the time required to perform instructions, it is desirable to perform as many operations as possible in parallel 3. Provision is made to complete computers for all initial boundary conditions to be applied. 4. Human needs and conventions have to be identified first and then converted to programs in the best possible way.
Task 5. Answer the questions:
1.What kind of current is mostly used in telegraphy nowadays? 2. What is the highest frequency to transmit messages by alternating current? 3. Why was it necessary to increase the number of messages that could be sent along one telegraph line? 4. Why are machines now used instead of human operators to transmit and receive telegraph messages?
Variant 2
Task 1. Translate the text:
MICROPROCESSORS: A BRAIN TO THE HARDWARE
(Part 2)
Central processing unit (CPU)-heart of the processor — consists of the register array, arithmetic and logic unit, control unit (including micro-ROM), and bus control circuits. Micro software may also include: microinstruction manual, micro assembler, etc.
Mini — has been used with computers and refers to the systems having mainframe only, no peripherals.
Micro-can refer to computers, processors, or processing units. Smaller size and lower cost are usually obtained through use of LSI circuits.
Monolithic — generally implies a single block or chip of silicon. A monolithic CPU is therefore a single-chip CPU, produced with LSI techniques. The term monolithic processor eliminates the need to differentiate between mini and micro. The acronym MP can represent either micro of monolithic processor.
Any processing unit has a logic and a control unit. Broadly speaking, a control system can be defined as an element or series of elements that implement the transformation of a physical input excitation into a corresponding physical output response in some deterministic manner. The logic element is an integral part of any control system. The logic element is known to be the basic component of all computers. A great deal of effort has been directed towards reducing the size of the basic logic element.
The very first microprocessors were fabricated using PMOS technology. These were, however, relatively slow devices principally because "holes" in the p-type material have a low mobility. Later, improved technology permitted microprocessors to be constructed using n-type MOS and these microprocessors are almost as fast as normal minicomputers with speeds of three or four microseconds per instruction. Some microprocessors are now made using CMOS. The speed and logic density of CMOS are inferior to n-type MOS but the process does have some significant advantages. First of all, it has a low power consumption since power is only consumed when a logic element changes a state. Secondly, it can operate over a wide voltage range. As a result, electronics based on CMOS can operate successfully with "noisy" power supplies and the low consumption makes it quite feasible to use a simple battery to maintain the security of supply for several weeks. This type of microprocessor has clear advantages over the other types if it is intended for use in exacting or inaccessible environments. Further development should improve the logic density of CMOS and it is likely to become a dominant technology in the microprocessor field.
Task 2.Make up a summary of the text.
Task 3.Translate the sentences:
1. Sometimes the microcomputer system is to be used as a general purpose computer. 2. Engineers must deal with the evolution of the existing systems as well as the design of new systems. 3. Properly designed information systems might be viewed as black boxes. 4. The computer has made it possible to mechanize much of the information interchange and processing that constitute the nervous system of our society. 5. Architectures should provide adequate flexibility to support the growing trend to distributed systems. 6. Information systems grow and new ones are continuously added. The architecture must support such growth.
Task 4. Answer the questions:
1. What is the function of the microprocessor? 2. What are the advantages of microcomputers in comparison with random-logic design? 3. What technology made the smaller size and lower cost of electronic devices possible? 4. What are the main factors resulting in greater cost savings of electronic devices? 5. What limits the numeric range of data the processor can handle? 6. What features of microprocessors are to be considered when dealing with their applications?
Task 5. Translate the sentences:
1. The impact of micros on the big machines, especially large centralized computer systems, is that large systems will decline in number but increase in power. 2. Designers of mini-micro systems are becoming aware of their background limitations. The digital designers are finding that software is an indispensable tool, and the programmers are learning that lack of knowledge in electronics may be disastrous to successful project realization
Variant 3.
Task 1. Translate the text:
MICROPROCESSORS: A BRAIN TO THE HARDWARE
(Part 3)
The only cloud on the CMOS horizon comes from a new development of the normal bipolar circuit. A new semiconductor configuration called integrated injection logic (IIL) has been devised which eliminates the need for any resistors, capacitors or transistor isolation. This enables an extremely compact logic circuit to be formed which has a low power consumption while maintaining the normal speed of transistor-transistor logic (TTL).
The bulk of present-day microprocessor and memory logic is implemented using PMOS and NMOS processes, since these processes are now well developed and offer good logic density. In the future IIL and CMOS are likely to become the most popular types, and the general trends in technology indicate that lower power consumption, higher speeds and improved logic densities can be confidently anticipated?
The key features to consider in any microprocessor are: word length; architecture; speed; programming flexibility, etc. Word length should be the first feature to consider. The processor handles binary data in the form of "words". A word is a set of binary bits which is used to represent a binary number within the computer. It is the number of bits in the computer "word" which units the numerical range of the data that the processor can handle. Microprocessors are structured for fixed word length or for modular expansion by a parallel combination of building-block chips.
The versatility of the microprocessor has altered the entire architecture of modern computer systems. No longer is the processing of information carried out only in the computer's central processing unit. Today there is a trend towards distributing more processing capability throughout a computer system, with various areas. For example, an input-output port may have a controller to regulate the flow of information through it. At times the controller may accept commands from the CPU and send signals back in order to coordinate its operations with those of the rest of the system; at other times the controller may operate independently of the CPU.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences:
1. The system ran in continuous operation for several months. 2. The problem is now ready for running. 3. The value of variable/ is computed at run time. 4. A factory can run non-stop. 5. Many new projects are being run. 6. This paper will explain the background and principles needed to select and apply microprocessors and microcomputers. 7. Some readers have no background in digital electronics. 8. Tradeoffs versus other logic solutions must be considered more carefully than ever before.
Task 4. Answer the questions:
1. In what way can electronic brain be compared with human brain? 2. What is a micro? How is it used? Is it merely a cheap replacement for a conventional computer? 3. What problems does the advent of the micro pose? 4. What do we mean by the "machine communication barrier"?
Task 5. Translate the sentences:
1. The concept of distributed computing is spurred by the inexpensive availability of minis and micros. 2. The mind boggles at the concepts microcomputers permit designers to realize. 3. The potential for microcomputer applications has already out stepped even the most inventive minds. 4. One-chip computers rival the power of the digital computers.
Variant 4.
Task 1. Translate the text:
MICROPROCESSORS: A BRAIN TO THE HARDWARE
(Part 4)
Distributing micro processing is a technique in which the main microprocessor of the PC directs other microprocessors throughout the PC system to perform specific functions for it and report their status.
New forms of I/O are also acquiring sophisticated capabilities with distributed micro processing. These "intelligent" I/O modules perform some of the calculations formerly done by the main microprocessor, store information temporarily, and do other functions under the direction of the main microprocessor.
Some remote I/O modules have microprocessors resident in the modules. Remote I/O modules use the resident micro processors to shorten the effective scan time. However, with independent intelligence in the I/O, if something happens to the PC, the I/O module might already have acted on misinformation. Hence, I/O modules with a resident microprocessor should include appropriate instructions for fail-safe shutdown should the PC develop a fault.
A trend that is beginning to emerge in microprocessor design is the incorporation of troubleshooting aids heretofore (äî ñèõ ïîð) available only on larger computers.
Provisions can and are being made in the architecture. Whereas early developments were concerned with implementation of simple architectures with fundamental concepts and operations, the technology has now advanced to the point where significantly more sophisticated hardware can be (and is being) implemented in current and future microprocessor generations. For example, some relatively new functions available in today's PC's may include: Moving blocks of data from memory location to memory location or from I/O location to memory location with a single instruction; Matrix operations such as logical AND and logical OR for comparing on/off bit patterns; Expanded mathematical abilities. Most PCs have double precision arithmetic.
The ease or difficulty with which each element can communicate with another will affect how much the data are manipulated before they are transmitted through the network. The major obstacle to designing an effective distributed-processing system is the difficulty involved in writing the system's software, which must enable the various elements of the network to operate and interact efficiently.
There is a crucial need for easy methods of documenting programs and changes made to them.
Task 2. Make up a summary of the text:
Task 3. Translate the sentences:
1. The design effort necessary for assembling several dice \vithin the same package was more easily and earlier achieved than the integration of several discrete components onto a single die. 2. Being quite different from vacuum tubes and transistors, masers operate entirely on quantum principles. 4. Using the same mask-making programs and machines as for silicon, we use photolithography to define the topology of resistors, capacitors and interconnections.
Task 4. Answer the questions:
1. What steps can be taken to overcome the barrier? 2. What are the disadvantages of the high-level languages? 3. What are the main features' of information systems? 4. What changes does the world of personal computers bring about?
Task 5. Translate the sentences:
1. In order to shorten the time required to perform instructions, it is desirable to perform as many operations as possible in parallel. 2. To be more economically competitive, more and more systems will incorporate micros. 3. By fabricating dozens of transistors together on a single small silicon chip, using the same fabrication techniques used for single isolated transistors, a whole flip-flop could be integrated. 4. Viewed from the outer space the most striking feature of the Earth is the large expanse of water.
Variant 5.
Task 1. Translate the text:
MICROPROCESSORS: A BRAIN TO THE HARDWARE
(Part 5)
Programmability —that flexible feature not found in random-logic designs — can be obtained in microprocessors on one of two levels. A very detailed level of control is provided at the micro-instruction level. These micro-instructions may be used to obtain a macro, or machine-language, instruction set, which is then used to write control programs for microprocessor. New machine-language instructions may be defined by coding new micro routines. In this way an instruction set can be tailored to an application. Control programs can also be written in microcode. This provides increased execution speed and more detailed control at the expense of more difficult programming. Microprocessors that are not micro programmable contain fixed, general-purpose instruction sets, that are often adequate for most applications.
Users have long felt a need to have a means of automatically adding comments and explanations to a hard copy of user program. With the high-level language's code format and programming capabilities, this need is reaching a critical point.
The use of microprocessors makes systems easier operate and maintain. Microprocessors provide greater application flexibility. Today microprocessors are designed with communications in mind so it is possible to link these processors together in a network. It is attractive for a number of reasons.
We can look forward to even more sophisticated system functions including digital to analog conversion and vice versa, more arithmetic capability such as matrix inversion, etc., and massive amounts of memory.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences:
A computer is nothing more than a collection of circuits that do a few simple tasks, one at a time. The key is the speed at which these circuits operate and signals that control the flow of electricity through the circuits.
So, how about a tour hi the computer jungle? We start with a look at the hardware itself. The part that looks like a small television set is called a video display or CRT for cathode ray tube or simply the tube. It actually is a lot like a television set in that it may display several colors or just one.
Next is the keyboard which allows the user to communicate with the computer. It is important that the keys be comfortable.
The last major piece of hardware is the processor and disc storage unit or units. This may be one box or several different boxes.
Task 4. Answer the questions:
1. What is the (computer) like? 2. What is the (computer) used for? 3. What does the (computer) do in (commerce)? 4. What do you know about the (central processing unit)?
Task 5. Explain this words and word combinations:
1. insulator; 2. conductor; 3. semiconductor; 4. doping; 5. do pant; 6. hole; 7. deficiency, 8. a silicon wafer; 9. mask; 10. n-type semiconductor; 11. thermal oxidation; 12. deposition; 13. sputtering
Control Work 5.
Variant 1
Task 1. Translate the text:
The Heart of the Computer
The processor is the "brains" of the computer, the location of those fantastically small circuits. Think of it as an overworked adding machine that also can make simple logic decisions.
It can decide that two numbers are equal or not equal, that a certain condition does or does not exist in the circuitry. It can decide that things are true or false based on rules the programmer supplies to make that decision. This, combined with the ability to add and subtract at lightning-fast speeds and store the results of these processes, allows the programmer to give step-by-step instructions to be carried out on command.
Although the idea of an automatic computing engine occurred first to Charles Babbage in 1832, it was more than a century later, in 1945, that John von Neumann set out the principles that were to fix the pattern of computer design for the next twenty years. We are now operating third and fourth generation computers, and looking ahead to the fifth, but these are generations marked by evolutionary changes in component technology rather than by revolutionary new concepts. Most of today's computers follow the von Neumann model, and probably many of tomorrow's will do so also. In particular, they have a rather rigidly organized store, holding both instructions and data; and, although some overlap of operations occurs, in general they tiptoe through their programs in ministeps. There can be no doubt that computers of this kind are powerful, versatile tools; but it would be surprising indeed if one type of machine were to prove equally suitable for all types of problems; and it may be that some problems of practical interest to us are too difficult, or too expensive, to solve on von Neumann machines.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences:
1. The numerical value-of the conductivity changes due to the concentration of impurities. 2. The significance a semiconductor achieved is due to the electrons being raised to the conduction band. 3. Current due to holes injected into the collector from the base can be neglected since it is very small. 4. New design tools and development systems are appearing. 5. The limiting point appears to be between 10 and 30 Ohms. 6. Recent technological ÷ / advances in software development are now opening new horizons. 7. The advances made by device fabrication have allowed all functions to be integrated onto just one chip.
Task 4. Answer the questions:
1. What is the origin of the word computer! 2. What were the first computers intended for? 3. What kind of a machine is the computer? 4. Why has man made extensive use of the computer? 5. What are the similarities of the computer with human brain? 6. What does the computer do in science, in commerce, in industry and in government? 7. Why do we widely use the computer in ë spite of its high cost?
Task 5. Explain this words and word combinations:
1. in addition, besides; 2. hence, thus, therefore; 3. however, yet, nevertheless; 4. further, then, now, 5. consequently, as a result; 6. similarly, in the same way, 7. to sum up, in conclusion
Variant 2
Task 1. Translate the text.
Personal Computer
The first personal computer (PC) was put on the market in 1975.
Today the personal computer can serve as a work station for the individual. Moreover, just as it has become financially feasible to provide a computer for the individual worker, so also technical developments have made the interface between man and machine increasingly "friendly", so that a wide array of computer functions are now accessible to people with no technical background.
A personal computer is a small computer based on a microprocessor; it is a microcomputer. Not all microcomputers, however, are personal computers. A microcomputer can be dedicated to a single task such as controlling a machine tool or metering the injection of fuel into an automobile engine; it can be a word processor, a video game or a "pocket computer" that is not quite a computer. A personal computer is something different: a standalone computer that puts a wide array of capabilities at the disposal of an individual.
The first generation of true personal computers, which came on the market between 1977 and 1981, had eight-bit microprocessors; the most recently introduced systems have 16-bit ones. Now 32-bit microprocessor chips are available, and soon they will be included in complete computer systems. As for clock frequency, the trend has been from one megahertz (one million cycles per second) a few years ago to 10 megahertz or more today.
Task 2. Make up a summary of the text.
Task 3. Complete the sentences using this word combinations:
1. The pattern is influenced (was influenced, has been influenced, has to be influenced, is to be influenced); 2. The experiment was followed (has been followed) by; 3. the packing is watched (is being watched, has been watched, will be watched)
Task 4.Translate the sentences:
1. We are still learning how to exploit the potential of the integrated circuits. 2. Small and reliable sensing and control devices are the essential elements in complex systems. 3. The attempts to miniaturize electronic components are largely successful. 4. Testing is needed in the course of production. 5. The most striking characteristic of the microelectronics industry has been a rapid decline in cost. 6. Electronics has extended man's intellectual power. 7. Several kinds of microelectronic transistors have been developed, and for each of them families of associated circuit elements and circuit patterns have evolved. 8. The fundamental units of electronic logic circuits are called gates.
Task 5.Answer the questions:
1. What is a storage device? 2. What are the most important characteristics of memory? 3. What were the fist electronic memories like? 4.What were their drawbacks? 5. What are the advantages of semiconductor memories? 6. What new memory technologies emerged in the 2002’s? 7. What are research laboratories aimed at? 8. What is expected of a new generation of super fast computers?
Variant 2.
Task1.Translate the text.
Database Systems
Database systems were born and have evolved as an application technology due to the necessity for managing the large amount of data produced in the real world. However, it was soon recognized that the emergence of the, technology is one of the most significant features of transition in computer application from data processing to information processing and further to knowledge processing. The problem so far has been involving various topics: data models, database languages and query (çàïðîñ) processing, database design, database system design, file organization, database system evaluation, integrity, database machine, distributed database system, high level database applications and so on.
Database systems were the means by which computer technology began to make effective and systematic use of a permanent store, which has been an important feature of information processing capability belonging only to human beings. In this sense, the emergence of database technology is probably a revolutionary development in the world of information processing by computers. It made computers more like human beings than ever and offered us a chance to reconsider the information processing by computers in comparison with that of the human beings. It is expected that analyzing the problem solving process and creative activity by man will serve us in designing future information processing systems.
Knowledge representation has also become a crucial issue in the field of artificial intelligence. In fact, whichever system we consider, how to represent knowledge and then utilize it on a computer is a key problem for the realization of advanced information system such as natural language processing, image or speech understanding, machine vision, intelligent information retrieval, and intelligent man-machine communication.
Task 2. Make up a summary of the text.
Task 3. Translate these sentences:
1. Before discussing the patterns themselves it is necessary to examine factors which are likely to interfere with the results. 2. In order to shorten the time required to perform instructions, it is desirable to perform as many operations as possible in parallel 3. Provision is made to complete computers for all initial boundary conditions to be applied. 4. Human needs and conventions have to be identified first and then converted to programs in the best possible way. 5. Sometimes the microcomputer system is to be used as a general purpose computer.
Task 4. Answer the questions:
1. What is the function of the microprocessor? 2. What are the advantages of microcomputers in comparison with random-logic design? 3. What technology made the smaller size and lower cost of electronic devices possible? 4. What are the main factors resulting in greater cost savings of electronic devices? 5. What limits the numeric range of data the processor can handle? 6. What features of microprocessors are to be considered when dealing with their applications?
Task 5. Translate these sentences:
1. Engineers must deal with the evolution of the existing systems as well as the design of new systems. 2. Properly designed information systems might be viewed as black boxes. 3. The computer has made it possible to mechanize much of the information interchange and processing that constitute the nervous system of our society. 4. Architectures should provide adequate flexibility to support the growing trend to distributed systems. 5. Information systems grow and new ones are continuously added. The architecture must support such growth.
Variant 3.
Task 1. Translate the text:
Microelectronics in Data-Processing
In many computer systems today a number of processors are connected together to form a distributed-processing network. Most commonly the network consists of a number of minicomputers, but mainframe computers and microcomputers can also be incorporated into it. Input-output ports and data-transmission hardware are considered an active part of the network only if they are able to process information. Parts of a task are distributed among the elements of the network. Each element works independently for some period of time, communicating as necessary with other elements.
Distributed-processing systems can be organized in several ways. A large distributed-processing system can be organized into a hierarchical structure. At the top of the hierarchy is a single mainframe computer that communicates with processors in the network at a secondary level, which in turn can communicate with other processors on a tertiary level and so on. In a pure hierarchy the processors on any particular level cannot communicate directly with one another. Instead communications must be routed through the next higher level.
Alternatively a distributed-processing system can be organized into a peer structure. All the computers are on the same level and communicate with one another on an equal footing. Except for very small networks, however, it seldom happens that every element in the network can communicate with every other element. Instead the hierarchical structure and peer structure can be combined into a hybrid system in which the processors on a particular level can communicate with one another and with processors on the next higher level.
Task 2. Make up a summary of the text.
Task 3. Translate these sentences:
Microprocessors were the first step toward the introduction of logic devices and it will be possible within a few years for a current large-size processor with about one hundred thousand gates to be produced on a single chip by way of VLSI technology. Such a possibility will undermine conventional computer technology which has advanced via (ïîñðåäñòâîì) the effective utilization of simple logic (circuits) serving as a central standard for evaluation. Stated otherwise, a technological foundation is in the process of being matured which will allow computers totally different from those existing today, something similar to artificial brains, to appear.
On the one hand, individuals will be able to have personal computers which are comparable in functions and performance with present day large-size computers and, on the other hand, by revaluating package systems of various functions which have thus far been considered impractical new computers having advanced functions and performance will make possible the opening of new fields of applications.
Task 4. Answer the questions:
1. What can you tell about software. 2.What are most important characteristics of memory? 3. What do you know about different types of memories? What do you know about analogue and digital recording? 5.Can you compare random access memories and serial access memories? 6. What developments can be expected by the end of the century in the field of computer memories?&. What is being done at present to improve memory capacity and speed?
Task 5. Explain this sentences:
1.The application of microprocessors into control systems, particularly for vehicles.
2. The application into manufacturing systems and the means of productions, which may include instruments as well as control devices.
3.The inclusion of microprocessors in the consumer goods to be produced.
Variant 4
Task 1. Translate the text.
Microprocessor
A microprocessor is a tool that deals with memories by reading and writing process. At first sight it is all it can actually do.
One can consider that it is surprising how a computer can answer a question only by dealing with Î and 1 but the fact is that it works.
Only human brain can teach a computer how to 'listen" to a question and "elaborate" an answer only by dealing with Î and 1. A microprocessor is the next step, dealing with memories in complete "traditional" 8 bit bytes.
So the microprocessor is addressing a memory, a location inside the selected memory, and then achieves a read or write operation.
Additional tools have been designed to allow exchanges with external memories or devices.
First of all an address bus, for instance 16 bits allowing a se-X/lection of 1 word among 65.000, Then comes the data bus, generally 8 bits allowing read or write operation in the selected location of the memory. At last comes the control bus, for instance including memory read or write and I/O read or write, giving 4 wires the indication of the type exchange and the position of the receiver, inside or outside the system.
Present microprocessors vary in their detailed architecture depending on their manufacture and in some cases on the particular semiconductor technology adopted. One of the major distinctions is whether all the elements of the microprocessor are divided among several identical modular chips that can be linked in parallel, the total number of chips depending on the length of the “word" the user wants to process: four bits (binary digits), eight bits,'16 bits or more. Such a multichip arrangement is known as a bit-sliced organization. A feature of bit-sliced chips made by the bipolar technology is that they are "microprogrammable": they al low the user to create specific sets of instructions, a definite advantage for many applications.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences:
1. The architectural research and development efforts are directed at integrated circuits, computer architecture, operating systems, and programming languages.
2. Integrated circuit researchers are examining complementary metal-oxide semiconductor (CMOS) design styles, the effects of scaling very large scale integration (VLSI) circuits and control and clocking issues. 3. Computer architecture researchers are studying multiprocessor address trace analysis, cache consistency, virtually-tagged caches, in-cache address translation, multi-level cache design, coprocessor interfaces, instruction delivery, hardware support, and floating-point implementations. 4. Operating system researchers are investigating network file systems, network page servers, the effects of large physical memories on virtual memory implementations, and workload distribution. 5. Programming language researchers are examining parallel garbage collection algorithms, techniques for specifying parallel programs, and methods of compiling parallel Lisp programs.
Task 4. Complete sentences using following words combination:
the memory capacity is spectacular; to store information; regardless of the advances; to feed information through the input-output ports; the instructions are retrieved on command; to fill an entire space; to depend entirely on gap; to issue commands
Task 5.Answer the questions:
1.What is a storage device? 2. What are the most important characteristics of memory? 3. What were the first electronic memories like? 4. What were their drawbacks? 5. What new memory technologies emerged in the 2002’s? 6. What are the advantages of semiconductor memories? 7.What are research laboratories aimed at? 8. What is expected of a new generation of super fast computers?
Task 5. Complete sentences using following words combination:
to read information from the memory; to affect the instrument readings; to interpret the commands; to mount substrates; to mount 1C on a single printed card; to need a flexible processing system; the flexible processing system; the flexibility of the procedure; to execute computing operations; to execute a task; to implement sputtering, to implement a substitution; to incorporate many components
Variant 5.
Task 1 Translate the text.
Software
The chips and other electronic elements and the various peripheral devices constitutes the computer's hardware. The hard- / ware can do nothing by itself; it requires the array of programs, or instructions, collectively called software. The core of the software is an “operating system” that controls the computer’s operations and manages the flow of information.
The operating system mediates between the machine and the human operator and between the machine and an “application” program that enables the computer to perform a specific task.
To understand the kind of tasks done by the operating system, consider the sequence of steps that must be taken to transfer a file of data from the primary memory to disk storage. It is first necessary to make certain there is enough space available on the disk to hold the entire file. Other files might have to be deleted in order to assemble enough continuous blank sectors. For the transfer itself sequential portions of the file must be called up from the primary memory and combined with “housekeeping” information to from a block of data that will exactly fill a sector. Each block must be assigned a sector address and transmitted to the disk. Numbers called checksums that allow errors in storage or transmission to be detected and sometimes corrected must be calculated. Finally, some record must be kept of where the file of information has been stored.
If all these tasks had to be done under the direct supervision of the user, the storage of information in a computer would not be worth the trouble. Actually the entire procedure can be handled by the operating system; the user merely issues a single command , such as “Save file”. When the information in the file is needed again an analogous command (perhaps “Load file”) begins a sequence of events in which the operating system recovers the file from the disk and restores it to the primary memory.
Task 2. Make up a summary of the text.
Task 3. Translate the sentences:
1. Microchip hardware components, computers memory and software have been moving into the future along multiple trend paths. 2. Some of these trends are taking new directions, while others are merging. 3.Computer technology will soon advance into mixed-technology, silicon microchips that combine digital and analogue circuitry. 4. Contained within the same component chips could be: digital logic, memory, communications circuits, signal processing, sensor circuits, interface logic, data converters, display elements, voice synthesis, voice recognition and much more. In this fashion, a new set of basic components will exist to smarten up (óëó÷øèòü äåéñòâèå) most computers and communication subsystems in the future — thus marrying the computer with communications and forcing more changes, more uses and more distribution.
Task 4. Complete sentences using following words combination:
the trend of development; to check the performance of an operation; to denote residual errors; a current event, current efforts to define; superficial knowledge; the mode of handling in formation; to intend to complete, an intended perfection; the image of a mask
Task 5.Answer the questions:
1. Why is telecommunication volume growing exponentially? 2. What does the term “microelectronics” mean? 3. What fact does the primary interest in microelectronics stem from? 4. What component parts are used to assemble micro miniature electronic circuits? 5. How many technologies are there for integrating component parts into one single circuit? 6. What approaches are commonly referred to as hybrid circuitry?
HOMEREADING
1. What is a computer?
Computers are electronic machines which can accept data in a certain form, process the data and give the results of the processing in a specified format as information. Three basic steps are involved in the process: First, data is fed into the computer's memory. Then, when the program is run, the computer performs a set of instructions and processes the data. Finally, we can see the results (the output) on the screen or in printed form (see Fig). Information in the form of data and programs is known as software, and the electronic and mechanical parts that make up a computer system are called hardware. A standard computer system consists of three main sections: the Central Processing Unit (CPU), the main memory and the peripherals.
Perhaps the most influential component is the Central Processing Unit. Its function is to execute program instructions and coordinate the activities of all the other units. In a way, it is the 'brain' of the computer. The main memory holds the instructions and data which are currently being processed by the CPU. The peripherals are the physical units attached to the computer. They include storage devices and input/output devices. Storage devices (floppy or hard disks) provide a permanent storage of both data and programs. Disk drives are used to handle one or more floppy disks. Input devices enable data to go into the computer's memory. The most common input devices are the mouse and the keyboard. Output devices enable us to extract the finished product from the system. For example, the computer shows the output on the monitor or prints the results onto paper by means of a printer. On the rear panel of the computer there are several ports into which we can plug a wide range of peripherals - modems, fax machines, optical drives and scanners.
These are the main physical units of a computer system, generally known as the configuration.
2. What can computers do?
Computers and microchips have become part of our everyday lives: we visit shops and offices which have been designed with the help of computers, we read magazines which have been produced on computer, we pay bills prepared by computers. Just picking up a telephone and dialing a number involves the use of a sophisticated computer system, as does making a flight reservation or bank transaction.
We encounter daily many computers that spring to life the instant they're switched on (e.g. calculators, the car's electronic ignition, the timer in the microwave, or the programmer inside the TV set), all of which use chip technology.
What makes your computer such a miraculous device? Each time you turn it on, it is a tabula rasa that, with appropriate hardware and software, is capable of doing anything you ask. It is a calculating machine that speeds up financial calculations. It is an electronic filing cabinet which manages large collections of data such as customers' lists, accounts, or inventories. It is a magical typewriter that allows you to type and print any kind of document - letters, memos or legal documents. It is a personal communicator that enables you to interact with other computers and with people around the world. If you like gadgets and electronic entertainment, you can even use your PC to relax with computer games.
3. Units of memory
Bits - basic units of memory
Information is processed and stored in computers as electrical signals. A computer contains thousands of electronic circuits connected by switches that can only be in one of two possible states: ON (the current is flowing through the wire) or OFF (the current is not flowing through the wire). To represent these two conditions we use binary notation in which 1 means ON and 0 means OFF. This is the only way a computer can 'understand' anything. Everything about computers is based upon this binary process. Each 1 or 0 is called a binary digit, or bit. Bytes and characters
Is and Os are grouped into eight-digit codes that typically represent characters (letters, numbers and symbols). Eight bits together are called a byte. Thus, each character in a keyboard has its own arrangement of eight bits. For example, 01000001 for the letter A, 01000010 for  and 01000011 forC. The ASCII code
The majority of computers use a standard system for the binary representation of characters. This is the American Standard Code for Information Interchange, known popularly as ASCII' (pronounced 'ask-key'). There are 256 different ways of combining 0 and 1 bits in a byte. So they can give us 256 different signals. However, the ASCII code only uses 128 bytes to represent characters. The rest of the bytes are used for other purposes.
The first 32 codes are reserved for characters such as the Return key, Tab, Escape, etc. Each letter of the alphabet, and many symbols (such as punctuation marks), as well as the ten numbers, have ASCII representations. What makes this system powerful is that these codes are standard. Kilobytes, megabytes and gigabytes In order to avoid astronomical figures and sums in the calculation of bytes we use units such as kilobytes, megabytes and gigabytes. One kilobyte is 1,024 bytes (210) and it is represented as KB, or more informally as K. One megabyte is equivalent to 1,024 kilobytes, and one gigabyte is 1,024MB.
We use these units (KB, MB, GB) to describe the RAM memory, the storage capacity of disks and the size of any application or document. For instance, the text of this book contains roughly 1 MB of information.
4. Five Types of Printers
Printing is the final stage in creating a document. That is the purpose of the printers joined to your computing equipment. Since the results you can obtain with different types of printers will vary-substantially, here is a guide to help you decide which one is most suitable for your needs. To begin with, it must be taken into account that printers vary in cost, speed, print quality and other factors such as, noise or compatibility. In fact, printing technology is evolving so quickly that there is always a printer for every application or personal requirement.
Daisywheel printers were very common a few years ago. They used a sort of wheel with solid characters which rotated and hammered against the ribbon, but they couldn't print pictures or diagrams, and were very slow and noisy. Dot-matrix printers use pins to print the dots required to shape a character. They print text and graphics and nowadays some of them can print up to 450 characters per second (cps); however, they produce relatively low resolution output — 72 or 144 dots per inch. This level of quality, while suitable for preliminary drafts, is not recommended for reports or books that have a wide audience. They are slower than laser printers but much cheaper.
One common type of non-impact printer is an ink-jet printer. It operates by projecting small ink droplets onto paper to form the required image. This type of printer is quite fast, silent and not so expensive as a laser printer. Nevertheless, you can expect high quality results because The first 32 codes are reserved for characters such as the Return key, Tab, Escape, etc. Each letter of the alphabet, and many symbols (such as punctuation marks), as well as the ten numbers, have ASCII representations. What makes this system powerful is that these codes are standard. Kilobytes, megabytes and gigabytes In order to avoid astronomical figures and sums in the calculation of bytes we use units such as kilobytes, megabytes and gigabytes. One kilobyte is 1,024 bytes (210) and it is represented as KB, or more informally as K. One megabyte is equivalent to 1,024 kilobytes, and one gigabyte is 1,024MB.
We use these units (KB, MB, GB) to describe the RAM memory, the storage capacity of disks and the size of any application or document. For instance, the text of this book contains roughly 1 MB of information.
repetition is low, we can perceive a flickering, unsteady screen, which can cause eye fatigue. However, a fast-moving 75 Hz 'refresh rate' eliminates this annoying flicker.
What we see on the screen is created and stored in n area of RAM, so that there is a memory cell allocated to each pixel. This type of display is ailed bit-mapped. On monochrome monitors, bits 0 are visualized as white dots, and bits 1 as black dots.
On color displays, there are three electron guns at the back of the monitor's tube. Each electron gun shoots out a beam of electrons; there is one beam for each of the three primary colors: red, green and blue. These electrons strike the inside of the screen which is coated with substances called phosphors that glow when struck by electrons. Three different phosphor materials are used - one each for red, green and blue. To create different colors, the intensity of each of the three electron beams is varied. The monitor is controlled by a separate circuit board, known as the display adaptor, which plugs into the motherboard of the computer. Different boards drive different types of displays. For example, the VGA (Video Graphics Array) card has become a standard for color monitors.
Portable computers use a flat Liquid-Crystal Display, instead of a picture tube. An LCD uses a grid of crystals and polarizing filters to show the image. The crystals block the light in different amounts to generate the dots in the image.
5. Point and dick!
Typically, a mouse is a palm-sized device, slightly smaller than a pack of cards. On top of the mouse there are one or more buttons for communicating with the computer. A 'tail' or wire extends from the mouse to a connection on the back of the computer.
The mouse is designed to slide around on your desktop. As it moves, it moves an image on the screen called a pointer or mouse cursor. The pointer usually looks like an arrow or I-bar, and it mimics the movements of the mouse on your desktop.
What makes the mouse especially useful is that it is a very quick way to move around on a screen. Move the desktop mouse half an inch and the screen cursor will leap four inch. Making the same movements with the arrow keys takes much longer. The mouse also issues instructions to the computer very quickly. Point to an available option with the cursor, click on the mouse, and the option has been chosen.
Mice are so widely used in graphics applications because i they can do things that are difficult, if not impossible, to do with keyboard keys. For example, the way you move an image with a mouse is to put the pointer on the object you want to move, press the mouse button and drag the image from one place on the screen to another. When you have the image where you want it, you release the mouse button and the image stays there. Similarly, the mouse is used to grab one corner of the image (say a square) and stretch it into another shape (say a rectangle). Both of these actions are so much more difficult to perform with a keyboard that most graphics programs require a mouse. The buttons on the mouse are used to select items at which the mouse points. You position the pointer on an object on the screen, for example, on a menu or a tool in a paint program, and then you press the mouse button to 'select1 it. Mice are also used to load documents into a program: you put the pointer on the file name and double-click on the name — that is, you press a mouse button twice in rapid succession.
6. When buying a hard disk...
Hard disks have important advantages over floppy disks: they spin at a higher speed, so you can store and retrieve information much faster than with floppies. They can also hold vast amounts of information, from 20 MB up to several gigabytes. Apart from this, both types of disks work in the same way. To access directly the necessary information, the read/write heads of rigid disks seek the required tracks and sectors, and then transfer the information to the main memory of the computer or to another form of storage, all of which is done in a few milliseconds (ms). Bearing in mind that you always need disk storage, it is good sense to ask yourself some vital questions: What size capacity do I need? What speed can I use? What kind of storage device is the most suitable for my requirements? If you only use word-processing programs, you will need less storage capacity than if you use CAD, sound and animation programs. For most users, 500 MB on the hard disk is enough.
Now let's turn our attention to speed. Access times vary from 10 ms to 28 ms. Access time' - or seek time - is the time it takes your read/write heads to find any particular record. You have to distinguish clearly between seek time (e.g. 20 ms) and 'data transfer rate' (the average speed required to transmit data from a disk system to the RAM, e.g. at 10 megabits per second). Remember that the transfer rate depends also on the power of your computer.
When buying a hard disk you should consider the kinds of drive mechanisms and products available. There are ‘internal’ and ‘external’ drives which are both fixed hard drives, i.e. rigid disks sealed into the drive unit, either within or attached to the computer. A third type of hard drive, known as 'removable', allows information to be recorded on 'cartridges', which can be removed and stored offline for security purposes. These systems provide 80 MB to 1 GB transportable cartridges, so if you can afford it, a removable drive gives you a great deal of extra storage capacity.
Finally, a few words about 'optical' technology: erasable optical disks and CD-ROM drives are gaining popularity very quickly. Unlike the magnetic hard disk, the CD-ROM disk (which is optical) is not used for personal data storage but for recording huge amounts of information such as a dictionary or encyclopedia.
• CAD: computer-aided design.
• CD-ROM: acronym for Compact Disk-Read only Memory. The development of optical technology has resulted in mass storage media such as CD-ROM drives and erasable optical disks.
7. Operating systems
This is the Disk Operating System developed in 1981 by Microsoft Corp. It is the standard OS for all IBM PC compatibles, or clones. In this text-based operating system, you communicate with the computer by typing instructions (commands) that exist within its library. For example, some basic DOS commands include: DIR (shows a list of all the files in a directory), COPY (makes a duplicate of a file), DEL (deletes files from your disk).
This is a graphical environment that runs on top of the MS-DOS operating system. Microsoft Windows enhances MS-DOS with many Macintosh-like features and provides a graphical environment for managing files and starting programs. Its toolbox contains the Program Manager, the File Manager, the Print Manager, a task list, and various accessories (a calculator, calendar, notepad, Paintbrush, Windows Write, etc.). Buttons and scroll bars in Windows have an attractive, three-dimensional look. This is a bootable operating system in its own right, with a new graphical interface.
Most of the Macintosh OS code is in the ROM chips. These contain undress of routines (sequences of instructions) which perform such tasks as starting up the computer, transferring data from disks to peripherals and controlling the RAM space. Large parts of the Macintosh OS are also inside the System file and the Finder, kept in the System folder. The content of the System file is loaded automatically at start-up, and contains important information which modifies the routines of the OS in the ROM chips. The Finder is the application that displays the Macintosh's desktop and enables the user to work with disks, programs and files. The Macintosh OS allows multitasking.
Ill is the PC world's most technically sophisticated operating system. It provides true multitasking. In a nutshell, it allows an application program to be divided into 'threads', many of which can run at the same time. Thus, not only can numerous programs run simultaneously, but one program can perform numerous tasks at the same time. The OS/2 package includes a Communications Manager that ensures easy access to networks via modems.
This operating system, designed by BeU Laboratories in the USA for minicomputers, has been widely adopted by many corporate installations. From the very first it was designed to be a multitasking system. It is written in C, a high-level programming language. It has become an operating environment for software development, available for any type of machine, from IBM PS/2s to Macs to Cray supercomputers. Unix is the most commonly used system for advanced CAD programs. Today it is almost impossible to find a computer that cannot run a version of Unix. Graphical interfaces for Unix and its various versions include X-windows, Motif, and the NexT user interface (NextStep).
The Open VMS operating system is Digital's popular general-purpose OS for all VAX computers. It provides data and access security. OpenVMS supports all types of Digital and multivendor networks.
This is Digital's operating system based on Unix. It provides compatibility between VAX and DEC-system computers.
8. Word-processing facilities
Writing letters, memos or reports are the ways most people use computers. They manipulate words and text on a screen - primarily to print at some later time and store for safe keeping. Computers alleviate much of the tedium associated with typing, proofing, and manipulating words. Because computers can store and recall information so readily, documents need not be retyped from scratch just to make corrections or changes. The real strength of word processing lies in this ability to store, retrieve and change information. Typing is still necessary (at least, for now) to put the information into the computer initially, but once in, the need to retype only applies to new information. Word processing is more than just typing, however. Features such as Search and Replace allow users to find a particular phrase or word no matter where it is in a body of text. This becomes more useful as the amount of text grows.
Word processors usually include different ways to view the text. Some include a view that displays the text with editor's marks that show hidden characters or commands (spaces, returns, paragraph endings, applied styles, etc.). Many word processors include the ability to show exactly how the text will appear on paper when printed. This is called WYSIWYG (What You See Is What You Get, pronounced “wizzy-wig”). WYSIWYG shows bold, italic, underline and other type style characteristics on the screen so that the user can clearly see what he or she is typing. Another feature is the correct display of different typefaces and format characteristics (margins, indents, super- and subscripted characters, etc.). This allows the user to plan the document more accurately and reduces the frustration of printing something that doesn't look right. Many word processors now have so many features that they approach the capabilities of layout applications for desktop publishing. They can import graphics, format multiple columns of text, run text around graphics, etc. Two important features offered by word processors are automatic hyphenation and mail merging. Automatic hyphenation is the splitting of a word between two lines so that the text will fit better on the page. The word processor constantly monitors words typed and when it reaches the end of a line, if a word is too long to fit, it checks that word in a hyphenation dictionary. This dictionary contains a list of words with the preferred places to split it. If one of these cases fits part of the word at the end of the line, the word processor splits the word, adds a hyphen at the end, and places the rest on the next line. This happens extremely fast and gives text a more polished and professional look. Mail merge applications are largely responsible for the explosion of 'personalized' mail. Form letters with designated spaces for names and addresses are stored as documents with links to lists of names and addresses of potential buyers or clients. By designating what information goes into which blank space, a computer can process a huge amount of correspondence substituting the 'personal' information into a form letter. The final document appears to be typed specifically to the person addressed.
Many word processors can also generate tables of numbers or figures, sophisticated indexes and comprehensive tables of contents.
9. GUIs
The term user interface refers to the standard procedures the user follows to interact with a particular computer. A few years ago, the way in which users had access to a computer system was quite complex. They had to memorize and type a lot of commands just to see the content of a disk, to copy files or to respond to a single prompt. In fact, only experts used computers, so there was no need for a user-friendly interface. Now, however, computers are used by all kinds of people and as a result there is a growing emphasis on the user interface.
A good user interface is important because when you buy a program you want to use it easily. Moreover, a graphical user interface saves a lot of time: you don't need to memorize commands in order to execute an application; you only have to point and click so that its content appears on the screen.
Macintosh computers with a user interface based on graphics and intuitive tools were designed with a single clear aim: to facilitate interaction with the computer. Their interface is called WIMP: Window, Icon, Mouse and Pointer (as shown in Fig. 1) and software products for the Macintosh have been designed to take full advantage of its features using this interface. In addition, the ROM chips of a Macintosh contain libraries that provide program developers with routines for generating windows, dialog boxes, icons and popup menus. This ensures the creation of applications with a high level of consistency. Today, the most innovative GUIs are the Macintosh, Microsoft Windows and OS/2's graphical Presentation Manager. These three platforms include similar features: a desktop with icons, windows and folders, a printer selector, a file finder, a control panel and various desk accessories. Double-clicking a folder opens a window which contains programs, documents or further nested folders. At any time within a folder, you can launch the desired program or document by double-clicking the icon, or you can drag it to another location.
The three platforms differ in other areas such as device installation, network connectivity or compatibility with application programs. These interfaces have been so successful because they are extremely easy to use. It is well known that computers running under an attractive interface stimulate users to be more creative and produce high quality results, which has a major impact on the general public.
10. Basic features of database programs
With a database you can store, organize and retrieve a large collection of related information on computer. If you like, it is the electronic equivalent of an indexed filing cabinet. Let us look at some features and applications of a computer database:
• Information is entered on a database via
fields. Each field holds a separate piece of information, and the fields are
collected together into records. For example, a record about an employee might
consist of several fields which give his/her name, address, telephone number,
age, salary, and length of employment with the company.
Records are grouped together into files which hold large amounts of
information. Files can easily be updated: you can always change fields, add new
records or delete old ones. With the right database software, you are able to keep
track of stock, sales, market trends, orders, invoices
and many more details that can make your company successful.
* Another feature of database
programs is that you can automatically look up and find records
containing particular information. You can also search on more than one field
at a time. For example, if a managing director wanted to know all the customers
that spend more than
£7,000 per month, the program would search on the name field and the money
field simultaneously.
If we had to summarize the most relevant advantages of a database program over a card index system, we would say that it is much faster to consult and update, occupies a lot less space, and records can be automatically sorted into numerical or alphabetical order using any field. The best packages also include networking facilities, which add a new dimension of productivity to businesses. For example, managers of different departments can have direct access to a common database, which represents an enormous advantage. Thanks to security devices, you can share part of your files on a network and control who sees the information. Most aspects of the program can be protected by user-defined passwords. For example, if you wanted to share an employee's personal details, but not his commission, you could protect the commission field. Other features like mail merging, layout design and the ability to import and export data are also very useful. In short, a database manager helps you control the data you have at home, in the library or in your business.
11. Computer graphics
Computer graphics are pictures and drawings produced by computer. A graphics program interprets the input provided by the user and transforms it into images that can be displayed on the screen, printed on paper or transferred to microfilm. In the process the computer uses hundreds of mathematical formulas to convert the bits of data into precise shapes and colors. Graphics can be developed for a variety of uses including presentations, desktop publishing, illustrations, architectural designs and detailed engineering drawings.
Mechanical engineers use sophisticated programs for applications in computer-aided design and computer-aided manufacturing. Let us take, for example, the car industry. CAD software is used to develop, model and test car designs before the actual parts are made. This can save a lot of time and money.
Computers are also used to present data in a more understandable form: electrical engineers use computer graphics to design circuits and people in business can present information visually to clients in graphs and j diagrams. These are much more effective ways of communicating than lists of figures or long explanations. Today, three-dimensional graphics, along with color and animation are essential for such applications as fine art, graphic design, computer-aided engineering and academic research. Computer animation is the process of creating objects and pictures which move across the screen; it is used by scientists and engineers to analyze problems. With the appropriate software they can study the structure of objects and how it is affected by particular changes. Basically, computer graphics help users to understand complex information quickly by presenting it in a clear visual form.
12. Multimedia magic!
Until now multimedia applications have been used mainly-in the fields of information, training and entertainment. For example, some museums, banks and estate agents have information kiosks that use multimedia. Several companies produce training programmers on optical disks, and marketing managers use presentation packages (like Microsoft PowerPoint or Lotus Freelance Graphics for Windows) to make business presentations. All these people have found that moving images, sound and music involve viewers emotionally as well as inform them, and make their message more memorable.
Sound is an important component of the multimedia approach. The effective use of sound can be used to grab the attention of the participant, set the mood or underscore a point. The most popular way of delivering sound is the hardware sound board. Such boards offer two important capabilities. The first of these is a built-in stereo synthesizer complete with a built-in audio amplifier. Just connect a set of speakers and you've got instant sound, music and speech capabilities. The second capability is the Musical Instrument Digital Interface, or MIDI. This is a specialized serial interface that allows an electronic musical instrument to communicate with other MIDI-equipped instruments or PCs.
Between 80 and 90 per cent of all multimedia applications are distributed on CD-ROM, some just on CD, some on several media (as with Autodesk's Multimedia Explorer, which comes with both a CD-ROM and diskettes). The reason for CD-ROM’s popularity in multimedia is simple — a single CD can contain 660 MB of data. That's over 500 floppy disks' worth of programs, sound and graphics. The newest CD-ROM standard, CD-ROM XA (for extended Architecture) uses data compression to fit even more on these shiny discs. Many XA drives are also compatible with Kodak's PhotoCD technology, that digitizes photographs and places them on a CD-ROM.
13. What is 'desktop publishing’?
'Desktop publishing' refers to the use of personal computers to design, implement and publish books, newsletters, magazines and other printed pieces. Desktop publishing is really a combination of a few different processes including word processors, graphic design, information design, output and pre-press technologies, and sometimes image manipulation. There are also many applications that support these processes, including font creation applications (that allow users to design and create their own typefaces, called fonts) and type manipulation applications (that allow users to modify text in visually creative ways). Desktop publishing centers around a layout application. A layout application is used to import text from word processing applications, graphics from paint and drawing applications and images from scanning or image manipulation applications, and to combine and arrange them all on a page. They typically can bring in or import many different types of files. It is this ability to manipulate so many different items and control how they are used that makes layout software so popular and useful. This software is usually the last stop before a document is printed. Once composed and designed, these files can be printed onto film by high quality devices, called image-setters, and printed on a traditional printing press.
Because image setters are expensive devices, most people cannot afford to buy their own. There are, however, companies called service bureaus that specialize in printing other people's files on image setters, just like copy stores make copiers available to others. Service bureaus can offer a variety of equipment and services. Some offer image set output, laser printer output, color laser printer output and even slide or film recorder output. In addition, some have color scanning equipment.
14. What is PostScript?
In the past ten years the world of computers has witnessed the ‘PostScript’ revolution. PostScript was developed by Adobe Systems, Inc. in 1982 as a page description language for printers like Apple LaserWriter and Allied Linotronic photo-setters, among other output devices. Today it is used in most laser printers and is becoming a standard for high-quality type and graphics. PostScript is mainly used to describe the appearance of text, graphics and images on the printed page. It works in Vectorial format, which means that it stores graphics not as images made up of dots but as geometric descriptions, in equation form. This allows text fonts and graphics to be enlarged or reduced with no loss of quality in the output. A PostScript file consists of two main parts: the 'prolog', which contains a set of subroutines used to form different graphic elements (rectangles, curves, etc.), and the 'script' which contains the elements introduced by the user. The script calls up the subroutines stored in the prolog and adds the parameters: for example, if you have drawn a square of 10x5 cm, the script calls up the subroutine Square and specifies the values 10x5.
All the features of PostScript can be used with Macintosh, Windows or OS/2 environments. PostScript is device-independent, which means that it can speak to different output devices (printers, film recorders, image setters) and adjust the quality of the final output to the highest capabilities of the output devices. As for the computer, you only need a machine able to send a file to an output device containing a PostScript interpreter. Each PostScript-based printer has a microprocessor, at least 2 MB of RAM, and an operating system that interprets the PostScript code. In the case of image setters, the hardware that interprets the code is called a Raster Image Processor.
Some drawing programs can produce pictures drawn in PostScript directly. These programs, such as Illustrator, Freehand, or CorelDraw, can often give more precise control over drawing than non-PostScript packages. Pictures created in PostScript and saved as separate files (known as Encapsulated PostScript - EPS - files) can be imported into a document generated by page-layout applications like Aldus PageMaker or QuarkXPress. PostScript is an indispensable tool for illustrators, graphic designers and DTP professionals, and has become a universal device-independent data vehicle. It has support for sound, video and other formats: you can rotate portions of the page, mix scanned images, specify halftone screens and introduce any number of effects. In fact, the only barrier is your imagination.
15. Network configurations
A data communications network is a group of devices (CPUs, printers, etc.) or 'nodes' interconnected by communications circuits so that users can share data, software programs and hardware resources. There are two different elements in this kind of network: the physical structure that links the equipment, and the software that allows communication.
The physical distribution of nodes and their interconnecting communication circuits is known as network 'topology' or 'architecture'. The software consists of the protocols, i.e. the rules which determine the formats by which information may be exchanged between different systems. We could say that cables and transceivers (the architecture) allow computers to 'hear' one another, while the software is the 'language' that they use to 'talk' to one another over the network.
As regards the cables, they consist essentially of the transceiver - the hardware that sends and receives network signals. At present the most widely used transceivers are: Token Ring, Ethernet and LocalTalk. Token Ring is the most common method of connecting PCs and IBM mainframes. Most Token Ring adapters transmit data at a speed of 16 megabits per second. With Ethernet, data is transmitted at 10 Mbits/sec. Ethernet provides a very robust, trouble-free architecture with good levels of performance. In this regard, Ethernet is the best solution for fast and intensive activity. It is also recommended for electronic colour printing or three-dimensional CAD. LocalTalk transceivers are the cheapest of all because they are included in each Apple Macintosh. However a LocalTalk network is a bit slow, which is why most Macs come with additional circuitry for connecting to a high-speed network.
As for protocols, these are rules which describe things like transmission speed and physical interfaces. They also define functions such as printing and file sharing. The Token Ring protocol avoids the possibility of collisions. To transmit data, a workstation needs a token, and as there is only one token per network, holding one guarantees sole use of the network. With Ethernet there are other options, of which TCP/IP (Transmission Control Protocol/Internet Protocol) is perhaps the most useful since it allows different operating systems to communicate with each other. With regard to LocalTalk networks, they use AppleTalk protocols. The Macintosh operating system includes the AppleTalk manager and a set of drivers mat let programs on different Macs exchange information. LANs can be interconnected by gateways. These devices help manage communications and control traffic on large networks. They can translate protocols of different networks which means that a LocalTalk network running an AppleTalk protocol can be connected to an Ethernet network running TCP/IP.
16. Channels of communication
What you need to telecommunicate
In the modern world, some companies are rinding it more efficient to have certain employees stay at home and do all of their work on their home computers. Then, using telecommunications, they transmit their work over a modem into the office where it is printed and distributed. Telecommunications are used now for hundreds of different applications. Investors routinely check their stock market holdings, pilots file flight plans and get weather briefings, and shoppers compare and purchase merchandise on their computers. National and international electronic mail is sent and received with local phone calls, and electronic bulletin boards are used for everything from selling used cars to finding dates.
Telecommunicating is accomplished by linking your computer to telephone lines and contacting someone through a device called a modem. But with whom will you communicate? Of course, you can call up an individual who owns a modem and talk to him or her, but generally, you will communicate with bulletin boards and online services.
Local bulletin boards
Bulletin boards are frequently free because they are maintained by community-minded computer enthusiasts. There are local bulletin boards sponsored by user groups, individuals and businesses. How do you find a bulletin board? Ask the salesman at your local computer store or a i friend who is involved in telecommunications. If the bulle tin board requires registration, you will be subjected to a friendly interrogation and be required to enter your name, address, telephone number and other information such as the kind of computer and modem you are using. Then, the system operator (called a sysop - - pronounced SIS-op) will contact you over the telephone to assure him/herself of your identity.
Once you are in telephone contact with the board, you can download (receive) artwork, games and useful programs; or you can play games or 'talk1 to the other people online. If you upload (send) programs, make sure that those programs are shareware or public domain programs — those that specifically permit public access.
Commercial online services
A commercial online service differs from a local bulletin board m two key ways: (1) they are larger and more comprehensive, and (2) they are operated to make a profit. On a commercial online service, you will find such diverse services as a low-cost stock broker, an airline reservations service, technical support personnel for hardware and software manufacturers, and access to massive databases containing all kinds of information.
Two popular commercial services are CompuServe and Prodigy. Among CompuServe's many services are the following: news, electronic mail, telex, games, airline reservations, online shopping, conferences and special interest groups.
Prodigy's services are aimed particularly at shoppers and the needs of children. For adults, Prodigy provides the range of services from banking to shopping, as well as helpful document files from experts on managing money, cooking and other useful information. For children, there is an online encyclopedia, as well as adventure, science and entertainment features.
A modem
Your PC is a digital device (it works with strings of Is and Os). However, the telephone connection is an analogue device, designed to transmit the sounds and tones of the human voice. That's why we need a modem - - a bridge between digital and analogue signals. The word “modem” is an abbreviation of Modulator/Demodulator. When a modem modulates, it sends very rapid on/off pulses. The computer on the other end
translates (demodulates) those signals into intelligible text or graphics.
Modem transmission speeds are measured in baud, roughly equivalent to bits per second (bps). Typical speeds are 9600,14400 and 28800 baud
Electronic mail requires some special software. You type a message onto your computer screen, click a Send button and it pops up on the recipient's screen -provided that he/she is connected to your computer via a network like the Internet.
Voice-mail is similar to e-mail except that it includes sending recorded sound in addition to text fax-modem is a modem with software and hardware which can emulate a fax machine. This allows you to receive a fax directly into your computer, where you can read it or print it on ó our printer. To send a fax you prepare the document on ó our computer -for example, by using a word processor
A stand-alone fax service is a facsimile machine which transmits copies of original documents. It operates by scanning pictorial or textual documents so that the image is converted into electrical signals which are sent to and used by a receiving machine that produces a copy of the original Teletext on ITV and Channel Four is an information service in Britain which broadcasts a database alongside the TV signal. It provides constantly updated and real time information
17. New technologies
1
The Philips
Screen phone is a telephone that comes with an LCD and a pull-out keyboard. The
computer interface lets you use applications that combine voice and data.
Companies manufacturing this kind of computer-telephone also include services
which enable you to order airline and concert tickets, pay bills, bank
electronically, and send e-mail and faxes by telephone.
2 A new service from Walk Soft (Rochester. NY) takes electronic publishing a step further, delivering once a week via modem or disk a formatted 'newspaper' that includes color pictures and animations. Walk Soft's News In Motion costs $250 for 52 issues - including telephone charges to download the data files, if you use a modem.
When you subscribe to News In Motion, Walk Soft provides software that includes everything you need to download, read, and search articles. Each issue is 700 KB compressed or 1.4 MB uncompressed, which means it fits on a single disk.
3
Virtual
reality lets people interact with artificial objects and environments
through three-dimensional computer simulation. In a VR system, you are hooked
to a computer through a controlling device, such as a glove, and head- mounted
displays give you the feeling of being propelled
into an artificial 3D world. The computer brings to life events in a distant,
virtual world using databases or real time objects and sounds. Your senses are
immersed in an illusionary, yet sensate, world.
18. WAN
For long-distance or worldwide communications, computers and LANs are usually connected into a wide area network (WAN) to form a single, integrated network. Two good examples of wide area networks are Internet and Arpanet. They transfer data and e-mail for university researchers and academics, commercial groups, military installations and ordinary people.
Networks can be linked together by either telephone lines or fibre-optic cables. For example, ISDN (Integrated Services Digital Network) is an international standard for transmitting digital text, sound, voice and video data over telephone lines. On the other hand, FDDI (Fiber Distributed Data Interface) is an optical-fibre network. This new standard transmits data at great speed - 100 megabits per second.
Modern telecommunications use fibre-optic cables because data can be transmitted at a very high speed through extremely wide bandwidth of glass fibres. The fibre system operates by transmitting light pulses at high frequencies I along the glass fibre. This offers considerable advantages: (i) the cables require little physical space; (ii) they are safe because they don't carry electricity; (iii) they avoid electromagnetic interference.
Networks on different continents can also be connected via satellite. Computers are connected by a modem either to ordinary telephone wires or fibre-optic cables, which are linked to a dish aerial. This aerial has a large concave
visiting a virtual exhibition, to checking out imaginary kitchen designs.
I- Video teleconferencing is a new technology that allows organizations to create Virtual' meetings with participants in. multiple locations.
A video teleconferencing system combines data, voice and video. Participants see color images of each other, accompanied by audio, and they can exchange textual and graphical information.
In Video teleconferencing, images are captured by computer-mounted cameras. Video processors digitize and compress the images, which are transmitted over a network bi-directionally. Data and sound travel via telephone lines.
Reflector for the reception and sending of signals. Then, when signals are received by the satellite, they are amplified and sent on to workstations in another part of the world.
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