A/B switch box -thru- America Online
A/B Switch box ~ America On-line AMI BIOS ~ Arithmetic Operation ARP ~ AVI Backbone ~ Bit Image Bit Map ~ Boot Disk Boot Drive ~ Bytes Per Inch C++ ~ Carrier Frequency carrier system ~ certification CGI ~ Chooser extension cipher ~ Clipper Chip clock ~ color color bits ~ communications satellite communications server ~ computer security CON ~ copy copy program ~ cycle time daemon ~ defragmentation demand paging ~ digitize DikuMUD ~ disk disk buffer ~ Document Style Semantics and Specification Language document window ~ dynamic Web page Easter egg ~ erase erase head ~ ezine F2F ~ finger2 firewall ~ font suitcase footer ~ FYI Game Control Adapter ~ GUI HAL ~ hot key1 hot key2 ~ Hz i486DX ~ internal modem internet ~ ISO 9660 ISO/OSI model ~ just-in-time K1 ~ knowledge base L1 cache ~ LU luggable computer ~ LZW compression MAC ~ MILNET mime ~ msec MTBF ~ MYOB named anchor ~ network drive Network File System ~ number crunching object ~ overwrite mode P5 ~ PC/XT keyboard PDA ~ pipeline processing piracy ~ preventive maintenance preview ~ pwd quasi-language ~ QWERTY keyboard R&D ~ registration marks Registry ~ RFI RF shielding ~ run-time library SAA ~ server error server push-pull ~ soft return software ~ style sheet stylus ~ System T1 ~ ToggleKeys token ~ typography UART ~ uupc V.120 ~ view2 viewer ~ VxD w3 ~ WinG WINS ~ WWW X.25 ~ X Windows Yahoo! ~ yotta- Z39.50 standard ~ Zulu time
A/B switch box
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).
AC adapter
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.
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.
access1
n. 1. The act of reading data from or writing data to memory. 2. Connection to the Internet or other network or system.
ACCESS.bus
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.
access control
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.
access control list
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.
accessibility
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.
access number
n. The telephone number used by a subscriber to gain access to an online service.
access privileges
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.
access rights
n. The permission to view, enter, or modify a file, folder, or system.
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.
account
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.
account policy
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).
ACK
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.
acronym
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).
active cell
n. The highlighted cell on a spreadsheet display that is the current focus of operation. Also called current cell, selected cell. See also range.
active content
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.
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.
active hub
n. The central computer that regenerates and retransmits all signals in an active star network. See also active star.
active-matrix display
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.
ActiveMovie
n. Cross-platform digital video technology developed by Microsoft for online and desktop multimedia.
active window
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.
ActiveX
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).
ActiveX controls
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.
adapter
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.
adaptive system
n. A system that is capable of altering its behavior based on certain features of its experience or environment. See also expert system.
add-on
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.
address1
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.
address2
vb. To reference a particular storage location. See also absolute address, address space, physical address, virtual address.
address book
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.
address decoder
n. An electronic device that converts a numeric address so as to select a memory location on one or more RAM chips.
addressing
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.
address mapping table
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.
address resolution
n. The identification of a computer's hardware address by finding the corresponding match in an address mapping table. See also address mapping table.
address space
n. The total range of memory locations addressable by a computer.
address translation
n. The process of converting one kind of address to another, such as a virtual address to a physical address.
Adobe Type Manager
n. Software from Adobe Systems, Inc. that manages PostScript fonts on a system. See also PostScript. Acronym: ATM.
Advanced Digital Network
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.
Advanced Power Management
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 RISC
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.
agent
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.
AIFF
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.
AIX
n. Acronym for Advanced Interactive Executive. A version of the UNIX system provided by IBM for its UNIX workstations and its PCs.
alarm
n. A visual or auditory signal from a computer alerting the user to an error or hazardous situation.
alert
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).
alert box
n. An on-screen box, in a graphical user interface, that is used to deliver a message or warning. Compare dialog box.
algorithm
n. A finite sequence of steps for solving a logical or mathematical problem.
algorithmic language
n. A programming language, such as Ada, Basic, C, or Pascal, that uses algorithms for problem solving.
alias
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.
aliasing
n. In computer graphics, the jagged appearance of curves or diagonal lines on a display screen, which is caused by low screen resolution.
alignment
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.
allocate
vb. To reserve a resource, such as sufficient memory, for use by a program. Compare deallocate.
allocation
n. In operating systems, the process of reserving memory for use by a program.
alpha2
n. A software product that has been completed and is ready for initial testing in a laboratory. Compare beta.
Alpha
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.
Alpha AXP
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.
alphabet
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.
Alpha box
n. A computer built around the DECchip 21064 processor (called Alpha). See also DECchip 21064.
alpha channel
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.
alphanumeric
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.
alpha test
n. The process of user testing that is carried out on a piece of alpha software.
AltaVista
n. A World Wide Web search site hosted by Digital Equipment Corporation. AltaVista may be found at URL Altavista Digital.
alternating current
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.
Alt key
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.
alt. newsgroups
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.
America Online
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.
A/B Switch box ~ America On-line AMI BIOS ~ Arithmetic Operation ARP ~ AVI Backbone ~ Bit Image Bit Map ~ Boot Disk Boot Drive ~ Bytes Per Inch C++ ~ Carrier Frequency carrier system ~ certification CGI ~ Chooser extension cipher ~ Clipper Chip clock ~ color color bits ~ communications satellite communications server ~ computer security CON ~ copy copy program ~ cycle time daemon ~ defragmentation demand paging ~ digitize DikuMUD ~ disk disk buffer ~ Document Style Semantics and Specification Language document window ~ dynamic Web page Easter egg ~ erase erase head ~ ezine F2F ~ finger2 firewall ~ font suitcase footer ~ FYI Game Control Adapter ~ GUI HAL ~ hot key1 hot key2 ~ Hz i486DX ~ internal modem internet ~ ISO 9660 ISO/OSI model ~ just-in-time K1 ~ knowledge base L1 cache ~ LU luggable computer ~ LZW compression MAC ~ MILNET mime ~ msec MTBF ~ MYOB named anchor ~ network drive Network File System ~ number crunching object ~ overwrite mode P5 ~ PC/XT keyboard PDA ~ pipeline processing piracy ~ preventive maintenance preview ~ pwd quasi-language ~ QWERTY keyboard R&D ~ registration marks Registry ~ RFI RF shielding ~ run-time library SAA ~ server error server push-pull ~ soft return software ~ style sheet stylus ~ System T1 ~ ToggleKeys token ~ typography UART ~ uupc V.120 ~ view2 viewer ~ VxD w3 ~ WinG WINS ~ WWW X.25 ~ X Windows Yahoo! ~ yotta- Z39.50 standard ~ Zulu time