document window-through-dynamic Web page
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
document window
n. In windowing environments, such as the Apple Macintosh and Microsoft Windows, an on-screen window (enclosed work area) in which the user can create, view, or work on a document.
domain
n. 1. In database design and management, the set of valid values for a given attribute. For example, the domain for the attribute AREA-CODE might be the list of all valid three-digit numeric telephone area codes in the United States. See also attribute (definition 1). 2. For Windows NT Advanced Server, a collection of computers that share a common domain database and security policy. Each domain has a unique name. 3. In the Internet and other networks, the highest subdivision of a domain name in a network address, which identifies the type of entity owning the address (for example, .com for commercial users or .edu for educational institutions) or the geographical location of the address (for example, .fr for France or .sg for Singapore). The domain is the last part of the address (for example, www.acm.org). See also domain name.
domain name
n. An address of a network connection in the format that identifies the owner of that address in a hierarchical format: server.organization.type. For example, www.whitehouse.gov identifies the Web server at the White House, which is part of the U.S. government.
domain name address
n. The address of a device connected to the Internet or any other TCP/IP network, in the hierarchical system that uses words to identify servers, organizations, and types, such as www.logos.net. See also TCP/IP.
DOS
n. Acronym for disk operating system. A generic term describing any operating system that is loaded from disk devices when the system is started or rebooted. The term originally differentiated between disk-based systems and primitive microcomputer operating systems that were memory-based or that supported only magnetic or paper tape. See also MS-DOS, PC-DOS.
DOS box
n. 1. An OS/2 process that supports the execution of MS-DOS programs. Also called compatibility box. 2. A computer that uses the MS-DOS or PC-DOS operating system, as opposed to one that runs some other operating system, such as UNIX.
DOS extender
n. A program designed to extend the 640 KB of conventional memory available for use by DOS and DOS-based applications. A DOS extender works by claiming a portion of reserved memory (memory used by other parts of the system, such as the video adapter, the ROM BIOS, and the I/O ports).
DOS prompt
n. The visual indication from the MS-DOS command processor that the operating system is ready to accept a new command. The default DOS prompt is a path followed by a greater-than sign (for example, C:>); the user can also design a custom prompt with the PROMPT command.
dot
n. 1. In the UNIX, MS-DOS, OS/2, and other operating systems, the character that separates a filename from an extension as in TEXT.DOC (pronounced "text-dot- doc"). 2. In computer graphics and printing, a small spot combined with others in a matrix of rows and columns to form a character or a graphic element in a drawing or design. The dots forming an image on the screen are called pixels. The resolution of a display or printing device is often expressed in dots per inch (dpi). Dots are not the same as spots, which are groups of dots used in the halftoning process. See also pixel, resolution (definition 1). Compare spot. 3. In an Internet address, the character that separates the different parts of the domain name, such as the entity name from the domain. See also domain (definition 3), domain name.
dot address
n. An IP address in dotted quad form. See also IP address.
dot-addressable mode
n. A mode of operation in which a computer program can address ("point to") individual dots on the screen or in a printed character. See also all points addressable.
dot file
n. A file under UNIX whose name begins with a period. Dot files do not appear in ordinary listings of the files in a directory. Dot files are often used to store program setup information for the particular user; for example, .newsrc in a user's account indicates to a newsreader which newsgroups the user subscribes to.
dot-matrix1
adj. Referring to video and print hardware that forms character and graphic images as patterns of dots.
dot matrix2
n. The rectangular grid, or matrix, of tiny "cells" in which dots are displayed or printed in the patterns required to form text characters, circles, squares, and other graphical images. Depending on the frame of reference, the size of a dot matrix varies from a few rows and columns to an invisible grid covering an entire display screen or printed page. See also dot-matrix printer, raster.
dot-matrix printer
n. Any printer that produces characters made up of dots using a wire-pin print head. The quality of output from a dot-matrix printer depends largely on the number of dots in the matrix, which might be low enough to show individual dots or might be high enough to approach the look of fully formed characters. Dot-matrix printers are often categorized by the number of pins in the print head--typically 9, 18, or 24. Compare daisy-wheel printer, laser printer.
dots per inch
n. A measure of screen and printer resolution that is expressed as the number of dots that a device can print or display per linear inch. Acronym: dpi.
double-click
vb. To press and release a mouse button twice without moving the mouse. Double-clicking is a means of rapidly selecting and activating a program or program feature. Compare click, drag.
double-density disk
n. A disk created to hold data at twice the density (bits per inch) of a previous generation of disks. Early IBM PC floppy disks held 180 KB of data. Double-density disks increased that capacity to 360 KB. Double-density disks use modified frequency modulation encoding for storing data. See also floppy disk, microfloppy disk, modified frequency modulation encoding. Compare high-density disk.
double-sided disk
n. A floppy disk that can hold data on both its top and bottom surfaces.
double word
n. A unit of data consisting of two contiguous words (connected bytes, not text) that are handled together by a computer's microprocessor.
down
adj. Not functioning, in reference to computers, printers, communications lines on networks, and other such hardware.
downlink
n. The transmission of data from a communications satellite to an earth station.
download
vb. 1. In communications, to transfer a copy of a file from a remote computer to the requesting computer by means of a modem or network. 2. To send a block of data, such as a PostScript file, to a dependent device, such as a PostScript printer. Compare upload.
downloadable font
n. A set of characters stored on disk and sent (downloaded) to a printer's memory when needed for printing a document. Downloadable fonts are most commonly used with laser printers and other page printers, although many dot-matrix printers can accept some of them. Also called soft font.
downsizing
n. In computing, the practice of moving from larger computer systems, such as mainframes and minicomputers, to smaller systems in an organization, generally to save costs and to update to newer software. The smaller systems are usually client/server systems composed of a combination of PCs, workstations, and some legacy system such as a mainframe, connected in one or more local area networks or wide area networks. See also client/server architecture, legacy system.
downstream
n. The direction in which a news feed for a newsgroup is passed from one news server to the next. See also news feed, newsgroup, news server.
downtime
n. The amount or percentage of time a computer system or associated hardware remains nonfunctional. Although downtime can occur because hardware fails unexpectedly, it can also be a scheduled event, as when a network is shut down to allow time for maintenance.
downward compatibility
n. The capability of source code or programs developed on a more advanced system or compiler version to be executed or compiled by a less advanced (older) version. Compare upward-compatible.
drag
vb. In graphical user interface environments, to move an image or a window from one place on the screen to another by "grabbing" it and pulling it to its new location using the mouse. The mouse pointer is positioned over the object, and the mouse button is pressed and held while the mouse is moved to the new location.
drag-and-drop
vb. To perform operations in a graphical user interface by dragging objects on the screen with the mouse. For example, to delete a document in the Mac OS, a user can drag the document icon across the screen and drop it on the trashcan icon. See also drag, graphical user interface.
DRAW
n. Acronym for direct read after write. A technique used with optical discs to verify the accuracy of information immediately after it has been recorded (written) on the disc. Compare DRDW.
drawing program
n. A program for manipulating object-oriented graphics, as opposed to manipulating pixel images. In a drawing program, for example, the user can manipulate an element, such as a line, a circle, or a block of text, as an independent object simply by selecting the object and moving it. See also object-oriented graphics, pixel image, vector graphics.
DRDW
n. Acronym for direct read during write. A technique used with optical discs to verify the accuracy of information at the time it is being recorded on the disc. Compare DRAW.
drill down
vb. To start at a top-level menu, directory, or Web page and pass through several intermediate menus, directories, or linked pages, until the file, page, menu command, or other item being sought is reached. Drilling down is common practice in searching for files or information on the Internet, where high-level Gopher menus and World Wide Web pages are frequently very general and become more specific at each lower level. See also Gopher, menu, Web page.
drive bay
n. A hollow, rectangular area in a computer chassis designed to hold a disk drive. A drive bay always has side walls, usually made of metal, that generally contain holes to facilitate installation of a disk drive. Some drive bays, such as those intended to hold hard disks, are not visible to the user. Most drives are located on the front of the chassis so that the user can interact with the drive.
drive letter
n. The naming convention for disk drives on IBM and compatible computers. Drives are named by letter, beginning with A, followed by a colon.
drive mapping
n. The assignment of a letter or name to a disk drive so that the operating system or network server can identify and locate it. For example, in PCs, the primary drive mappings are A: and B: for floppy disk drives and C: for the hard disk. See also A:, disk drive, hard disk.
drive number
n. The naming convention for Macintosh disk drives. For example, a two-drive system calls its drives 0 and 1.
driver
n. A hardware device or a program that controls or regulates another device. A line driver, for example, boosts signals transmitted over a communications line. A device driver is a device-specific control program that enables a computer to work with a particular device, such as a printer or a disk drive. See also device driver.
drop cap
n. A large capital letter at the beginning of a text block that occupies the vertical depth of two or more lines of regular text.
drop-down menu
n. A menu that drops from the menu bar when requested and remains open without further action until the user closes it or chooses a menu item. Compare pull-down menu.
drum
n. A rotating cylinder used with some printers and plotters and (in the early days of mainframe computing) as a magnetic storage medium for data. In laser printers, a rotating drum is coated with a photoelectric material that retains a charge when struck by a laser beam. The electrically charged spots on the drum then attract toner particles that the drum transfers to the paper as the paper passes by.
dual boot
n. A computer configuration that allows a user to boot one of a choice of two operating systems on a PC. Some possible dual boot combinations include Windows 95/Windows NT, Windows NT/OS/2, and Windows 95/Linux. Some operating systems, such as Windows 95 and OS/2, include a multiple boot option. Older operating systems, such as Windows 3.X and DOS, require the use of a boot utility to perform a dual boot. See also boot1.
dual density
adj. Of, pertaining to, or characteristic of floppy disk drives that can read from and write to disks in more than one density format.
dual disk drive
adj. Of, pertaining to, or characteristic of a computer that has two floppy disk drives.
dual processors
n. Two processors used in a computer to speed its operation--one processor to control memory and the bus, and another to manage input/output. Many personal computers use a second processor to perform floating-point mathematical operations. See also coprocessor, floating-point notation.
dumb quotes
n. Quotation marks that have the same appearance (usually upright like the apostrophe ' and quotation marks " on a typewriter) whether they stand before or after the material being quoted. Compare smart quotes.
dumb terminal
n. A terminal that does not contain an internal microprocessor. Dumb terminals are typically capable of displaying only characters and numbers and responding to simple control codes. Compare smart terminal.
duplex1
adj. Capable of carrying information in both directions over a communications channel. A system is full-duplex if it can carry information in both directions at once; it is half-duplex if it can carry information in only one direction at a time.
duplex2
n. 1. Simultaneous communications, in both directions, between the sender and receiver. Also called duplex transmission, full-duplex transmission. See also half-duplex transmission. 2. Photographic paper on which an image can be printed on both sides.
duplex printer
n. A printer capable of printing on both sides of the page.
duplex system
n. A system of two computers, one of which is active while the other remains on standby, ready to take over processing if the active machine malfunctions.
duplicate key
n. A value assigned to an indexed field in one record in a database that duplicates a value assigned to the same field in another record in the database. For example, a key (or index) composed of ZIP-CODE would necessarily contain duplicate values if the file contained a number of addresses from a single ZIP code. A field in which duplicate values are permitted cannot serve as a primary key because the primary key must be unique, but it can serve as a component of a composite primary key. See also field (definition 1), key (definition 2), primary key.
Dvorak keyboard
n. A keyboard layout developed by August Dvorak and William L. Dealey in 1936 as an alternative to the overwhelmingly popular QWERTY keyboard. The Dvorak keyboard was designed to speed typing by placing the characters on the keyboard for easiest access to the most frequently typed letters. In addition, pairs of letters that often occur sequentially were separated so that the hands could alternate typing them. See also ergonomic keyboard, keyboard. Compare QWERTY keyboard.
dynalink
n. Short for dynamic link. See dynamic-link library.
dynamic
adj. Occurring immediately and concurrently. The term is used in describing both hardware and software; in both cases it describes some action or event that occurs when and as needed. In dynamic memory management, a program is able to negotiate with the operating system when it needs more memory.
dynamic address translation
n. On-the-fly conversion of memory-location references from relative addresses (such as "three units from the beginning of X") to absolute addresses (such as "location number 123") when a program is run. Acronym: DAT.
dynamic-link library
n. A feature of the Microsoft Windows family of operating systems and OS/2 that allows executable routines to be stored separately as files with DLL extensions and to be loaded only when needed by a program. A dynamic-link library has several advantages. First, it does not consume any memory until it is used. Second, because a dynamic-link library is a separate file, a programmer can make corrections or improvements to only that module without affecting the operation of the calling program or any other dynamic-link library. Finally, a programmer can use the same dynamic-link library with other programs. Acronym: DLL.
dynamic memory allocation
n. The allocation of memory to a process or program at run time. Dynamic memory is allocated from the system heap by the operating system upon request from the program.
dynamic RAM
n. A form of semiconductor random access memory (RAM). Dynamic RAMs store information in integrated circuits containing capacitors. Because capacitors lose their charge over time, dynamic RAM boards must include logic to refresh (recharge) the RAM chips continuously. While a dynamic RAM is being refreshed, it cannot be read by the processor; if the processor must read the RAM while it is being refreshed, one or more wait states occur. Despite being slower, dynamic RAMs are more commonly used than RAMs because their circuitry is simpler and because they can hold up to four times as much data. See also RAM. Compare static RAM. Acronym: DRAM.
dynamic Web page
n. A Web page that has fixed form but variable content, allowing it to be tailored to a customer's search criteria.
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