daemon-through-defragmentation
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
daemon
n. A program associated with UNIX systems that performs a housekeeping or maintenance utility function without being called by the user. A daemon sits in the background and is activated only when needed, for example, to correct an error from which another program cannot recover.
daisy chain
n. A set of devices connected in series. In order to eliminate conflicting requests to use the channel (bus) to which all the devices are connected, each device is given a different priority, or, as in the Apple Desktop Bus, each device monitors the channel and transmits only when the line is clear.
daisy wheel
n. A print element consisting of a set of formed characters with each character mounted on a separate type bar, all radiating from a center hub. See also daisy-wheel printer, thimble, thimble printer.
daisy-wheel printer
n. A printer that uses a daisy-wheel type element. Daisy-wheel output is crisp and slightly imprinted, with fully formed characters resembling typewriter quality. Daisy-wheel printers were standard for high-quality printing until being superseded by laser printers. See also daisy wheel, thimble, thimble printer.
DARPANET
n. Short for Defense Advanced Research Projects Agency Network. See ARPANET.
DASD
n. Acronym for direct access storage device. A data storage device by which information can be accessed directly, instead of by passing sequentially through all storage areas. For example, a disk drive is a DASD, but a tape unit is not, because, with a tape unit, the data is stored as a linear sequence. See also direct access. Compare sequential access.
data
n. Plural of the Latin datum, meaning an item of information. In practice, data is often used for the singular as well as the plural form of the noun. Compare information.
data acquisition
n. The process of obtaining data from another source, usually one outside a specific system.
data bank
n. Any substantial collection of data.
database
n. A file composed of records, each containing fields together with a set of operations for searching, sorting, recombining, and other functions.
database administrator
n. One who manages a database. The administrator determines the content, internal structure, and access strategy for a database, defines security and integrity, and monitors performance. Also called database manager. Acronym: DBA.
database analyst
n. One who provides the analytic functions needed to design and maintain applications requiring a database.
database designer
n. One who designs and implements functions required for applications that use a database.
database engine
n. The program module or modules that provide access to a database management system (DBMS).
database management system
n. A software interface between the database and the user. A database management system handles user requests for database actions and allows for control of security and data integrity requirements. Also called database manager. See also database engine. Acronym: DBMS.
database publishing
n. The use of desktop publishing or Internet technology to produce reports containing information obtained from a database.
database structure
n. A general description of the format of records in a database, including the number of fields, specifications regarding the type of data that can be entered in each field, and the field names used.
data bit
n. In asynchronous communications, one of a group of from 5 to 8 bits that represents a single character of data for transmission. Data bits are preceded by a start bit and followed by an optional parity bit and one or more stop bits. See also asynchronous transmission, bit, communications parameter.
data cable
n. Fiber-optic or wire cable used to transfer data from one device to another.
datacom
n. Short for data communications. See communications.
data-driven processing
n. A form of processing where the processor or program must wait for data to arrive before it can advance to the next step in a sequence.
data encryption key
n. A sequence of data that is used to encrypt and decrypt other data. See also decryption, encryption, key (definition 3). Acronym: DEK.
data entry
n. The process of writing new data to computer memory.
data/fax modem
n. A modem that can handle both serial data and facsimile images to either send or receive transmissions.
data field
n. A well-defined portion of a data record, such as a column in a database table.
data file
n. A file consisting of data in the form of text, numbers, or graphics, as distinct from a program file of commands and instructions. Compare program file.
data format
n. The structure applied to data by an application program to provide a context in which the data can be interpreted.
datagram
n. One packet, or unit, of information, along with relevant delivery information such as the destination address, that is sent through a packet-switching network. See also packet switching.
data interchange format
n. A format consisting of ASCII codes in which database, spreadsheet, and similar documents can be structured to facilitate their use by and transfer to other programs. See also ASCII. Acronym: DIF.
data link
n. A connection between any two devices capable of sending and receiving information, such as a computer and a printer or a main computer and a terminal. Sometimes the term is extended to include equipment, such as a modem, that enables transmission and receiving. Such devices follow protocols that govern data transmission. See also communications protocol, data-link layer, DCE, DTE.
data-link layer
n. The second of seven layers in the ISO/OSI model for standardizing computer-to-computer communications. The data-link layer is one layer above the physical layer. Its concern is packaging and addressing data and managing the flow of transmissions. It is the lowest of the three layers (data-link, network, and transport) involved in actually moving data between devices. See also ISO/OSI model.
data mining
n. The process of identifying commercially useful patterns or relationships in databases or other computer repositories through the use of advanced statistical tools.
data network
n. A network designed for transferring data encoded as digital signals, as opposed to a voice network, which transmits analog signals.
data processing
n. 1. The general work performed by computers. Also called ADP, automatic data processing, EDP, electronic data processing. See also centralized processing, decentralized processing, distributed processing. 1. More specifically, the manipulation of data to transform it into some desired result. Acronym: DP.
data protection
n. The process of ensuring the preservation, integrity, and reliability of data. See also data integrity.
data set
n. 1. A collection of related information made up of separate elements that can be treated as a unit in data handling. 2. In communications, a modem. See also modem.
data transfer
n. The movement of information from one location to another, either within a computer (as from a disk drive to memory), between a computer and an external device (as between a file server and a computer on a network), or between separate computers.
data transmission
n. The electronic transfer of information from a sending device to a receiving device.
data type
n. In programming, a definition of a set of data that specifies the possible range of values of the set, the operations that can be performed on the values, and the way in which the values are stored in memory. Defining the data type allows a computer to manipulate the data appropriately. Data types are most often supported in high-level languages and often include types such as real, integer, floating point, character, Boolean, and pointer. How a language handles data typing is one of its major characteristics. See also cast, constant, enumerated data type, strong typing, type checking, user-defined data type, variable, weak typing.
data value
n. The literal or interpreted meaning of a data item, such as an entry in a database, or a type, such as an integer, that can be used for a variable.
data warehouse
n. A database, frequently very large, that can access all of a company's information. While the warehouse can be distributed over several computers and may contain several databases and information from numerous sources in a variety of formats, it should be accessible through a server. Thus, access to the warehouse is transparent to the user, who can use simple commands to retrieve and analyze all the information. The data warehouse also contains data about how the warehouse is organized, where the information can be found, and any connections between data. Frequently used for decision support within an organization, the data warehouse also allows the organization to organize its data, coordinate updates, and see relationships between information gathered from different parts of the organization. See also database, decision support system, server (definition 1), transparent (definition 1).
date stamping
n. A software feature that automatically inserts the current date into a document.
DCA
n. 1. Acronym for Document Content Architecture. A formatting guideline used in IBM's Systems Network Architecture (SNA) that enables the exchange of text-only documents between differing types of computers. DCA provides for two types of document formatting: Revisable-Form-Text DCA (RFTDCA), which allows for modification of formatting, and Final-Form-Text DCA (FFTDCA), which cannot be modified. See also DIA, SNA. 2. Acronym for Directory Client Agent. See DUA.
DCD
n. Acronym for Data Carrier Detected. A signal in serial communications that is sent from a modem to its computer to indicate that the modem is ready for transmitting. Also called RLSD (Received Line Signal Detect). See also RS-232-C standard.
DCOM
n. Acronym for Distributed Component Object Model. The version of Microsoft's Component Object Model (COM) specification that stipulates how components communicate over Windows-based networks. It permits the distribution of different components for a single application across two or more networked computers, running an application distributed across a network so that the distribution of components is not apparent to the user, and remotely displaying an application. Also called Distributed COM. See also COM (definition 2), component (definition 2).
DDE
n. Acronym for Dynamic Data Exchange. An interprocess communication method featured in Microsoft Windows and OS/2. DDE allows two or more programs that are running simultaneously to exchange data and commands. In Windows 3.1, DDE was largely supplanted by OLE, which is an extension of DDE. In Windows 95 and Windows NT, OLE and ActiveX are more commonly used. See also ActiveX, interprocess communication, OLE.
dead key
n. A key used with another key to create an accented character. When pressed, a dead key produces no visible character (hence its name) but indicates that the accent mark it represents is to be combined with the next key pressed. See also key (definition 1).
debug
vb. To detect, locate, and correct logical or syntactical errors in a program or malfunctions in hardware. In hardware contexts, the term troubleshoot is the term more often used, especially when the problem is a major one. See also bug, debugger.
debugger
n. A program designed to aid in debugging another program by allowing the programmer to step through the program, examine the data, and monitor conditions such as the values of variables. See also bug (definition 1), debug.
DECchip 21064
n. A Digital Equipment Corporation microprocessor introduced in February 1992. The DECchip 21064 is a 64-bit, RISC-based, superscalar, superpipelined chip with 64-bit registers, a 64-bit data bus, a 64-bit address bus, and a 128-bit data path between the microprocessor and memory. It also has a built-in 8-KB instruction cache, a built-in 8-KB data cache, and a floating-point processor. The DECchip 21064 contains 1.7 million transistors and operates at 3.3 volts. The 200-MHz version runs at a peak rate of 400 MPS. The chip's architecture is SMP compliant, so that several chips can be used in a parallel (multiprocessor) configuration. See also floating-point processor, MIPS, pipelining (definition 1), RISC, superpipelining, superscalar.
decentralized processing
n. The distribution of computer processing facilities in more than one location. Decentralized processing is not the same as distributed processing, which assigns multiple computers to the same task to increase efficiency.
decibel
n. Abbreviated dB. One tenth of a bel (named after Alexander Graham Bell), a unit used in electronics and other fields to measure the strength of a sound or signal. Decibel measurements fall on a logarithmic scale and compare the measured quantity against a known reference. The following formula gives the number of decibels between two values:
decision tree
n. Similar to a decision table, an analysis instrument where possible outcomes of some condition are represented as branches, which may in turn generate other branches. See also branch (definition 1), tree.
declarative markup language
n. In text processing, a system of text-formatting codes that indicates only that a unit of text is a certain part of a document. Document formatting is then done by another program, called a parser. SGML and HTML are examples of declarative markup languages. See also HTML, SGML. Acronym: DML.
decoder
n. 1. A device or program routine that converts coded data back to its original form. This can mean changing unreadable or encrypted codes into readable text or changing one code to another, although the latter type of decoding is usually referred to as conversion. Compare conversion. 2. In electronics and hardware, a type of circuit that produces one or more selected output signals based on the combination of input signals it receives.
decompiler
n. A program that attempts to generate high-level source code from assembly language code or machine code. This can be a difficult task, as some assembly language code has no corresponding high-level source code. See also disassembler. Compare compiler (definition 2).
decrement1
n. The amount by which a number is decreased. Compare increment1. decryption
n. The process of restoring encrypted data to its original form. Compare encryption.
DECstation
n. 1. A small computer system used primarily for word processing, introduced by Digital Equipment Corporation in 1978. 2. One of a series of personal computers introduced by Digital Equipment Corporation in 1989. 3. One of a series of single-user UNIX workstations introduced by Digital Equipment Corporation in 1989 and based on RISC processors. See also RISC.
dedicated channel
n. A communications link reserved for a particular use or a particular user.
dedicated line
n. 1. A communications channel that permanently connects two or more locations. Dedicated lines are private or leased lines, rather than public ones. T1 lines, which are used by many organizations for Internet connectivity, are examples of dedicated lines. Also called leased line, private line. Compare switched line. 2. A telephone line that is used for one purpose only, such as to receive or send faxes or to serve as a modem line.
de facto standard
n. A design, program, or language that has become so widely used and imitated that it has little competition, but whose status has not been officially recognized as standard by an organization such as the American National Standards Institute (ANSI) or the International Organization for Standardization (ISO). See also standard. Compare de jure standard.
default1
n. A choice made by a program when the user does not specify an alternative. Defaults are built into a program when a value or option must be assumed for the program to function.
default2
vb. In reference to programs, to make a choice when the user does not specify an alternative.
default button
n. The control that is automatically selected when a window is introduced by an application or operating system, typically activated by pressing the Enter key.
default drive
n. The disk drive that an operating system reads to and writes from when no alternative is specified.
default home page
n. On a Web server, the file that is returned when a directory is referenced without a specific filename. This is specified by the Web server software and is typically the file called index.html or index.htm.
default printer
n. The printer to which a computer sends documents for printing unless an alternative is specified.
Defense Advanced Research Projects Agency
n. The U.S. government agency that provided the original support for the development of the interconnected networks that later grew into the Internet. See also ARPANET. Acronym: DARPA.
defragmentation
n. The process of rewriting parts of a file to contiguous sectors on a hard disk to increase the speed of access and retrieval. When files are updated, the computer tends to save these updates on the largest continuous space on the hard disk, which is often on a different sector than the other parts of the file. When files are thus "fragmented," the computer must search the hard disk each time the file is accessed to find all of the file's parts, which slows down response time. Windows 95 and Windows NT include defragmentation utilities (or defraggers) as part of the operating system. For the MAC OS, Windows 3.x, and DOS systems, defragmentation utilities must be purchased separately. See also optimization (definition 1). Compare fragmentation.
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