A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
n. An International Telecommunications Union (ITU) standard that governs serial communications over ISDN lines. Data is encapsulated using a protocol similar to the Lightweight Directory Access Protocol (LDAP), and more than one connection may be multiplexed on a communications channel. See also communications channel, communications protocol, International Telecommunications Union, ISDN, Lightweight Directory Access Protocol, multiplexing, standard (definition 1).
n. NEC microprocessors that were slight improvements on Intel's 8088 and 8086, using the same command sets but different microcode.
n. The CCITT (now ITU-T) recommendation that specifies the modulation scheme used in Group 3 facsimile for image transfer at 2,400 and 4,800 bits per second (bps). See also CCITT V series, fax, International Telecommunications Union.
n. The CCITT (now ITU-T) recommendation that specifies the modulation scheme used in Group 3 facsimile for image transfer at 9,600 and 7,200 bits per second (bps) over dial-up telephone lines. See also CCITT V series, fax, International Telecommunications Union.
n. See CCITT V series, International Telecommunications Union.
n. A modem protocol developed by AT&T for 19,200-bps modems, with fallback to the speeds supported by the CCITT V.32 standard. This protocol is proprietary to AT&T and was not adopted by CCITT. In the CCITT V series, V.34 takes the place of V.32terbo See also CCITT V series, International Telecommunications Union.
n. The CCITT (now ITU-T) recommendation that specifies the operation of loop test devices in modems. See also CCITT V series, International Telecommunications Union.
n. The ITU-T recommendation that defines a network transmission model for evaluating modem performance over two-wire voice-grade connections. See also International Telecommunications Union.
n. A quantity assigned to an element such as a variable, symbol, or label. See tone (definition 1).
n. A communications network that offers additional services, such as message routing, resource management, and conversion facilities, for computers communicating at different speeds or using different protocols. Acronym: VAN.
n. A company that buys hardware and software and resells it to the public with added services, such as user support. Acronym: VAR.
n. Software that has been announced but not released to customers. The term implies sarcastically that the product exists only in the minds of the marketing staff. Compare freeware, shareware.
n. In programming, a named storage location capable of containing data that can be modified during program execution. See also data structure, data type, global variable, local variable. Compare constant.
n. Acronym for virtual address extension. A family of 32-bit minicomputers introduced by Digital Equipment Corporation in 1978. The VAX, like the later 68000 microprocessor, has a flat address space and a large instruction set. The VAX was highly favored within the hacker community but has been superseded by microprocessors and RISC workstations. See also flat address space, instruction set, microprocessor, minicomputer, RISC.
n. See Visual Basic for Applications.
n. See Visual Basic Scripting Edition.
n. Short for Visual Basic custom control. A software module that, when called by a Visual Basic application, produces a control that adds some desired feature to the application. A VBX is a separate executable file, usually written in C, that is dynamically linked to the application at run time and can be used by other applications, including some applications not developed in Visual Basic. Although VBX technology was developed by Microsoft, most VBXs have been written by third-party developers. VBXs are still in use, but the technology has been superseded by OCXs and ActiveX controls. See also control (definition 2), Visual Basic. Compare ActiveX controls, dynamic-link library, OCX.
n. The disk caching software used with Windows 95's VFAT driver. VCACHE uses 32-bit code, runs in protected mode, and automatically allocates space in RAM rather than requiring the user to reserve space for the cache. See also cache, driver, protected mode, RAM, VFAT.
n. The communications device driver in Windows 95 that provides the interface between Windows-based applications and drivers on one side, and port drivers and modems on the other. See also driver.
n. 1. A user interface for playing movie files that has controls similar to those on a videocassette recorder (VCR). 2. A type of motorized docking mechanism in which a laptop or notebook computer is physically locked into place by the docking station. The advantage to a VCR-style mechanism is that it provides an electrically consistent, secure bus connection. See also docking mechanism, docking station, laptop, portable computer.
n. Acronym for virtual display device driver. See virtual device driver.
n. 1. In mathematics and physics, a variable that has both distance and direction. Compare scalar. 2. In computer graphics, a line drawn in a certain direction from a starting point to an endpoint, both of whose locations are identified by the computer using x-y-coordinates on a grid. Vectors are used in the output of some graphics programs instead of groups of dots (on paper) or pixels (on screen). See also vector graphics. 3. In data structures, a one-dimensional array--a set of items arranged in a single column or row. See also array, matrix.
n. A CRT (cathode-ray tube), commonly used in oscilloscopes and DVST (direct view storage tube) displays, that allows the electron beam to be arbitrarily deflected, based on x-y-coordinate signals. For example, to draw a line on a vector display, the video adapter sends signals to the X and Y yokes to move the electron beam over the path of the line; there is no background composed of scan lines, so the line drawn on the screen is not constructed of pixels. See also CRT, yoke. Compare raster display.
n. A font in which the characters are drawn using arrangements of line segments rather than arrangements of bits. See also font. Compare bitmapped font.
n. Images generated from mathematical descriptions that determine the position, length, and direction in which lines are drawn. Objects are created as collections of lines rather than as patterns of individual dots or pixels. Compare raster graphics.
adj. Displaying messages as English text rather than as concise (but cryptic) codes.
n. A particular issue or release of a hardware product or software title.
n. A number assigned by a software developer to identify a particular program at a particular stage, before and after public release. Successive public releases of a program are assigned increasingly higher numbers. Version numbers usually include decimal fractions. Major changes are usually marked by a change in the whole number, whereas for minor changes only the number after the decimal point increases.
adj. Having VL bus expansion slots. Also called VLB. See also expansion slot, VL bus. Compare VESA/EISA, VESA/ISA.
n. Acronym for Video Electronics Standards Association. An organization of hardware manufacturers and vendors dedicated to drafting and improving standards for video and multimedia devices. Standards developed by VESA include the Display Data Channel (DDC), Display Power Management Signaling (DPMS), and the VESA local bus (VL bus). See also DDC, DPMS, VL bus.
adj. Having both EISA and VL bus expansion slots. See also EISA, expansion slot, VESA2, VL bus. Compare VESA1, VESA/ISA.
adj. Having both ISA and VL bus expansion slots. See also expansion slot, ISA, VESA2, VL bus. Compare VESA1, VESA/EISA.
n. See VL bus.
n. A marketing term used by some modem manufacturers to describe modems that comply with both the CCITT V.34 standard and the various proprietary protocols that were used before the standard was adopted, such as V.Fast Class. A V.everything modem should be compatible with any other modem that operates at the same speed. See also CCITT V series, V.Fast Class.
n. A de facto modulation standard for modems implemented by Rockwell International prior to approval of the V.34 protocol, which is the standard. Although both V.Fast Class and V.34 are capable of 28.8-Kbps transmission, V.Fast Class modems cannot communicate with V.34 modems without an upgrade. See also CCITT V series. Acronym: V.FC.
n. Acronym for Virtual File Allocation Table. The file system driver software used under Windows 95's Installable File System Manager (IFS) for accessing disks. VFAT is compatible with MS-DOS disks but runs more efficiently. VFAT uses 32-bit code, runs in protected mode, uses VCACHE for disk caching, and supports long filenames. See also Installable File System Manager, long filenames, protected mode, VCACHE, Windows 95. Compare file allocation table.
See V.Fast Class.
n. Acronym for Video Graphics Adapter. A video adapter that duplicates all the video modes of the EGA (Enhanced Graphics Adapter) and adds several more. See also video adapter. Compare EGA.
adj. Of or pertaining to the visual component of a television signal. In relation to computers, video refers to the rendering of text and graphics images on displays. Compare audio.
n. See graphics engine (definition 1).
n. The electronic components that generate the video signal sent through a cable to a video display. The video adapter is usually located on the computer's main system board or on an expansion board, but it is sometimes built into the terminal. Also called video adapter board, video board, video card, video controller, video display adapter.
n. An expansion board that converts analog video signals to digital form and stores them in a computer's hard disk or other mass storage device. Some video capture devices are also capable of converting digital video to analog video for use in a VCR. Also called video capture board, video capture card. See also expansion board.
n. A file that contains a short video item, usually an excerpt from a longer recording.
n. Reduction of the size of files containing video images stored in digital form. If no compression were done, 24-bit color video at 640 × 480 pixels would occupy almost one megabyte per frame, or over a gigabyte per minute. Video compression can, however, be lossy without affecting the perceived quality of the image. See also lossy compression, Motion JPEG, MPEG.
n. Teleconferencing in which video images are transmitted among the various geographically separated participants in a meeting. Originally done using analog video and satellite links, today video conferencing uses compressed digital images transmitted over wide area networks or the Internet. A 56K communications channel supports freeze-frame video; with a 1.544-Mbps (T1) channel, full-motion video can be used. See also 56K, desktop conferencing, freeze-frame video, full-motion video, T1, teleconferencing. Compare data conferencing.
n. Software that provides the interface between the video adapter hardware and other programs, including the operating system. The user can access the video driver to specify the resolution and color-bit depth of images on the monitor during the setup process. See also driver, monitor, video adapter.
n. Memory from which a display image is created, located in the video adapter or video subsystem. If both the video processor and the central processing unit (CPU) have access to video memory, images are produced by the CPU's modification of video memory. Video circuitry normally has priority over the processor when both attempt to read or write to a video memory location, so updating video memory is often slower than accessing main memory. See also video RAM.
n. A special type of dynamic RAM (DRAM) used in high-speed video applications. Video RAM uses separate pins for the processor and the video circuitry, providing the video circuitry with a "back door" to the video RAM. The video circuitry can access the video RAM serially (bit by bit), which is more appropriate for transferring pixels to the screen than is the parallel access provided by conventional DRAM. See also dynamic RAM. Acronym: VRAM.
n. 1. The display of data or an image from a given perspective or location. 2. In relational database management systems, a logical table created through the specification of one or more relational operations on one or more tables. A view is equivalent to a divided relation in the relational model. See also relational database, relational model.
vb. To cause an application to display information on a computer screen.
n. An application that displays or otherwise outputs a file in the same way as the application that created the file. An example of a viewer is a program to display the images stored in GIF or JPEG files. See also GIF, JPEG.
n. In a virtual memory system, the address the application uses to reference memory. The memory management unit (MMU) translates this address into a physical address before the memory is actually read or written to. See also physical address, virtual memory. Compare real address.
n. In Asynchronous Transfer Mode (ATM), the path taken by data sent from one sender to one receiver. See also ATM (definition 1), virtual path (definition 2).
n. A communications link that appears to be a direct connection between sender and receiver, although physically the link can be routed through a more circuitous path.
n. See online community.
n. A specification for MS-DOS programs to allow access to extended memory under a multitasking environment (for example, Microsoft Windows) for 80386, and higher-level processors. See also 80386DX, extended memory, multitasking. Compare protected mode. Acronym: VCPI.
n. A desktop enhancement tool that provides access to the desktop when it is covered by open windows or that expands the size of the working desktop. See also desktop.
n. A device that can be referenced but that does not physically exist. Virtual-memory addressing, for example, uses magnetic disk storage to simulate memory larger than that physically available.
n. Software in Windows 95 that manages a hardware or software system resource. If a resource retains information from one access to the next that affects the way it behaves when accessed (for example, a disk controller with its status information and buffers), a virtual device driver must exist for it. Virtual device drivers are described using three-letter abbreviations beginning with V and ending with D; the middle letter indicates the type of device, such as D for a display, P for a printer, T for a timer, and x when the type of device is not under discussion. See also device driver. Acronym: VxD.
n. Short for virtual local area network. A local area network consisting of groups of hosts that are on physically different segments but that communicate as though they were on the same wire. See also LAN.
n. Software that mimics the performance of a hardware device, such as a program that allows applications written for an Intel processor to be run on a Motorola chip. Acronym: VM.
n. Memory that appears to an application to be larger and more uniform than it is. Virtual memory may be partially simulated by secondary storage such as a hard disk. Applications access memory through virtual addresses, which are translated (mapped) by special hardware and software onto physical addresses. Also called disk memory. See also paging, segmentation. Acronym: VM.
n. The set of all hierarchical sequences of names that can be used by an application to locate objects. One such sequence of names defines a path through the virtual name space, regardless of whether the hierarchy of names reflects the actual arrangement of objects around the system. For example, the virtual name space of a Web server consists of all possible URLs on the network on which it runs. See also URL.
n. 1. A sequence of names that is used to locate a file and that has the same form as a pathname in the file system but is not necessarily the actual sequence of directory names under which the file is located. The part of a URL that follows the server name is a virtual path. For example, if the directory c:\bar\sinister\forces\distance on the server miles is shared on the local area network at foo.com under the name \\miles\baz and contains the file elena.html, that file may be returned by a Web request for http://miles.foo.com/baz/elena.html. 2. In Asynchronous Transfer Mode (ATM), a set of virtual channels that are switched together as a unit through the network. See also ATM (definition 1), virtual channel.
n. A feature in many operating systems that allows printer output to be saved to a file until a printer becomes available.
n. 1. A set of nodes on a public network such as the Internet that communicate among themselves using encryption technology so that their messages are as safe from being intercepted and understood by unauthorized users as if the nodes were connected by private lines. 2. A wide area network formed of permanent virtual circuits (PVCs) on another network, especially a network using technologies such as ATM or frame relay. See also ATM (definition 1), frame relay, PVC. Acronym: VPN.
n. A simulated 3-D environment that a user can experience and manipulate as if it were physical. The user sees the environment on display screens, possibly mounted in a special pair of goggles. Special input devices, such as gloves or suits fitted with motion sensors, detect the user's actions. Acronym: VR.
n. A feature of the Intel 80386 (SX and DX) and higher microprocessors that allows them to emulate several 8086 (real-mode) environments simultaneously. The microprocessor provides a set of virtual registers and virtual memory space to each virtual 8086 environment. A program running in a virtual 8086 environment is completely protected from other virtual 8086 environments in the system and behaves as if it had control of the entire system. Also called 86 mode, V86 mode, virtual 8086 mode, virtual 86 mode. See also real mode.
n. One of multiple web sites running on the same server, each with a unique domain name and IP address. A web server that supports virtual servers is called a multi-hosting (or multi-homing) web server. See multi-hosting.
n. 1. A 3-D modeled environment, often created in VRML, where a user can interact with the viewer to change variables. See also viewer, VRML. 2. An electronic environment that has no basis in the physical world. Multiuser dungeons (MUDs), talkers, and chat rooms are often considered virtual worlds. See also chat1 (definition 1), MUD, talker.
n. An intrusive program that infects computer files by inserting in those files copies of itself. The copies are usually executed when the file is loaded into memory, allowing them to infect still other files, and so on. Viruses often have damaging side effects--sometimes intentionally, sometimes not. For example, some viruses can destroy a computer's hard disk or take up memory space that could otherwise be used by programs. See also Good Times virus, Trojan horse, worm.
n. A portion of unique computer code contained in a virus. Antivirus programs search for known virus signatures to identify infected programs and files. See also virus.
n. A high-level, visual-programming version of Basic. Visual Basic was developed by Microsoft for building Windows-based applications. See also Basic, Visual Basic for Applications, Visual Basic Scripting Edition, visual programming.
n. A macro-language version of Visual Basic that is used to program many Windows 95 applications and is included with several Microsoft applications. See also macro language, Visual Basic. Acronym: VBA.
n. See Visual Basic, Scripting Edition.
n. A subset of the Visual Basic for Applications programming language, optimized for Web-related programming. As with JavaScript, code for Visual Basic Scripting Edition is embedded in HTML documents. This version is included with the Internet Explorer Web browser. Also called VBScript. See also Visual Basic for Applications. See Visual Basic Script.
n. A Microsoft application development system for the programming language C++ that runs under MS-DOS and Windows. Visual C++ is a visual programming environment. See also visual programming. Compare Visual Basic, Visual J++.
n. Microsoft's Java visual programming environment, which can be used to create applets and applications in the Java language. See also applet, Java, Java applet, visual programming.
n. A method of programming using a programming environment or language in which basic program components can be selected through menu choices, buttons, icons, and other predetermined methods.
n. Short for VESA local bus. A type of local bus architecture introduced by the Video Electronics Standards Association. The VL bus specification allows up to three VL bus slots to be built into a PC motherboard and allows for bus mastering (wherein "intelligent" adapter cards can do some processing independently of the CPU). A VL bus slot consists of a standard connector plus an additional 16-bit Micro Channel Architecture connector and must be built into the motherboard by the manufacturer. Standard connectors cannot simply be converted to VL bus slots. A non-VL bus adapter card can be used in a VL bus slot, but it cannot use the local bus and so performs as it normally would in a non-VL bus slot. Also called VL local bus. See also local bus, PCI local bus.
n. Acronym for Virtual Machine. An operating system for IBM mainframes that provides virtual-machine capability. VM was developed by IBM customers and later taken over by IBM itself under the name OS/VM. See virtual machine, virtual memory.
n. A modem that can support voice messaging applications along with its data-handling functions.
n. A system that records and stores telephone messages in a computer's memory. Unlike a simple answering machine, a voice mail system has separate mailboxes for multiple users, each of whom can copy, store, or redistribute messages.
n. A modulation/demodulation device that supports a switch to change between telephony and data transmission modes. Such a device might contain a built-in loudspeaker and microphone for voice communication, but more often it uses the computer's sound card. See also modem, sound card, telephony.
n. A term used on the Internet to refer to the telephone system, often preceding the user's telephone number in an e-mail signature.
n. 1. A disk or tape that stores computer data. Sometimes, large hard disks are divided into several volumes, each of which is treated as a separate disk. 2. The loudness of an audio signal.
n. A name for a disk or tape. MS-DOS systems, which seldom use disk names except in directory listings, use the term volume label. Apple Macintosh systems, which often refer to disks by name, use the term volume name.
n. The optional identifying volume number of a disk or tape. MS-DOS systems use the term volume serial number. Apple Macintosh systems use the term volume reference number. A volume serial number is not the same as a volume label or volume name. Compare volume label.
n. Acronym for virtual printer device driver. See virtual device driver.
n. Acronym for Virtual Reality Modeling Language. A scene description language for creating 3-D interactive Web graphics similar to those found in some video games, allowing the user to "move around" within a graphic image and interact with objects. VRML, a subset of Silicon Graphics' Inventor File Format (ASCII), was created by Mark Pesce and Tony Parisi in 1994. VRML files can be created in a text editor, although CAD packages, modeling and animation packages, and VRML authoring software are the tools preferred by most VRML authors. VRML files reside on an HTTP server; links to these files can be embedded in HTML documents, or users can access the VRML files directly. To view VRML Web pages, users need a VRML-enabled browser, such as WebSpace from Silicon Graphics, or a VRML plug-in for Internet Explorer or Netscape Navigator. See also 3-D graphic, HTML document, HTTP server (definition 1).
n. See CCITT V series.
n. A popular set of control codes used in terminals with those model numbers that were originally manufactured by Digital Equipment Corporation. Appropriate software can enable a microcomputer to use these codes to emulate such terminals.
n. Acronym for virtual timer device driver. See virtual device driver.
n. See virtual device driver.
