MPE/iX Glossary of Terms and Acronyms (32650-90887)

50 Chapter1
Glossary of Terms
peripheral A hardware device attached to and controlled by a computer, such as a
terminal, a tape or disk drive, or a printer.
permanent file A disk file that continues to exist even after a job or session logs off. To
delete the permanent file, it must be erased from the system with the
PURGE command or with the FCLOSE intrinsic.
permanent space Disk space reserved for use by permanent structures such as files, the
label table, or the free space map.
personal computer (PC) A portable microcomputer usually sold with software
packages useful in word processing, financial management, storing lists,
and other general usage business/personal activities.
physical layer Layer one of the Open Systems Interconnection (OSI) network model.
The physical layer transmits the electrical signals over the link.
physical record One or more logical records, treated as a unit when transmitted to or
from devices. The number of logical records contained in a single block is
determined by the blocking factor, specified when the file is first created
with the BUILD command or the FOPEN intrinsic.
physical unit (PU) In systems network architecture (SNA), the component that
manages and monitors the resources of a node.
pipelining A computer design technique that gives an effective execution rate of one
instruction per cycle. Pipelining exploits the fact that it is not necessary to
wait until one instruction has completed before the next can begin. Fetch,
execute, and load/store instructions can be executed on a three-stage
pipeline.
pixel A contraction for picture element. Any of the tiny elements that form a
digitized picture such as on a CRT screen. Each pixel represents the
degree of brightness assigned to a point in the picture.
platter A single disk coated with magnetic material. One or more platters are
mounted on a central spindle, and together they form a disk pack.
Information may be recorded on one or both sides of each platter within
the pack.
pointer The address of a piece of data or a data structure used by the programmer
in data manipulation.
point-to-point network A network in which communication travels from one node
(point) to another by a unique, unshared physical link. The opposite of
broadcast bus network.
polling In electronic mail or data communications, the systematic calling of
terminals to determine if messages are waiting to be transmitted or if the
terminal is ready to accept messages.
port An outlet from the computer used to connect the computer to peripheral
devices. A cable runs between the outlet and the device.
positional parameters One or more terms, appearing in a specific order on the
command line, that modify the intent or effect of the command. If a