n. In Windows and some other operating systems, the identifier used for the first, or primary, floppy disk drive; unless otherwise specified by changing the CMOS startup instructions, this is the drive the operating system checks first for startup instructions.
n. See angstrom.
n. 1. Acronym for Atanasoff-Berry Computer. The first electronic digital computer, created by John Atanasoff and Clifford Berry of Iowa State University in 1942. 2. Acronym for automatic brightness control. A circuit that changes the luminance of a monitor to compensate for ambient lighting conditions. 3. An imperative language and programming environment from CWI, Netherlands. This interactive, structured, high-level language is easy to learn and use. It is not a systems-programming language, but it is good for teaching or prototyping.
n. On the Internet, the major geographic domain specifying that an address is located in Alberta, Canada.
or ABEND n. Short for abnormal end. The premature ending of a program because of program error or system failure. See also abort, crash1.
n. See application binary interface.
n. Acronym for Advanced Basic Input/Output System. A set of input/output service routines designed to support multitasking and protected mode that were built into IBM PS/2 PCs. See also BIOS.
n. See abend.
vb. To terminate abruptly, often used in reference to a program or procedure in progress.
n. A means of specifying a precise memory location in a program by using its address (number) rather than an expression to calculate the address. Also called direct address, machine address, real address. See also absolute coding. Compare relative address, virtual address.
n. Program code that uses absolute addressing rather than indirect addressing. See also absolute address, indirect address.
n. Coordinates that are defined in terms of their distance from the origin, the point where the axes intersect. Graphs and computer graphics use absolute coordinates to locate points on a chart or display grid--for example, points in relation to the x- and y-axes on a graph or the x-, y-, and z-axes used to specify the location of a three-dimensional graphic object on the screen. See also Cartesian coordinates.
n. A path specification to a file that begins from the topmost level of the identification of a disk drive (for example, C:\docs\work\contract.txt). See also path (definition 2). Compare relative path.
n. A mechanical or physical pointing device whose location is associated with the position of the on-screen cursor. For example, if the user of a graphics tablet places the pen on the upper right corner of the tablet, the cursor moves to the upper right corner of the screen or on-screen window associated with the pen. See also absolute coordinates, graphics tablet. Compare relative pointing device.
n. The magnitude of a number, irrespective of its sign (+ or
adj. 1. In character recognition systems, of, pertaining to, or being a type of symbol that, unlike a letter or numeral, has no intrinsic meaning and must be defined before it can be interpreted. 2. In programming, of, pertaining to, or being a data type defined by the operations that can be performed on objects of that type rather than by the properties of the objects themselves. See also abstract data type.
n. In information processing and library science, a summary typically consisting of a paragraph or a few paragraphs at the beginning of an investigative document, such as a scientific paper.
n. In the C++ programming language, the opposite of a concrete class (one in which objects can be created). An abstract class is a class of which no objects can be created; rather, the class is used to define subclasses, and objects are created from the subclasses. See also object (definition 2).
n. In programming, a data set defined by the programmer in terms of the information it can contain and the operations that can be performed with it. An abstract data type is more generalized than a data type constrained by the properties of the objects it contains--for example, the data type "pet" is more generalized than the data types "pet dog," "pet bird," and "pet fish." The standard example used in illustrating an abstract data type is the stack, a small portion of memory used to store information, generally on a temporary basis. As an abstract data type, the stack is simply a structure onto which values can be added (pushed) and from which they can be removed (popped). The type of value, such as integer, is irrelevant to the definition. The way in which the program performs operations on abstract data types is encapsulated, or hidden, from the rest of the program. Encapsulation enables the programmer to change the definition of the data type or its operations without introducing errors to the existing code that uses the abstract data type. Abstract data types represent an intermediate step between traditional programming and object-oriented programming. See also data type, object-oriented programming.
n. A design for a processor that is not meant for implementation but that represents a model for processing an intermediate language, called abstract machine language, used by an interpreter or compiler. Its instruction set can use instructions that more closely resemble the compiled language than the instructions used by an actual computer. It can also be used to make the implementation of the language more portable to other platforms.
n. A data structure description that is independent of hardware structures and encodings.
n. The ISO standard notation for independent specification of data types and structures for syntax conversion. See also data type, ISO, syntax. Acronym: ASN.1.
n. A treelike representation of programs used in many integrated programming environments and structure-oriented editors.
n. An enclosure that contains a two-position selector switch. When a user selects a switch setting, the signal passing through the box may be directed either from a single input to one of two outputs, or from the selected input to a single output. See also switch (definition 1).
n. See alternating current.
n. An external power supply that converts from a 110 VAC or 220 VAC domestic electric supply ("house current" or "main power") to low-voltage DC, which is required to operate solid-state electronic equipment (such as a laptop computer) that does not include an internal power supply.
n. 1. In applications, a key or key combination used to perform a defined function. Also called shortcut key. 2. In hardware, a device that speeds or enhances the operation of one or more subsystems, leading to improved program performance. See also accelerator card, Windows-based accelerator.
n. See accelerator card.
n. A printed circuit board that replaces or augments the computer's main microprocessor, resulting in faster performance. Also called accelerator board. See also expansion board, graphics accelerator.
n. A statement issued by an Internet service provider or an online information service that indicates what activities users may or may not engage in while logged into the service. For example, some providers prohibit users from engaging in commercial activity on the network. See also ISP, online information service. Acronym: AUP.
n. A formal evaluation of a hardware product performed by the customer, usually at the factory, to verify that the product is performing according to specifications.
n. 1. The act of reading data from or writing data to memory. 2. Connection to the Internet or other network or system.
vb. To gain entry to memory in order to read or write data.
n. A mechanical arm that moves the read/write head(s) over the surface of a disk in a disk drive. Also called head arm.
n. A bidirectional bus for connecting peripherals to a PC. The ACCESS.bus can connect up to 125 low-speed peripherals, such as printers, modems, mice, and keyboards, to the system through a single, general-purpose port. Peripherals that support the ACCESS.bus provide a connector or port connection that is similar to a phone-jack connector and are daisy-chained together. However, the PC communicates directly with each peripheral and vice versa. Connecting an ACCESS.bus device (for example, a printer) to a system results in the system automatically identifying and configuring it for optimum performance. Peripherals can be connected while the computer is running (hot plugging) and are automatically assigned a unique address (auto-addressing). Developed by DEC, the ACCESS.bus competes with Intel's USB. See also bidirectional, bus, daisy chain, hot plugging, input/output port, peripheral. Compare USB.
n. See password.
n. The mechanisms for limiting access to certain items of information or to certain controls based on users' identity and their membership in various predefined groups. Access control is typically used by system administrators for controlling user access to network resources, such as servers, directories, and files. See also access privileges, system administrator.
n. A list associated with a file that contains information about which users or groups have permission to access or modify the file. Acronym: ACL.
n. The quality of a system incorporating hardware or software that makes it usable by people with one or more physical disabilities, such as restricted mobility, blindness, or deafness.
n. 1. The disk drive components that move the read/write head(s) to the proper track of a magnetic disk or optical disc. 2. A circuit that allows one part of a computer system to send signals to another part. See also disk controller. 3. In programming, the means by which an application can read from or write to a resource. Also called access method.
n. See access mechanism (definition 3).
n. The telephone number used by a subscriber to gain access to an online service.
n. See peripheral.
n. The route followed by an operating system to find the location of a stored file. The access path begins with a drive or volume (disk) designator, continues through a chain of directories and subdirectories, if any, and ends with the filename. C:\books\diction\start.exe is an example of an access path.
n. The type of operations permitted a given user for a certain system resource on a network or a file server. A variety of operations, such as the ability to access a server, view the contents of a directory, open or transfer files, and create, modify, or delete files or directories, can be allowed or disallowed by the system administrator. Assigning access privileges to users helps the system administrator to maintain security on the system, as well as the privacy of confidential information, and to allocate system resources, such as disk space. See also file protection, file server, permission, system administrator, write access.
n. See ISP.
n. The permission to view, enter, or modify a file, folder, or system.
n. See access time.
n. 1. The amount of time it takes for data to be delivered from memory to the processor after the address for the data has been selected. 2. The time needed for a read/write head in a disk drive to locate a track on a disk. Access time is usually measured in milliseconds and is used as a performance measure for hard disks and CD-ROM drives. See also read/write head, seek time, settling time, wait state. Compare cycle time.
n. 1. A record-keeping arrangement used by the vendor of an online service to identify a subscriber and to maintain a record of customer usage for billing purposes. 2. A record kept by local area networks and multi-user operating systems for each authorized user of the system for identification, administration, and security purposes.
n. A file generated by a printer controller that keeps track of the number of pages printed per job as well as the user that requested the print job.
n. 1. One of the earliest applications of automatic data processing, used in business accounting primarily during the 1940s and 1950s. The first accounting machines were nonelectronic and used punched cards and wires arranged in plugboard panels. 2. A computer in which an accounting software package starts up whenever the machine is turned on, the computer thus becoming a dedicated machine with accounting as its sole function.
n. 1. On local area networks and multiuser operating systems, a set of rules governing whether a new user is allowed access to the system and whether an existing user's rights are expanded to include additional system resources. An account policy also generally states the rules with which the user must comply while using the system in order to maintain access privileges. 2. In Windows NT, a set of rules controlling the use of passwords by the user accounts of a domain or of an individual computer. See also domain (definition 2).
n. See Association of C and C++ Users.
n. A register used for logic or arithmetic, usually to count items or accumulate a sum.
n. The degree to which the result of a calculation or measurement approximates the true value. Compare precision (definition 1).
n. Acronym for Andy, Charles, Ian's System. An object-oriented geometric modeling toolkit designed for use as a "geometry engine" within 3-D modeling applications. ACIS provides an open architecture framework for wire-frame, surface, and solid modeling from a common, unified data structure. ACIS is generally considered the de facto standard for solids modeling. ACIS is developed by Spatial Technology Inc.
n. Short for acknowledgment. A message sent by the receiving unit to the sending station or computer indicating either that the unit is ready to receive transmission or that a transmission was received without error. Compare NAK.
n. See access control list.
n. See Association for Computing Machinery.
n. A communications device with a built-in insulated cradle into which a telephone handset is fitted to establish a connection between sending and receiving computers. See also modem.
n. A commercial program from Adobe that converts a fully formatted document created on a Windows, Macintosh, MS-DOS, or UNIX platform into a Portable Document Format (PDF) file that can be viewed on several different platforms. Acrobat enables users to send documents that contain distinctive typefaces, color, graphics, and photographs electronically to recipients, regardless of the application used to create the originals. Recipients need the Acrobat reader, which is available free, to view the files.
n. A word derived from the first letters or groups of letters in a multiword descriptive noun or other expression, often serving as a mnemonic, such as RAM (random access memory) and AUTOEXEC.BAT (automatically executed batch file).
n. See Association Control Service Element.
n. See statement.
n. A data structure that represents the state of some construct (such as a procedure, function, block, expression, or module) of a running program. An activation record is useful for the run-time management of both data and sequencing. See also data structure.
adj. Pertaining to the device, program, file, or portion of the screen that is currently operational or subject to command operations. Usually the cursor or a highlighted section shows the active element on the display screen.
n. The highlighted cell on a spreadsheet display that is the current focus of operation. Also called current cell, selected cell. See also range.
n. Material on a Web page that changes on the screen with time or in response to user action. Active content is implemented through ActiveX controls. See also ActiveX controls.
n. The file affected by a current command--typically a data file.
Active Framework for Data Warehousing
n. A data warehousing solution developed by Microsoft and Texas Instruments that represents Microsoft's standard for managing meta data. See also ActiveX, meta data. Acronym: AFDW.
n. The central computer that regenerates and retransmits all signals in an active star network. See also active star.
n. A liquid crystal display (LCD) made from a large array of liquid crystal cells using active-matrix technology. The active matrix is a method of addressing an array of simple LC cells--one cell per pixel. In its simplest form there is one thin-film transistor (TFT) for each cell. Active-matrix displays are used most frequently in laptop and notebook computers because of their thin width and are notable for their high-quality color displays, which are viewable from all angles, unlike passive-matrix displays. Also called TFT, TFT display, TFT LCD. See also liquid crystal display, TFT. Compare passive-matrix display.
n. Cross-platform digital video technology developed by Microsoft for online and desktop multimedia.
n. The program that is currently in control of a microprocessor.
n. A form of the star network topology in which the central computer actively regenerates and retransmits all signals. See also star network.
n. In an environment capable of displaying multiple on-screen windows, the window containing the display or document that will be affected by current cursor movements, commands, and text entry. See also graphical user interface. Compare inactive window.
n. A set of technologies that enables software components to interact with one another in a networked environment, regardless of the language in which the components were created. ActiveX, which was developed as a proposed standard by Microsoft in the mid 1990s and is currently administered by the Open Group, is built on Microsoft's Component Object Model (COM). Currently, ActiveX is used primarily to develop interactive content for the World Wide Web, although it can be used in desktop applications and other programs. ActiveX controls can be embedded in Web pages to produce animation and other multimedia effects, interactive objects, and sophisticated applications. See also ActiveX controls, COM. Compare applet, plug-in (definition 2).
n. Reusable software components that incorporate ActiveX technology. These components can be used to add specialized functionality, such as animation or pop-up menus, to Web pages, desktop applications, and software development tools. ActiveX controls can be written in a variety of programming languages, including C, C++, Visual Basic, and Java. See also ActiveX. Compare helper program.
n. The number of records in use compared with the total number of records in a database file. See also database, record.
n. An object-oriented language developed by The Whitewater Group, Ltd., designed primarily to facilitate Microsoft Windows programming. See also object-oriented programming.
n. A disk drive mechanism for moving the read/write head(s) to the location of the desired track on a disk. See also disk drive, stepper motor, voice coil.
n. On the Internet, the major geographic domain specifying that an address is located in Andorra.
n. A high-level Pascal-based programming language designed under the direction of the U.S. Department of Defense (DoD) in the late 1970s and intended to be the primary language for DoD software development. Ada was named after Augusta Ada Byron, who assisted Charles Babbage in developing programs for his Analytical Engine, the first mechanical computer, in the nineteenth century. See also Pascal.
or adaptor n. A printed circuit board that enables a personal computer to use a peripheral device, such as a CD-ROM drive, modem, or joystick, for which it does not already have the necessary connections, ports, or circuit boards. Commonly, a single adapter card can have more than one adapter on it. Also called interface card. See also controller, expansion board, network adapter, port, video adapter.
n. The ability of a modem to detect whether an incoming call is a fax or a data transmission and respond accordingly. See also modem.
adaptive delta pulse code modulation
n. A class of compression encoding and decoding algorithms used in audio compression and other data compression applications. These algorithms store digitally sampled signals as a series of changes in value, adapting the range of the change with each sample as needed, thus increasing the effective bit resolution of the data. See also pulse code modulation. Compare adaptive differential pulse code modulation. Acronym: ADPCM.
adaptive differential pulse code modulation
n. A digital audio compression algorithm that stores a sample as the difference between a linear combination of previous samples and the actual sample, rather than the measurement itself. The linear combination formula is modified every few samples to minimize the dynamic range of the output signal, resulting in efficient storage. See also pulse code modulation. Compare adaptive delta pulse code modulation.
n. A system that is capable of altering its behavior based on certain features of its experience or environment. See also expert system.
n. See Apple Desktop Bus.
n. See analog-to-digital converter.
n. See analog-to-digital converter.
n. 1. A CPU (central processing unit) component that adds two numbers sent to it by processing instructions. See also central processing unit. 2. A circuit that sums the amplitudes of two input signals. See also full adder, half adder.
n. See add-on.
n. 1. A file that describes new record entries (such as a new customer, employee, or product) in a database so that they can later be scrutinized and posted. 2. A record in a change file specifying a new entry. See also change file.
n. 1. A hardware device, such as an expansion board or chip, that can be added to a computer to expand its capabilities. Also called add-in. See also open architecture (definition 2). 2. A supplemental program that can extend the capabilities of an application program. See also utility program.
n. 1. A number specifying a location in memory where data is stored. See also absolute address, address space, physical address, virtual address. 2. A name or token specifying a particular site on the Internet or other network. 3. A code used to specify an e-mail destination.
vb. To reference a particular storage location. See also absolute address, address space, physical address, virtual address.
n. A cursor programmed so that it can be moved to any location on the screen, as by means of the keyboard or a mouse.
n. 1. In an e-mail program, a reference section listing e-mail addresses and individuals' names. 2. As a Web page, an informal e-mail or URL phone book.
n. A hardware path usually consisting of 20 to 64 separate lines used to carry the signals specifying a memory location. See also bus.
n. An electronic device that converts a numeric address so as to select a memory location on one or more RAM chips.
n. The process of assigning or referring to an address. In programming, the address is typically a value specifying a memory location. See also address1.
n. A table used by routers or Domain Name System (DNS) servers to resolve Internet Protocol (IP) addresses from a text entry such as a name. See also DNS server, IP address, router. Acronym: AMT.
n. See index mark.
n. A number that, when compared by the computer with a network address number, will block out all but the necessary information. For example, in a network that uses XXX.XXX.XXX.YYY and where all computers within the network use the same first address numbers, the mask will block out XXX.XXX.XXX and use only the significant numbers in the address, YYY. See also address1 (definition 2).
n. The method used to indicate an address in memory. See also absolute address, indexed address, paged address, relative address.
n. The process of updating an address during computation.
n. A high-speed memory circuit that holds a memory address for the transfer of information.
n. The identification of a computer's hardware address by finding the corresponding match in an address mapping table. See also address mapping table.
n. See ARP.
n. The total range of memory locations addressable by a computer.
n. The process of converting one kind of address to another, such as a virtual address to a physical address.
n. Short for adjacent. A Boolean qualifier to indicate cases where two instances are adjacent to each other. In the case of a search string, "Microsoft ADJ Word" would return only instances where "Microsoft" and "Word" are adjacent in the string.
n. See Advanced Digital Network.
n. Software from Adobe Systems, Inc. that manages PostScript fonts on a system. See also PostScript. Acronym: ATM.
n. See data processing.
n. See adaptive delta pulse code modulation.
n. See asymmetric digital subscriber line.
n. A dedicated line service capable of transmitting data, video, and other digital signals with exceptional reliability, offered as a premier service by communications companies. Usually Advanced Digital Network refers to speeds at or above 56 kilobits per second (Kbps). See also dedicated line.
n. An application programming interface developed by Microsoft and Intel to monitor and conserve power on a PC-based system, particularly a battery-powered laptop computer, by enabling programs to communicate their power requirements so that the system can route power away from unused hardware components. See also application programming interface. Acronym: APM.
Advanced Program-to-Program Communication
n. See APPC.
Advanced Research Projects Agency Network
n. See ARPANET.
n. Short for Advanced reduced instruction set computing. A specification for a RISC microchip architecture and system environment designed by MIPS Computer Systems to provide binary compatibility among software applications. See also RISC.
Advanced RISC Computing Specification
n. The minimum hardware requirements enabling a RISC-based system to comply with the Advanced Computing Environment standard. See also Advanced RISC.
Advanced SCSI Programming Interface
n. An interface specification developed by Adaptec, Inc. for sending commands to SCSI host adapters. The interface provides an abstraction layer that insulates the programmer from considerations of the particular host adapter used. See also adapter, SCSI. Acronym: ASPI.
n. On the Internet, the major geographic domain specifying that an address is located in United Arab Emirates.
n. On the Internet, the major geographic domain specifying that an address is located in Afghanistan.
n. See Active Framework for Data Warehousing.
n. Acronym for American Federation of Information Processing Societies. An organization formed in 1961 for the advancement of computing and information-related concerns. The U.S. representative of the International Federation of Information Processing, AFIPS was replaced by the Federation on Computing in the United States (FOCUS) in 1990.
adv. Acronym for away from keyboard. A phrase occasionally seen in live chat services on the Internet and online information services as an indication that one is momentarily unable to answer. See also chat1 (definition 1).
n. On the Internet, the major geographic domain specifying that an address belongs to the United States Air Force.
n. Acronym for Andrew File System. Carnegie-Mellon's distributed file system for facilitating accessibility to remote files in large networks.
n. On the Internet, the major geographic domain specifying that an address is located in Antigua and Barbuda.
n. 1. A program that performs a background task for a user and reports to the user when the task is done or some expected event has taken place. 2. A program that searches through archives or other repositories of information on a topic specified by the user. Agents of this sort are used most often on the Internet and are generally dedicated to searching a single type of information repository, such as postings on Usenet groups. Spiders are a type of agent used on the Internet. Also called intelligent agent. See also spider. 3. In client/server applications, a process that mediates between the client and the server. 4. In SNMP (Simple Network Management Protocol), a program that monitors network traffic. See also SNMP.
n. On the Internet, the major geographic domain specifying that an address is located in Anguilla.
n. See artificial intelligence.
n. The file extension that identifies audio files in the sound format originally used on Apple and Silicon Graphics (SGI) computers.
n. The sound format originally used on Apple and Silicon Graphics (SGI) computers. AIFF stores waveform files in an 8-bit monaural format. See also waveform.
n. Acronym for Advanced Interactive Executive. A version of the UNIX system provided by IBM for its UNIX workstations and its PCs.
n. On the Internet, the major geographic domain specifying that an address is located in Alaska, United States.
n. On the Internet, the major geographic domain specifying that an address is located in Albania.
n. A visual or auditory signal from a computer alerting the user to an error or hazardous situation.
n. 1. On the Macintosh and in many graphical user interfaces, an audible or visual alarm that signals an error or represents a warning of some sort. See also alert box. 2. In programming, an asynchronous notification sent by one thread to another. The alert interrupts the recipient thread at defined points in its execution and causes it to execute an asynchronous procedure call. See also asynchronous procedure call, thread (definition 1).
n. An on-screen box, in a graphical user interface, that is used to deliver a message or warning. Compare dialog box.
n. Short for Algorithmic Language. The first structured procedural programming language, developed in the late 1950s and once widely used in Europe.
n. A finite sequence of steps for solving a logical or mathematical problem.
n. A programming language, such as Ada, Basic, C, or Pascal, that uses algorithms for problem solving.
n. 1. An alternative label for some object, such as a file or data collection. 2. A name used to direct e-mail messages to a person or group of people on a network. 3. A false signal that results from the digitization of an analog audio sample.
n. In computer graphics, the jagged appearance of curves or diagonal lines on a display screen, which is caused by low screen resolution.
n. A class of subtle programming errors that can arise in code that performs dynamic allocation. If several pointers address the same chunk of storage, the program may free the storage using one of the pointers, but then attempt to use another one (an alias), which would no longer be pointing to the desired data. This bug is avoidable by the use of allocation strategies that never use more than one copy of a pointer to allocated core memory, or by the use of higher-level languages, such as LISP, which employ a garbage collection feature. Also called stale pointer bug. See also alias, dynamic allocation, garbage collection.
vb. 1. In an application such as a word processor, to position lines of type relative to some point, such as the page margin. The most common types of alignment are shown.
n. The arrangement of objects in fixed or predetermined positions, rows, or columns. For example, the Macintosh Finder can do automatic alignment of icons in a folder or on the desktop.
vb. To reserve a resource, such as sufficient memory, for use by a program. Compare deallocate.
n. In operating systems, the process of reserving memory for use by a program.
n. The size of an individual block on a storage medium, such as a hard drive, which is determined by factors such as total disk size and partitioning options.
n. See cluster.
n. The mode in computer graphics in which all pixels can be individually manipulated. See also graphics mode. Acronym: APA.
adj. Of or pertaining to software that is an alpha.
n. A software product that has been completed and is ready for initial testing in a laboratory. Compare beta.
n. Digital Equipment Corporation's (DEC's) internal name for its 64-bit RISC-based microprocessor product introduced in February 1992 as the DECchip 21064. For trademark reasons, DEC has expanded the name to Alpha AXP, used as an adjective to describe the DECchip technology. The term Alpha is sometimes used in literature to describe the DECchip product, in such phrases as "Alpha-based computer." See also DECchip 21064.
adj. Of, pertaining to, or characteristic of Digital Equipment Corporation's 64-bit RISC-based microprocessor technology implemented in its DECchip product. The designation AXP is used by DEC in its personal computer products to indicate that a product has a DECchip microprocessor. See also Alpha, DECchip 21064, RISC.
n. 1. The set of characters composed of the letters used in a written language. 2. In communications and data processing, the subset of a complete character set, including letters, numerals, punctuation marks, and other common symbols as well as the codes used to represent them. See also ASCII, CCITT, character set, EBCDIC, ISO.
adj. Arranged in order according to the letters of the alphabet.
n. A computer built around the DECchip 21064 processor (called Alpha). See also DECchip 21064.
n. The high-order 8 bits of a 32-bit graphics pixel used to manipulate the remaining 24 bits for purposes of coloring or masking.
n. See DECchip 21064.
adj. In reference to computer graphics, especially videotext and teletext systems, pertaining to or being a display method that uses codes for alphanumeric characters and creates graphics using geometric primitives. Shapes such as horizontal and vertical lines and corners are alphageometric. See also alphamosaic.
adj. In reference to computer graphics, especially videotext and teletext systems, pertaining to or being a display technique that uses codes for alphanumeric characters and creates graphics using rectangular arrangements of elements to form a mosaic. See also alphageometric.
adj. Consisting of letters or digits, or both, and sometimes including control characters, space characters, and other special characters. See also ASCII, character set, EBCDIC.
n. A terminal capable of displaying characters but not graphics.
n. See text mode.
n. A method of sorting data, such as a set of records, that typically uses the following order: punctuation marks, numerals, alphabetic characters (with capitals preceding lowercase letters), and any remaining symbols.
n. The process of user testing that is carried out on a piece of alpha software.
n. A small computer introduced in 1975 by Micro Instrumentation Telemetry Systems of New Mexico and sold primarily in kit form. The Altair was based on the 8-bit Intel 8080 microprocessor, had 256 bytes of random access memory, received input through a bank of switches on the front panel, and displayed output via a row of light-emitting diodes. Although it was short-lived, the Altair is considered the first successful personal computer, which was then called a home computer.
n. A World Wide Web search site hosted by Digital Equipment Corporation. AltaVista may be found at URL http://www.altavista.digital.com/.
n. Any candidate key in a database not designated as the primary key. See Alt key.
n. Electric current that reverses its direction of flow (polarity) periodically according to a frequency measured in hertz, or cycles per second. Compare direct current. Acronym: AC.
n. A key included on PC and other standard keyboards that is used in conjunction with another key to produce some special feature or function and is typically marked with the letters Alt.
n. Internet newsgroups that are part of the alt. ("alternative") hierarchy and have the prefix alt. Unlike the seven Usenet newsgroup hierarchies (comp., misc., news., rec., sci., soc., and talk.) that require formal votes among users in the hierarchy before official newsgroups can be established, anybody can create an alt. newsgroup. Therefore, newsgroups devoted to discussions of obscure or bizarre topics are generally part of the alt. hierarchy.
n. See arithmetic logic unit.
n. On the Internet, the major geographic domain specifying that an address is located in Armenia.
n. See amplitude modulation.
American Federation of Information Processing Societies
n. See AFIPS.
American National Standards Institute
n. See ANSI.
American Standard Code for Information Interchange
n. See ASCII.
n. An online information service, based in Vienna, Virginia, that provides e-mail, news, educational and entertainment services, and computer support by means of a graphical user interface. America Online is one of the largest American Internet access providers. Acronym: AOL.
n. A ROM BIOS developed and marketed by American Megatrends, Inc. (AMI), for use in IBM-compatible computers. A popular feature is that its configuration software is stored in the ROM chip along with the BIOS routines, so that the user does not need a separate configuration disk to modify system settings, such as amount of memory installed and number and types of disk drives. See also BIOS, Phoenix BIOS, ROM BIOS.
n. A model of desktop computer introduced by Commodore in 1985. The Amiga was especially strong in its ability to support sound and video, which made it popular among broadcast and multimedia producers, but it was overshadowed by the IBM Personal Computer (and its clones) and the Apple Macintosh. The ownership of the Amiga design has been through the hands of several companies in the United States and Germany.
n. See ampere.
n. Abbreviated a, A, amp. The basic unit of electric current. One ampere is equivalent to a flow of 1 coulomb per second.
n. A measure of the strength of a signal, such as sound or voltage, determined by the distance from the baseline to the peak of the waveform. See also waveform.
n. A method of encoding information in a transmission, such as radio, using a carrier wave of constant frequency but of varying amplitude. Acronym: AM.
n. Acronym for Advanced Mobile Phone Service. One of the original cellular phone services, relying on frequency-division multiplexing.
n. See AMPS, NAMPS.
n. See address mapping table.
n. On the Internet, the major geographic domain specifying that an address is located in the Netherlands Antilles.
adj. Pertaining to or being a device or signal having the property of continuously varying in strength or quantity, such as voltage or audio. Compare digital (definition 2).
n. A communications channel, such as a voice-grade telephone line, carrying signals that vary continuously and can assume any value within a specified range.
n. A computer that measures data varying continuously in value, such as speed or temperature.
n. Data that is represented by continuous variations in some physical property, such as voltage, frequency, or pressure. Compare digital data transmission.
n. A video display capable of depicting a continuous range of colors or shades rather than discrete values. Compare digital display.
n. A communications line, such as a standard telephone line, that carries continuously varying signals.
n. A device that generates continuously variable signals and is sometimes used to activate an actuator in a disk drive. See also actuator.
n. A device that converts a continuously varying (analog) signal, such as sound or voltage, from a monitoring instrument to binary code for use by a computer. Also called A-D converter. See also modem. Compare digital-to-analog converter. Acronym: ADC.
n. The evaluation of a situation or problem, including review from various aspects or points of view. In computing, analysis commonly involves such features as flow control, error control, and evaluation of efficiency. Often the overall problem is divided into smaller components that can be more easily dealt with. See also flow analysis, numerical analysis, systems analysis. Compare synthesis.
n. See presentation graphics.
n. A mechanical calculating machine designed by British mathematician Charles Babbage in 1833 but never completed. It was the first general-purpose digital computer. See also Difference Engine.
n. 1. A format code in a desktop publishing or word processing document that keeps an element in the document, such as a figure or a caption or label associated with the figure, in a certain position in the document. The anchored object is generally attached to another element in the document such as a piece of text (often a paragraph), a graphic, or a particular place in the document. As text and other objects are added to the document, the anchored object moves relative to the object to which it is anchored or remains stationary. 2. A tag in an HTML document that defines a section of text, an icon, or other element as a link to another element in the document or to another document or file. See hyperlink.
n. See peripheral.
n. A logical operation combining the values of two bits (0, 1) or two Boolean values (false, true) that returns a value of 1 (true) if both input values are 1 (true) and returns a 0 (false) otherwise. The possible combinations are shown in the following table.
n. A digital circuit whose output is a value of 1 only when all input values are 1. See also truth table.
n. See AFS.
n. See < >.
n. Abbreviated
n. A Windows 95 and Windows NT feature that allows a series of frames, one after another, to appear at the mouse pointer location instead of a single image, thus producing a short loop of animation. The animated cursors feature is designated by the .ani suffix.
n. A series of graphic images in GIF format, displayed sequentially in a single location to give the appearance of a moving picture. See also GIF.
n. The illusion of movement created by using a succession of static images. In computer graphics, the images can all be drawn separately, or starting and ending points can be drawn with the intervening images provided by software. See also 3-D graphic, surface modeling, tween, wire-frame model.
n. See artificial neural network.
n. A note or comment attached to some part of a document to provide related information. Some applications support voice annotations or annotations accessible by icons. See also comment.
n. A bot on an Internet Relay Chat (IRC) channel or multi-user dungeon (MUD) that interacts with the user in an obnoxious manner. See also bot, IRC, MUD.
n. In electronics, the positively charged terminal or electrode toward which electrons flow. Compare cathode.
n. The ability to send an e-mail message or an article to a newsgroup without one's identity becoming known. Ordinarily, the e-mail address of the sender appears automatically in a message's header, which is created by the client software. To achieve anonymity, a message must be sent through an anonymous remailer--which, however, maintains a record of the sender's identity to enable replies. See also anonymous remailer.
n. On the Internet, the standard login name used to obtain access to a public FTP file archive. See also anonymous FTP.
n. The ability to access a remote computer system on which one does not have an account, via the Internet's File Transfer Protocol (FTP). Users have restricted access rights with anonymous FTP and usually can only copy files to or from a public directory, often named /pub, on the remote system. Users can also typically use FTP commands, such as listing files and directories. When using anonymous FTP, the user accesses the remote computer system with an FTP program and generally uses anonymous or ftp as a logon name. The password is usually the user's e-mail address, although a user can often skip giving a password or give a false e-mail address. In other cases, the password can be the word anonymous. Many FTP sites do not permit anonymous FTP access in order to maintain security. Those that do permit anonymous FTP sometimes restrict users to only downloading files for the same reason. See also FTP1 (definition 1), logon, /pub.
n. A message in a newsgroup or mailing list that cannot be traced to its originator. Generally this is accomplished by using an anonymous server for newsgroup posts or an anonymous remailer for e-mail. See also anonymous remailer.
n. An e-mail server that receives incoming messages, replaces the headers that identify the original sources of the messages, and sends the messages to their ultimate destinations. The purpose of an anonymous remailer is to hide the identities of the senders of the e-mail messages.
n. 1. The software used by an anonymous remailer. See also anonymous remailer. 2. Software that provides anonymous FTP service. See also anonymous FTP. See anonymous remailer.
n. Acronym for American National Standards Institute. A voluntary, nonprofit organization of U.S. business and industry groups formed in 1918 for the development of trade and communication standards. ANSI is the American representative of the International Standards Organization and has developed recommendations for the use of programming languages including FORTRAN, C, and COBOL. See also ANSI C, ANSI.SYS, SCSI.
n. A version of the C programming language standardized by ANSI. See also ANSI, K&R C.
n. Acronym for American National Standards Institute Standards Planning and Requirements Committee. The ANSI committee that, in the 1970s, proposed a generalized, three-schema architecture that is used as the foundation for some database management systems.
n. An installable device driver for MS-DOS computers that uses ANSI commands (escape sequences) to enhance the user's control of the console. See also ANSI, driver, escape sequence, install.
n. A setting that allows a modem to answer an incoming call automatically. It is used in all fax machines. Also called auto answer.
n. A modem that can receive but not originate calls.
n. A modem that can both send and receive calls--the most common type of modem in use.
n. A software technique for smoothing the jagged appearance of curved or diagonal lines caused by poor resolution on a display screen. Methods of anti-aliasing include surrounding pixels with intermediate shades, and manipulating the size and horizontal alignment of pixels. See also dithering. Compare aliasing.
adj. Pertaining to any measure taken to reduce reflections of external light on a monitor screen. The screen may be coated with a chemical (which may reduce its brightness), covered with a polarizing filter, or simply rotated so that external light is not reflected into the user's eye.
n. A device designed to minimize shocks caused by the buildup of static electricity, which can disrupt computer equipment or cause data loss. An antistatic device may take the form of a floor mat, a wristband with a wire attached to the workstation, a spray, a lotion, or other special-purpose device. See also static, static electricity.
n. A computer program that scans a computer's memory and mass storage to identify, isolate, and eliminate viruses, and that examines incoming files for viruses as the computer receives them.
n. Any random key on a computer keyboard. Some programs prompt the user to "press any key" to continue. It does not matter which key the user presses. There is no key on the keyboard called Any.
n. The property of an integrated computer network environment where it is possible to share data across multiple protocols, host types, and network topologies.
n. On the Internet, the major geographic domain specifying that an address is located in Angola.
n. See America Online.
n. See all points addressable.
n. See asynchronous procedure call.
n. See application programming interface.
n. Acronym for A Programming Language. A high-level language introduced in 1968 for scientific and mathematical applications. APL is a subprogram-based interpreted language that uses a large set of special characters and terse syntax and is available for use on PC-compatible machines. See also interpreted language.
n. See Advanced Power Management.
n. See application.
n. Acronym for Advanced Program-to-Program Communication. A protocol developed as part of IBM's Systems Network Architecture and designed to enable applications programs running on different computers to communicate and exchange data directly.
vb. To place or insert as an attachment by adding data to the end of a file or database or extending a character string. See also file, string. Compare truncate.
n. A serial communications pathway built into Apple Macintosh and Apple IIGS computers. Typically a flexible cord, it enables low-speed input devices, such as a keyboard or mouse, to communicate with the computer. The bus functions like a simple local area network that can connect up to 16 devices, including light pens, trackballs, and graphics tablets, to the computer. Although there are only two external ports, more than two devices can be linked in a series called a daisy chain. See also bus, daisy chain, device driver, input/output port, serial communication. Acronym: ADB.
n. A shareware drawing application for Macintosh computers.
n. A feature added to Mac OS System 7 that enables one application to send a command, such as save or open, to another application. See also Mac OS.
n. A 105-key keyboard that works with the Macintosh SE, Macintosh II, and Apple IIGS computers. This keyboard marks Apple's first inclusion of function (F) keys, whose absence was long cited as a shortcoming of the Macintosh compared with IBM PCs and compatibles. This feature, along with other layout changes and the addition of new keys and lights, makes the Apple Extended Keyboard quite similar in form to the IBM enhanced keyboard. See also enhanced keyboard.
n. The second computer introduced by the Apple Computer Corporation, in April 1977. The Apple II featured 4K dynamic RAM, expandable to 48K (with 16K chips), and used the 6502 microprocessor. The Apple II was the first computer to offer a TV video adapter as an optional alternative to a color computer monitor. It also featured sound and eight expansion slots. See also 6502.
n. A key on Apple keyboards labeled with an outline of the Apple logo. On the Apple Extended Keyboard, this key is the same as the Command key, which functions similarly to the Control key on IBM and compatible keyboards. It is generally used in conjunction with a character key as a shortcut to making menu selections or starting a macro.
n. See Macintosh.
n. See Newton.
n. A script language used with Macintosh computers running under the System 7 operating system to execute commands and automate functions. See also script.
n. File server software that works with the Mac OS and allows one Macintosh computer to share files with another on the same network. See also file server, Mac OS.
n. A small piece of code that can be transported over the Internet and executed on the recipient's machine. The term is especially used to refer to such programs as they are embedded in line as objects in HTML documents on the World Wide Web.
n. An inexpensive local area network developed by Apple that can be used by Apple and non-Apple computers to communicate and share resources such as printers and file servers. Non-Apple computers must be equipped with AppleTalk hardware and suitable software. The network uses a layered set of protocols similar to the ISO/OSI model and transfers information in the form of packets called frames. AppleTalk supports connections to other AppleTalk networks through devices known as bridges, and it supports connections to dissimilar networks through devices called gateways. See also bridge, frame (definition 2), gateway.
n. A program designed to assist in the performance of a specific task, such as word processing, accounting, or inventory management. Compare utility.
n. A set of instructions that specifies how an executable file interacts with the hardware and how information is stored. Compare application programming interface. Acronym: ABI.
adj. Of, pertaining to, or characteristic of an operating system in which a user invokes an application to open or create documents (such as word processing files or spreadsheets). Command-line interfaces and some graphical user interfaces such as the Windows 3.x Program Manager are application-centric. Compare document-centric.
n. An individual who designs and analyzes the appearance and operation of an application program.
application development environment
n. An integrated suite of programs for use by software developers. Typical components of application development environments include a compiler, file browsing system, debugger, and text editor for use in creating programs.
application development language
n. A computer language designed for creating applications. The term is usually restricted to refer to languages with specific high-level constructs geared toward record design, form layout, database retrieval and update, and similar tasks. See also 4GL, application, application generator.
application development system
n. A programming environment designed for the development of an application, typically including a text editor, compiler, and linker, and often including a library of common software routines for use in the developed program.
n. See program file.
n. Software running on a machine that is intended to maintain security on a secluded network yet allow certain traffic to go between the private network and the outside world. See also firewall.
n. Software for generating source or machine code for running an application based on a description of the desired functionality. Limited in scope, application generators are included with some database programs and use built-in instruction sets to generate program code. See also application.
n. A block of RAM used by an application to store its code, resources, records, document data, and other information. See also heap (definition 1), RAM.
n. The highest layer of standards in the Open Systems Interconnection (OSI) model. The application layer contains signals that perform useful work for the user, such as file transfer or remote access to a computer, as opposed to lower levels, which control the exchange of data between transmitter and receiver. See also ISO/OSI model.
n. A processor dedicated to a single application.
n. See application.
application programming interface
or application program interface n. A set of routines used by an application program to direct the performance of procedures by the computer's operating system. Acronym: API.
n. A key or combination of keys that when pressed will quickly perform an action within an application that would normally require several user actions, such as menu selections. Also called keyboard shortcut.
n. See application.
application-specific integrated circuit
n. See gate array.
n. See suite (definition 1).
n. On the Internet, the major geographic domain specifying that an address is located in Antarctica.
n. On the Internet, the major geographic domain specifying that an address is located in Argentina.
n. A set of rules for resolving competing demands for a machine resource by multiple users or processes. See also contention.
n. The file extension that identifies compressed archive files encoded using the Advanced RISC Computing Specification (ARC) format. See also compressed file.
n. 1. A coin-operated computer game for one or more players that features high-quality screen graphics, sound, and rapid action. 2. Any computer game designed to mimic the style of a coin-operated arcade game, such as games marketed for the home computer. See also computer game.
n. An Internet utility for finding files in public archives obtainable by anonymous FTP. The master Archie server at McGill University in Montreal downloads FTP indexes from participating FTP servers and merges them into a master list and sends updated copies of the master list to other Archie servers each day. Archie is a shortened form of archive. See also anonymous FTP, FTP1 (definition 1). Compare Jughead, Veronica.
n. See Archie.
n. On the Internet, a server that contains Archie indexes to the names and addresses of files in public FTP archives. See also Archie, FTP1 (definition 1), server (definition 2).
n. 1. The physical construction or design of a computer system and its components. See also cache, CISC, closed architecture, network architecture, open architecture, pipelining, RISC. 2. The data-handling capacity of a microprocessor. 3. The design of application software incorporating protocols and the means for expansion and interfacing with other programs.
n. 1. A tape or disk containing files copied from another storage device and used as backup storage. 2. A compressed file. 3. A file directory on the Internet that is available by File Transfer Protocol (FTP) or an Internet directory established for dissemination of stored files.
vb. 1. To copy files onto a tape or disk for long-term storage. 2. To compress a file.
n. A bit that is associated with a file and is used to indicate whether or not the file has been backed up. See also back up, bit.
n. A file that contains a set of files, such as a program with its documentation and example input files, or collected postings from a newsgroup. On UNIX systems, archive files can be created using the tar program; they can then be compressed using compress or gzip. PKZIP under MS-DOS and Windows and StuffIt under Mac OS create archive files that are already compressed. See also compress1, gzip, PKZIP, StuffIt, tar1.
n. A site on the Internet that stores files. The files are usually accessed through one of the following ways: downloaded through anonymous FTP, retrieved through Gopher, or viewed on the World Wide Web. See also anonymous FTP, Gopher.
n. A graphical presentation, such as of quarterly sales figures, that uses shading or coloring to emphasize the difference between the line representing one set of data points and the line representing a separate but related set of data points.
n. In information management, the examination of a group of documents for the purpose of identifying those that are relevant to a particular subject or category.
n. See argument.
n. An independent variable, used with an operator or passed to a subprogram that uses the argument to carry out specific operations. See also algorithm, operator (definition 1), parameter, subprogram.
adj. Pertaining to the mathematical operations of addition, subtraction, multiplication, and division.
n. The branch of mathematics dealing with the addition, subtraction, multiplication, and division of real numbers.
n. A series of elements, including data labels and constants as well as numbers, that are joined by arithmetic operators, such as + and
n. A component of a microprocessor chip used for arithmetic, comparative, and logical functions. See also gate (definition 1). Acronym: ALU.
n. Any of the standard calculations performed in arithmetic--addition, subtraction, multiplication, or division. The term is also used in reference to negative numbers and absolute values.
n. An operator that performs an arithmetic operation: +, -, x, or /. An arithmetic operator usually takes one or two arguments. See also argument, binary, logical operator, operator (definition 1), unary.
n. The DOS file extension used with archive files created with the ARJ compression program.
n. On the Internet, the major geographic domain specifying that an address belongs to the United States Army.
n. Acronym for Address Resolution Protocol. A TCP/IP protocol for determining the hardware address (or physical address) of a node on a local area network connected to the Internet, when only the IP address (or logical address) is known. An ARP request is sent to the network, and the node that has the IP address responds with its hardware address. Although ARP technically refers only to finding the hardware address, and RARP (for Reversed ARP) refers to the reverse procedure, ARP is commonly used for both senses. See also IP address, TCP/IP.
n. A large wide area network created in the 1960s by the U.S. Department of Defense Advanced Research Projects Agency (ARPA, renamed DARPA in the 1970s) for the free exchange of information between universities and research organizations, although the military also used this network for communications. In the 1980s MILNET, a separate network, was spun off from ARPANET for use by the military. ARPANET was the network from which the Internet evolved. See also Internet, MILNET.
n. Short for Address Resolution Protocol request. An ARP packet containing the Internet address of a host computer. The receiving computer responds with or passes along the corresponding Ethernet address. See also ARP, Ethernet, IP address, packet.
n. In programming, a list of data values, all of the same type, any element of which can be referenced by an expression consisting of the array name followed by an indexing expression. Arrays are part of the fundamentals of data structures, which, in turn, are a major fundamental of computer programming. See also array element, index, record1, vector.
n. A data value in an array.
n. A group of interconnected, identical processors operating synchronously, often under the control of a central processor.
n. Any of four keys labeled with arrows pointing up, down, left, and right, used to move the cursor vertically or horizontally on the display screen or, in some programs, to extend the highlight.
n. A message that appears in an Internet newsgroup. Also called post. See also newsgroup.
n. The branch of computer science concerned with enabling computers to simulate such aspects of human intelligence as speech recognition, deduction, inference, creative response, the ability to learn from experience, and the ability to make inferences given incomplete information. Two common areas of artificial-intelligence research are expert systems and natural-language processing. See also expert system, natural-language processing. Acronym: AI.
n. The study of computer systems that simulate some aspects of the behavior of living organisms. Artificial life includes systems in which programs intended to perform some particular task compete for survival and reproduction based on their performance; the offspring can combine pieces of code and undergo random variations, and the programs so modified compete in turn, until an optimal solution is found.
n. A form of computer artificial intelligence that uses software based on concepts understood from biological neural networks to adaptively perform a task. Acronym: ANN.
n. On the Internet, the major geographic domain specifying that an address is located in Arkansas, United States.
n. On the Internet, the major geographic domain specifying that an address is located in American Samoa.
n. A filename extension most commonly indicating that the file contains ASCII text that can be processed by all types of word processing software, including MS-DOS Edit, Windows Notepad, Windows-95/NT WordPad, and Microsoft Word. Some systems may use this extension to indicate that a file contains image information. See also ASCII.
n. The portion of a lowercase letter that extends above the main body (x-height) of the letter. See also baseline, x-height. Compare descender.
n. The arrangement of a sequence of items from lowest to highest, such as from 1 to 10 or from A to Z. The rules for determining ascending order in a particular application can sometimes be very complicated: capital letters before lowercase letters, extended ASCII characters in ASCII order, and so on.
n. A sort that results in the arrangement of items in ascending order. See also alphanumeric sort, ascending order. Compare descending sort.
n. In an FTP client program, the command that instructs the FTP server to send or receive files as ASCII text. See also ASCII, FTP client. Compare binary2.
n. Acronym for American Standard Code for Information Interchange. A coding scheme using 7 or 8 bits that assigns numeric values to up to 256 characters, including letters, numerals, punctuation marks, control characters, and other symbols. ASCII was developed in 1968 to standardize data transmission among disparate hardware and software systems and is built into most minicomputers and all personal computers. See also ASCII file, character, character code, control character, extended ASCII. Compare EBCDIC.
n. A standard 7-bit code for representing ASCII characters using binary values; code values range from 0 to 127. Most PC-based systems use an 8-bit extended ASCII code, with an extra 128 characters used to represent special symbols, foreign-language characters, and graphic symbols. The ASCII character set appears in Appendix A. See also ASCII, character, EBCDIC, extended ASCII.
n. The sequence of bytes that indicates the end of a line of text. For Windows and MS-DOS systems, this is the hexadecimal sequence 0D 0A or the decimal sequence 13 10. Data files imported from other kinds of computers may not display correctly if the software used is not capable of recognizing these differences and adjusting for them. See also ASCII, EOL.
n. A document file in ASCII format, containing characters, spaces, punctuation, carriage returns, and sometimes tabs and an end-of-file marker, but no formatting information. Also called ASCII file, text file, text-only file. See also ASCII, text file. Compare binary file.
n. The preferred mode of electronic exchange for text files. In ASCII mode, character conversions to and from the network-standard character set are performed. See also ASCII. Compare binary transfer.
n. In programming, an ASCII string terminated by the NULL character (a byte containing the character whose ASCII value is 0). Also called null-terminated string.
n. Acronym for application-specific integrated circuit. See gate array.
n. See Abstract Syntax Notation One.
n. In computer displays and graphics, the ratio of the width of an image or image area to its height. An aspect ratio of 2:1, for example, indicates that the image is twice as wide as it is high. The aspect ratio is an important factor in maintaining correct proportions when an image is printed, rescaled, or incorporated into another document.
n. See Advanced SCSI Programming Interface.
n. See automatic system reconfiguration.
vb. In programming, to convert an assembly language program to equivalent machine language instructions, called object code. See also assembler, assembly language, linker, object code.
n. A program that converts assembly language programs, which are understandable by humans, into executable machine language. See also assemble, assembly language, assembly listing, compiler (definition 2), machine code.
n. A low-level programming language using abbreviations or mnemonic codes in which each statement corresponds to a single machine instruction. An assembly language is translated to machine language by the assembler and is specific to a given processor. Advantages of using an assembly language include increased execution speed and direct programmer interaction with system hardware. See also assembler, compiler, high-level language, low-level language, machine code.
n. A file created by an assembler that includes the statements of an assembly language program, the machine language generated by the assembler, and a list of the symbols used in the program. See also assembler, assembly language.
n. A Boolean statement used in a program to test a condition that, if the program is operating correctly, should always evaluate as true; otherwise the program will typically terminate with an appropriate error message. Assertions are used for debugging programs and for documenting how a program should operate.
n. An operator used to assign a value to a variable or data structure. See also assignment statement, operator (definition 1).
n. A programming language statement used to assign a value to a variable. It usually consists of three elements: an expression to be assigned, an assignment operator (typically a symbol such as = or :=), and a destination variable. On execution of the assignment statement, the expression is evaluated and the resulting value is stored in the specified destination. See also assignment operator, expression, variable.
vb. To inform the operating system that a particular filename extension is linked to a specific application. When a file is opened that has an extension associated with a given application, the operating system automatically starts the application and loads the file.
Association Control Service Element
n. An Open Systems Interconnection (OSI) method to establish a call between two applications by checking the identities and contexts of the application entities and performing an authentication security check. See also ISO/OSI model. Acronym: ACSE.
Association for Computing Machinery
n. A membership society founded in 1947 and devoted to the advancement of knowledge and technical proficiency of information processing professionals. Acronym: ACM.
Association of C and C++ Users
n. An organization of people interested in the programming language C and its variants. Members of the association include professional programmers, manufacturers and vendors of compilers, and nonprofessional programming enthusiasts. Acronym: ACCU.
n. A memory-based storage method in which data items are accessed not on the basis of a fixed address or location but by analysis of their content. Also called content-addressed storage.
n. See operator associativity.
n. 1. The character (*) used in applications and programming languages to signify multiplication. 2. In Windows, MS-DOS, OS/2, and other operating systems, a wildcard character that can be used in place of other characters, as in *.*, which represents any combination of filename and extension. See also question mark, star-dot-star, wildcard character. 3. In the C and C++ programming languages, the character used to dereference a pointer to a class or structure. See also dereference, pointer (definition 1).
n. A form of transmission used by high-speed modems, typically those that operate at rates of 9,600 bps or more, that allows simultaneous incoming and outgoing transmission by dividing a telephone line bandwidth into two channels: one in the range of 300 to 450 bps and one at a speed of 9,600 bps or more.
asymmetric digital subscriber line
n. Technology and equipment allowing high-speed digital communication, including video signals, across an ordinary twisted-pair copper phone line, with speeds up to 9 megabits per second (9 Mbps) downstream (to the customer) and up to 800 kilobits per second (800 kbps) upstream. Also called asymmetric digital subscriber loop. Compare symmetric digital subscriber line. Acronym: ADSL.
asymmetric digital subscriber loop
n. See asymmetric digital subscriber line.
n. A device whose internal operations are not synchronized with the timing of any other part of the system.
n. An operation that proceeds independently of any timing mechanism, such as a clock. For example, two modems communicating asynchronously rely upon each sending the other start and stop signals in order to pace the exchange of information. Compare synchronous operation.
n. A function call that executes separately from an executing program when a set of enabling conditions exist. After the conditions have been met, the operating system's kernel issues a software interrupt and directs the executing program to execute the call. See also function call. Acronym: APC.
Asynchronous Protocol Specification
n. The X.445 standard. See CCITT X Series.
n. See ATM (definition 1).
n. In modem communication, a form of data transmission in which data is sent intermittently, one character at a time, rather than in a steady stream with characters separated by fixed time intervals. Asynchronous transmission relies on the use of a start bit and stop bit(s), in addition to the bits representing the character (and an optional parity bit), to distinguish separate characters.
n. On the Internet, the major geographic domain specifying that an address is located in Austria.
n. Acronym for Advanced Technology Attachment. ANSI group X3T10's official name for the disk drive interface standard commonly known as Integrated Drive Electronics (IDE). Also called AT Attachment.
n. Expansion card used to control and interface with an ATA hard disk drive. These cards are usually ISA cards. See also ATA, ISA.
n. IDE (Integrated Drive Electronics--or numerous other interpretations) and ATA (AT Attachment) are one and the same thing: a disk drive implementation designed to integrate the controller onto the drive itself, thereby reducing interface costs and making firmware implementations easier.
n. The interface used by the IBM PC AT system for accessing CD-ROM devices.
n. See ATA.
n. The electric pathway used by IBM AT and compatible computers to connect the motherboard and peripheral devices. The AT bus supports 16 bits of data, whereas the original PC bus supports only 8 bits. Also called expansion bus. See also EISA, ISA, Micro Channel Architecture.
n. See TIA.
n. Acronym for Attention Dial Pulse, a command that initiates pulse (as opposed to touch-tone) dialing in Hayes and Hayes-compatible modems. Compare ATDT.
n. Acronym for Attention Dial Tone, a command that initiates touch-tone (as opposed to pulse) dialing in Hayes and Hayes-compatible modems. Compare ATDP.
n. On the Internet, the major geographic domain specifying that an address is located in Atlanta, Georgia, United States.
n. Acronym for Asynchronous Transfer Mode. A network technology capable of transmitting data, voice, video, and frame relay traffic in real time. Data, including frame relay data, is broken into packets containing 53 bytes each, which are switched between any two nodes in the system at rates ranging from 1.5 Mbps to 622 Mbps. ATM is defined in the broadband ISDN protocol at the levels corresponding to levels 1 and 2 of the ISO/OSI model. It is currently used in local area networks involving workstations and personal computers, but it is expected to be adopted by the telephone companies, which will be able to charge customers for the data they transmit rather than for their connect time. See also broadband, ISDN, ISO/OSI model. See Adobe Type Manager.
n. Forum created in 1991 and including more than 750 companies related to communications and computing, as well as government agencies and research groups. The forum aims to promote Asynchronous Transfer Mode for data communication. See also ATM (definition 1).
n. An operation considered or guaranteed to be indivisible (by analogy with an atom of matter, once thought to be indivisible). Either the operation is uninterruptible or, if it is aborted, a mechanism is provided that ensures the return of the system to its state prior to initiation of the operation.
n. See @.
vb. To include an external document as part of an e-mail message, using MIME or some other encoding application. Most modern e-mail clients have the ability to attach documents, as well as to decode attached documents that are received.
n. An ASCII text file or a binary file, such as a document created in a word processing system, that is included with an e-mail message as an attachment. The file is not part of the actual e-mail message, and it is generally encoded using uuencoding, MIME, or BinHex. Most e-mail programs automatically encode an attached document for transmission with a message. The recipient of the message must have an e-mail program capable of decoding the attached document or use a separate utility to decode it in order to read the document. See also ASCII, binary file, BinHex, MIME, uuencode.
n. A secondary processor attached to a computer system, such as a keyboard or video subsystem processor.
n. The weakening of a transmitted signal, such as the distortion of a digital signal or the reduction in amplitude of an electrical signal, as it travels farther from its source. Attenuation is usually measured in decibels and is sometimes desirable, as when signal strength is reduced electronically, for example, by a radio volume control, to prevent overloading.
prefix Metric prefix meaning 10
n. 1. In a database record, the name or structure of a field. For example, the files LASTNAME, FIRSTNAME, and PHONE would be attributes of each record in a PHONELIST database. The size of a field or the type of information it contains would also be attributes of a database record. 2. In screen displays, an element of additional information stored with each character in the video buffer of a video adapter running in character mode. Such attributes control the background and foreground colors of the character, underlining, and blinking. 3. In markup languages such as SGML and HTML, a name-value pair within a tagged element that modifies certain features of that element. See also HTML, SGML.
n. See System V.
n. A specification for PC motherboard architectures with built-in audio and video capabilities, introduced by Intel in 1995. ATX supports USB and full-length boards in all sockets. See also board, motherboard, specification, USB.
n. On the Internet, the major geographic domain specifying that an address is located in Australia.
adj. Relating to frequencies within the range of perception by the human ear--from about 15 to 20,000 hertz (cycles per second). See also audio response, synthesizer.
n. See audio card.
n. An expansion card that converts analog audio signals from a microphone, audio tape, or other source to digital form that can be stored as a computer audio file, and converts computer audio files to electrical signals that can be played through a speaker. Output sounds can be routed through speakers or headphones. Input can be entered through a microphone connected to the computer. Most audio cards support MIDI. Audio cards enable sounds to be heard from CD-ROMs and other storage media or over the Internet. Also called audio board, sound board, sound card. See also MIDI.
n. The transmission of an audio signal using IP protocols. See also IP.
n. A method of reducing the overall loudness of an audio signal. This is accomplished by limiting the amount of apparent distortion when the signal is played back through a speaker or transmitted through a communications link.
n. See audio response.
n. A circuit consisting of a digital-to-analog converter that transforms signals from the computer to audible tones. It is used in conjunction with an amplifier and speaker. See also digital-to-analog converter.
n. Any sound produced by a computer; specifically, spoken output produced by a computer in response to some specific type of input. Such output may be generated using a combination of words from a digitized vocabulary or through the synthesis of words from tables of phonemes. See also frequency response, phoneme.
n. An application allowing users to send and receive information by telephone. Users typically call an audiotex system and are presented with a series of choices or a series of questions through a voice mail system. When users select choices by pressing the buttons on the phone (rotary dial phones cannot be used for audiotex) or by speaking aloud, a database host responds by sending information to the voice mail system, which then converts the data to a spoken message for the user, or it responds by receiving and storing the information entered by the user. Also called audiotext. See also voice mail.
n. See audiotex.
n. See AVI.
adj. Relating to or being any material that uses a combination of sight and sound to present information.
n. In reference to computing, an examination of equipment, programs, activities, and procedures to determine how efficiently the overall system is performing, especially in terms of ensuring the integrity and security of data.
n. The process an operating system uses to detect and record security-related events, such as an attempt to create, to access, or to delete objects such as files and directories. The records of such events are stored in a file known as a security log, whose contents are available only to those with the proper clearance. See also security log.
n. In reference to computing, a means of tracing all activities affecting a piece of information, such as a data record, from the time it is entered into a system to the time it is removed. An audit trail makes it possible to document, for example, who made changes to a particular record and when.
n. See acceptable use policy.
n. In a multiuser or network operating system, the process by which the system validates a user's logon information. A user's name and password are compared against an authorized list, and if the system detects a match, access is granted to the extent specified in the permission list for that user. See also logon, password, permission, user account, user name.
n. A computer language or application development system designed primarily for creating programs, databases, and materials for computer-aided instruction (CAI). A familiar example in relation to microcomputers is PILOT, a language used to create lessons. See also CAI, PILOT.
n. Application software that enables the operator to create and format a document for a specific kind of computer environment. An authoring system, especially for multimedia work, often consists of several applications within the framework of a single, controlling application. See also authoring language.
n. In reference to computing, especially remote computers on a network, the right granted an individual to use the system and the data stored on it. Authorization is typically set up by a system administrator and verified by the computer based on some form of user identification, such as a code number or password. Also called access privileges, permission. See also network, system administrator.
n. See password.
n. See answer mode.
n. A function in Microsoft Word for Windows that automatically corrects errors and makes other substitutions as soon as a user types text. For example, AutoCorrect can be set up to fix misspellings, such as teh for the, or to change "straight" quotation marks to "smart" quotation marks. The user can select which AutoCorrect features to enable. See also smart quotes.
n. A feature enabling a modem to open a telephone line and initiate a call by transmitting a stored telephone number as a series of pulses or tones.
n. A special-purpose batch file (set of commands) that is automatically carried out by the MS-DOS operating system when the computer is started or restarted. Created by the user or (in later versions of MS-DOS) by the operating system at system installation, the file contains basic startup commands that help configure the system to installed devices and to the user's preferences.
n. See typematic.
n. 1. The study of computing processes and their capabilities and limitations; that is, how systems receive and process input and produce output. See also cellular automata. 2. The study of the relationship between behavioral theories and the operation of automated devices.
n. A broad term used to refer to an office where work is carried out with the aid of computers, telecommunications facilities, and other electronic devices.
n. See answer mode.
n. See data processing.
n. See auto dial.
n. A process that, upon detection of an internal processing or data transmission error, invokes a routine designed to correct the error or retry the operation.
Automatic Sequence Controlled Calculator
n. See Mark I.
automatic system reconfiguration
n. Automation of configuration by the system to accommodate some change in either the software or the hardware. Acronym: ASR.
n. A process or system feature capable of assessing the status of its own internal environment.
n. A feature in Windows 95 that allows it to automatically operate a CD-ROM. When a CD is inserted into a CD-ROM drive, Windows 95 looks for a file called AUTORUN.INF on the CD. If the file is found, Windows 95 will open it and carry out its instructions, which are usually to set up an application from the CD-ROM on the computer's hard disk or to start the application once it has been installed. If an audio CD is inserted into the drive, Windows 95 will automatically launch the CD Player application and play it.
n. The process of periodically determining the status of each device in a set so that the active program can process the events generated by each device, such as whether a mouse button was pressed or whether new data is available at a serial port. This can be contrasted with event-driven processing, in which the operating system alerts a program or routine to the occurrence of an event by means of an interrupt or message rather than having to check each device in turn. Also called polling. Compare event-driven processing, interrupt-driven processing.
n. See typematic.
n. A process or system feature that can automatically restart the system after the occurrence of certain types of errors or a power system failure.
n. A program feature that automatically saves an open file to a disk or other medium at defined intervals or after a certain number of keystrokes to ensure that changes to a document are periodically saved.
n. The ability of a monitor to accept signals at one resolution and display the image at a different resolution. A monitor capable of autosizing maintains the aspect ratio of an image but enlarges or reduces the image to fit in the space available. See also monitor, resolution.
n. A process by which a system or device is automatically prepared for operation with the occurrence of powering up, or turning the system on, or some other predetermined event. See also AUTOEXEC.BAT, autorestart, bootstrap, power up.
n. A drawing program feature that draws lines along the edges of a bitmapped image to convert the image to an object-oriented one. See also bitmapped graphics, object-oriented graphics.
n. The logical device name for auxiliary device; a name reserved by the MS-DOS operating system for the standard auxiliary device. AUX usually refers to a system's first serial port, also known as COM1.
n. A version of the multi-user, multitasking UNIX operating system provided by Apple Computer for various Macintosh computers and based on the AT&T System V, release 2.2 of UNIX with some enhancements. A/UX incorporates a number of Apple features, including support for the Macintosh Toolbox, so that applications can provide users with the graphics-based interface characteristic of that computer. See also System V.
n. See peripheral.
n. Any storage medium, such as disk or tape, not directly accessed by a computer's microprocessor, as is random access memory (RAM). In current usage, such media are typically referred to as storage or permanent storage, and the RAM chips that the microprocessor uses directly for temporary storage are referred to as memory.
n. In processing, the accessibility of a computer system or resource, such as a printer, in terms of usage or of the percentage of the total amount of time the device is needed.
n. See uptime.
n. In virtual-reality environments such as certain types of Internet chat rooms, a graphical representation of a user. An avatar typically is a generic picture or animation of a human of either gender, a photograph or caricature of the user, a picture or animation of an animal, or an object chosen by the user to depict his or her virtual-reality "identity." See superuser.
n. The file extension that identifies an audiovisual interleaved data file in the Microsoft RIFF format.
n. Acronym for Audio Video Interleaved. A Windows multimedia file format for sound and moving pictures that uses the Microsoft RIFF (Resource Interchange File Format) specification.
n. See transceiver cable.
n. On the Internet, the major geographic domain specifying that an address is located in Aruba.
n. In a chart or other two-dimensional system using coordinates, the horizontal line (x-axis) or vertical line (y-axis) that serves as a reference for plotting points. In a three-dimensional coordinate system, a third line (z-axis) is used to represent depth. See also Cartesian coordinates.
n. On the Internet, the major geographic domain specifying that an address is located in Azerbaijan.