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Glossary Of Computer Terms
A B C D
E F G H I J K L M N O
P Q R S T U V W X Y Z
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P5: n. Intel Corporation's internal working name for the Pentium microprocessor.
Although it was not intended to be used publicly, the name P5 leaked out to the computer-industry trade press and
was commonly used to reference the microprocessor before it was released. See also 586, Pentium.
packet: n. 1. A unit of information transmitted as a whole from one device
to another on a network. 2. In packet-switching networks, a transmission unit of fixed maximum size that consists
of binary digits representing both data and a header containing an identification number, source and destination
addresses, and sometimes error-control data. See also packet switching.
packet assembler/disassembler: n. An interface between non-packet-switching
equipment and a packet-switching network. Acronym: PAD.
Packet Internet Groper: n. See ping1 (definition 1).
packet switching: n. A message-delivery technique in which small units of information
(packets) are relayed through stations in a computer network along the best route available between the source
and the destination. A packet-switching network handles information in small units, breaking long messages into
multiple packets before routing. Although each packet may travel along a different path, and the packets composing
a message may arrive at different times or out of sequence, the receiving computer reassembles the original message.
Packet-switching networks are considered to be fast and efficient. To manage the tasks of routing traffic and assembling/disassembling
packets, such a network requires some "intelligence" from the computers and software that control delivery.
The Internet is an example of a packet-switching network. Standards for packet switching on networks are documented
in the CCITT recommendation X.25.
PAD: n. Portable Application Description, or PAD for short, is a data set that
is used by shareware authors to disseminate information to anyone interested in their software products. To find
out more go to http://www.asp-shareware.org. Also see packet assembler/disassembler.
page: n. 1. In word processing, the text and display elements to be printed
on one side of a sheet of paper, subject to formatting specifications such as depth, margin size, and number of
columns. 2. A fixed-size block of memory. When used in the context of a paging memory system, a page is a block
of memory whose physical address can be changed via mapping hardware. See also EMS, memory management unit, virtual
memory. 3. In computer graphics, a portion of display memory that contains one complete full-screen image; the
internal representation of a screenful of information.
page break: n. The point at which the flow of text in a document moves to the
top of a new page. Most word processors automatically place page breaks when the material on the page reaches a
specified maximum. By contrast, a "hard" or "manual" page break is a command or code inserted
by the user to force a page break at a specific place in the text. See also form feed.
paged address: n. In the 80386, i486, and Pentium paged-memory architecture,
an address in memory created by combining the process of segment translation and page translation. In the paged-memory
scheme, which requires that the microprocessor's paging feature be enabled, logical addresses are transformed into
physical addresses in two steps: segment translation and page translation. The first step, segment translation,
converts a logical to a linear address--an address that refers indirectly to a physical address. After the linear
address is obtained, the microprocessor's paging hardware converts the linear address to a physical address by
specifying a page table (an array of 32-bit page specifiers), a page (a 4-KB unit of contiguous addresses within
physical memory) within that table, and an offset within that page. This information collectively refers to a physical
Page Down key: n. A standard key (often labeled "PgDn") on most computer
keyboards whose specific meaning is different in different programs. In many cases, it moves the cursor down to
the top of the next page or a specific number of lines.
page fault: n. The interrupt that occurs when software attempts to read from
or write to a virtual memory location that is marked "not present." The mapping hardware of a virtual
memory system maintains status information about every page in the virtual address space. A page either is mapped
onto a physical address or is not present in physical memory. When a read or write to an unmapped virtual address
is detected, the memory management hardware generates the page fault interrupt. The operating system must respond
to the page fault by swapping in the data for the page and updating the status information in the memory management
unit. See also page (definition 2), swap (definition 2), virtual memory.
page layout: n. In desktop publishing, the process of arranging text and graphics
on the pages of a document. Page-layout programs excel in text placement and management of special effects applied
to text. Although page-layout programs are generally slower than word-processing programs, they can perform such
advanced tasks as flowing text into complex multicolumn page designs, printing documents in signatures, managing
color separations, and supporting sophisticated kerning and hyphenation.
page makeup: n. The assembling of graphics and text on a page in preparation
Page Up key: n. A standard key (often labeled "PgUp") on most computer
keyboards whose specific meaning is different in different programs. In many cases, it moves the cursor up to the
top of the previous page or a specific number of lines.
paging: n. A technique for implementing virtual memory. The virtual address
space is divided into a number of fixed-size blocks called pages, each of which can be mapped onto any of the physical
addresses available on the system. Special memory management hardware (MMU or PMMU) performs the address translation
from virtual addresses to physical addresses. See also memory management unit, paged memory management unit, virtual
paint1: n. A color and pattern used with graphics programs to fill areas of
a drawing, applied with tools such as a paintbrush or a spraycan.
paint2: vb. To fill a portion of a drawing with paint.
paintbrush: n. An artist's tool in a paint program or another graphics application
for applying a streak of solid color to an image. The user can usually select the width of the streak. See also
paint program. Compare spraycan.
palmtop: n. A portable personal computer whose size enables it to be held in
one hand while it is operated with the other hand. A major difference between palmtop computers and laptop computers
is that palmtops are usually powered by off-the-shelf batteries such as AA cells. Palmtop computers typically do
not have disk drives; rather, their programs are stored in ROM and are loaded into RAM when they are switched on.
More recent palmtop computers are equipped with PCMCIA slots to provide wider flexibility and greater capability.
See also handheld PC, PCMCIA slot, portable computer. Compare laptop.
Pantone Matching System: n. In graphic arts and printing, a standard system
of ink color specification consisting of a swatch book in which each of about 500 colors is assigned a number.
See also color model. Acronym: PMS.
PAP: n. 1. Acronym for Password Authentication Protocol. A method for verifying
the identity of a user attempting to log on to a Point-to-Point Protocol (PPP) server. PAP is used if a more rigorous
method, such as the Challenge Handshake Authentication Protocol (CHAP), is not available or if the user name and
password that the user submitted to PAP must be sent to another program without encryption. 2. Acronym for Printer
Access Protocol. The protocol in AppleTalk networks that governs communication between computers and printers.
paper feed: n. A mechanism that moves paper through a printer. In laser printers
and other page printers, the paper feed is usually a series of rollers that firmly grip and align the paper. In
dot-matrix printers, the paper feed is usually a pin feed or tractor feed, in which small pins drag or push paper
that has detachable edges punched with sprocket holes. Friction feed is another type of paper feed, in which the
paper is gripped between the platen and pressure rollers and pulled by rotation of the platen.
paperless office: n. The idealized office in which information is entirely
stored, manipulated, and transferred electronically rather than on paper.
paradigm: n. An archetypical example or pattern that provides a model for a
process or system.
paragraph: n. 1. In word processing, any part of a document preceded by one
paragraph mark and ending with another. To the program, a paragraph represents a unit of information that can be
selected as a whole or given formatting distinct from the surrounding paragraphs. 2. On IBM and other computers
built around the Intel 8088 or 8086 microprocessor, a 16-byte section of memory beginning at a location (address)
that can be divided evenly by 16 (hexadecimal 10).
parallel: adj. 1. Of or relating to electronic circuits in which the corresponding
terminals of two or more components are connected. 2. In geometry and graphics, of, relating to, or being lines
that run side by side in the same direction in the same plane without intersecting. 3. In data communications,
of, relating to, or being information that is sent in groups of bits over multiple wires, one wire for each bit
in a group. See also parallel interface. Compare serial. 4. In data handling, of or relating to handling more than
one event at a time, with each event having its own portion of the system's resources. See also parallel processing.
parallel computing: n. The use of multiple computers or processors to solve
a problem or perform a function. See also array processor, massively parallel processing, pipeline processing,
parallel port: n. The input/output connector for a parallel interface device.
See also input/output port.
parallel printer: n. A printer that is connected to the computer via a parallel
interface. In general, a parallel connection can move data between devices faster than a serial connection can.
The parallel interface is preferred in the IBM PC world because its cabling is more standardized than that of the
serial interface and because the MS-DOS operating system assumes that the system printer is attached to the parallel
port. See also parallel interface. Compare serial printer.
parallel server: n. A computer system that implements some form of parallel
processing to improve its performance as a server. See also SMP server.
parallel transmission: n. The simultaneous transmission of a group of bits
over separate wires. With microcomputers, parallel transmission refers to the transmission of 1 byte (8 bits).
The standard connection for parallel transmission is known as the Centronics interface. See also Centronics parallel
interface. Compare serial transmission.
parameter: n. In programming, a value that is given to a variable, either at
the beginning of an operation or before an expression is evaluated by a program. Until the operation is completed,
a parameter is effectively treated as a constant value by the program. A parameter can be text, a number, or an
argument name assigned to a value that is passed from one routine to another. Parameters are used as a means of
customizing program operation. See also argument, pass by address, pass by value, routine.
PARC: n. See Xerox PARC.
parity: n. The quality of sameness or equivalence, in the case of computers
usually referring to an error-checking procedure in which the number of 1s must always be the same--either even
or odd--for each group of bits transmitted without error. If parity is checked on a per-character basis, the method
is called vertical redundancy checking, or VRC; if checked on a block-by-block basis, the method is called longitudinal
redundancy checking, or LRC. In typical modem-to-modem communications, parity is one of the parameters that must
be agreed upon by sending and receiving parties before transmission can take place. Types of parity are shown in
the following table. See also parity bit, parity check, parity error. k:\compdict\database\2297.doc
parity bit: n. An extra bit used in checking for errors in groups of data bits
transferred within or between computer systems. With microcomputers, the term is frequently encountered in modem-to-modem
communications, in which a parity bit is often used to check the accuracy with which each character is transmitted,
and in RAM, where a parity bit is often used to check the accuracy with which each byte is stored.
parity check: n. The use of parity to check the accuracy of transmitted data.
See also parity, parity bit.
parity error: n. An error in parity that indicates an error in transmitted
data or in data stored in memory. If a parity error occurs in communications, all or part of a message must be
retransmitted; if a parity error occurs in RAM, the computer usually halts. See also parity, parity bit.
park: vb. To position the read/write head over a portion of a disk that stores
no data (and therefore can never be damaged) or beyond the surface of the disk, prior to shutting down the drive,
especially in preparation for moving it. Parking can be performed manually, automatically, or, most typically,
by a disk utility program.
parse: vb. To break input into smaller chunks so that a program can act upon
partition: n. 1. A logically distinct portion of memory or a storage device
that functions as though it were a physically separate unit. 2. In database programming, a subset of a database
table or file.
Pascal: n. A concise procedural language designed between 1967 and 1971 by
Niklaus Wirth. Pascal, a compiled, structured language built upon ALGOL, simplifies syntax while adding data types
and structures such as subranges, enumerated data types, files, records, and sets. See also ALGOL, compiled language.
password: n. A security measure used to restrict access to computer systems
and sensitive files. A password is a unique string of characters that a user types in as an identification code.
The system compares the code against a stored list of authorized passwords and users. If the code is legitimate,
the system allows the user access at whatever security level has been approved for the owner of the password.
Password Authentication Protocol: n. See PAP (definition 1).
password protection: n. The use of passwords as a means of allowing only authorized
users access to a computer system or its files.
paste: vb. To insert text or a graphic that has been cut or copied from one
document into a different location in the same or a different document. See also cut, cut and paste.
patch1: n. A piece of object code that is inserted in an executable program
as a temporary fix of a bug.
patch2: vb. In programming, to repair a deficiency in the functionality of
an existing routine or program, generally in response to an unforeseen need or set of operating circumstances.
Patching is a common means of adding a feature or a function to a program until the next version of the software
is released. Compare hack (definition 2), kludge (definition 2).
path: n. 1. In communications, a link between two nodes in a network. 2. A
route through a structured collection of information, as in a database, a program, or files stored on disk. 3.
In programming, the sequence of instructions a computer carries out in executing a routine. 4. In information processing,
such as the theory underlying expert (deductive) systems, a logical course through the branches of a tree of inferences
leading to a conclusion. 5. In file storage, the route followed by the operating system through the directories
in finding, sorting, and retrieving files on a disk. 6. In graphics, an accumulation of line segments or curves
to be filled or drawn.
pattern recognition: n. 1. A broad technology describing the ability of a computer
to identify patterns. The term usually refers to computer recognition of visual images or sound patterns that have
been converted to arrays of numbers. 2. The recognition of purely mathematical or textual patterns.
Pause key: n. 1. A key on a keyboard that temporarily stops the operation of
a program or a command. The Pause key is used, for example, to halt scrolling so that a multiscreen listing or
document can be read. 2. Any key that creates a pause in an operation. For example, many game programs have a Pause
key, often simply the P key, that temporarily suspends the game.
PBX: n. Acronym for Private Branch Exchange. An automatic telephone switching
system that enables users within an organization to place calls to each other without going through the public
telephone network. Users can also place calls to outside numbers.
PC: n. 1. A microcomputer that conforms to the standard developed by IBM for
personal computers, which uses a microprocessor in the Intel 80x86 family (or compatible) and can execute the BIOS.
See also 8086, BIOS, clone, IBM PC. 2. A computer in IBM's Personal Computer line. Also called IBM PC. See also
PC-compatible (definition 1). See personal computer.
PC Card: n. A trademark of the Personal Computer Memory Card International
Association (PCMCIA) that is used to describe add-in cards that conform to the PCMCIA specification. A PC Card
is a removable device, approximately the same size as a credit card, that is designed to plug into a PCMCIA slot.
Release 1 of the PCMCIA specification, introduced in June 1990, specified a Type I card that is 3.3 millimeters
thick and is intended to be used primarily as a memory-related peripheral. Release 2 of the PCMCIA specification,
introduced in September 1991, specifies both a 5-millimeter-thick Type II card and a 10.5-millimeter-thick Type
III card. Type II cards accommodate devices such as modem, fax, and network cards. Type III cards accommodate devices
that require more space, such as wireless communications devices and rotating storage media (such as hard disks).
See also PCMCIA, PCMCIA slot.
PC-compatible: adj. Conforming to IBM PC/XT and PC/AT hardware and software
specifications, which has been the de facto standard in the computing industry for personal computers that use
the Intel 80x86 family or compatible chips. Most PC-compatible computers today are developed outside of IBM; they
are still sometimes referred to as clones. Also called IBM PC. See also 8086, clone, de facto standard, IBM AT.
PC-DOS: n. Acronym for Personal Computer Disk Operating System. The version
of MS-DOS sold by IBM. MS-DOS and PC-DOS are virtually identical, although filenames of utility programs sometimes
differ in the two versions. See also MS-DOS.
PCI local bus: n. Short for Peripheral Component Interconnect local bus. A
specification introduced by Intel Corporation that defines a local bus system that allows up to 10 PCI-compliant
expansion cards to be installed in the computer. A PCI local bus system requires the presence of a PCI controller
card, which must be installed in one of the PCI-compliant slots. Optionally, an expansion bus controller for the
system's ISA, EISA, or Micro Channel Architecture slots can be installed as well, providing increased synchronization
over all the system's bus-installed resources. The PCI controller can exchange data with the system's CPU either
32 bits or 64 bits at a time, depending on the implementation, and it allows intelligent, PCI-compliant adapters
to perform tasks concurrently with the CPU using a technique called bus mastering. The PCI specification allows
for multiplexing, a technique that permits more than one electrical signal to be present on the bus at one time.
See also local bus. Compare VL bus.
PCL: n. See Printer Control Language.
PCMCIA: n. Acronym for Personal Computer Memory Card International Association.
A group of manufacturers and vendors formed to promote a common standard for PC Card-based peripherals and the
slot designed to hold them, primarily on laptop, palmtop, and other portable computers, as well as for intelligent
electronic devices. PCMCIA is also the name of the standard for PC Cards, first introduced in 1990 as release 1.
See also PC Card, PCMCIA slot.
PCMCIA connector: n. The 68-pin female connector inside a PCMCIA slot designed
to hold the 68-pin male connector on a PC Card. See also PC Card, PCMCIA slot.
PCMCIA slot: n. An opening in the housing of a computer, peripheral, or other
intelligent electronic device designed to hold a PC Card. Also called PC Card slot. See also PC Card, PCMCIA connector.
PC memory card: n. 1. An add-in circuit card that increases the amount of RAM
in a system. See also memory card. 2. A Type I PC Card as specified by PCMCIA. In this context, such a card consists
of conventional static RAM chips powered by a small battery and is designed to provide additional RAM to the system.
See also PC Card. Compare flash memory.
PCX: n. A graphical file format that compresses its image data with RLE-type
compression, used by early versions of Windows Paintbrush.
PC/XT: n. The original IBM Personal Computer, introduced in 1981, which used
the Intel 8088 CPU. See also IBM PC.
PC/XT keyboard: n. The original keyboard for the IBM Personal Computer. Strong,
reliable, and equipped with 83 keys, the PC/XT keyboard offers a typist an audible click. See also IBM PC, PC/XT.
PDA: n. Acronym for Personal Digital Assistant. A lightweight palmtop computer
designed to provide specific functions like personal organization (calendar, note taking, database, calculator,
and so on) as well as communications. More advanced models also offer multimedia features. Many PDA devices rely
on a pen or other pointing device for input instead of a keyboard or mouse, although some offer a keyboard too
small for touch typing to use in conjunction with a pen or pointing device. For data storage, a PDA relies on flash
memory instead of power-hungry disk drives. See also firmware, flash memory, PC Card, pen computer.
PDC: n. See Primary Domain Controller.
PDF: n. See Portable Document Format.
PDL: n. See page-description language.
PDM: n. See pulse duration modulation.
PDO: n. See Portable Distributed Objects.
peer: n. Any of the devices on a layered communications network that operate
on the same protocol level. See also network architecture.
peer-to-peer architecture: n. A network of two or more computers that use the
same program or type of program to communicate and share data. Each computer, or peer, is considered equal in terms
of responsibilities and each acts as a server to the others in the network. Unlike a client/server architecture,
a dedicated file server is not required. However, network performance is generally not as good as under client/server,
especially under heavy loads. Also called peer-to-peer network. See also peer, peer-to-peer communications, server.
Compare client/server architecture.
peer-to-peer communications: n. Interaction between devices that operate on
the same communications level on a network based on a layered architecture. See also network architecture.
pel: n. Short for picture element. See pixel.
Pentium: n. A microprocessor introduced by Intel Corporation in March 1993
as the successor to the i486. The Pentium is a superscalar, CISC-based microprocessor containing 3.3 million transistors.
The Pentium has a 32-bit address bus, a 64-bit data bus, a built-in floating-point unit and memory management unit,
two built-in 8-KB L1 caches, and a System Management Mode (SMM), which provides the microprocessor with the ability
to slow or halt some system components when the system is idle or performing non-CPU-intensive tasks, thereby lessening
power consumption. The Pentium also employs branch prediction, resulting in faster system performance. In addition,
the Pentium has some built-in features to ensure data integrity, and it supports functional redundancy checking
(FRC). See also branch prediction, CISC, functional redundancy checking, i486DX, L1 cache, microprocessor, P5,
superscalar. Compare Pentium Pro (definition 1).
Pentium Pro: n. 1. Intel's 150-200 MHz family of 32-bit processors, released
in November 1995. The Pentium Pro is considered the next generation of processors in the 8086 family, following
the Pentium, and is designed for running 32-bit operating systems and applications. See also 32-bit application,
32-bit operating system, 8086, microprocessor, Pentium. 2. A PC that has a Pentium Pro processor.
Pentium upgradable: n. 1. An i486 motherboard capable of being adapted to run
a Pentium-class processor. See also i486DX, microprocessor, motherboard, Pentium. 2. A 486 PC that can be upgraded
to Pentium class by adding a Pentium processor. See also i486DX.
performance monitor: n. A process or program that appraises and records status
information about various system devices and other processes.
period: n. The length of time required for an oscillation to complete one full
cycle. For an oscillation electrical signal, the period is the time between waveform repetitions. If f is the frequency
of oscillation in hertz, and t is the period in seconds, then t = 1/f.
peripheral: n. In computing, a device, such as a disk drive, printer, modem,
or joystick, that is connected to a computer and is controlled by the computer's microprocessor. Also called peripheral
device. See also console.
peripheral power supply: n. An auxiliary source of electricity used by a computer
or a device as a backup in case of a power failure. Acronym: PPS.
Perl: n. Acronym for Practical Extraction and Report Language. An interpreted
language, based on C and several UNIX utilities. Perl has powerful string-handling features for extracting information
from text files. Perl can assemble a string and send it to the shell as a command; hence, it is often used for
system administration tasks. A program in Perl is known as a script. Perl was devised by Larry Wall at NASA's Jet
permanent storage: n. A recording medium that retains the data recorded on
it for long periods of time without power. Ink on paper is by far the most widely used permanent storage, but data
can be transferred from paper to a computer only with difficulty. Typically, some form of magnetic medium, such
as floppy disk or tape, is preferable. Magnetic media are generally accepted as permanent, even though the magnetic
fields that encode data in the media tend to fade eventually (in five years or more). See also nonvolatile memory.
permanent swap file: n. In Windows, a file composed of contiguous disk sectors
used for virtual memory operations. See also swap file, virtual memory.
permission: n. In a networked or multiuser computer environment, the ability
of a particular user to access a particular resource by means of his or her user account. Permissions are granted
by the system administrator or other authorized person; these permissions are stored in the system (often in a
file called a permissions log) and are checked when a user attempts to access a resource.
persistent link: n. See hot link (definition 1).
personal certificate: n. In Microsoft Internet Explorer, a personal certificate
guarantees that you are who you say you are. You specify information about yourself, such as your user name and
password. This information is used when you send personal information over the Internet to a Web site that requires
a certificate verifying your identity.See also certificate, digital ID, web site certificate.
personal computer: n. A computer designed for use by one person at a time.
Personal computers do not need to share the processing, disk, and printer resources of another computer. IBM PC-compatible
computers and Apple Macintoshes are both examples of personal computers. Acronym: PC.
peta-: prefix. Abbreviated P. Denotes 1 quadrillion (1015). In computing, which
is based on the binary (base-2) numbering system, peta- has a literal value of 1,125,899,906,842,624, which is
the power of 2 (250) closest to 1 quadrillion.
petabyte: n. Abbreviated PB. Either 1 quadrillion bytes or 1,125,899,906,842,624
PGP: n. Acronym for Pretty Good Privacy. A program for public key encryption,
using the RSA algorithm, developed by Philip Zimmermann. PGP software is available in unsupported free versions
and supported commercial versions from Pretty Good Privacy, Inc., Redwood Shores, Calif. See also privacy, public
key encryption, RSA encryption.
phase modulation: n. A method of imposing information onto a waveform signal
by shifting the phase of the wave to represent information, such as the binary digits 0 and 1. See also phase-shift
Phoenix BIOS: n. An IBM-compatible ROM BIOS manufactured by Phoenix Technologies,
Ltd. A popular ROM BIOS in many so-called PC "clone" computers, the Phoenix BIOS was an early leader
in IBM-compatible computers shortly after they began to appear in the marketplace. See also BIOS, ROM BIOS. Compare
phone connector: n. An attachment, usually an RJ-11 connector, used to join
a telephone line to a device such as a modem.
PhotoCD: n. A digitizing system from Kodak that allows 35mm film pictures,
negatives, slides, and scanned images to be stored on a compact disc. Images are stored in a file format called
Kodak PhotoCD IMAGE PAC File Format, or PCD. Many photography or film development businesses offer this service.
Images stored on a PhotoCD can usually be viewed by any computer with CD-ROM capabilities and the software required
to read PCD. Such images can also be viewed using one of a variety of players designed to display images stored
photo editor: n. A graphics application used to manipulate an image, such as
a scanned photograph, digitally.
photorealism: n. The process of creating images that are as close to photographic
or "real-life" quality as possible. In computer graphics, photorealism requires powerful computers and
highly sophisticated software and is heavily mathematical. See also ray tracing.
phototypesetter: n. A printer similar to a laser printer but capable of resolutions
over 2000 dots per inch. Phototypesetters apply light directly to a photographic film or photosensitive paper.
See also photocomposition. Compare imagesetter.
physical: adj. In computing, of, pertaining to, or characteristic of a real,
as opposed to a conceptual, piece of equipment or frame of reference. Compare logical (definition 2).
physical address: n. An address that corresponds to a hardware memory location.
In simple processors such as the 8088 and the 68000, every address is a physical address. In processors supporting
virtual memory, programs reference virtual addresses, which are then mapped by memory management hardware onto
physical addresses. See also memory management unit, paging, virtual memory.
physical layer: n. The first, or lowest, of the seven layers in the International
Organization for Standardization's Open Systems Interconnection (OSI) model for standardizing computer-to-computer
communications. The physical layer is totally hardware-oriented and deals with all aspects of establishing and
maintaining a physical link between communicating computers. Among specifications covered on the physical layer
are cabling, electrical signals, and mechanical connections. See also ISO/OSI model.
physical memory: n. Memory actually present in the system, as opposed to virtual
memory. A computer might have only 4 megabytes of physical RAM but support a virtual memory capacity of 20 MB.
Compare virtual memory.
PIC: n. See programmable interrupt controller.
pica: n. 1. With reference to typewriters, a fixed-width type font that fits
10 characters to the linear inch. See also pitch (definition 1). 2. As used by typographers, a unit of measure
equal to 12 points or approximately 1/6 inch. See also point1 (definition 1).
pico-: prefix. Abbreviated p. Denotes one trillionth (10-12), or, in the British
numbering system, one million millionth.
picoJava: n. A microprocessor developed by Sun Microsystems, Inc., that executes
Java code. See also Java.
picosecond: n. Abbreviated psec. One trillionth of a second.
PICS: n. Acronym for Platform for Internet Content Selection. A standard for
enabling users to filter their Web access automatically using software (such as Internet Explorer 3.0) that detects
codes for ratings in the sites' HTML files. In addition to filtering out undesirable material, PICS can be used
to screen sites according to whether they contain material of interest. Several rating systems, emphasizing different
sets of criteria, are in use.
PICT: n. A file-format standard for encoding graphical images, both object-oriented
and bitmapped. The PICT file format was first used in Apple Macintosh applications, but many IBM PC-compatible
applications can read the format too. See also bitmapped graphics, object-oriented graphics.
PID: n. Short for product identification number.
pie chart: n. A type of graph that presents values as percentages (slices)
of a whole (a pie).
PIM: n. Acronym for personal information manager. An application that usually
includes an address book and organizes unrelated information, such as notes, appointments, and names, in a useful
pin: n. A slender prong. Pins are commonly encountered as the contacts protruding
from a male connector. Connectors are often identified by the number of pins they have. Other types of pins are
the spidery, leglike metal appendages that connect computer chips to sockets on a circuit board or directly to
the circuit board.
PIN: n. Acronym for personal identification number. A unique code number assigned,
as with automatic teller machine cards, to the authorized user.
ping1: n. 1. Acronym for Packet Internet Groper. A protocol for testing whether
a particular computer is connected to the Internet by sending a packet to its IP address and waiting for a response.
The name actually comes from submarine active sonar, where a sound signal--called a "ping"--is broadcast,
and surrounding objects are revealed by their reflections of the sound. 2. A UNIX utility that implements the ping
ping2: vb. 1. To test whether a computer is connected to the Internet using
the ping utility. 2. To test which users on a mailing list are current by sending e-mail to the list asking for
Ping of Death: n. A form of Internet vandalism that entails sending a packet
that is substantially larger than the usual 64 bytes over the Internet via the ping protocol to a remote computer.
The size of the packet causes the computer to crash or reboot. See also packet (definition 2), ping1 (definition
pinout: n. A description or diagram of the pins of a chip or connector. See also pin.
pipe: n. 1. A portion of memory that can be used by one process to pass information
along to another. Essentially, a pipe works like its namesake: it connects two processes so that the output of
one can be used as the input to the other. See also input stream, output stream. 2. The vertical line character
(|) that appears on a PC keyboard as the shift character on the backslash (\) key. 3. In UNIX, a command function
that transfers the output of one command to the input of a second command.
pipeline processing: n. A method of processing on a computer that allows fast
parallel processing of data. This is accomplished by overlapping operations using a pipe, or a portion of memory
that passes information from one process to another. See also parallel processing, pipe (definition 1), pipelining
piracy: n. 1. The theft of a computer design or program. 2. Unauthorized distribution
and use of a computer program.
pixel: n. Short for picture (pix) element. One spot in a rectilinear grid of
thousands of such spots that are individually "painted" to form an image produced on the screen by a
computer or on paper by a printer. A pixel is the smallest element that display or print hardware and software
can manipulate in creating letters, numbers, or graphics. Also called pel.
pixel image: n. The representation of a color graphic in a computer's memory.
A pixel image is similar to a bit image, which also describes a screen graphic, but a pixel image has an added
dimension, sometimes called depth, that describes the number of bits in memory assigned to each on-screen pixel.
pixel map: n. A data structure that describes the pixel image of a graphic,
including such features as color, image, resolution, dimensions, storage format, and number of bits used to describe
each pixel. See also pixel, pixel image.
PKUNZIP: n. A shareware utility program that uncompresses files compressed
by the PKZIP shareware utility program. PKUNZIP is generally made available with PKZIP; distribution of PKUNZIP
for commercial purposes is not permitted without permission from its publisher, PKware, Inc. See also PKZIP.
PKZIP: n. A widely used shareware utility program for compressing files. Developed
by PKware, Inc., in 1989 and available from a wide variety of sources, PKZIP can combine one or more files into
a compressed output file having the extension .zip. A companion utility program, PKUNZIP, is required to uncompress
the compressed files. See also PKUNZIP, shareware, utility program.
PLA: n. Acronym for programmable logic array. See field-programmable logic
plaintext: n. 1. Nonencrypted or decrypted text. See also decryption, encryption.
2. A file that is stored as plain ASCII data.
plain vanilla: adj. Ordinary; the standard version of hardware or software
without any enhancements. For example, a plain vanilla modem might have data transfer capability but no fax or
platform: n. 1. The foundation technology of a computer system. Because computers
are layered devices composed of a chip-level hardware layer, a firmware and operating-system layer, and an applications
program layer, the bottommost layer of a machine is often called a platform. 2. In everyday usage, the type of
computer or operating system being used.
platter: n. One of the individual metal data storage disks within a hard disk
drive. Most hard disks have from two to eight platters. See also hard disk.
PL/C: n. A version of the PL/I programming language developed at Cornell University
and used on mainframe computers. See also PL/I.
plot: vb. To create a graphic or a diagram by connecting points representing
variables (values) that are defined by their positions in relation to a horizontal (x) axis and a vertical (y)
axis (and sometimes a depth, or z, axis).
plotter: n. Any device used to draw charts, diagrams, and other line-based
graphics. Plotters use either pens or electrostatic charges and toner. Pen plotters draw on paper or transparencies
with one or more colored pens. Electrostatic plotters "draw" a pattern on electrostatically charged dots
on the paper and then apply toner and fuse it in place. Plotters use three basic types of paper handling: flatbed,
drum, and pinch roller. Flatbed plotters hold the paper still and move the pen along both x and y axes. Drum plotters
roll the paper over a cylinder. The pen moves along one axis while the drum, with the paper attached, moves along
the other. Pinch-roller plotters are a hybrid of the two, in which the pen moves only along one axis while the
paper is moved back and forth by small rollers.
Plug and Play: n. A set of specifications developed by Intel that allows a
PC to configure itself automatically to work with peripherals such as monitors, modems, and printers. A user can
"plug" in a peripheral and "play" it without manually configuring the system. A Plug and Play
PC requires both a BIOS that supports Plug and Play and a Plug and Play expansion card. See also BIOS, expansion
plug-in: n. 1. A small software program that plugs into a larger application
to provide added functionality. 2. A software component that plugs into the Netscape Navigator. Plug-ins permit
the Web browser to access and execute files embedded in HTML documents that are in formats the browser normally
would not recognize, such as many animation, video, and audio files. Most plug-ins are developed by software companies
who have proprietary software in which the embedded files are created. Compare helper application, helper program.
PNG: n. Short for Portable Network Graphics.
PNP transistor: n. A type of bipolar transistor in which a base of N-type material
is sandwiched between an emitter and a collector of P-type material. The base, emitter, and collector are the three
terminals of the transistor through which current flows. In a PNP transistor, holes (electron "vacancies")
are the majority of the charge carriers, and they flow from the emitter to the collector. See also N-type semiconductor,
P-type semiconductor. Compare NPN transistor.
point1: n. 1. A unit of measure used in printing, equal to approximately 1/72
of an inch. Character height and the amount of space (leading) between lines of text are usually specified in points.
2. A single pixel on the screen, identified by its row and column numbers. 3. A location in a geometric form, represented
by two or more numbers that constitute its coordinates.
point2: vb. To move an arrow or other such indicator to a particular item or
position on the screen by using direction keys or by maneuvering a pointing device such as a mouse.
point-and-click: adj. Enabling a user to select data and activate programs
by using a mouse or other pointing device to move a cursor to a desired location ("point") and pressing
a button on the mouse or other pointing device ("click").
PointCast: n. An Internet service that delivers and displays a personalized
set of news articles to individual users. Unlike the World Wide Web and other Internet applications, PointCast
is a push technology, where the server automatically uploads data without a specific command from the client. See
also server (definition 2).
pointing device: n. An input device used to control an on-screen cursor for
such actions as "pressing" on-screen buttons in dialog boxes, choosing menu items, and selecting ranges
of cells in spreadsheets or groups of words in a document. A pointing device is often used to create drawings or
graphical shapes. The most common pointing device is the mouse, which was popularized by its use with the Apple
Macintosh. Other pointing devices include graphics tablets, styluses, light pens, joysticks, pucks, and trackballs.
See also graphics tablet, joystick, light pen, mouse, puck, stylus, trackball.
point of presence: n. 1. A point in a wide area network to which a user can
connect with a local telephone call. 2. A point at which a long distance telephone carrier connects to a local
telephone exchange or to an individual user. Acronym: POP.
Point-to-Point Tunneling Protocol: n. A specification for virtual private networks
in which some nodes of a local area network are connected through the Internet. See also virtual network. Acronym:
polymorphism: n. In an object-oriented programming language, the ability to
redefine a routine in a derived class (a class that inherited its data structures and routines from another class).
Polymorphism allows the programmer to define a base class that includes routines that perform standard operations
on groups of related objects, without regard to the exact type of each object. The programmer then redefines the
routines in the derived class for each type, taking into account the characteristics of the object. See also class,
derived class, object (definition 2), object-oriented programming.
Pong: n. The first commercial video game, a table tennis simulation, created
by Nolan Bushnell of Atari in 1972.
POP3: n. Acronym for Post Office Protocol 3. This is the current version of
the Post Office Protocol standard in common use on TCP/IP networks. See also Post Office Protocol, TCP/IP.
populate: vb. 1. To put chips in the sockets of a circuit board. 2. To import
prepared data into a database from a file using a software procedure rather than by having a human operator enter
pop-up Help: n. An online help system whose messages appear as pop-up windows
when the user clicks on a topic or area of the screen about which help is desired. Typically, a special form of
click, such as clicking the right mouse button or Option-clicking, will activate pop-up Help, if it is available.
See also balloon help.
pop-up menu or popup menu: n. In a graphical user interface, a menu that appears
on-screen when a user selects a certain item. Pop-up menus can appear anywhere on the screen and generally disappear
when the user selects an item in the menu. Also called popup. Compare drop-down menu, pull-down menu.
pop-up messages: n. The messages that appear when pop-up Help is used.
pop-up window: n. A window that appears when an option is selected. Typically,
the window remains visible until the mouse button is released.
port1: n. One of the network input/output channels of a computer running TCP/IP.
On the World Wide Web, port usually refers to the port number a server is running on. A single computer can have
many Web servers running on it, but only one server can be running on each port. The default port for Web servers
is 80. See input/output port.
port2: vb. 1. To change a program in order to be able to run it on a different
computer. 2. To move documents, graphics, and other files from one computer to another.
portable: adj. 1. Capable of running on more than one computer system or under
more than one operating system. Highly portable software can be moved to other systems with little effort, moderately
portable software can be moved only with substantial effort, and nonportable software can be moved only with effort
similar to or greater than the effort of writing the original program. 2. Light enough, rugged enough, and free
enough of encumbering external connections to be carried by a user.
portable computer: n. Any computer designed to be moved easily. Portable computers
can be characterized by size and weight as in the table below. k:\compdict\database\5011.doc
Portable Distributed Objects: n. Software from NeXT, running under UNIX, that
supports an object model in which objects to be stored at various locations on a network can be accessed as though
they were at a single location. Acronym: PDO.
Portable Document Format: n. The Adobe specification for electronic documents
that use the Adobe Acrobat family of servers and readers. See also Acrobat, .pdf. Acronym: PDF.
Portable Network Graphics: n.New bitmapped graphics format conforming to the
Portable Network Graphics Tenth Specification (Version 1.0). PNG format is similar to GIF (Graphics Interchange
Format), however, it does not use patented data compression and is license-free. The World Wide Web consortium
approved it as a standard to replace GIF. PNG is supported in the latest versions of Microsoft Internet Explorer
and Netscape Navigator.
portrait mode: n. A vertical print orientation in which a document is printed
across the narrower dimension of a rectangular sheet of paper. This is the print mode typical of most letters,
reports, and other such documents. Compare landscape mode.
POS: n. Acronym for point of sale. The place in a store at which goods are
paid for. Computerized transaction systems, such as those in use at automated supermarkets, use scanners for reading
tags and bar codes, electronic cash registers, and other special devices to record purchases at this point.
POSIX: n. Acronym for Portable Operating System Interface for UNIX. An IEEE
standard that defines a set of operating-system services. Programs that adhere to the POSIX standard can be easily
ported from one system to another. POSIX was based on UNIX system services, but it was created in a way that allows
it to be implemented by other operating systems.
post: vb. To submit an article in a newsgroup or other online conference. The
term is derived from the "posting" of a notice on a physical bulletin board. See also newsgroup.
postmaster: n. The logon name (and therefore the e-mail address) of an account
that is responsible for maintaining e-mail services on a mail server. When an accountholder is having trouble with
e-mail, a message to "postmaster" or "email@example.com" will usually reach
a human who can solve the problem.
Post Office Protocol: n. A protocol for servers on the Internet that receive,
store, and transmit e-mail and for clients on computers that connect to the servers to download and upload e-mail.
PostScript: n. A page-description language from Adobe Systems that offers flexible
font capability and high-quality graphics. The most well-known page-description language, PostScript uses English-like
commands to control page layout and to load and scale outline fonts. Adobe Systems is also responsible for Display
PostScript, a graphics language for computer displays that gives users of both PostScript and Display PostScript
absolute WYSIWYG (what-you-see-is-what-you-get), which is difficult when different methods are used for displaying
and printing. See also outline font, page-description language.
PostScript font: n. A font defined in terms of the PostScript page-description
language rules and intended to be printed on a PostScript-compatible printer. PostScript fonts are distinguished
from bitmapped fonts by their smoothness, detail, and faithfulness to standards of quality established in the typographic
industry. See also PostScript. Compare screen font.
POTS: n. Acronym for Plain Old Telephone Service. Basic dial telephone connections
to the public switched network, without any added features or functions. A POTS line is nothing but a phone line
connected to a simple desktop telephone instrument.
PowerBook: n. Any of several computers in the family of portable Macintosh
computers made by Apple.
power down: vb. To shut down (a computer); to turn off the power.
power failure: n. Loss of electricity, which causes a loss of unsaved data
in a computer's random access memory (RAM) if no backup power supply is connected to the machine. Compare surge.
Power Macintosh: n. An Apple Macintosh computer based on the PowerPC processor.
The first Power Macintoshes, 6100/60, 7100/66, and 8100/80, were unveiled in March 1994. Also called Power Mac.
See also PowerPC.
Power-on key: n. A special key on the Apple ADB and Extended keyboards used
for turning on a Macintosh II. The Power-on key is marked with a left-pointing triangle and is used in lieu of
the on/off switch. There is no Power-off key; the system is shut down by choosing the Shut Down command from the
power-on self test: n. A set of routines stored in a computer's read-only memory
(ROM) that tests various system components such as RAM, the disk drives, and the keyboard to see if they are properly
connected and operating. If problems are found, these routines alert the user by sounding a series of beeps or
displaying a message, often accompanied by a diagnostic numeric value, to the standard output or standard error
device (usually the screen). If the power-on self test is successful, it passes control to the system's bootstrap
loader. See also bootstrap loader. Acronym: POST.
PowerPC: n. A microprocessor architecture developed in 1992 by Motorola and
IBM, with some participation by Apple. A PowerPC microprocessor is RISC-based and superscalar, with a 64-bit data
bus and a 32-bit address bus. It also has separate data and instruction caches, although the size of each varies
by implementation. All PowerPC microprocessors have multiple integer and floating-point units, and all have an
operating voltage of 3.3 volts, except for the 601, which operates at 3.6 volts. The operating speed and number
of instructions executed per clock cycle varies with the implementation. The 601 is available in a 80-MHz or 100-MHz
version and executes three instructions per clock cycle. The 603, available in 80-MHz, 100-MHz, and 200-MHz versions,
executes three instructions per clock cycle. The 604, available in 100-MHz, 120-MHz, and 133-MHz versions, executes
four instructions per clock cycle. The 620, available in a 133-MHz version, also executes four instructions per
clock cycle. PowerPC is a registered trademark of IBM. See also microprocessor, RISC.
PowerPC Platform: n. A platform developed by IBM, Apple, and Motorola based
on the 601 and later chips. This platform supports the use of multiple operating systems such as Mac OS, Windows
NT, and AIX as well as software designed for those individual operating systems.
PowerPC Reference Platform: n. An open system standard developed by IBM. IBM's
goal in designing the PowerPC Reference Platform was to ensure compatibility among PowerPC systems built by different
companies. Apple's PowerPC Macintoshes are not yet compliant with the PowerPC Reference Platform, but future versions
are expected to be. See also Common Hardware Reference Platform, open system, PowerPC. Acronym: PPCP., PReP (prep,
power supply: n. An electrical device that transforms standard wall outlet
electricity (115-120 VAC in the United States) into the lower voltages (typically 5 to 12 volts DC) required by
computer systems. Personal computer power supplies are rated by wattage; they usually range from about 90 watts
at the low end to 250 watts at the high end.
power up: vb. To start up a computer; to begin a cold boot procedure; to turn
on the power.
power user: n. A person adept with computers, particularly on an applications-oriented
level rather than on a programming level. A power user is someone who knows a considerable amount about computers
and is comfortable enough with applications to be able to work with their most sophisticated features.
PPP: n. Acronym for Point-to-Point Protocol. A data link protocol developed
by the Internet Engineering Task Force in 1991 for dial-up telephone connections, such as between a computer and
the Internet. PPP provides greater protection for data integrity and security than does SLIP, at a cost of greater
overhead. Compare SLIP.
PPTP: See Point-to-Point Tunneling Protocol.
PRAM: n. Short for parameter RAM. A portion of RAM in Macintosh computers that
contains configuration information such as the date and time, desktop pattern, and other control panel settings.
See also RAM.
P-rating: n. Short for performance rating. A microprocessor rating system by
IBM, Cyrix, and others, based on throughput in realistic applications. Formerly, microprocessor clock speed was
widely used as a method of rating, but it does not account for differing chip architectures or different types
of work people do with computers. See also central processing unit, clock (definition 1), microprocessor.
preemptive multitasking: n. A form of multitasking in which the operating system
periodically interrupts the execution of a program and passes control of the system to another waiting program.
Preemptive multitasking prevents any one program from monopolizing the system. Also called time-slice multitasking.
See also multitasking.
Preferences: n. A menu choice in many graphical user interface applications
that allows the user to specify how the application will act each time it is used. For example, in a word processing
application the user may be allowed to specify whether the ruler will appear, whether the document will appear
in the same way as it will print (including margins), and other choices. Also called Options, Prefs.
presentation graphics: n. The representation of business information, such
as sales figures and stock prices, in chart form rather than as lists of numbers. Presentation graphics are used
to give viewers an immediate grasp of business statistics and their significance. Common examples are area charts,
bar charts, line charts, and pie charts. Also called business graphics.
presentation layer: n. The sixth of the seven layers in the International Organization
for Standardization's Open Systems Interconnection (ISO/OSI) model for standardizing computer-to-computer communications.
The presentation layer is responsible for formatting information so that it can be displayed or printed. This task
generally includes interpreting codes (such as tabs) related to presentation, but it can also include converting
encryption and other codes and translating different character sets. See also ISO/OSI model.
Presentation Manager: n. The graphical user interface provided with OS/2 versions
1.1 and later. The Presentation Manager derives from the MS-DOS-based Windows environment and provides similar
capabilities. The user sees a graphical, window-oriented interface, and the programmer uses a standard set of routines
for handling screen, keyboard, mouse, and printer input and output, no matter what hardware is attached to the
system. See also OS/2, Windows.
preventive maintenance: n. Routine servicing of hardware intended to keep equipment
in good operating condition and to find and correct problems before they develop into severe malfunctions.
preview: n. In word processors and other applications, the feature that displays
a formatted document on the video monitor rather than sending it directly to the printer.
primary channel: n. The data-transmission channel in a communications device,
such as a modem. Compare secondary channel.
Primary Domain Controller: n. 1. In Windows NT, a database providing a centralized
administration site for resources and user accounts. The database allows users to log onto the domain, rather than
onto a specific host machine. A separate account database keeps track of the machines in the domain and allocates
the domain's resources to users. 2. In any local area network, the server that maintains the master copy of the
domain's user accounts database and that validates logon requests. Acronym: PDC.
primitive: n. 1. In computer graphics, a shape, such as a line, circle, curve,
or polygon, that can be drawn, stored, and manipulated as a discrete entity by a graphics program. A primitive
is one of the elements from which a large graphic design is created. 2. In programming, a fundamental element in
a language that can be used to create larger procedures that do the work a programmer wants to do.
printer: n. A computer peripheral that puts text or a computer-generated image
on paper or on another medium, such as a transparency film. Printers can be categorized in any of several ways.
The most common distinction is impact versus nonimpact. Impact printers physically strike the paper and are exemplified
by pin dot-matrix printers and daisy-wheel printers; nonimpact printers include every other type of print mechanism,
including laser, ink-jet, and thermal printers. Other possible methods of categorizing printers include (but are
not limited to) the following: See also ball printer, character printer, color printer, daisy-wheel printer, dot-matrix
printer, draft quality, electrophotographic printers, graphics printer, impact printer, ink-jet printer, ion-deposition
printer, laser printer, LCD printer, LED printer, letter quality, line printer, near-letter-quality, nonimpact
printer, page printer, parallel printer, serial printer, thermal printer, thermal wax-transfer printer, thimble
Printer Control Language: n. A printer control language from Hewlett-Packard,
used in its LaserJet, DeskJet, and RuggedWriter printer lines. Because of the LaserJet's dominance in the laser
printer market, Printer Control Language has become a de facto standard. Also called Hewlett-Packard Printer Control
Language, PCL. Acronym: PCL.
printer controller: n. The processing hardware in a printer, especially in
a page printer. It includes the raster image processor, the memory, and any general-purpose microprocessors. A
printer controller can also reside in a personal computer, attached via a high-speed cable to a printer that simply
carries out its instructions. Compare printer engine.
printer driver: n. A software program designed to enable other programs to
work with a particular printer without concerning themselves with the specifics of the printer's hardware and internal
"language." Application programs can communicate properly with a variety of printers by using printer
drivers, which handle all of the subtleties of each printer so that the application program doesn't have to. Today
graphical user interfaces offer their own printer drivers, eliminating the need for an application that runs under
the interface to have its own printer driver.
printer font: n. A font residing in or intended for a printer. A printer font
can be internal, downloaded, or on a font cartridge. Compare screen font.
printer port: n. A port through which a printer can be connected to a personal
computer. On PC-compatible machines, printer ports are usually parallel ports and are identified in the operating
system by the logical device name LPT. On many newer PCs, the parallel port on the case of the CPU has a printer
icon beside it to identify it as a printer port. Serial ports can also be used for some printers (logical device
name COM), although configuration is generally required. On Macintoshes, printer ports are usually serial ports
and are also used to connect Macs to an AppleTalk network. See also AppleTalk, central processing unit, logical
device, parallel port, serial port.
print job: n. A single batch of characters printed as a unit. A print job usually
consists of a single document, which can be one page or hundreds of pages long. To avoid having to print individual
documents separately, some software can group multiple documents into a single print job. See also print spooler.
print quality: n. The quality and clarity of characters produced by a printer.
Print quality varies with the type of printer; in general, dot-matrix printers produce lower-quality output than
laser printers. The printer mode can also affect quality. See also resolution (definition 1).
print queue: n. A buffer for documents and images waiting to be printed. When
an application places a document in a print queue, it is held in a special part of the computer's memory, where
it waits until the printer is ready to receive it.
Print Screen key: n. A key on IBM PC and compatible keyboards that normally
causes the computer to send a character-based "picture" of the screen contents to the printer. The print
screen feature works only when the display is in text mode or CGA graphics mode (the lowest-resolution color and
graphics mode available on IBM compatibles). It will not work properly in other graphics modes. Some programs use
the Print Screen key to capture a screen image and record it as a file on disk. These programs can typically work
in any graphics mode and record the file as a graphics image. When the user is working directly with the MS-DOS
operating system, and with some programs, the combination Control-Print Screen toggles the printer on or off. With
printing turned on, the system sends every character to the printer as well as to the screen. The Print Screen
key on the Apple Extended Keyboard is included for compatibility with operating systems such as MS-DOS. Also called
print server: n. A workstation that is dedicated to managing printers on a
network. The print server can be any station on the network.
print spooler: n. Computer software that intercepts a print job on its way
to the printer and sends it to disk or memory instead, where the print job is held until the printer is ready for
it. The term spooler is an acronym created from "simultaneous peripheral operations on line."
print to file: n. A command in many applications that instructs the program
to format a document for printing and store the formatted document as a file rather than sending it to a printer.
privacy: n. The concept that a user's data, such as stored files
and e-mail, is not to be examined by anyone else without that user's permission. A right to privacy is
not generally recognized on the Internet. Federal law protects only e-mail in transit or in temporary storage,
and only against access by Federal agencies. Employers often claim a right to inspect any data on their systems.
To promote privacy, the user must take active measures such as encryption. See also encryption,
PGP, Privacy Enhanced Mail. Compare security.
Privacy Enhanced Mail: n. An Internet standard for e-mail systems that use
encryption techniques to help protect the privacy and security of messages. See also encryption, standard.
Compare PGP. Acronym: PEM.
Private Communications Technology: n. A specification designed to help protect
general-purpose business and personal communications on the Internet, and includes features such as authentication
and mutual identification.
private folders: n. In a shared network environment, those folders on a user's
computer that are not currently accessible by other users on the network. Compare public folders.
private key: n. One of two keys in public key encryption. The user keeps the
private key secret and uses it to encrypt digital signatures and to decrypt received messages. See also public
key encryption. Compare public key.
procedure call: n. In programming, an instruction that causes a procedure to
be executed. A procedure call can be located in another procedure or in the main body of the program. See also
process1: n. A program or part of a program; a coherent sequence of steps undertaken
by a program.
process2: vb. To manipulate data with a program.
process color: n. A method of handling color in a document in which each block
of color is separated into its subtractive primary color components for printing: cyan, magenta, and yellow (as
well as black). All other colors are created by blending layers of various sizes of halftone spots printed in cyan,
magenta, and yellow to create the image. See also color model, color separation (definition 1). Compare spot color.
processing: n. The manipulation of data within a computer system. Processing
is the vital step between receiving data (input) and producing results (output)--the task for which computers are
processor: n. See central processing unit, microprocessor.
progressive JPEG: n. An enhancement to the JPEG image format specification
that allows an image to be gradually displayed in a Web browser, showing increasingly detailed versions of the
entire image until all of the data has finished downloading. While this is similar to interlaced GIF images, progressive
JPEG images can retain the high quality of 24-bit color and offer the same efficient compression as standard JPEG.
See also JPEG. Compare interlaced GIF.
Prodigy Information Service: n. An online information service founded by
IBM and Sears. Like its competitors America Online and CompuServe, Prodigy offers access to databases and file
libraries, online chat, special interest groups, e-mail, and Internet connectivity. Also called Prodigy.
Product Identification Number: n.An identification number that appears either
on the bottom of a device or on the opening screen or in the About dialog box of an application program.
profile: vb. To analyze a program to determine how much time is spent in different
parts of the program during execution.
program: n. A sequence of instructions that can be executed by a computer.
The term can refer to the original source code or to the executable (machine language) version. Also called software.
See also program creation, routine, statement.
program file: n. A disk file that contains the executable portion(s) of a computer
program. Depending on its size and complexity, an application or other program, such as an operating system, can
be stored in several different files, each containing the instructions necessary for some part of the program's
overall functioning. Compare document file.
programmable: adj. Capable of accepting instructions for performing a task
or an operation. Being programmable is a characteristic of computers.
programmer: n. 1. An individual who writes and debugs computer programs. Depending
on the size of the project and the work environment, a programmer might work alone or as part of a team, be involved
in part or all of the process from design through completion, or write all or a portion of the program. See also
program. 2. In hardware, a device used to program read-only memory chips. See also PROM, ROM (definition 2).
programming: n. The art and science of creating computer programs. Programming
begins with knowledge of one or more programming languages, such as Basic, C, Pascal, or assembly language. Knowledge
of a language alone does not make a good program. Much more can be involved, such as expertise in the theory of
algorithms, user interface design, and characteristics of hardware devices. Computers are rigorously logical machines,
and programming requires a similarly logical approach to designing, writing (coding), testing, and debugging a
program. Low-level languages, such as assembly language, also require familiarity with the capabilities of a microprocessor
and the basic instructions built into it. In the modular approach advocated by many programmers, a project is broken
into smaller, more manageable modules--stand-alone functional units that can be designed, written, tested, and
debugged separately before being incorporated into the larger program. See also algorithm, kludge (definition 2),
modular design, object-oriented programming, spaghetti code, structured programming.
programming language: n. Any artificial language that can be used to define
a sequence of instructions that can ultimately be processed and executed by the computer. Defining what is or is
not a programming language can be tricky, but general usage implies that the translation process--from the source
code expressed using the programming language to the machine code that the computer needs to work with--be automated
by means of another program, such as a compiler. Thus, English and other natural languages are ruled out, although
some subsets of English are used and understood by some fourth-generation languages. See also 4GL, compiler (definition
2), natural language, program.
project life cycle: n. A sequence of preplanned stages for taking a project
from beginning to end.
project management: n. The process of planning, monitoring, and controlling
the course and development of a particular undertaking.
PROM: n. Acronym for programmable read-only memory. A type of read-only memory
(ROM) that allows data to be written into the device with hardware called a PROM programmer. After a PROM has been
programmed, it is dedicated to that data, and it cannot be reprogrammed. See also EEPROM, EPROM, ROM (definition
promiscuous-mode transfer: n. In network communications, a transfer of data
in which a node accepts all packets regardless of their destination address.
prompt: n. 1. In command-driven systems, one or more symbols that indicate
where users are to enter commands. For instance, in MS-DOS, the prompt is generally a drive letter followed by
a "greater than" symbol (C>). In Unix, it is usually %. See also command-driven system, DOS prompt.
2. Displayed text indicating that a computer program is waiting for input from the user.
property: n. In Windows 95, a characteristic or parameter of an object or device.
Properties of a file, for example, include type, size, and creation date and can be identified by accessing the
file's property sheet. See also property sheet.
property sheet: n. A type of dialog box in Windows 95, accessed by choosing
Properties in the File menu or by right-clicking on an object and selecting Properties, that lists the attributes
or settings of an object such as a file, application, or hardware device. A property sheet presents the user with
a tabbed, index-card-like selection of property pages, each of which features standard dialog-style controls for
proportional font: n. A set of characters in a particular style and size in
which a variable amount of horizontal space is allotted to each letter or number. In a proportional font, the letter
i, for example, is allowed less space than the letter m. Compare monospace font.
proportional spacing: n. A form of character spacing in which the horizontal
space each character occupies is proportional to the width of the character. The letter w, for example, takes up
more space than the letter i. Compare monospacing.
proprietary: adj. Of, pertaining to, or characteristic of something that is
privately owned. Generally, the term refers to technology that has been developed by a particular corporation or
entity, with specifications that are considered by the owner to be trade secrets. Proprietary technology may be
legally used only by a person or entity purchasing an explicit license. Also, other companies are unable to duplicate
the technology, both legally and because its specifications have not been divulged by the owner. Compare public
proprietary software: n. A program owned or copyrighted by an individual or
a business and available for use only through purchase or by permission of the owner. Compare public-domain software.
protected mode: n. An operating mode of the Intel 80286 and higher microprocessors
that supports larger address spaces and more advanced features than real mode. When started in protected mode,
these CPUs provide hardware support for multitasking, data security, and virtual memory. The Windows NT and OS/2
operating systems run in protected mode, as do most versions of UNIX for these microprocessors. Compare real mode.
protocol stack: n. The set of protocols that work together on different levels
to enable communication on a network. For example, TCP/IP, the protocol stack on the Internet, incorporates more
than 100 standards including FTP, IP, SMTP, TCP, and Telnet. Also called protocol suite. See also ISO/OSI model.
prototyping: n. The creation of a working model of a new computer system or
program for testing and refinement. Prototyping is used in the development of both new hardware and software systems
and new systems of information management. Tools used in the former include both hardware and support software;
tools used in the latter can include databases, screen mockups, and simulations that, in some cases, can be developed
into a final product.
proxy server: n. A firewall component that manages Internet traffic to and
from a local area network (LAN) and can provide other features, such as document caching and access control. A
proxy server can improve performance by supplying frequently requested data, such as a popular Web page, and can
filter and discard requests that the owner does not consider appropriate, such as requests for unauthorized access
to proprietary files. See also firewall.
PSN: n. Acronym for packet-switching network. See packet switching.
public directory: n. A directory on an FTP server that is accessible by anonymous
users for the purpose of retrieving or storing files. Often the directory is called /pub. See also anonymous FTP,
FTP (definition 1), FTP server, /pub.
public key: n. One of two keys in public key encryption. The user releases
this key to the public, who can use it for encrypting messages to be sent to the user and for decrypting the user's
digital signature. See also public key encryption. Compare private key.
public key encryption: n. An asymmetric scheme that uses a pair of keys for encryption: the public key
encrypts data, and a corresponding secret key decrypts it. For digital signatures, the process is reversed: the
sender uses the secret key to create a unique electronic number that can be read by anyone possessing the corresponding
public key, which verifies that the message is truly from the sender. See also private key, public key.
pull: vb. The process of retrieving data from a network server. Compare push
(definition 2). See pop.
pull-down menu: n. A menu that is pulled down from the menu bar and that remains
available as long as the user holds it open. Compare drop-down menu.
punched card: n. An outdated computer-input medium made of stiff paper that stores data bits in columns
containing patterns of punched holes. The method for creating the patterns used for different byte values is called
Hollerith coding. Also called Hollerith tabulating/recording machine.
punched-card reader: n. See card reader.
purge: vb. To eliminate old or unneeded information systematically; to clean
up, as files.
push: vb. 1. To add a new element to a stack, a data structure generally used
to temporarily hold pieces of data being transferred or the partial result of an arithmetic operation. See also
stack. Compare pop. 2. In networks and the Internet, to send data or a program from a server to a client at the
instigation of the server. Compare pull (definition 1).
put: vb. In programming, to write data, typically to a file; in particular,
to write a very small unit of data, such as a character.
PVC: n. Acronym for permanent virtual circuit. A permanent logical connection
between two nodes on a packet-switching network. The PVC appears as a dedicated line to the nodes, but the data
can be transmitted on a common carrier. VPN. See also common carrier, node (definition 2), packet switching. Compare
pwd: n. Acronym for print working directory. The UNIX command for displaying
the current directory.
Many definitions maybe similar to the Microsoft Computer Dictionary,
5th Edition. Purchase information found at Microsoft Press.
The contributors of these definitions is far too numerous to mention, however
if you see something that you feel shouldn't be here let us know.