18WuD2x

146 control loop • convergence magnet
control loop See CONTROL TAPE.
control mark See TAPE MARK.
control panel 1. An accessible surface on which are
mounted switches, buttons, potentiometers, meters,
digital indicators, monitoring devices, and
other apparatus essential to regulating and supervising
an electronic system. 2. The console that a
computer operator or programmer uses to communicate
with the central processing unit (CPU).
control plate The metallic plate or disk that serves
as the antenna of a CAPACITANCE RELAY or
TOUCHPLATE RELAY.
control program A program that arranges computer-operation
programs in a certain order. Puts
information in the computer memory for later
use.
control rectifier A semiconductor diode device,
used for the purpose of switching large currents.
A small control signal can provide switching of
high-power devices.
control register In a computer, the register that
stores the address of the next instruction in the
program being run.
control sequence The order in which instructions
are executed in a digital computer.
control stack In a computer system, a unit of
hardware having storage locations and used to
perform arithmetic, assist in allocating memory
to programs, and to control internal processes.
control statement In a programming language, an
instruction that causes some action to be taken,
as specified by a condition; it is also applicable to
source program statements that affect the compiler’s
operation without modifying the machine
code.
control tape Punched paper or plastic tape in the
form of a closed loop and used to control printing
devices. Also called control loop.
control total For a file or record group, a total derived
during an operation; it is used to verify that
all the records have been processed similarly.
control transfer The situation in which the control
unit of a digital computer leaves the main sequence
of instructions and takes its next instruction
from an out-of-sequence address.
control transfer instruction See BRANCH IN-
STRUCTION.
control-voltage winding In a servomotor, the
winding that receives a varying voltage of a phase
different from that applied to the fixed-voltage
windings.
control winding In a magnetic amplifier, the winding
that conducts the control-signal current.
control word A word (a bit group) stored in a computer
memory and used for a control function.
convection The flow of a gas or liquid that results in
the transfer of heat from one location to another.
convection cooling The removal of excess heat
from a component, such as a power vacuum tube
or transistor, via upward movement of surrounding
air that has been heated by the component.
Transistor
Air currents
Air currents
convection
cooling
Heatsink
convection current 1. The motion of current carriers
or a charge across the surface of a conductor
or dielectric. 2. Air currents rising above a
heat source or heated body.
convective discharge The continuous highvoltage
current discharge across a spark gap.
convectron A device that indicates the angle, with
respect to the vertical, based on convection cooling
of a straight wire. The temperature difference
is greatest when the angle is 0 degrees (the wire is
vertical); the temperature difference decreases as
the angle increases, reaching a minimum at 90
degrees (when the wire is horizontal).
convenience outlet 1. In North America, a wall
outlet providing a nominal 117 volts alternating
current (ac) at 60 Hz for common household appliances.
2. An outlet in a laboratory that provides
power for a certain application.
conventional current The notion that current
flows from the positive pole to the negative pole in
an electric circuit. This representation is used
most often by physicists. Electron flow is opposite
to conventional current flow; positively charged
particles, such as holes, move in the same direction
as the conventional current.
convergence 1. The eventual meeting of values or
bodies at some point (sometimes at infinity, as in
certain mathematical series). 2. The intersection
point of the beams from separate electron guns in
a cathode-ray tube (CRT).
convergence coil One of a pair of coils used in a
color television receiver to produce dynamic beam
convergence (see CONVERGENCE, 2).
convergence control In a color television receiver,
a potentiometer in the high-voltage circuit for convergence
adjustment (see CONVERGENCE, 2).
convergence electrode An electrode that provides
an electrostatic field for converging electron
beams. Compare CONVERGENCE MAGNET.
convergence frequency The frequency of the last
member of a spectrum series.
convergence magnet An assembly that provides a
magnetic field to converge electron beams. Compare
CONVERGENCE ELECTRODE.