In the countryside, housing conditions continue to be marked by mass poverty, malnutrition, dilapidated housing, -poor water supply, inadequate sanitation, and a lack of services.

This situation, coupled with lack of employment opportunities, continues to drive rural people away from their homes, in the hope of improving their lot in the "cities". The decline of traditional agriculture, rapid population growth, absence of alternative centres to disperse migratory flows, the concentration of economic activities in a few major cities - these factors will guarantee that the urban population of primate cities wall continue to expand rapidly, this leading to the further expansion of slums and squatter settlements.

Task 24. Translate the text.

The Role of Microelectronics m Communication

It is possible now to have a telephone that 'remembers" frequently called numbers, any one of which can be reached by pushing a single button. On television one can frequently see events in Europe and other areas overseas while they are happening. Computers "talk" digitally to one another over telephone lines at remarkably high speeds. These developments and many more reflect the impact of microelectronics on communication.

Until perhaps 15 years ago the vacuum tube was the dominant active component of the electronic circuits that are fundamental to the operation of telecommunication systems. Its limitations were made evident by the rapid growth of communication by telephone, radio and television. The vacuum tube was too large, required too much power and was too unreliable to meet the need of those systems for large numbers of signal-processing devices clustered in complex circuits and required to operate with extreme reliability. The alternative came in the form of the transistor, which provided electronic gain in a semiconductor and was small and reliable. It led to the silicon integrated circuit, a revolution in electronics and a vast improvement in telecommunication.

Today, millions of circuit elements are simultaneously fabricated on a thin "wafer" of silicon. Typically the wafer holds several hundred copies of the same circuit, and is divided into small chips holding one circuit each. The chips are usually packaged individually as integrated-circuit components. The designer of communication equipment employs these components to build complex systems, usually by placing a number of integrated circuits on a circuit board containing the printed wiring necessary to interconnect them.

A typical communication system requires a number of circuit technologies. For example, signals transmitted with high power or at high frequency often call for currents and voltages that cannot be handled by conventional integrated circuits. Some circuits require highly stable components: often they are best provided by thin-film techniques which involve depositing conductors, insulators and resistive films on a ceramic substrate. To properly describe the role of microelectronics in communication I shall discuss several of the more important circuit technologies, with primary emphasis on silicon integrated circuits because they have had by far the greatest impact on modem telecommunication.

Microelectronics in the form of integrated circuits is an important factor in telecommunication largely because of the combined effects of low cost, high reliability and wide applicability. As increasing numbers of circuits elements are fabricated on a silicon chip, the cost of a basic circuit function decreases markedly. A circuit function is of outstanding importance in communication systems (and also in computing systems) in the digital logic "gate". It controls the flow of information, providing an output signals are in prescribed states. From this basic element large digital signal-processing systems can be built. Hence the cost of a logic gate has a considerable influence on the cost of communication equipment: on terminals, which provide the interface between people or machines and communication channels; on switching machines, which establish communication paths, and on the equipment that processes signals so that they can be transmitted over wires and cables, by radio and by light waves.

Digital technology has progressed rapidly from the logic gate consisting of vacuum tubes to the logic gate consisting of transistors to the integrated logic gate and now to thousands of logic gates within a single integrated circuit.

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Psychological Availability of Information

Even when a person knows all the facts about a problem, he cannot immediately see all the consequences of those facts. This statement, taken by itself, seems so obvious and trivial that it is not worth uttering. However, neglect of tills fact explains in part why we find it difficult to see how a machine can produce a result which may be surprising to the person who programmed it - and why a machine is not often thought of as an intellectual partner in creative work. Lady Lovelace was the first person to make a point which has been repeated frequently in recent years. She stated in her Scientific Memoirs that "the Analytic Engine has no pretentious to originate anything. It can do whatever we know how to order it to perform." Although the latter statement is indubitably true, for several good reasons it is misleading to conclude that because in a sense the machine is the slave of the programmer, it cannot serve him in a creative capacity.

One reason has already been, alluded to above. Suppose, for example, that we have done a study of the driving patterns of people in a city. We know how fast they go on the average, what proportion go in various directions on each street at certain times of the day and toward various designations. Suppose further that we know the maximum volume that each street can handle and the consequences of exceeding this limit. Even though we have all these facts, it is by no means obvious to us what would happen if certain conditions were changed. What would happen, for example, if one street were made wider, another were converted to a one-way street, and an expressway were added in another part of the city. Each of these changes would have an effect ultimately on the traffic on every other street. Furthermore, this effect is completely determined by or is predictable from the data we have. Getting the data out is another matter, however.

This kind of problem is commonly approached by representing the cars and driving patterns in a model inside the computer. We write a program to simulate the flow of traffic, subject to the various constraints of the problem (location, direction, number, and capacity of the streets). We can then experiment by changing the constraints and observing what happens to the flow of traffic. If such a simulation were developed m sufficient detail, it would even be possible to simulate an individual automobile traveling a given route through the city and to determine the average time and the best route under various conditions. In fact something very similar is being done by American Airlines to determine the optimum routing of aircraft between distant cities, taking into account air temperature, wind direction, velocity, and altitude. The technique of simulating in a computer the operation of complex processes - such as chemical processes, production schedules, military operations, communications networks, social interactions, and even psychological processes - is an important intellectual application of computers. It enables known facts to be put together so that the consequences of these facts are made available in a way which would otherwise be impossible or very tedious.

The computer can have a role in the creative or intellectual area in another way. This process also relies on making known facts more available to people by combining some of the special abilities of the computer with special human talents in a creative partnership. Here the computer serves as an extension to many of man's abilities to process information, such as his abilities to visualize, remember, draw, search (or scan) a text, solve problems, and learn. An example of this application is the use of computers to manipulate graphical displays. Systems such as SKETCHPAD (MTT) or DAC (Ford) are being used in a variety of applications to help engineers design automobile bodies, airplane fuselages, space vehicles, bridges, and electrical circuits. The tasks of visualizing the three-dimensional object from all angles and of making sure design changes do not affect functional requirements have been taken over by the computer; the engineer-designer is thus free to exercise his creativity in the central task of imaginative design.

Reliance on the computer to render information more available is also the purpose of a variety of information-retrieval applications, including the retrieval of information in science to avoid duplication of research, in law to establish precedents, in medicine to find relevant case studies and to facilitate diagnosis, and m literature to study style. Of these, only two are at present widely available as commercial services - the scientific and the legal data retrieval systems.

We should add to our list yet one more reason why a computer may produce a result, surprising even to its programmer. A computer can be made to respond not only to its original program but also to changes in its environment. In this case we have a program which "teams" as it proceeds. Programs have in fact been written which do this. A.L Samuel's checker-playing program improves its strategy the more it plays. It can in fact play another checker-playing computer to increase its skill. Such a program not only produces results not anticipated by its designer but may in fact excel him if given a good learning environment.

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