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
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.
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.
n. An interface between non-packet-switching equipment and a packet-switching network. Acronym: PAD.
n. See ping1 (definition 1).
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.
n. See packet assembler/disassembler.
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.
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.
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 address.
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.
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.
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.
n. The assembling of graphics and text on a page in preparation for printing.
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.
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 memory.
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.
vb. To fill a portion of a drawing with paint.
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.
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.
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.
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.
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.
n. The idealized office in which information is entirely stored, manipulated, and transferred electronically rather than on paper.
n. An archetypical example or pattern that provides a model for a process or system.
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).
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.
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, SMP.
n. The input/output connector for a parallel interface device. See also input/output port.
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.
n. A computer system that implements some form of parallel processing to improve its performance as a server. See also SMP server.
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.
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.
n. See Xerox PARC.
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
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.
n. The use of parity to check the accuracy of transmitted data. See also parity, parity bit.
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.
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.
vb. To break input into smaller chunks so that a program can act upon the information.
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.
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. Compare C.
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.
n. See PAP (definition 1).
n. The use of passwords as a means of allowing only authorized users access to a computer system or its files.
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.
n. A piece of object code that is inserted in an executable program as a temporary fix of a bug.
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).
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.
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.
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.
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.
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.
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.
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. See Wintel.
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.
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.
n. See Printer Control Language.
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.
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.
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.
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.
n. A graphical file format that compresses its image data with RLE-type compression, used by early versions of Windows Paintbrush.
n. The original IBM Personal Computer, introduced in 1981, which used the Intel 8088 CPU. See also IBM PC.
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.
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.
n. See Primary Domain Controller.
n. See Portable Document Format.
n. See page-description language.
n. See pulse duration modulation.
n. See Portable Distributed Objects.
n. Any of the devices on a layered communications network that operate on the same protocol level. See also network 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.
n. Interaction between devices that operate on the same communications level on a network based on a layered architecture. See also network architecture.
n. Short for picture element. See pixel.
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).
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.
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.
n. A process or program that appraises and records status information about various system devices and other processes.
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.
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.
n. An auxiliary source of electricity used by a computer or a device as a backup in case of a power failure. Acronym: PPS.
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 Propulsion Laboratory.
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.
n. In Windows, a file composed of contiguous disk sectors used for virtual memory operations. See also swap file, virtual memory.
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.
n. See hot link (definition 1).
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.
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.
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.
n. Abbreviated PB. Either 1 quadrillion bytes or 1,125,899,906,842,624 bytes.
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.
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 keying.
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 AMI BIOS.
n. An attachment, usually an RJ-11 connector, used to join a telephone line to a device such as a modem.
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 on CDs.
n. A graphics application used to manipulate an image, such as a scanned photograph, digitally.
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.
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.
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).
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.
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.
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.
n. See programmable interrupt controller.
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).
prefix. Abbreviated p. Denotes one trillionth (10-12), or, in the British numbering system, one million millionth.
n. A microprocessor developed by Sun Microsystems, Inc., that executes Java code. See also Java.
n. Abbreviated psec. One trillionth of a second.
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.
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.
n. Short for product identification number.
n. A type of graph that presents values as percentages (slices) of a whole (a pie).
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 way.
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.
n. Acronym for personal identification number. A unique code number assigned, as with automatic teller machine cards, to the authorized user.
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 protocol.
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 a response.
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 1).
n. A description or diagram of the pins of a chip or connector. See also pin.
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.
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 (definition 3).
n. 1. The theft of a computer design or program. 2. Unauthorized distribution and use of a computer program.
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.
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.
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.
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.
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.
n. Acronym for programmable logic array. See field-programmable logic array.
n. 1. Nonencrypted or decrypted text. See also decryption, encryption. 2. A file that is stored as plain ASCII data.
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 voice features.
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.
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.
n. A version of the PL/I programming language developed at Cornell University and used on mainframe computers. See also PL/I.
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).
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.
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 board, peripheral.
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.
n. Short for Portable Network Graphics.
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.
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.
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.
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").
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).
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.
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.
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: PPTP.
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.
n. The first commercial video game, a table tennis simulation, created by Nolan Bushnell of Atari in 1972.
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.
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 individual records.
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.
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.
n. The messages that appear when pop-up Help is used.
n. A window that appears when an option is selected. Typically, the window remains visible until the mouse button is released.
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.
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.
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.
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
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.
n. The Adobe specification for electronic documents that use the Adobe Acrobat family of servers and readers. See also Acrobat, .pdf. Acronym: PDF.
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.
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.
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.
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.
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.
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 "postmaster@machine.org.domain.name" will usually reach a human who can solve the problem.
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. Acronym: POP.
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.
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.
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.
n. Any of several computers in the family of portable Macintosh computers made by Apple.
vb. To shut down (a computer); to turn off the power.
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.
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.
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 Special menu.
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.
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.
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.
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, P`R-E-P').
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.
vb. To start up a computer; to begin a cold boot procedure; to turn on the power.
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.
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.
See Point-to-Point Tunneling Protocol.
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.
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.
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.
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.
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.
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.
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.
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.
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.
n. The data-transmission channel in a communications device, such as a modem. Compare secondary channel.
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.
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.
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. k:\compdict\database\4548.doc
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.
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.
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.
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.
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.
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.
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).
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.
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 PrtSc key.
n. A workstation that is dedicated to managing printers on a network. The print server can be any station on the network.
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."
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.
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 obtain privacy, the user must take active measures such as encryption. See also encryption, PGP, Privacy Enhanced Mail. Compare security.
n. An Internet standard for e-mail systems that use encryption techniques to ensure the privacy and security of messages. See also encryption, standard. Compare PGP. Acronym: PEM.
n. A specification designed to secure general-purpose business and personal communications on the Internet, and includes features such as privacy, authentication, and mutual identification.
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.
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.
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 procedure.
n. A program or part of a program; a coherent sequence of steps undertaken by a program.
vb. To manipulate data with a program.
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.
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 designed.
n. See central processing unit, microprocessor.
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.
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.
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.
vb. To analyze a program to determine how much time is spent in different parts of the program during execution.
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.
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.
adj. Capable of accepting instructions for performing a task or an operation. Being programmable is a characteristic of computers.
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).
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.
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.
n. A sequence of preplanned stages for taking a project from beginning to end.
n. The process of planning, monitoring, and controlling the course and development of a particular undertaking.
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 2).
n. In network communications, a transfer of data in which a node accepts all packets regardless of their destination address.
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.
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.
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 customizing parameters.
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.
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.
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 domain.
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.
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.
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.
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.
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.
n. Acronym for packet-switching network. See packet switching.
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.
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.
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.
vb. The process of retrieving data from a network server. Compare push (definition 2). See pop.
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.
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.
n. See card reader.
vb. To eliminate old or unneeded information systematically; to clean up, as files.
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).
vb. In programming, to write data, typically to a file; in particular, to write a very small unit of data, such as a character.
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 SVC.
n. Acronym for print working directory. The UNIX command for displaying the current directory.
