Parallel and Serial Communications

When connecting the printer to a computer, you have to determine whether a parallel or serial connection should be used. Many computers only provide one type of connection for a printer. If both types of connection are available on the computer, it is normally better to use the parallel interface for the printer, leaving the serial port free for devices such modems. If you are in any doubt about which type of connection to make, consult your Epson dealer.

What are parallel and serial communications? All the texts and programs used by your computer are stored internally as electrical signals which represent binary numbers. These electrical signals are switched on

to represent a binary 1 digit or off to represent a 0 digit. Binary digits are stored in groups of eight, capable of representing a number in the range 0 to 255. A group of eight binary digits, or bits, is called a byte.

Whenever data is transferred, a byte must be sent for each character of text. They can either be sent simultaneously (parallel communication) using eight separate wires which form what is known as a data bus, or one at a time (serial communication) down a single wire.

The advantage of serial data transfer is that much simpler hardware can be used, with fewer wires. The disadvantage is that data has to be sent and received in a more complicated way. A stream of characters cannot simply be sent as a continuous sequence of binary digits, as it would be very difficult to tell where one character finished and the next began. Equally, the printer must know at what rate it is expecting data to be sent, and it must receive it in recognizable packages. The last problem is that the printer is not able to process the data as fast as it is received, so that there has to be a system for indicating that no more data can be received. The different settings which agree between the computer and printer form the communications protocol.

Parallel communication is much simpler from the point of user's view, since apart from the data wires, there are other wires by which the computer can control the printer, and the printer can tell the computer when it is ready to receive more data. There is no speed of transmission to set up or any of the other settings required for serial communication.

XIV. Раскройте скобки. Используйте Participle I или II.

1. A list of instructions (specified / specifying) a sequence of operations is called an algorithm.

2. The number of operations (performed / performing) during the course of computation depends on the particular problem.

3. The instructions (comprised / comprising) an algorithm define calculations.

4. Machine instructions (existing / existed) in the form of operands are in machine language.

5. The facts and figures (processed / processing) by a computer are usually known as data.

6. The data (put / putting) into the computer is input data.

7. Input data is processed according to a set of instructions (calling / called) a program.

8. Input and output devices collectively (calling / called) peripherals include printer and plotter.

9. The information (providing / provided) by satellite pictures is processed by a computer.

10. Maps (created / creating) by computers present valuable information on the environmental situation.

Unit 7

1. Определите принадлежность слов к частям речи. Слона переведите.

transmit – transmission – transmitter

compare – comparable – comparatively

change – changeable – changeability – interchangeable

distribution – distribute – distributor

equip – reequip – equipment

maintain – maintenance – maintainability

consumer – consume – consumption

local – locate – location – locality

primary – prime – primarily

value – valuable – invaluable – overvalue

upgrade – upgradable – upgradability

afford – affordable – afford ability

architecture – architectural – architect

generate – generation – generative – generator

competition – compete – competent – competence

competitioner – competitive – competitor

add – additional – addition – adder – additive

II. Запомните следующие слова.

critical – очень важный, значительный, решающий, принципиальный

Laboratory control plays a critical part.

The problem becomes somewhat critical.

There are critical differences between ...

The choice of structure is not critical.

critical components

critical hardware

critical dimensions

critical applications

desired – заданный; нужный; требуемый

desired operating temperature, desired region, desired value, desired level of reliability, desired functions, to define the desired parameters

early – первый; первоначальный; прежний

early microprocessors, in the early investigations of basic electromagnetic phenomena, early experiments

favourable – хороший; приемлемый; удачный

favourable thermal characteristics, less favourable results, favourable environment, favourable conditions, this system is favourable.

significantly – интересно, что; следует отметить

Significantly, the rapid turnover in minicomputer firms seems to be tapering off (суживаться).

Significantly, the memory can function not only as an electrically alterable ROM but also as ...

III. Переведите следующие предложения, обращая внимание на инфинитив.

1. These conflicts have to be resolved by the members of the committee acting as a group if a successful automatic computer installation is to be made.

2. Bold thinking has to be done. The result of such thinking are changes in goals, methods, and interests.

3. But how are we to find out whether the condition is fulfilled or not?

4. In order to increase production, manufacturers have to buy additional materials.

5. In order to meet the additional demand, producers of materials have to increase their output.

6. We are to take into consideration all the advantages and disadvantages to decide what system is the best for the future work.

7. We are to take certain steps to reduce the weight of the mechanical part.

8. To meet this large demand for power, more generating capacity has necessarily to be created.

9. An analog computer is able to calculate by using physical analogs of numerical measurement.

10. The educated man of today needs to have at least some significant knowledge of science, and at least a little significant knowledge about computers.