Text B. DEVICES FOR INPUT AND OUTPUT
The various pieces of hardware – the physical devices-of a computer system are used to input, and output data. Input devices, which range from keyboards and touch-sensitive screens to mice and light pens, translate the information into a series of on and off electrical signals. These signals called bits are combined in specific series to represent letters, numbers, and signals. Each series of 8 bits is called a byte. Other Input Devices. Input devices can take many forms. For example, graphics tablets use a stylus and a special sensitive tablet to let users draw on the screen as they would on paper; this is very useful for graphics work and CAD. Trackballs allow the user the functionality of a mouse without a large flat surface to move around on. Touch-sensitive displays and touch pads are used in various businesses and industries to allow people to control the computer with the touch of a finger. Voice-recognition software allows the user to talk to the computer to give commands; this is finding a use in computer applications for the disabled. Output devices Plotters. A plotter is an output device that produces line drawings. These devices move a piece of paper under a series of moving pens. As the paper moves, the pens draw. Many plotters produce colour output by drawing with several different-coloured pens. Because it uses fine-point pens, the lines produced with a plotter can be very precise. Plotters are most often used to produce architectural drawings, maps, charts, and other technical types of line art. Other Output Devices. While the most customary output devices are monitors and printers, not all such devices produce readable information. Computer-generated music and the movement of a robotic arm are just two items in a long list of different types of output from a variety of devices. Portable Monitors. Portable, laptop, and notebook computers are microcomputers that have become smaller and smaller in size and weight. One of the devices that has made their development possible is the flat-panel monitor. These compact devices consume little power, and their flat profile allows them to provide a full screen in a small folding unit. Early flat-panel displays were monochrome, but new technologies allow these screens to display colour. They can be LCD (liquid crystal display), EL (electrolumines-cent), or gas-plasma: - LCDs do not consume light of their own, but consist instead of crystal molecules. The backlit LCDs are easier to read than the original LCDs, which were difficult to read in strong light. - EL screens are an improvement over LCDs because they actively emit light when electrically charged. 1. Gas-plasma Screens use a gas that emits light in the presence of an electric current. Unfortunately, gas-plasma displays cannot be battery-operated and must be plugged into a regular AC outlet. This limits their use in portable computers. Devices for both Input and Output Some peripherals can be used for both input and output. Disk drives, tapes, and optical drives, while primarily thought of as storage devices, actually incorporated both input and output functions. One very important input/output device in common use is the modem (short for modulator/demodulator). A modem sends data from the computer out over telephone lines and accepts data over those same lines from other computers. It works by translating the electrical impulses of computer data into audible tones (modulation) and, at the other end, converting them back into electrical impulses (demodulation). A modem can be connected externally to the computer's serial port or mounted internally as an expansion board. The availability of modems has opened up staggering opportunities for people to link their computers via phone, to access information from remote databases, and communicate in a variety of ways.
Unit 4
Pre-reading activity
Guess the meaning of the following words. operating ['Opq'reItIN]; user ['jHzq]; perform [pq'fLm]; supervisor ["sjHpq'vaIzq]; command [kq'ma:nd]; resident ['rezIdqnt]; abbreviation [q"brJvI'eISqn]; Unix ['jHnJks]; mainframe ['meInfreIm]; available [q'veIlqbl]; XENIX ['zenIks]; icon ['aIkOn]; execute ['eksIkjHt]; package ['pxkIG]; Linux ['laInAks]
Read and learn the basic vocabulary terms. file ( n ) [faIl] файл (последовательность или множество однотипных записей) interface ( n ) ['IntqfeIs] интерфейс, стык wordprocessor ( n ) текстовый процессор; программа редактирования [wq:d'prousesq] текстов; система подготовки текстов (программные средства обеспечивающие ввод, хранение,просмотр, редактирование, форматирование и печать текстов) spreadsheet ( n ) ['spredSJt] электронная таблица to load ( v ) [loud] загружать prompt ( n ) [prOmt] приглашение, вопрос (текст или изображение, выдаваемые программой на экран дисплея и указывающие, что система ожидает ввод команд или данных пользователя) to click ( v ) [klIk] нажать и отпустить (клавишу) icon ( n ) ['aIkOn] пиктограмма (условное изображение информационного объекта или операции)
Memorise the following word-combinations. operating system операционная система computer hardware аппаратное обеспечение компьютера supervisor program управляющая программа, программа распорядитель command prompt командная строка; подсказка, запрос команды resident program резидентная программа, постоянно находящаяся в оперативной памяти command driven приводимый в действие командой graphical user interface графический интерфейс пользователя software package пакет программ multi-user mainframe большие компьютеры с computers многопользовательской системой
multi-tasking mainframe большие компьютеры с computers многозадачным режимом
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