18WuD2x

560 pseudo-offlining • pulling
pseudo-offlining During input/output operations
in a computer system, maximizing hardware by
disconnecting slow devices from the process in
question.
pseudo-operation In computer operations, an operation
that, rather than being performed by
hardware, is carried out by special software or by
macroinstruction.
pseudo-random numbers Numbers that, although
produced by a computer operating on an algorithm
for their generation, are useful for an application
requiring random numbers.
pseudo-stereophonic effect A somewhat heightened
binaural effect obtained when two loudspeakers
are situated, relative to the listener, so
that a transit-time difference of 1 to 30 milliseconds
results.
Short
path
Level
equalizer
Listener
Hi-fi
Amp.
Out
Long
path
pseudo-stereophonic effect
psf Abbreviation of pounds per square foot. (Also, lb
per sq ft, lb/ft 2 .)
psi 1. Abbreviation of pounds per square inch.
(Also, lb per sq in, lb/in 2 .)
psia Abbreviation of POUNDS PER SQUARE INCH
ABSOLUTE.
psig Abbreviation of POUNDS PER SQUARE INCH
GAUGE.
psi particle A massive elementary particle that
represents a resonance in an electron-positron
interaction.
PSK Abbreviation of PHASE-SHIFT KEYING.
PSM Abbreviation of pulse-spacing modulation,
more commonly called PULSE-INTERVAL MODU-
LATION.
psophometer A device used to measure noise in a
wire communications system. It provides quantitative
readings based on typical human observations.
psvm Abbreviation of phase-sensitive voltmeter.
PSWR Abbreviation of power standing-wave ratio.
psychoacoustics A field of acoustics, overlapping
with psychology, concerned with the effects of
sounds on human beings.
PT Abbreviation of Pacific Time.
Pt Symbol for PLATINUM.
PTC Abbreviation of POSITIVE TEMPERATURE
COEFFICIENT.
PtIr Symbol for PLATINIRIDIUM.
PTM Abbreviation of PULSE-TIME MODULATION.
PTO Abbreviation of PERMEABILITY-TUNED OS-
CILLATOR.
PTT Abbreviation for press-to-talk. See PRESS-TO-
TALK MICROPHONE; PRESS-TO-TALK SWITCH.
PTV Abbreviation of public television.
p-type conduction In a semiconductor, current
flow consisting of the movement of holes. Compare
N-TYPE CONDUCTION.
p-type material Semiconductor material that has
been doped with an acceptor-type impurity and,
consequently, conducts current mainly via hole
migration. Germanium, for example, when doped
with indium, becomes p-type. Compare N-TYPE
MATERIAL.
p-type semiconductor An acceptor-type semiconductor
(i.e., one containing an excess of holes in
its crystal lattice).
PU Abbreviation of PICKUP.
Pu Symbol for PLUTONIUM.
public-address amplifier A high-gain, high-power
audio amplifier designed especially for the reproduction
of speech and music at large gatherings.
public-address system A system of sound reproduction
especially designed for use at large gatherings
indoors or outdoors. The system includes
microphones, a public-address amplifier, loudspeakers,
and sometimes recorders and playback
devices. Also called PA system.
puck drive In a tape recorder, a speed-reduction
system for driving the flywheel from the shaft of
the (high-speed) motor. In some machines, a rubber
tire mounted on the flywheel is driven,
through friction, by the motor shaft. In others, an
intermediate rubber-tired wheel is placed between
the motor shaft and the rim of the flywheel.
puffer A meter or bridge for measuring small values
of capacitance. The name comes from the
spoken sound of pF, the abbreviation of PICO-
FARAD.
pulldown Descriptive of a circuit, device, or individual
component used to lower the value (e.g.,
impedance) of a circuit to which it is connected.
pull-in current The current required to close a relay.
pulling 1. The abnormal tendency of one circuit to
cause another to slip into tune with it. This often
results from coupling (intended or accidental)
that is too tight. Thus, when two oscillators feed a
common circuit, such as a mixer, one might pull
the other into tune with itself. 2. Lowering of a
crystal frequency by an external reactance.