PMOS P-channel metal-oxide semiconductor.
PMS Planned Maintenance System.
POFA Programmed Operational Functional Anal-
POST Power-on self test.
PPS Primary power supply.
PREVENTIVE MAINTENANCE Maintenance
performed specifically to prevent faults from
PRF Pulse-repetition frequency.
PRINTER An output device that produces a
durable record of data in the form of a se-
quence of discrete graphic characters belonging
to a predetermined character set.
PRO M Programmable read-only memory.
PRT Pulse-repetition time.
PS Power supply.
PW Pulse width.
QMOS Quick metal-oxide semiconductor.
RAC Radar azimuth converter.
RAM Random access memory.
RC Request control.
RD Read data.
RDUC Receive data from unit computer.
RECORD A set of related data or words treated as
RAS Refresh address strobe.
REI Requester extension interface.
RFI Radio frequency interference.
RLL Run length limited. A fixed disk controller
and data encoding system that increases the
density of data on the disk.
ROCU Remote operator control unit.
ROM Read-only memory.
ROTOR The rotating member of a synchro that
consists of one or more coils of wires wound on
a laminated core. Depending on the type of
synchro, the rotor functions in a manner similar
to the primary or secondary windings of a
RS-232 Recommended standard 232. ANSI stand-
ard serial interface.
RS Recommended standard.
RTC Real-time clock.
RTS Request to send.
RZ Return-to-zero recording method.
SCSI Small computer systems interface.
SDC Signal data converter.
SEEK To selectively position the access mechan-
ism of a direct access device.
SEM Standard electronic module.
SEM CHASSIS Standard electronic module
SERIAL An occurrence of events, such as pulses,
in a timed sequence rather than simultaneously.
SERIAL PRINTER Synonym for character printer;
prints one character at a time.
SERVO SYSTEM An automatic feedback control
system that compares a required condition with
an actual condition and uses the difference to
adjust a control device to achieve the desired
SIMMs Single inline memory modules.