IBM AT 5170 Technical Reference page 475

personal computer. A small home or business computer that has
a processor and keyboard and that can be connected to a
television or some other monitor.
An
optional printer is usually
available.
phototransistor. A transistor whose switching action is
controlled by light shining on it.
picture element (PEL). The smallest displayable unit on a
display.
polling. (1) Interrogation of devices for purposes such as to
avoid contention, to determine operational status, or to deternline
readiness to send or receive data. (2) The process whereby
stations are invited, one at a time, to transmit.
port. An access point for data entry or exit.
positive true. Synonym for active high.
positive-going edge. The edge of a pulse or signal changing in a
positive direction. Synonymous with rising edge.
potentiometer. A variable resistor with three terminals, one at
each end and one on a slider (wiper).
power supply. A device that produces the power needed to
operate electronic equipment.
printed circuit. A pattern of conductors (corresponding to the
wiring of an electronic circuit) formed on a board of insulating
material.
printed-circuit board. A usually copper-clad plastic board used
to make a printed circuit.
priority. A rank assigned to a task that determines its
precedence in receiving system resources.
processing program. A program that performs such functions as
compiling, assembling, or translating for a particular programming
language.
Glossary-29