PMOS— P-channel metal-oxide semiconductor.
PMS— Planned Maintenance System.
POFA— Programmed Operational Functional Anal-
ysis.
POST— Power-on self test.
PPS— Primary power supply.
PREVENTIVE MAINTENANCE— Maintenance
performed specifically to prevent faults from
occurring.
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— Resistance-capacitance.
RC— Request control.
RD— Read data.
RDUC— Receive data from unit computer.
RECORD— A set of related data or words treated as
a unit.
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
transformer.
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.
S/D— Synchro-to-digital.
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
chassis.
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
condition.
SIMMs— Single inline memory modules.
AI-8
