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Glossary of Academic Information Technology Terms

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Quick Index - Clicking on a letter jumps to the Academic Information Technology Terms starting with that letter.

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

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Please be aware that our collection of glossary terms is a compilation from many un-attributed sources. If you are aware of a term missing from this listing and would like it added, please send the term and its definition information via Email to webmaster@rohan.sdsu.edu for inclusion consideration.

A or Return to Quick Index

ABI/Inform
A database of articles in more than 800 business-related periodicals and specialty publications since 1986.

Access Provider
The company that provides you with Internet access and, in some cases, an online account on their computer system.

Acoustic Coupler
A type of modem which converts digital signals into sound for transmission through telephone lines, and performs the reverse operation when receiving such signals. Acoustic couplers generally have cups for the telephone handset.

Active Window
The top or front window in a multiple window environment.

A/D Converter
A device used to convert analog data to digital data. Analog data is continuously variable, while digital data contains discrete steps.

Additive Primaries
Red, green, and blue are the primary colors of light from which all other colors can be made.

Address Resolution
Conversion of an IP Address to the corresponding low-level physical address.

AIX
Advanced Interactive Executive - IBM's version of Unix.

Aliasing
Visibly jagged steps along angled or object edges, due to sharp tonal contrasts between pixels.

Analog
Continuously variable signals or data.

Anonymous Login Convention (FTP)
Standard username (anonymous) and password (guest) which allows login within FTP for the purpose of retrieving an unprotected file.

ANSI
American National Standards Institute. This organization is responsible for approving U.S. standards in many areas, including computers and communications. Standards approved by this organization are often called ANSI standards (e.g., ANSI C is the version of the C language approved by ANSI).

Application
Software that lets users do relatively complex tasks, as well as create and modify documents. Common application types include word processors, spreadsheets, database managers, and presentation graphics programs.

ARA
AppleTalk Remote Access. A protocol (and product) that provides system-level support for dial-in (modem) connections to an AppleTalk network. With ARA, you can call your desktop Mac from a PowerBook and remotely access all the available services - files, printers, servers, e-mail, etc.

Archie
An information system offering an electronic directory service for locating information in the Internet that is automatically updated. The best known use of archie is for scanning a database of the contents of more than 1000 Anonymous FTP sites around the world with more than 2,100,000 file names.

ARP
Address Resolution Protocol. Used to dynamically discover the low-level physical network hardware address that corresponds to the high level IP Address for a given host, for instance. ARP is limited to physical network systems that support broadcast packets that can be heard by all hosts on the network. See also Proxy ARP.

ARPANET
Advanced Research Projects Agency NETwork. A pioneering long-haul network funded by ARPA, an agency of the U.S. Department of Defense responsible for the development of new technology for the military. It served as the basis for early networking research as well as a central backbone during the development of the Internet. The ARPANET consisted of individual packet switching computers interconnected by leased lines.

ASCII
American (National) Standard Code for Information Interchange. A standard character-to-number encoding widely used in the computer industry.

Associate
Linking a document with the program that created it so that both can be opened with a single command.

AV
Audio-Visual. AV Macintosh models have video-capture hardware and have sophisticated sound (and video) recording capabilities.

AU sounds
A type of audio format used in the World Wide Web.

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B
Byte. One character of information, usually eight bits wide.

Backbone
Network used to interconnect several networks together.

Backup file
In Windows 95, a compressed version of the original file and its locations created by Backup.

Bandwidth
The capacity of the transmission medium stated in bits per second or as a frequency. The bandwidth of optical fiber is in the gigabit or billion bits per second range, while ethernet coaxial cable is in the megabit or million bits per second range.

Baseband System
A baseband system transmits signals without converting them to another frequency and is characterized by its support of one frequency of signals. Ethernet-based networks inside campus buildings are transmitted via baseband coaxial cable, with ethernet being the only service supported by the coaxial cable.

BAT
Filename extension for a batch file.

Batch Scanning
Sequential scanning of multiple originals using previously defined, unique settings for each.

Baud
A unit of measurement that denotes the number of bits that can be transmitted per second. For example, if a modem is rated at 9600 baud it is capable of transmitting data at a rate of 9600 bits per second. The term was derived from the name of J.M.E. Baudot, a French pioneer in the field of printing telegraphy.

BBS
Bulletin Board Service. A non commercial dial-up service usually run by a user group or software company. By dialing up a BBS with your modem, you can exchange messages with other users, and upload or download software.

BGI
Binary Gateway Interface. Provides a method of running a program from a Web server. Similar to a Common Gateway Interface (CGI). The BGI uses a binary DLL which is loaded into memory when the server starts. While more efficient han a CGI, the BGI must be compiled and is not easily portable to other environments.

Bilevel
A type of image containing only black and white pixels.

Binary
A numbering system with only two values: 0 (zero) and 1 (one).

Binary File
A file that contains more than plain text (i.e., photos, sounds, spreadsheet, etc.) In contrast to an ASCII file which only contains plain text.

Binary Number System
A counting system used in computers consisting of only 1's and 0's (zeros).

BinHex
A file conversion format that converts binary files to ASCII test files.

BIOS
Basic Input-Output System. Part of the computer's operating system that is built into the machine, rather than read from a disk drive at startup.

bit
A unit of measurement that represents one figure or character of data. A bit is the smallest unit of storage in a computer. Since computers actually read 0s and 1s, each is measured as a bit. The letter A consists of 8 bits which amounts to one byte. Bits are often used to measure the capability of a microprocessor to process data, such as 16-bit or 32-bit.

Bit Depth
The number of bits used to represent each pixel in an image, determining its color or tonal range.

Bit-map
Generally used to describe an illustration or font file as being created by a predefined number of pixels. Also see Object-oriented.

BITNET
An academic computer network that provides interactive electronic mail and file transfer services, using a store-and-forward protocol, based on IBM Network Job Entry protocols. BITNET-II encapsulates the BITNET protocol within IP packets and depends on the Internet to route them. There are three main constituents of the network: BITNET in the United States and Mexico, NETNORTH in Canada, and EARN in Europe. There are also AsiaNet, in Japan, and connections in South America. See CREN.

Black Point
A movable reference point that defines the darkest area in an image, causing all other areas to be adjusted accordingly.

Booting
Starting up a computer via the power switch, which loads the system software into memory. Restarting the computer via a keystroke combination is called rebooting or a warm boot.

Bridge
A dedicated computer used to connect two different networks. It uses data link layer address (i.e., ethernet physical addresses) to determine if packets should be passed between the networks.

Broadband System
A broadband system is capable of transmitting many different signals at the same time without interfering with one another. For local area networks, a broadband system is one that handles multiple channels of local area network signals distributed over Cable Television (CATV) hardware.

Broadcast
A packet whose special address results in its being heard by all hosts on a computer network.

Browser
A program that enables you to access information on the Internet through the World Wide Web.

bps
Bits Per Second is the unit used for measuring line speed, the number of information units transmitted per second.

BSD
Berkeley Software Distribution. Implementation of the UNIX operating system and its utilities developed and distributed by the University of California at Berkeley. BSD is usually preceded by the version number of the distribution, e.g., 4.3 BSD is version 4.3 of the Berkeley UNIX distribution. Many Internet hosts run BSD software, and it is the ancestor of many commercial UNIX implementations.

Bug
A mistake, or unexpected occurrence, in a piece of software or in a piece of hardware.

Byte
The amount of memory needed to store one character such as a letter or a number. Equal to 8 bits of digital information. The standard measurement unit of a file size.

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Cache
An area of RAM reserved for data recently read from disk, which allows the processor to quickly retrieve it if it's needed again.

Caching
A process in which frequently accessed data is kept on hand, rather than constantly being from the place where it is stored.

Case-dependent
Software differentiation between upper and lower case characters. Also referred to as case sensitive.

CCD
Charge-coupled device. An integrated, micro-electrical light sensing device built into some image capturing devices.

CD-ROM
Compact Disk, Read-Only Memory. A type of storage device that looks just like an audio CD and stores as much data as a large hard disk (600MB), making it a popular means of distributing fonts, photos, electronic encyclopedias, games, and multimedia offerings. As the name indicates, however, you can't save or change files on a CD-ROM, only read them. Pronounced see-dee rom.

CGI
Common Gateway Interface. A method of running an executable script or program from a Web server. When a client requests a URL pointing to a CGI, the program is run and the results are returned to the client. This enables dynamic web pages and the ability to do database queries and other complex operations across the web

CIE
The "Commission Internationale de l'Eclairage". An organization that has established a number of widely-used color definitions.

Circuit-switched
A type of network connection which establishes a continuous electrical connection between calling and called users for their exclusive use until the connection is released. Ericsson PBX is a circuit-switched network.

Clickable Image
Any image that has instructions embedded in it so that clicking on it initiates some kind of action or result. On a web page, a clickable image is any image that has a URL embedded in it.

Client/server relationship
A client application is one that resides on a user's computer, but sends requests to a remote system to execute a designated procedure using arguments supplied by the user. The computer that initiates the request is the client and the computer responding to the request is the server. Many network services follow a client and server protocol.

Clipboard
An area used to temporarily store cut or copied information. The Clipboard can store text, graphics, objects, and other data. The Clipboard contents are erased when new information is placed on the Clipboard or when the computer is shut down.

Clipping
The conversion of all tones lighter than a specified grey level to white, or darker than a specified grey level to black, causing loss of detail. This also applies to individual channels in a color image.

CMS
Color management system. This ensures color uniformity across input and output devices so that final printed results match originals. The characteristics or profiles of devices are normally established by reference to standard color targets.

CMYK
Cyan, magenta, yellow, and black are the base colors used in printing processes. CMY are the primary colorants of the subtractive color model.

Codec
Also called a compressor, a compression / decompression software component which translates video between its uncompressed form and the compressed form in which it is stored on media (disk, etc.). The two most commonly used video codecs for CD-ROM video are Cinepak and Indeo.

Colorimeter
A light-sensitive device for measuring colors by filtering their red, green, and blue components, as in the human eye. See also spectrophoto-meter.

Color Cast
An overall color imbalance in an image, as if viewed through a colored filter.

COM1, COM2, etc. -
Most serial ports and internal modems on DOS/WIN PCs can be configured to either COM1 or COM2 in order to accommodate the situation where both may exist. The DOS MODE command is used to change the output direction to such serial devices as modems.

Compression
The reduction in size of an image file. See also lossy and non-lossy.

Computer Search Service
Computer Search Service (CSS), a fee-based service, offers access to more than 500 databases, primarily in the sciences and social sciences, from which the Library can create customized bibliographies.

Configuration
1. The components that make up a computer system (which model and what peripherals). 2. The physical arrangement of those components (what's placed and where). 3. The software settings that enable two computer components to talk to each other (as in configuring communications software to work with a modem).

Contone (CT)
An abbreviation for continuous tone. A color or greyscale image format capable of illustrating continuously varying tonal ranges, as opposed to line art.

Cookies
A file sent to a web browser by a web server that is used to record once's activities.

Coprocessor
A chip designed specifically to handle a particular task, such as math calculations or displaying graphics on-screen. A coprocessor is faster at its specialized function than the main processor is, and it relieves the processor of some work. A coprocessor can reside on the motherboard or be part of an expansion card, as with an accelerator.

Coaxial Cable
A type of cable that contains two conductors. The center conductor is surrounded by a layer of insulation, which is then wrapped by a braided-metal conductor and an outer layer of insulation.

CPU
Central Processing Unit; the brains of the computer. The CPU interprets and executes the actual computing tasks.

Crash
A problem (often caused by a bug) that causes a program, or the entire operating system, to unexpectedly stop working.

CREN
Corporation for Research and Educational Networking. This organization was formed in October 1989, when BITNET and CSNET (Computer + Science NETwork) were combined under one administrative authority. CSNET is no longer operational, but CREN still runs BITNET. See BITNET.

Cross-platform
Refers to software (or anything else) that will work on more that one platform (type of computer).

CSUNET
California State University Network. A packet-switched network that connects the 22 campuses of the CSU system.

Cursor
The representation of the mouse on the screen. It may take many different shapes. Example: I-beam, arrow pointer, and hand.

Cyberspace
A term used to refer to the electronic universe of information available through the Internet.

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DAT
Digital Audio Tape. The most common type of tape backup.

Daughterboard
A board that attaches to (rides piggyback on) another board, such as the motherboard or an expansion card. For example, you can often add a daughtercard containing additional memory to an accelerator card.

Database
A file created by a database manager that contains a collection of information organized into records, each of which contains labeled categories (called fields).

DCS
Desktop color separation. An image format consisting of four separate CMYK PostScript files at full resolution, together with a fifth EPS master for placement in documents.

DDN
Defense Data Network. A global communications network serving the US Department of Defense composed of MILNET, other portions of the Internet, and classified networks which are not part of the Internet. The DDN is used to connect military installations and is managed by the Defense Information Systems Agency (DISA).

DEC
Digital Equipment Corporation.

Decompression
The expansion of compressed image files. See also lossy and non-lossy.

Dedicated line
A telephone or data line that is always available. For example, a leased telephone line can be dedicated for computer data communications. This line is not used by other computers or individuals, is available 24 hours a day, and is never disconnected.

Default Route
A routing table entry which is used to direct packets addressed to networks not explicitly listed in the routing table.

Densitometer
A measuring instrument that registers the density of transparent or reflective materials. Colors are read as tonal information. See also colorimeter and spectrophotometer.

Density
Density is a brightness control to lighten or darken a printout to more closely reflect its screen appearance and to compensate for deficiencies in toner or paper quality.

Descreening
Removal of halftone dot patterns during or after scanning printed matter by defocusing the image. This avoids moire patterning and color shifts during subsequent halftone reprinting.

Dialog box
A window that displays additional options or questions when a command is chosen.

Dial-up line
A communication connection from your computer to a host computer over standard phone lines. Unlike a dedicated line, you must dial the host computer in order to establish a connection. Dial-up line is currently the most popular form of Net connection for the home user.

Dichroic Mirror
A special type of interference filter, which reflects a specific part of the spectrum, whilst transmitting the rest. Used in scanners to split a beam of light into RGB components.

Digital
Data or voltages consisting of discrete steps or levels, as opposed to continuously variable analog data.

Digitizers
A machine which converts analog data into digital data on a computer (such as a scanner digitizing pictures or text).

DIP switches
Dual Interface Poll switches allow for either an ON or OFF setting with any number of circuits. DIP switches commonly allow you to change the configuration of a circuit board to suit your particular computer.

Direct connection
A permanent communication connection between your computer system (either a single CPU or a LAN) and the Internet. This is also called a leased line connection because you are leasing the telephone connection from the phone company. A direct connection is in contrast to a SLIP/PPP or dial-up connection.

Direct-To-Plate
Direct exposure of image data onto printing plates, without the intermediate use of film.

Direct-To-Press
Elimination of intermediate film and printing plates by the direct transfer of image data to printing cylinders in the press.

Directory
A system that your computer uses to organize files on the basis of specific information.

Disk Defragmenter
Arranges the blocks of information for a file into adjacent blocks on your hard drive, which may significantly improve the file access times.

Dmax
The point of maximum density in an image or an original.

Dmin
The point of minimum density in an image or an original.

DNS
Domain Name System. A general purpose distributed, replicated, data query service. Its principal use is the lookup of host IP addresses based on host names. The host names are also known as domain names. Some important domains are: .COM (commercial), .EDU (educational), .NET (network operations), .GOV (U.S. government), and .MIL (U.S. military). Most countries also have a domain. For example, .US (United States), .UK (United Kingdom), .AU (Australia).

Domain Name Server
A computer that converts host names, such as rohan.sdsu.edu to its corresponding IP Address, such as 191.130.1.10. An SDSU computer provides this service any time mail is sent or received and permits users to use TELNET and FTP between SDSU and other sites.

DOS
Disk Operating System. The operating system used on IBM personal computers and compatible machines.

Dotted Decimal Notation
The convention for writing 32-bit IP Addresses as a set of four 8-bit numbers written in base 10 with periods separating them.

Down-Sampling
The reduction in resolution of an image, necessitating a loss in detail.

Download
To retrieve a file from another computer using a modem.

dpi
Dots Per Inch. A measure of the resolution of a printer, scanner, or monitor. It refers to the number of dots in a one-inch line. The more dots per inch, the higher the resolution.

Driver
A piece of software that tells the computer how to operate an external device, such as a printer, hard disk, CD-ROM drive, or scanner. For instance, you can't print unless you have a printer driver. Hard disk drivers are invisible files that are loaded into memory when you start the computer, while scanner drivers are usually plug-ins accessed from within a particular application.

Drum Scanner
Early drum scanners separated scans into CMYK data, recording these directly onto film held on a second rotating drum.

DTP
Desktop Publishing.

Dump
Back-up of data.

Duplex (Full, Half)
Full duplex is data is flowing in both directions at the same time. When Remote echo is ON communication is occurring in full duplex. Half Duplex has data moving in only one direction at a time (Local echo is ON).

DXF
Drawing Interchange Format used for Macintosh graphic files. The standard file-exchange format for 3-D and CAD programs.

Dye Sublimation
A printing process using small heating elements to evaporate pigments from a carrier film, depositing these smoothly onto a substrate.

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