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program • promethium cell 557
(the necessary steps in solving a problem) that
can be implemented by a computer. 2. The content
of a radio or television broadcast during a
specified period of time. 3. In audio recording, the
composite output from the mixer, used to make
the master tape or disc.
program address counter See INSTRUCTION
REGISTER.
program amplifier A broadcast preamplifier used
at the studio or a remote location.
programatics The study of computer programming.
program circuit In wire telephony, a circuit capable
of handling music and other audio data that
covers a wide band of frequencies.
program compatibility The condition in which a
program written for one computer can be used
with another computer having a different architecture.
program controller In a central processor, a unit
that controls the sequence and execution of program
instructions.
program counter See CONTROL REGISTER.
program file A flexible reference system for software
library maintenance.
program flowchart A representation of a computer
program in the form of a flowchart. Each function
and transition point is indicated by a box in the
chart. A user can follow the flowchart and determine
the outcome of the program for any given
set of input parameters.
program library A collection of computer or programmable-calculator
programs. Usually, it
means the collection of programs used in a given
computer system, often a software package supplied
by the hardware vendor. It might also be a
catalog of programs with instructions for their use.
programmable calculator A calculator that can be
programmed to perform a chain of operations in a
given order repetitively.
programmable read-only memory In a computer,
a read-only memory (ROM) that can store a program.
program maintenance The ongoing correcting,
updating, and modification of computer programs
belonging to a system.
programmed dump A dump that occurs during a
program run, according to a program instruction.
programmed halt During a computer program
run, a temporary cessation resulting from an interrupt
or halt instruction.
programmed instruction See MACRO INSTRUC-
TION.
programmed timer See CYCLE TIMER.
programmer A person who writes computer programs.
program modification 1. In computer programming
operations, a change in the effect of instructions
and addresses during a program run by
performing arithmetic and logical operations on
them. 2. Rewriting, or adding a patch to, a computer
program. Also see PATCH, 3.
program register See CONTROL REGISTER.
program segment A unit within a computer program
that is stored with others in memory at the
time of the program’s execution, or sometimes, as
overlays loaded individually when the entire program
exceeds memory capacity.
program specification A description of the steps
involved in the solution of a problem, from which
a programmer devises a computer program.
program step An instruction in a computer program.
program tape In computer operations, a magnetic
or paper tape that contains programs for a system
or application.
program timer 1. A programmed timer (see CY-
CLE TIMER). 2. A timing unit that controls the
duration of a program.
progressive scanning Non-interlaced television
raster scanning, in which the lines are traced
from top to bottom in succession. Conventional
television broadcasting uses INTERLACED
SCANNING.
progressive wave A wave disturbance that travels
through a theoretically perfect homogeneous
medium. This can be a compression (longitudinal)
wave, a transverse wave, or an electromagnetic
wave.
projected cutoff For an amplifier circuit, the operating
point at which crossover distortion vanishes.
The direct-current bias voltage (grid or
gate) required for projected cutoff is somewhat
lower than the value corresponding to conventional
cutoff of plate or drain current.
project engineering A field of engineering dealing
with the coordination of a complete project.
projection television Large-screen television for
viewing by a relatively large group, usually accomplished
via a projection tube and optical system.
projection tube A cathode-ray tube, especially a
television picture tube, capable of producing a
bright image that can be projected onto a large
screen by means of a lens system.
projector 1. A device that transmits a visible image
onto a surface for reproduction. 2. In general, any
device that transmits a signal into space.
PROLOG Acronym for programming in logic. A
high-level computer programming language, similar
to LISP, used in artificial intelligence. The operator
inputs facts and rules; the computer, in
effect, derives theorems from the facts by following
the logical rules.
PROM Abbreviation of PROGRAMMABLE READ-
ONLY MEMORY.
promethium Symbol, Pm. A metallic element of
the rare-earth group, produced artificially.
Atomic number, 61. Atomic weight, approximately
145. Formerly called illinium.
promethium cell A radioactive battery cell using
an isotope of promethium. Radioactive particles
from this substance strike a phosphor, causing it