Analog and digital computers

There are two fundamentally different types of computers – analog and digital. (Hybrid computers combine elements of both types.)

An analog computer solves problems by using continuously changing data (such as temperature, pressure, or voltage) rather than by means of manipulating binary digits as a digital computer does.

People design analog computers for specialized fields (hydrodynamics, aerodynamics, industrial control, etc.). For example, an automobile speedometer is a mechanical analog computer that measures the rotations per minute of the drive shaft¹ and translates that measurement into a display of kilometers (or miles) per hour. Electronic analog computers in chemical plants monitor temperatures, pressures, and flow rates² of chemicals. Although digital computers have replaced most analog computers, analog computers are still being used for flight control systems in aviation and space vehicles.

Digital computers solve problems by manipulating discrete binary digits. A computer can represent any type of data – from numbers and letters to musical notes and other symbols – in the binary code (i.e, using only the two digits 0 and 1 instead of the ten digits, 0–9, that are usually used in everyday life). This process is called digitization. In computer terms, binary digits are called bits. For example, if a number must have seven digits for its binary representation, we say that it contains seven bits. The term "bit" is an abbreviation for " B inary dig IT ". An 8-bit string is called a byte.

A desk lamp can serve as an example of the difference between analog and digital. If the lamp has a simple on/off switch, then the lamp system is digital, because the lamp either produces light at a given moment or it does not. If a dimmer³ replaces the on/off switch, then the lamp is analog, because the amount of light can vary continuously from on to off and all intensities in between.

Digital computers are generally more effective than analog computers for three main reasons: they are not as susceptible to signal interference; they can transmit data with more precision; and their coded binary data are easier to store and transfer than are analog signals.

Notes: ¹drive shaft – ведущий вал;

²flow rate – скорость потока;

³dimmer – регулятор силы света.

UNIT FOUR HARDWARE

Ex. 1. Practice the reading of the following words and phrases:

mechanical, organization, cable, parallel, decoder, to regulate, component, to coordinate, functional, result, arithmetic, logic, technology, to interpret, procedure, cycle, synchronized, hertz, gigahertz, physical, type, aluminum, ceramic, standard, encyclopedia, ideal, variation, version, command, alphabet, cursor, stationary, vertical, special, microphone, module;

audio reproduction, multimedia format, graphical object, television program, visual information, analog signal.

Ex. 2. Revise the following words from your school active vocabulary:

to differ, to change, to press, to follow, to show, to draw, to lose (information); button, dictionary, button, example, sound, level; square, rectangular, circular, most, sometimes.