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`ELECTRONICS
`ENGINEERING
`DICTIONARY
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`1
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`CRUSOE 1026
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`1
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`CRUSOE 1026
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`Copyright © 2004 by John Wiley & Sons, Inc. All rights reserved.
`
`Published by John Wiley & Sons, Inc., Hoboken, New Jersey.
`Published simultaneously in Canada.
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`NO part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by
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`Library of Congress Cataloging-in-Publication Data is available.
`
`Kaplan, Steven M.
`
`Wiley Electrical and Electronics Engineering Dictionary
`
`ISBN 0-471-40224-9
`
`Printed in the United States of America.
`
`10 9 8 7 6 5 4 3 2 1
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`2
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`control panel program
`
`convection cooling
`
`145
`set many_ s~stem par_ameters, such as keyboard and mouse
`charactensttcs, momtor resolution, and printer settin s.
`Also called control panel program.
`g
`control panel program Same as control panel (2).
`control parall_el A computer architecture in which multiple
`processors smmltaneously and independently execute d'f'C. _
`.
`.
`d'f'C.
`1 1er
`ent mstructions on 1 ,erent sets of data. Also called multi-
`ple instruction stream-multiple data stream.
`control point . In an automatic control system, the target value
`towards which the system makes adjustments. In the case of
`a thermostat, for instance, it would be a given temperature.
`control processor A processor used in a control system.
`control program A p~ogram which controls the operations of
`a computer, performmg tasks such as managing system re(cid:173)
`sources. An operating system is an example of such a pro(cid:173)
`gram.
`control register In a CPU, a register that contains the address
`of the location in memory that is to be accessed by the next
`instruction. May also refer to the address of the current in(cid:173)
`struction. Also called by various other names, including
`control counter, current-instruction register, program
`counter, program register, instruction register, instruc(cid:173)
`tion counter, and sequence register.
`control rod A material utilized to control the reactivity of a
`nuclear reactor by absorbing neutrons. Examples include
`gadolinium, boron, and europium.
`control room A room which houses the necessary devices
`and equipment to monitor and control a facility such as a TV
`recording studio or a nuclear power plant.
`control sequence The order in which computer instructions
`are executed. For instance, the sequence followed while
`performing a given task.
`control signal 1. A signal utilized to control a device or proc(cid:173)
`ess. In a computer, for instance, such a signal may be an in(cid:173)
`2. In telecommunications, a signal that
`terrupt request.
`transmits control information, For example, a customer
`picks up a telephone receiver, hears a dial tone, dials a se(cid:173)
`quence of digits, and then gets a busy signal. All the tones
`heard are control signals.
`control statement 1. A computer statement which controls
`the flow of execution of a program. For instance, an IF(cid:173)
`THEN statement. 2. Same as control instruction.
`control station Within a communications network, the station
`that manages all operations, such as the orderly flow of traf(cid:173)
`fic.
`control system A system utilized to maintain one or more
`output quantities within specified parameters. In a closed(cid:173)
`loop control system, a feedback signal is incorporated for
`this purpose, while in an open-loop control system there is
`no such feedback. The components of a control system may
`be electrical, mechanical, thermal, and so on.
`control total A total, composed of several numbers taken
`from a file which is calculated before, during, and after
`processing. ' The numbers utilized to calculate the total do
`not necessarily have to be taken from numeric data. Control
`totals are used to verify the accuracy of processed data, or to
`help ensure that transmitted messages have not been tam(cid:173)
`pered with. At all stages the calculated totals must match,
`otherwise there is an error. Also called hash total.
`control track A track on a recordable magnetic medium, such
`as a tape or a disk, containing control signals such as tape
`playback speed.
`control transformer A transfonner utilized to supply a con(cid:173)
`trol device.
`control unit I. Jn a computer, circuitry that ~erfonn~ control
`functions such as sending control signals, mterpr~tmg pro(cid:173)
`gram instructions, handling peripherals, or managmg access
`
`to memory locations. 2. A unit which controls a given
`mechanism, piece of equipment, function, process, or sys(cid:173)
`tem.
`control winding A winding that carries a current that controls
`the output of a machine.
`control word A computer word which stores information
`used for a control function.
`controlled-avalanche device A semiconductor device with
`precisely defined avalanche voltage characteristics. Such
`devices can absorb repeated momentary power surges with(cid:173)
`out damage.
`controlled-avalanche diode A semiconductor diode with
`precisely defined avalanche voltage characteristics. Such
`diodes can absorb repeated momentary power surges with(cid:173)
`out damage, and can be used, for instance, for surge sup(cid:173)
`pression.
`controlled-carrier modulation A type of amplitude modula(cid:173)
`tion in which the amplitude of the carrier wave is varied ac(cid:173)
`cording to the percentage of modulation, providing for an
`essentially constant modulation factor. Also called floating(cid:173)
`carrier modulation, or variable-carrier modulation.
`controlled environment An enclosure, such as a room, in
`which measures are taken to provide an environment that
`meets certain requirements, such as maintaining a specified
`level of temperature and/or humidity, guarding against static
`electricity or electromagnetic radiation, or isolating from
`dust. Such environments may be used, for instance, for test(cid:173)
`ing, or to protect sensitive electronic equipment.
`controlled-path robot A robot whose movements are dictated
`by a controlled-path system.
`controlled-path system A computer control system in which
`a path of movement is numerically described. Used, for in(cid:173)
`stance, in robotics.
`controlled rectifier A rectifier, such as a silicon-controlled
`rectifier, whose output current may be regulated.
`controller 1. A circuit board or device which controls the way
`peripheral devices access the computer, and vice versa. It is
`usually contained on a single chip. Examples include disk
`controllers, graphics controllers, and video controllers. Also
`called peripheral controller, or host adapter. 2. A signal,
`circuit, device, or system which controls any given mecha(cid:173)
`nism, function, process, or piece of equipment. An example
`is an infrared remote control for electronic equipment. 3. A
`circuit, mechanism, device, or system, which monitors one
`or more variables, and automatically makes the necessary
`adjustments in order to maintain operation within the speci(cid:173)
`fied parameters. Also known as automatic controller. 4. The
`computer and programs which control a robot. Also called
`controller system, or robot controller.
`controller card A circuit board which controls the way pe(cid:173)
`ripheral devices access the computer, and vice versa. Ex(cid:173)
`amples include disk controllers, graphics controllers, and
`SCSI controllers.
`controller system 1. A system which monitors one or more
`variables, and automatically makes the necessary adjust(cid:173)
`ments, in order to maintain operation within the specified
`parameters. 2. Same as controller (4).
`convection The transmission of energy or matter through a
`medium, which is itself moved. For instance, in convection
`cooling, the air transferring the heat moves along with the
`heat. This contrasts with conduction, where the medium
`itself is not moved as a whole, and with radiation, where
`waves or particles are emitted.
`convection cooling A process by which an object transfers
`heat to the surrounding air. The heated air is less dense,
`hence moving upward so that cooler air is then available for
`further cooling. Used, for instance, to cool components
`which generate heat, such as transistors.
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