Text 15. Analog Versus Digital Computers

Even before the advent of the electronic digital computer, the analog computer was busy doing important jobs which could not be performed by desk calculators. For instance, instead of building a costly experimental model of an airplane and then running exhaus­tive wind-tunnel test, the whole “experiment” can be performed by the analog computer. Instead of using an actual airplane, design data for an airplane are fed into the analog computer. Instead of using a wind tunnel, formulas representing the effects produced by varying flight conditions are fed into the computer. The output of the analog computer is usually a curve representing results for a complete set of conditions. Effectively, the tests are performed without any hard­ware. Upon completion of one “experiment”, the computer is ready to perform a new “experiment”.

What exactly is an analog computer? or, more fundamentally, an analog device? An analog device is any device whose operation isanalogous to some physical quantity we want to measure. A thermo­meter is a simple analog device. It compares, or draws an analogy, between the expansion of mercury and temperature. A simple spring balance is another analog device. It compares the weight of an object with the force necessary to move a spring.

If an analogy can be formed between the operation of a device and a mathematical process, this device can form the basis for an analog computer. Many physical phenomena may be used to construct ana­log computers. But since electrons are so mobile, most present-day analog computers perform mathematical operations with the aid of electronic circuits. Electronic circuits have been built which perform operations analogous to those of addition, subtraction, multiplica­tion, division, and even higher mathematical operations such as inte­gration. For instance, to add 6 and 5, a 6-volt signal and a 5-volt signal are fed to an electronic adder. The circuit of the electronic adder is designed so that under these circumstances an 11-volt signal is produced as output

Notes

TEXTS (13) 1

(Радіотехніка і комп’ютерна 1

техніка) 1

АРІЙ 1

Radio Engineering 4

Text 1. Electronics 4

Text 2. Electron Emission 4

Text 5. Reception of Radio Signals 7

Text 6. Radio Receivers (I) 8

Text 8. Oscillators 8

Text 11. Detection 9

Text 13. Functions of Vacuum Tubes 10

Text 14. Basic Tube Types 11

Text 22. Bearing 13

Text 23. Transistors, the Basic Mechanism 13

Text 25. Transistor Radio Frequency Amplifiers 15

Text 1. The Computer 15

Text 2. Using the Computer 16

Text 3. Peripheral Equipment 16

Text 4. Computers on Wheels 17

Text 5. Programming a Computer 18

Text 6. The Robot’s Nervous System 19

Text 7. Menu System 19

Text 8. Input, Process, Store, Output 20

Text 10. Memory 22

Text 11. Automatic Translator 23

Text 12. Universal Electronic Computer 23

Text 13. What Is a Digital Computer? 24

Text 14. Digital Computers 24

Text 15. Analog Versus Digital Computers 25

Text 16. Age of Thinking Machines 27

Text 17. General- and Special-Purpose Computers 27

Text 18. Programming 28

Text 19. Types of Instructions 29

Text 20. Simple Hardware, Complicated Logic 30

Text 21. Machine Language and Language Structure 30

Text 23. Mechanical and Electronic Calculating Machines 32

проти

аналог; подібний

поява

виснажливий

тунель

completion [kam'plr/n] —

завершення

analogous [ae'naslagas] —

аналогічний; подібний

mercury ['maikjuri] —

ртуть

spring —

початок; пружина

mobile fmoubail] —

рухомий; рухливий

integration [^nta'grei/n] —

інтеграція