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PACKET SWITCHING. (ANSI/ISO) The process of routing and transferring data by means of addressed packets so that a channel is occupied only during the transmission of a packet; upon completion of the transmission, the channel is made available for the transfer of other packets.
PADDING. (1) (ANSI/ISO) A technique that incorporates fillers in data. (2) (ANSI) A technique that incorporates fillers into data. (2) (ANSI) A technique used to fill a field, record, or block with dummy data, usually zeroes or spaces.
PAGE PRINTER. (1) (ANSI/ISO) A printer that prints one page as a unit, e.g., COM printer; xerographic printer.
PAGING. (1) (ANSI/ISO) The transfer of pages between real storage and auxiliary storage. (2) (ANSI) An allocation technique by which main storage is divided into page frames. A computer program need not be located in contiguous page frames in order to be executed.
PARALLEL COMPUTER. (1) (ANSI) A computer that has multiple arithmetic or logic units that are used to accomplish parallel operations or parallel processing. (2) (ANSI) Contrast with serial computer.
PARALLEL PROCESSING. (1) (ANSI) The concurrent or simultaneous execution of two or more processes in a single unit. (2) (ANSI) Contrast with serial processing.
PARAMETER. (ANSI/ISO) A variable that is given a constant value for a specified application and that may denote the application.
PARITY BIT. (ANSI) A binary digit appended to a group of binary digits to make the sum of all the digits, including the appended binary digit, either odd or even, as predetermined.
PASSWORD. (ANSI/ISO) A character string that enables a user to have full or limited access to a system or to a set of data.
PATTERN RECOGNITION. (ANSI/ISO) The identification of shapes, forms, or configurations by automatic means.
PERIPHERAL UNIT. (ANSI) With respect to a particular processing unit, any equipment that can communicate directly with that unit. Syn: peripheral device.
PIXEL. (ANSI/ISO) The smallest element of a display surface that can be independently assigned color or intensity. Syn: picture element. (PEL)
PL/I. (ANSI) A programming language designed for use in a wide range of commercial and scientific computer applications.
PLOTTER. (ANSI/ISO) An output unit that presents data in the form of a two-dimensional graphic representation.
POLLING. (1) (ANSI/ISO) On a multipoint connection, the process whereby data stations are invited one at a time to transmit. (2) (ANSI) Interrogation of devices for purposes such as to avoid contention, to determine operational status, or to determine readiness to send or receive data.
PORTABILITY. (1) (ANSI) The ability to transfer data from one system to another without being required to recreate or reenter data descriptions or to significantly modify the application being transported. (2)
(ANSI) The ability of software or of a system to run on more than one type or size of computer or under more than one operating system. (3) (ANSI) Syn: transportability.
POSTPROCESSOR. (ANSI/ISO) A computer program that effects some final computation or organization.
PRECISION. (1) (ANSI/ISO) A measure of the ability to distinguish between nearly equal values; e.g., four-place numerals are less precise than six-place numerals; nevertheless, a properly computed four-placer numeral may be more accurate than an improperly computed six-place numeral. (2) (ANSI) The degree of discrimination with which a quantity is stated; e.g., a three-digit numeral discriminates among 1000 possibilities.
PREPROCESSOR. (ANSI/ISO) A computer program that effects some preliminary computation or organization.
PRINTER. (ANSI/ISO) An output unit that processes a durable record of data in the form of a sequence of discrete graphic characters belonging to a predetermined character set.
PRINT WHEEL. (ANSI/ISO) A rotating disk that presents characters at a single print position.
PROCEDURAL LANGUAGE. (See PROCEDURE-ORIENTED LANGUAGE.)
PROCEDURE-ORIENTED LANGUAGE. (ANSI) A problem-oriented language that facilitates the expression of a procedure as an explicit algorithm, e.g., FORTRAN, ALGOL, COBOL, PL/I. Syn: imperative language.
PROCESS CONTROL. (ANSI/ISO) Automatic control of a process, in which a computer system is used to regulate usually continuous operations or processes.
PROGRAM. (1) (ANSI/ISO) A sequence of instructions suitable for processing. Processing may include the use of an assembler, a compiler, an interpreter or another translator to prepare the program for execution; the instructions may include statements and necessary declarations. (2) (ANSI/ISO) To design, write, and test computer programs. (3) (ANSI) In programming languages, a set of one or more interrelated modules capable of being executed. (4) Loosely, a routine. (5) Loosely, to write a routine.
PROGRAMMABLE READ-ONLY MEMORY (PROM). (ANSI/ISO) A storage device that, after being written once, becomes a read-only memory.
PROGRAMMER. (ANSI) A person who designs, writes, and tests computer programs.
PROGRAMMING. (ANSI/ISO) The designing, writing, and testing of programs.
PROGRAMMING LANGUAGE. (ANSI/ISO) An artificial language designed to generate or to express programs.
PROM. (See PROGRAMMABLE READ-ONLY MEMORY.)
PROTOCOL. (ANSI/ISO) A set of semantic and syntactic rules that determines the behavior of functional units to achieve communication.
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