The Development of the Computer

 

1. The inventions and ideas of many mathematicians and scientists
led to the development of the computer. The first mechanical calculat­ing machines were invented during the 1600's. One of the more notable
of these devices was built in 1642 by the French mathematician and scientist Blaise Pascal.

2. During the 183O's, an English mathematician named Charles Babbage developed the idea of a mechanical digital computer. He tried to construct a machine called an analytical engine. The machine contained the basic elements of an automatic computer and was designed to perform complicated calculations according to a sequence of instructions. However, the technology of Babbage's time was not advanced enough to provide the precision parts needed to complete the machine.

3. Another important contribution to the development of the computer was made in the mid-1800's by George Boole, an English logician and mathematician. Boole devised a system of formulating logical statements symbolically so that they could be written and proved (in a way similar to that of ordinary algebra.

4. In 1930 the first reliable analog computer was built. This machine, called a differential analyzer, solved differential equations.

5. During the 1940's, John Von Neumann, an American mathema­
tician, introduced an idea that improved computer design. He proposed that programs could be coded as numbers and stored with data in a computer's memory.

6. The invention of the transistor in 1947 and of related solid-state devices during the 195O's and 1960's resulted in the production of faster and more reliable electronic computers. The new mashines also were smalle and less expensive than earlier models.

7. The continued miniaturization of electronic equipment during the late 1960's and 197O's led to further advances in computer technology. The development of the integrated circuit enabled engineers to design both minicomputers and high-speed mainframes with tremendous memory capacities.

8. Researchers are seeking ways to improve memories and auxiliary storage equipment. They expect to produce an efficient magnetic bubble unit, which is faster and cheaper to operate than mechanical tape or disk units. A magnetic bubble unit is a semiconductorlike chip that stores data in tiny, cylindrically shaped areas called bubbles. Up to a million bits of information can be stored in one bubble unit.

9. Scientists are also working to increase computing speed by designing circuits that are even more densely packed and closer together. One proposed device, called a very large-scale integrated circuit (VLSI), would contain hundreds of thousands of transistors and other parts. Projects also are being undertaken to devise hardware and software that would enable a computer to understand ordinary speech.

III. Say whether the following statements are true or false:

1. Charles Babbage developed the idea of an electronic digital com­puter. 2. George Boole devised a system of formulating logical statements symbolically. 3. The invention of the transistor in 1947 resulted in the production of faster and more reliable electronic computers. 4. Scientists are also working to decrease computing speed.

IV. Answer the following questions on paragraphs 1 and 2:

1. What did the inventions and ideas of many mathematicians and scientists lead to? 2. When were the first mechanical calculating machines invented? 3. Who developed the idea of a mechanical digital computer? 4. The technology of Babbage's time was not advanced enough, was it?

V. Find the place in paragraph 3 containing the information about Boole's invention. Share this information with your group-mate.

VI. In paragraphs 5 and 6 find the English equivalents of the following words:

вводить; улучшать (усовершенствовать); конструкция (проект); предлагать; хранить; данные (информация); изобретение; устройство (прибор); кончаться, иметь (своим) результатом; производство; надежный; дорогой (дорогостоящий).

VII. Translate paragraphs 7 and 8 into Russian.

VIII. Read paragraph 9 and say how scientists are working to increase computing speed.

IX. Write out of the text the words and word combinations for describing advances in computer technology.

X. Divide text A into logical parts and find the topical sentences in each part.

XI. Speak about the development of computers using the topical sentences and words from the logical diagram.

Appendix I

 

UNIT NINE

LESSON 1

 

1. Translate  the text. Use a dictionary.

    Scientists and mathematicians of the nineteenth century laid the foundation of telecommunication and wireless technology, which has affected all facets of modern society. In 1864, James C. Maxwell put forth fundamental relations of electro­magnetic fields that not only summed up the research findings of Laplace, Poisson, Faraday, Gauss, and others but also predicted the propagation of electrical signals through space. Heinrich Hertz subsequently verified this in 1887 and Guglielmo Marconi successfully transmitted wireless signals across the Atlantic Ocean in 1900. Interested readers may find an excellent reference on the historical developments of radio frequencies (RF) and microwaves in the IEEE Transactions on Microwave Theory and Technique (Vol. MTT-32, September 1984).

Wireless communication systems require high-frequency signals for the efficient transmission of information. There are several factors that lead to this requirement. For example, an antenna radiates efficiently if its size is comparable to the signal wavelength. Since the signal frequency is inversely related to its wavelength, antennas operating at radio frequencies and microwaves have higher radiation efficiencies. Further, their size is relatively small and hence convenient for mobile communication. Another factor to favor RF and microwaves is that the transmission of broadband information signals requires a high-frequency carrier signal. In the case of a single audio channel, the information bandwidth is about 20 kHz. If amplitude modulation is used to superimpose this information on a carrier then it requires at least this much bandwidth on one side of the spectrum. Further, commercial AM transmission requires a separation of 10 kHz between the two transmitters. On the other hand, the required bandwidth increases significantly if frequency modulation is used. Each FM transmitter typically needs a bandwidth of 200 kHz for audio transmission. Similarly, each television channel requires about 6 MHz bandwidth to carry the video information as well. Table 1.1 shows the frequency bands used for commercial radio and television broadcasts.

In the case of digital transmission, a standard monochrome television picture is sampled over a grid of 512 x 480 elements that are called pixels. Eight bits are required to represent 256 shades of the gray display. In order to display motion, 30 frames are sampled per second. Thus, it requires about 59Mb/s (512 x 480 x 8 x 30 = 58,982,400). Color transmission requires even higher band­width (on the order of 90 Mb/s).

Wireless technology has been expanding very fast, with new applications reported every day. Besides the traditional applications in communication, such as radio and television, RF and microwave signals are being used in cordless phones, cellular communication, LAN, WAN, MAN, and PCS. Keyless door entry, radio-frequency identification (RFID), monitoring of patients in a hospital or a nursing home, and cordless mice or keyboards for computers are some of the other areas where RF technology is being applied. While some of these applications have traditionally used infrared (IR) technology, current trends are moving toward RF. The fact is that RF is superior to infrared technology in many ways. Unlike RF, infrared technology requires unobstructed line-of-sight connection. Although RF devices are more expensive in comparison with IR, this is expected to change soon as their production and use increases. The electromagnetic frequency spectrum is divided into bands as shown in Table 1.2. Hence, AM radio transmission operates in the medium frequency (MF) band; television channels 2-12 operate in the very high frequency (VHF) band; and channels 18-90 operate in ultra high frequency (UHF) band. Table 1.3 shows the band designations in the microwave frequency range.

 

                                                           

Besides the natural and human-made changes, electrical characteristics of the atmosphere affect the propagation of electrical signals. Figure 1.1 shows various layers of the ionosphere and the troposphere that are formed due to the ionization of atmospheric air. As illustrated in Figure 1.2(a) and (b), a radio frequency signal can reach the receiver by propagating along the ground or after reflection from the ionosphere. These signals may be classified as ground and sky waves, respectively. Behavior of the sky wave depends on the season, day or night, and solar radiation. The ionosphere does not reflect microwaves and the signals propagate line-of-sight, as shown in Figure 1.2(c). Hence, curvature of the earth limits the range of a microwave communication link to less than 50 km. One way to increase the range is to place a human-made reflector up in the sky. This kind of arrangement is called the satellite communication system. Another way to increase the range of a microwave link is to place the repeaters at periodic intervals. This is known as the terrestrial communication system.

Figures 1.3 and 1.4 list selected devices used at RF and microwave frequencies. Solid-state devices as well as vacuum tubes are used as active elements in RF and microwave circuits. Predominant applications for microwave tubes are in radar, communications, electronic countermeasures (ECM), and microwave cooking. They are also used in particle accelerators, plasma heating, material processing, and power transmission. Solid-state devices are employed mainly in the RF region and in low-power microwave circuits, such as low-power transmitters for LAN, and receiver circuits. Some of the applications of solid-state devices are listed in Table 1.4.

Figure 1.5 lists some applications of microwaves. Besides terrestrial and satellite communications, microwaves are used in radar systems as well as in various industrial and medical applications. Civilian applications of radar include air-traffic control, navigation, remote sensing, and law enforcement. Its military uses include surveillance, guidance of weapons, and C³ (command, control, and communication). Radio frequency and microwave energy is also used in industrial heating as well as household cooking. Since this process does not use a conduction mechanism for the heat transfer, it can improve the quality of certain products significantly. For example, the hot air used in a printing press to dry the ink adversely affects the paper and shortens its life span. On the other hand, only the ink portion is heated in microwave drying and the paper is barely affected by it. Microwaves are also used in material processing, telemetry, imaging, and hyperthermia.

LESSON 2

1. Translate the text. Use a dictionary.