ࡱ>    !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~Root Entry FPрJWordDocument CompObjnAssociation for Computing Machinery; a group dedicated to the advancement of computing knowledge.acquisition (n.) The process of capturing assets or transferring information from an analog to a digital format.Acrobat (n.) A program developed by Adobe for cross-platform document exchange in which files are created in Portable Document Format (.pdf) from PostScript files. The full complement of Acrobat tools consists of the Distiller, the Exchange package, the Catalog package, and the Reader. The Reader is freely distributed so that it can be installed and used on any computer along with an Acrobat document.ActionMedia II (n.) An early video capture card developed by Intel that employs their Digital Video Interactive (DVI) compression technology. It has been replaced by the Intel Smart Video Recorder.active-matrix display (n.) An LCD panel that has three transistors (R,G,B) for each pixel and yields better color and resolution than a passive-matrix display. Thin film transistor (TFT) technology makes this possible.active video lines (n.) Lines of video that are scanned on the screen between the horizontal and vertical blanking intervals. About 483 lines are visible or active in the NTSC 525-line system used in the United States.active window (n.) The portion of the screen that is prepared to accept input from an input device.adapter (n.) An interface card that connects to peripherals or a network.Adaptive Data Compression See ADC.adaptive differential pulse code modulation See ADPCM.ADB (n.) Apple Desktop Bus; the standard I/O port and protocol used on a Macintosh to connect the keyboard, mouse, and other devices.ADC 1. (n.) Adaptive Data Compression (a Hayes modem protocol). 2. (n.) Analog-to-digital converter.ADCCP (n.) Advanced Data Communications Control Procedures; a standard protocol used by the United States government for communications.ADCIS (n.) Association for the Development of Computer-Based Instruction Systems.A/D converter (n.) Analog-to-digital converter; a circuit that converts changes in voltage, pressure, or motion over time into a stream of digits that defines an event with time-based binary data.additive color mixing (n.) The process of creating hues by mixing colors of light rather than pigments. Mixing the additive primary colors in equal proportions results in white.additive color mixingadditive synthesis (n.) The production of a composite waveform by summing multiple individual waveforms. address 1. (n.) Any label that identifies the location of data in either static or dynamic memory, such as a frame number on coded videotape. 2. (v.) To send a message to a particular location.address code 1. (n.) Time code stamped on a tape that identifies each frame of video. The hour, minute, second, and frame numbers are expressed by eight digits in the format hh:mm:ss:ff. 2. (n.) The cue code placed in the vertical blanking interval of a videodisc frame as a point of reference.addressable converter (n.) A device connected to a cable television receiver to give the program provider the capacity to send or block services to individual subscribers.Address Resolution Protocol See ARP.Adobe Type Manager See ATM.ADPCM (n.) Adaptive differential pulse code modulation; the IMA version of this standard is used for storing audio information in a digital format in multiple-session CD-ROM XA and CD-i. The procedure reduces the amount of data needed by examining previously encoded data and adaptively predicting future encoding, eliminating some redundancy, and storing the differences between successive digital samples rather than full values. It is an extension of the PCM audio encoding format. Standardized by the CCITT for telecommunications applications, another version of this audio encoding process can transmit a voice over a 32-kilobit per second (Kbps) digital channel. Each sample is defined by three or four bits that represent the difference between adjacent samples.ADR (n.) Automatic dialog replacement; in audio sweetening, an automated process for substituting a new voice track for the oܥe# ,l,l  X(T!#XMS Sans Serif Symbol SystemTimes New RomanCourier NewA:B:C notation (n.) The standard way to describe relationships in digital video formats. Three numbers are used to represent ratios as follows: (A) The basic sample rate compared to the color clock rate.(B) The color horizontal downsampling rate compared to the basic sampling rate.(C) The color vertical downsampling rate plus 1.A standard 4:2:2 format indicates that sampling is done at four times the color clock, which is 3.58 megahertz (MHz); two horizontal chroma samples are taken for every four luminance samples; there is no reduction in vertical color resolution (1+1).abend (n.) Abnormal end; an error message that indicates unexpected termination of a program or signal, which may be either recoverable or unrecoverable.ABI (n.) Application binary interface; the emulation in software of a hardware/software platform other than the native one, which allows foreign applications to run. An example would be running a Windows application under the UNIX operating system.ABIOS (n.) Advanced Basic Input/Output System; service routines built into IBM-compatible computers that support multitasking.ablation (n.) Using a laser beam, the burning of pits into thin metal film for optical data storage.abort (v.) To cancel a computing procedure while in progress.A-B roll (n.) An editing process in which videotape is played from two tape machines. The tapes are rolled sequentially, in order to dub portions of each onto a third tape, the composite master. Video editors use this technique to import footage from multiple sources. The resulting product is often enhanced by placing transitions between the cuts and using special effects.absolute time (n.) The time elapsed from the exact beginning of an audio CD or a digital audio tape (DAT) to any given point in the program material that follows. It is useful to determine the start and stop times of sound segments. The term refers to the time elapsed from the beginning of an entire sequence or group of events rather than a single piece.abstract class (n.) In object-oriented programming, a class without instances. Instead it has concrete classes as subclasses. For example, mammal is an abstract class, and cow is a concrete class.AC (n.) Alternating current; in the United States, 120-volt electricity that is delivered by utility companies and changes polarity from positive to negative 60 times per second. In other countries, the rate of alternation is often 50 cycles per second. Direct current, by contrast, is a continuous stream of current in one direction with constant polarity. The regular pulse of AC can be picked up by audio systems that are not well grounded, introducing a 60-cycle hum.accelerator card (n.) A circuit board inserted into a slot on the motherboard that increases the processing speed and performance of the CPU. Graphics accelerators are used to increase the productivity of artists.acceptable use policy See AUP.access (v.) To seek and retrieve information from a hard disk, floppy disk, CD-ROM, or any other digital or analog storage medium.access time (n.) The time required to locate and load data from storage after the seek command. Typically, this measurement includes the time it takes the reading head to move between the most distant segments of the media.ACD (n.) Automatic call distribution; in telecommunications, a method of routing and tracking telephone signals.ACID test (n.) A test of the atomicity, consistency, isolation, and durability of transaction processing. Passing the ACID test exhibits a high degree of resilience and recoverability. The term is derived from the process of testing metals with strong acid to determine gold content.ACK (n.) An acknowledgment character that is returned to a sending device by a receiving device to indicate that the data has been received correctly.ACM (n.) riginal. ADSL (n.) Asynchronous Digital Subscriber Line; a communications protocol that allows the transfer of high data rates over twisted-pair telephone wire connections. It is useful for networking compressed video and audio at up to 1.5 megabits per second (Mbps).ADSR (n.) Attack, decay, sustain, release; refers to a common way of shaping synthesized sounds and the circuit that performs the process. ADSR stands for four stages in the envelope of a sound. In sound synthesis, the ADSR settings define the shape of a note or its amplitude over time, not the pitch.ADSR curveAdvanced Data Communications Control Procedures See ADCCP.Advanced Research Projects Agency See ARPA.Advanced RISC Machine See ARM.Advanced SCSI Programming Interface See ASPI.advanced wave effects See AWE.AECT (n.) Association for Educational Communications and Technology. AES/EBU (n.) Audio Engineering Society/European Broadcast Union; the two groups that developed similar digital audio transmission standards, specifying transmission of data in a stream with encoded stereo audio signals along with optional information.AF (n.) Audio frequency; sounds within the normal range of human hearing, approximately 20 hertz (Hz)-20 kilohertz (kHz).AFC (n.) Automatic frequency control; the process of locking a receiver to a TV or FM station's frequency. affordance (n.) A tangible aspect of an object that allows action or manipulation. Examples are handles, buttons, and scroll bars.AFSK (n.) Audio frequency-shift keying. In telecommunications, a method of modulating a carrier wave with audio frequencies (AF) to send digital signals.AGC (n.) Automatic gain control; a limiting circuit used in audio playback systems to prevent damaging high volume levels.AI (n.) Artificial intelligence; software that makes decisions based on accumulated experience and information. Functions normally associated with human intelligence, such as learning, adapting, reasoning, and self-correction are features of the software.AIFF (n.) Audio interchange file format; a sound file format defined by Apple Computer and others that can include both sampled sound and MIDI data. The AIFF-C variation stores the data in compressed form. AIFF files may be imported by most multimedia authoring programs for the Macintosh and by some programs running on IBM-compatible computers.A-law (n.) A digital audio encoding method for telephony used primarily in Europe. Defined by the CCITT G.711 standard, it is based on the 2048-kilobit (Kb), 30-channel PCM system. It compresses at a 2:1 ratio and is similar to the mu-law encoding scheme used in the United States and Japan.algorithm (n.) A type of formula that defines a sequence of steps necessary to perform a process.algorithmic (adj.) Describes a program structured like a mathematical procedure that solves a problem in a limited number of steps.alias (n.) In a Macintosh system 7.0 and higher, an icon that represents or points to the original file. Multiple aliases may be created and placed where they may provide convenient access to the original file.aliasing 1. (n.) The appearance of unwanted visual effects, known as "jaggies," in digitized images. An example is the stair-step effect on raster display systems without high enough resolution to reproduce smooth diagonal lines or circles. 2. (n.) In audio sampling, all frequency components higher than half the sampling frequency are reflected in the lower range. This distortion-producing reflection is referred to as aliasing, and it results in artifacts. It can be avoided by processing the waveform to be sampled with a low-pass filter at half the sample rate before digitizing.alignment 1. (n.) In a tape recorder, the positioning of the head in relation to the tape path. 2. (n.) In a word-processed or graphic document, the horizontal and vertical relationships of elements.alpha blending (n.) A technique used to produce atmospheric effects in three-dimensional graphics. Alpha values determine the degree of transparency of a pixel.alpha channel (n.) In video production, a separate signal used to control visual effects such as overlay and transparency. In a digital graphics environment, the bits that control the percentage of visibility between upper and lower layers, or foreground and background elements.alphanumeric (adj.) Describes a combination of alphabet letters, numerals, and other symbols used for codes and computational expressions.alpha test (n.) The initial testing on software that evaluates general functionality. It occurs prior to a beta test, in which it is field-tested by users. AM (n.) Amplitude modulation; the process of adding information to a constant carrier signal by modulating or changing its amplitude in direct correlation to another signal. ambient (adj.) Describes a natural state, such as room temperature. Ambient sounds are referred to as "environmental" because they exist in a natural environment.American Society of Composers, Authors, and Publishers See ASCAP.American Standard Code for Information Interchange See ASCII.America Online See AOL.Amiga (n.) A computer system based on the Motorola 68000 family of processors and similar in design to a Macintosh. It was developed by Commodore International, which is no longer in existence. A popular application for the Amiga is the Video Toaster, a digitizing card that facilitates titling and effects for digital video production. The presence of onboard genlock capabilities made the Amiga system unique among microcomputers. A-mode (n.) The mode a video editing system is in while it is assembling the segments in the order listed on the edit decision list (EDL). This process usually involves multiple changes of source reels.ampere (n.) A measurement of electrical current equal to one volt applied to one ohm of resistance.amplifier (n.) An electronic device that boosts signal strength. Amplifiers, or amps, are required to drive speakers for audio output. They are also required at regular intervals in a cable television system between the headend and the subscriber, approximately every 1500 feet.amplify (v.) To increase the amplitude or power of a given signal. Related to audio, to increase the sound pressure level (SPL). Amplitude is the height of a waveform, or the measurement of a signal from trough to peak.amplitude modulation See AM. amplitude-shift keying See ASK.analog (n.) A method of representing physical variables, such as voltage, pressure, or motion, that flow and change continuously and are values expressed as the quantitative magnitude of the variables. Analog devices are often controlled by knobs and sliders, and their output is shown by dials, gauges, and meters.analog RGB (n.) A video signal that sends separate signal lines for red, green, and blue picture information. Each of the signals is encoded as a proportional voltage rather than as digital bits. Video systems for microcomputers employ this system. analog-to-digital converter See A/D converter.analog video (n.) A continuous electronic signal generated by a camera or a videotape source that represents an infinite number of smooth gradations between video levels. By contrast, a digital video signal assigns a finite series of steps in the gradations and is stored as data.anchor (n.) In a hypertext environment, such as an HTML document, a word or icon that is colored or underlined and links to another document or location. By clicking on the hypertext link, a user is transported to the new location.anchor point (n.) In a drawing program, the beginning or ending point of a Bezier curve. See Bezier curve.animatic (n.) A compilation of key scenes used to plan and lay out video spots and motion pictures.animation (n.) The rapid display of a series of still images or objects that are repositioned in each frame to achieve the effect of movement on a still background.anonymous FTP (n.) A procedure that downloads files from a public FTP server to the user. It is possible to log on to an anonymous FTP server by using "anonymous" as the login name and an e-mail address as the password.ANSI (n.) American National Standards Institute. anti-aliasing (n.) Software alterations in the representation of data that help diagonal or curved lines appear smooth and continuous when displayed from computer-generated sources. In audio applications, the smoothing of steps between discrete samples to reduce the undesirable effects of low bit-rate capture. anti-aliased letter on left, aliased letter on rightAOL (n.) America Online; a commercial networking service for individual users who have a computer and a modem. APDA (n.) Apple Programmers and Developers Association; the source for all the tools needed to conduct high-level multimedia development using the Macintosh platform. They may be contacted at 1-800-282-2732 in the United States, or 1-800-637-0029 in Canada.API (n.) Application Program Interface; software that defines the interface with an operating system or another program via a set of calls or special messages.Apple Desktop Bus See ADB.Apple Programmers and Developers Association See APDA.Apple Remote Access See ARA.applet (n.) A small application program that performs a specific function or handles media.AppleTalk (n.) A local area network (LAN) protocol developed by Apple Computer for connecting peripherals and computers. It is a part of the system software from Apple Computer and operates over a variety of wiring types. Technically, it is a CSMA/CD network running at 230 kilobits per second (Kbps) that can connect up to 32 devices using shielded, twisted-pair cable for a distance of approximately 1000 feet.AppleUNIX See A/UX.Apple Video Compressor (n.) Developed by Apple Computer, this is the original compression and decompression codec used for QuickTime. These algorithms have been updated.application 1. (n.) A software program that creates or reads a data file. 2. (n.) The set of data and program software contained on a compact disc.application binary interface See ABI.Application Program Interface See API.application-specific integrated circuit See ASIC.ARA (n.) Apple Remote Access; a communications protocol through which a user can dial up a host Macintosh from a remote modem and share the desktop of the host on the remote computer. Files can be downloaded or uploaded between the two connected computers.Archie (n.) Available as a UNIX command via Telnet, this tool allows users to search a database of anonymous FTP sites.architecture (n.) The general design of a computer hardware and software system. A system with "open architecture" allows the addition of internal cards and external peripherals. archival (adj.) Describes a storage medium that preserves data for an extended period. Archival media must remain stable without degradation over time.archive (v.) To record information in long-term storage.archiving (n.) The process of moving data from online storage to nearline (optical disk) or offline (tape) storage. A directory is stored along with the data.ARCnet (n.) Attached Resource Computer Network; a local area network (LAN) configuration that operates at 2.5 megabits per second (Mbps) over coaxial cable using a token-passing protocol. It features a distributed star topology and is reliable and easily expanded.ARM 1. (n.) Advanced RISC machine; a miniature reduced instruction set computing processor, such as the one used in the Apple Newton PDA. 2. (n.) Asynchronous response mode; in an unbalanced data connection, a mode in which the secondary station may begin transmission to the primary station without obtaining permission.ARP (n.) Address Resolution Protocol; a standard used on the Internet that assigns IP addresses to workstations on a local area network (LAN).ARPA (n.) Advanced Research Projects Agency; a United States government organization that developed packet-switching techniques and created the network that was the precursor to the Internet.ARQ (n.) Automatic request for retransmission; a case in which the receiver asks the transmitter to resend a frame or a block of information, generally as a result of error correction.array (n.) A set of coordinates that define rows and columns. A two-dimensional array is described with x and y coordinates, while a three-dimensional array requires x, y, and z coordinates.artifact (n.) An undesirable distortion that appears in digitized audio or video files as a result of inaccurate information introduced during capture or compression.artificial intelligence See AI. artwork (n.) Any type of graphics prepared for computer display, printing, or video. This may include drawings, paintings, photographs, maps, graphs, charts, captions, titles, and all elements in which artistic design considerations are of primary concern.ASCAP (n.) American Society of Composers, Authors, and Publishers; a licensing agency that controls the rights for broadcast and performance of musical compositions.ASCII (n.) American Standard Code for Information Interchange; developed by ANSI, the standardized data character system used internationally to code letters, numbers, and other symbols into the binary values used in most microcomputer applications. It is a seven-bit-plus-parity character code in which each bit can be a one or a zero, and it is capable of representing only 128 items. ASCII files contain text characters only: letters, numbers, and punctuation with no formatting. The other major method of encoding is EBCDIC, an 8-bit code used by mainframe computers. (Pronounced as-kee.) See table.ASIC (n.) Application-specific integrated circuit; a gate array or logic array. This type of chip has its gates configured to perform a particular function.ASK (n.) Amplitude-shift keying; a form of digital modulation in which discrete changes in the amplitude of the carrier signal convey a digital signal. aspect ratio (n.) The resolution expressed in relative height and width values. The standard ratio for computer screens is 3:4. This is the basis for the standard resolutions of 120:160, 180:240, 240:320, 480:640, or 600:800 used by video monitors. The aspect ratio for television monitors is wider, and the problem of overscan introduces variables related to the safe viewing area around the edges. The ratio of modern motion pictures varies from 3:5 to 3:7, creating a problem when a wide-format motion picture is transferred to a 3:4-ratio screen. A 35mm photograph has dimensions of 24 36mm, resulting in a 2:3 ratio. A letterbox effect occurs when photos are ported to the computer screen. See illustration.ASPI (n.) Advanced SCSI Programming Interface; developed by Adaptec, a protocol used to configure devices and media on a SCSI chain.assemble editing (n.) The placement of video sequences back-to-back without a constant reference signal, a process that is prone to minor timing errors. Insert editing, or placing sequences on top of an existing reference track, is more stable.assembly (n.) The conversion of instructions and data written in a computer programming language into lower-level machine code.assembly language (n.) A lower-level programming language that consists of words and phrases that are used to control a microprocessor. An assembler converts the subroutines of assembly language into machine code that a computer can read. The source code consists of statements, while machine code consists of binary digits.asset (n.) Any piece of data used in a multimedia program, such as an audio, graphic, text, or video file.Association for Computing Machinery See ACM.asymmetrical compression (n.) Any video or audio compression process in which more time and resources are required to encode than to decode.asynchronous 1. (adj.) Describes the performance of computer operations in sequential stages, rather than in a continuous variable stream. 2. (adj.) The opposite of "real-time" conferencing in e-mail applications, where more than one person can participate in a conversation at the same time from different locations. In asynchronous communication they must take turns. 3. (adj.) In telecommunications, a mode in which two devices are free to send data in a continuous stream at any time. Each byte begins with a start bit and ends with a stop bit. It is the most common mode of communication between computer modem users.Asynchronous Digital Subscriber Line See ADSL.Asynchronous Response Mode See ARM.Asynchronous Transfer Mode See ATM. ATAPI (n.) AT Attachment Packet Interface; an enhancement to the original ATA hard disk controller system that allows packets to be sent to a CD-ROM player.ATDT (n.) Attention dial tone; a modem command.ATM 1. (n.) Adobe Type Manager; a utility that extrapolates a screen-resolution character (72 dots per inch) from a PostScript character. 2. (n.) Asynchronous transfer mode; a means of transmitting data that combines different data types (audio, video, or text) with a sophisticated formula for allocating bandwidth and shuttling packets, or cells, of a fixed length (53 bytes). It provides a common means of transporting all types of data, some of which exist as streams that are reassembled on reception. Attached Resource Computer Network See ARCnet.attachment (n.) Any file linked to an e-mail message that can be opened and viewed by an application resident on the recipient's computer.attachment unit interface See AUI.attention dial tone See ATDT.attenuate (v.) To reduce the strength of a signal. In audio applications, attenuators often appear as faders or sliding switches that control the decibel levels of output channels on mixing boards.audio (adj.) Related to sound, as in audio tape, audio track, or audio file.audio bridge (n.) An electronic device that controls multiple telephone lines connected for two-way audio and data transmission; commonly used for audioconference applications.audioconference (n.) A meeting over telephone lines with participants in different geographic locations who speak with one another simultaneously. Full-duplex systems allow users to hear other voices while they speak into their headsets. Half-duplex systems allow either reception or transmission of a signal at any given moment, but not synchronous two-way communication.Audio Engineering Society/European Broadcast Union See AES/EBU.audio frequency See AF.audio frequency-shift keying See AFSK.audio graphics (n.) A hardware and software system that permits computer users in different locations to connect over telephone lines and share data, graphics, and audio information. With an audiographic connection, users can work on the same application or document simultaneously, both can see the data on their computer screens, and they can discuss their progress over a voice channel. In the most basic application, it refers to any single-frame transmission of graphics with audio signals. audio interchange file format See AIFF.audio track (n.) The section or layer of an audio/videotape or disc that contains the sound signal that accompanies the video signal. Systems with two separate audio tracks can produce stereo sound or two independent tracks.audio-video interleaved See AVI.AUI (n.) Attachment unit interface; a 15-pin connector used to couple computers on an Ethernet network.AUP (n.) Acceptable use policy; an Internet service provider's statement of permissible uses.author 1. (v.) To create an interactive computer program with the use of an authoring language or system. Developers without formal programming skills can prepare applications for computer systems or CD-ROMs by "scripting" commands. Authoring requires a disciplined approach to preparing the elements of a multimedia program with careful planning and design. 2. (n.) A person who participates in the creation of a multimedia program or an interactive CD-ROM.authoring software (n.) A program that facilitates the development of interactive multimedia. Systems vary widely in their capabilities, and factors such as the platform, audience, and desired results are taken into consideration when selecting the appropriate tool. It requires less time to develop interactive multimedia with the aid of an authoring system than it does to program it in compiled code. The methods used to develop graphics, text, video, audio, animation, and other media objects generally are not affected by the choice of an authoring system. Software designed for the creation and editing of specific media types is used to refine objects to be imported into the authoring environment, although an authoring tool may have some rudimentary editing features. The following is a description of the primary types of authoring paradigms:Scripting language: An approach similar to traditional programming. File names identify multimedia elements, sequencing, and hot spots. An object-oriented version of the scripting language is usually implemented.Flow control with icons: Rapid proto typing and short development time are characteristic. A palette of icons presents the tools for interaction, and a flow line connects the icons. Runtime speed may be slower than with other development tools.Frame-based system: Uses screens, frames, or cards as the work place and brings media types onto each frame. A way to control the timing of a presentation and the layering of assets generally is provided. An icon palette is available, and conceptual links are made between objects that represent media types, such as graphics, audio, and video files. A scripting language is provided to set up interaction. With this type of tool it is difficult to see the connections while building a program. Some frame-based systems provide a matrix, or a score, that shows the progression of frames on the horizontal axis and the media channels, or tracks, on the vertical axis.Hierarchical object: A system that defines relationships with metaphors represented by embedded objects (media types or events) and iconic properties (controls or conditional statements), similar to an object-oriented programming language.Hypermedia linking: A tool that allows conditional relationships to be built between elements and gives the author a means to direct traffic. Most programs show the relationship between elements but do not offer a visual map of the connections.The table on the following page lists widely used authoring programs, identifies the publisher, indicates the platforms on which programs may be developed or run, and describes the authoring paradigm and prominent features. Programs that offer a cross-platform "player" require that the authoring be done in the original environment. After development, the program may be ported to the player platform as a self-contained module. See table on following page.auto-assembly (n.) In video post-production, the use of an edit decision list, or EDL, as well as a computerized edit controller to automate the process of making a final edited master tape.autochanger (n.) An optical media system that can store and retrieve data from multiple discs; similar to a jukebox that plays phonograph records.Autodesk Animator (n.) Developed by Autodesk, a collection of PC animation tools that create files in the Autodesk proprietary "FLC" and "FLI" formats.autoexec.bat (n.) A batch file, or command set, that is automatically executed by a PC running MS-DOS whenever the system is turned on or booted.autofeed (n.) A mode in which a scanner can operate continuously. A new page is loaded automatically when the scan of the previous page is completed.automatic call distribution See ACD.automatic dialog replacement See ADR.automatic frequency control See AFC.automatic gain control See AGC.automatic request for retransmission See ARQ.AutoPlay (n.) A CD-ROM standard developed by Microsoft that allows Windows 95 to detect a disc and load its program automatically. auto-repeat (n.) A feature of many media playback devices, this is a mode that allows continuous replay of program material until interrupted.A/UX (n.) Apple UNIX; a version of UNIX that runs on networked Apple computers.auxiliary data field (n.) A 288-byte field that precedes the data field in a CD-ROM sector. It contains error-correction codes in a Mode 1 disc, but it may contain data on a Mode 2 disc.AVC (n.) Association of Visual Communicators. AVI (n.) Audio-video interleaved; developed by Microsoft, this is a digital video architecture for use in Microsoft Windows. It is a common standard for synchronized audio/video delivery on IBM-compatible computers, known as Video for Windows. In this file format, blocks of audio data are woven into a stream of video frames.AWE (n.) Advanced Wave Effects; a proprietary method of sound synthesis employed by the 32-bit Sound Blaster card.backbone (n.) The primary trunk or high-speed connection within a network that connects shorter, often slower circuits or LANs. It carries the heaviest traffic and is central to any network design.background 1. (n.) The area of a screen or frame over which images or objects are placed; the most distant element in composite layering. 2. (n.) During shared processing in a multitasking environment, less critical events or operations are conducted here. Print spooling while a document is being edited is an example, as is the ability to receive a facsimile while performing other computing functions.back up (v.) To create an archival copy of data recorded on a storage medium. backup (n.) The copy of data that is recorded for archival purposes, typically to offline tape storage.balanced line (n.) A two-conductor line with a ground present is balanced if the two conductors carry equal voltages that are opposite in polarity. In a balanced-to-ground line, the impedance-to-ground levels in both conductors are equal in strength. bandpass filter (n.) A device that blocks all frequencies not in a specified range. It may be used to process audio signals.bandwidth (n.) The transmission capacity of an electronic medium, such as network wiring, fiber-optic cable, or microwave links; also the range of signal frequencies where a piece of audio or video gear can operate, or the difference between high and low limiting frequencies. See the table on the following page for commonly accepted definitions of bandwidths in telecommunications and broadcasting.bandwidth between 1K and 5K is shadedbar code (n.) A pattern of parallel lines whose variable thickness and separation encode a message that can be read by an optical scanner or wand for decoding by a computer. Many businesses use it as a universal product code (UPC) on retail items, and libraries use it to catalog books. It may be used to control videodisc playback as well. bar codebarrel distortion (n.) The opposite of pincushioning in a video display. The vertical sides of the display area curve outwards. See illustration.barrel distortionbaseband (n.) A method of transmitting digital information over short distances. The complete bandwidth of the cable is used to transmit a single signal. No modulation of signals exists, and they are transmitted individually. Simultaneous transmission of signals is possible using time-division multiplexing. This is a less expensive, simpler means to transmit information than broadband transmission.base multitimbral specification (n.) A synthesizer subsystem standard that Multimedia PC audio board manufacturers follow in implementing MIDI playback. According to this specification, three pitched tones are available at once to play up to six notes, and two percussive timbres can play two percussive notes.BASIC (n.) Beginners' All-purpose Symbolic Instruction Code; an algebraic computer programming language that was developed at Dartmouth College. The language employs if-then logic statements and other English commands as well as mathematical formulas. basic input/output system See BIOS.basic rate interface See BRI. batch file (n.) In MS-DOS, a text-based file using the file extension .bat that carries out commands when executed. Batch files can be used to avoid retyping commands, to load other programs, or to change a computer's parameters. Batch processing consists of the continuous execution of a series, or batch, of commands.bay (n.) In the physical frame of a microcomputer case, a space where an internal drive or a peripheral is installed.baud (n.) A unit of transmission speed named for Jean-Maurice-Emile Baudot that defines the number of discrete signaling elements per second. One baud is approximately equal to one bit per second, but at high speeds, one signal can contain more than one bit. Common baud rates are 300, 1200, 2400, 9600, 14 400, and 28 800 bits per second (bps). Bayonet-Neill-Concelman See BNC. BBS (n.) Bulletin Board System; a system that provides computer users with access to files for downloading and areas for e-mail. Usually developed for local users, many of these systems are accessible through the Internet and FidoNet mail.BCC (n.) Block check character; when data is transmitted in blocks, each packet has a control character, or BCC, appended so that the receiver can check for errors and request retransmission if necessary.BCD (n.) Binary-coded decimal; each digit in this binary number system is represented by four bits. The weighting of each column is 8, 4, 2, 1. 0 = 00001 = 00012 = 00103 = 00114 = 01005 = 01016 = 01107 = 01118 = 1000 B-channel (n.) An ISDN user channel that carries digital data at 64 kilobits per second (Kbps). It may carry a mixture of data types, including PCM-encoded voice data.Because It's Time Network See BITNET.Beginners' All-Purpose Symbolic Instruction Code See BASIC.Bell 43401 (n.) A publication from Bell that defines the requirements for data transmission over dc-continuous, private metallic circuits provided by the telephone company, primarily for limited-distance applications.Bell standards (n.) A set of standards defined by AT&T for modem communications, numbered as follows:Bell 103: Any AT&T 0-300-bps modem that provides asynchronous transmission with originate and answer capabilities. (FSK type.)Bell 113: Any AT&T 0-300-bps modem that provides asynchronous transmission with either originate or answer capabilities, not both. (FSK type.)Bell 201, 201B, and 201C: Any AT&T 2400-bps modem that provides synchronous transmission. 201B applies to full-duplex, public telephone line operation; 201C applies to half-duplex public telephone line operation. (DPSK type.)Bell 202: Any AT&T 1800-bps modem that provides asynchronous transmission and uses a 4-wire circuit for full-duplex operation; also describes an AT&T 1200-bps modem that provides asynchronous transmission and uses a 2-wire circuit for half-duplex operation. (FSK type.)Bell 208, 208A, and 208B: Any AT&T 4800-bps modem that provides synchronous transmission. 208A refers to leased-line applications, while 208B was designed for public telephone line operation. (PSK type.)Bell 209: Any AT&T 9600-bps modem that provides synchronous transmission and uses a 4-wire leased-line circuit for full-duplex operation. (Combined PSK and ASK type, or quadrature amplitude modulation.)Bell 212 and 212A: Any AT&T 1200-bps modem that provides synchronous transmission and uses a public telephone line for full-duplex operation. (PSK type.)benchmark (n.) A task or series of tasks used to test capabilities of a processor or system for speed and performance. BER (n.) Bit error rate; a unit of measurement that defines the number of bit writing errors compared to the total number of bits received during a transmission, or the percentage of bits in error found in a given volume or area of storage medium.bespoke (adj.) Describes custom-made computer-based training software or courseware.beta or betamax (n. or adj.) A consumer videotape format developed by Sony. Beta uses .5-inch (12.65 mm) tape in a 6-inch 3.75-inch (155 mm 95 mm) cassette. Although the format offers superior resolution, it was eclipsed in popularity by the VHS system developed by Matsushita and JVC.betacam (n.) A professional-quality .5-inch video recording and playback format developed by Sony. Betacam is portable and provides video quality comparable to 1-inch videotape. Betacam SP is a higher-quality version that uses true component video signals.beta test (n.) A second and final test for a software product, usually done by actual users in real-world situations with the "beta release."bezel (n.) The housing that encases the front of a video monitor. Touch screens usually have a large bezel for their controlling electronics.Bezier curve (n.) A graphic element defined by a formula consisting of two anchor points and two vector values, as opposed to a bitmap. See vector data.Bezier curvebilinear filtering (n.) A means of predicting the most appropriate texture pixel for the screen based on interpolation from the four adjacent pixels in the texture.binary code (n.) Each element in binary code has one of two possible values, a one or a zero, expressed by the presence or absence of a pulse or a high or low voltage level.binary-coded decimal See BCD.binary digit (n.) A numeral in the binary system, base-two; a one or a zero.binary file (n.) A file that contains non-textual data, such as an image or an application.binary notation (n.) The base-two numbering system that uses the digits one and zero. It may be used to represent any type of data. Logic circuits can define these two digits as different states in many ways.binary synchronous communication See BSC.binary transfer (n.) A method of transferring information between computers that involves the use of error-correction protocol, such as XMODEM or SNA. This is useful if the data is not purely text-based ASCII characters.binaural audio (n.) Two audio tracks that are recorded with special microphone placement for each track to provide the listener with a perception of depth, or three-dimensional sound, when the tracks are played back together. This is different from simple stereo audio.BinHex (n.) A standard Macintosh format for converting a binary file to an ASCII file for network transfer. BIOS (n.) Basic input/output system; the BIOS file contains system control instructions for a microcomputer. Instructions in the ROM of the BIOS help start up a system and define the existing input and output connections.bipolar (n.) A signaling method used in digital transmission in which a signal carrying a binary value alternates between positive and negative polarities. The signal amplitude can represent a zero or one at either polarity, and the spaces with no value are represented by zero amplitude. bis (n.) The second version of an original Consultative Committee on International Telegraphy and Telephony (CCITT) standard. In common usage, it appears after the "V.x" designation, as in "V.42 bis," which refers to a modem specification. The third version in a succession is referred to as "V.x ter," as in "V.27 ter."B-ISDN (n.) The second generation of the International Telephone and Telegraph Consultative Committee's (CCITT) ISDN. It is designed for transmission of real-time multimedia via plain old telephone service (POTS).bit (n.) A contraction of the words binary digit that represents a unit (either zero or one) of data equal to one binary decision; it is the smallest unit in computer information handling. Computer processing capability is evaluated by the number of bits handled at once. PCs use 8-, 16-, 32-, or 64-bit microprocessors.bit-block transfer (n.) A technique for moving pixel blocks in memory onto a monitor. It is more efficient than moving individual bits or bytes and is referred to as "blitting." bit depth (n.) On computer monitors, each pixel can be represented by a variable number of bits used to describe the color of the pixel. Bit depth is the number of bits used in this capacity. A bit depth of two means that only black or white pixels can be shown; a bit depth of four allows the display of 16 colors; a bit depth of eight allows 256 colors; a bit depth of 16 represents 65 536 colors, and 24-bit color yields 16.7 million colors.bit error rate See BER. bitmap 1. (n.) An image defined by discrete values that are assigned to each pixel. 2. (n.) A common PC graphics file format whereby the image is stored as a pattern of dots with the extension .bmp.BITNET (n.) Because It's Time Network; widely used by educational institutions in the 1980s, this network had nodes on hundreds of college campuses. It was officially discontinued in 1996.bit rate (n.) The speed at which data is moved expressed as bits per second (bps). A bit rate expressed in megabits per second is a factor of 8.192 times the same rate expressed in kilobytes per second (KBps) because a kilobyte is equal to 1024 bits times 8. If a file size is known and the data transfer rate at which it streams is known, it is possible to determine the duration of time that an audio or video file will play based on its size. To convert an existing MPEG file of known size and bit rate into the duration for which it will play back, divide the file size in megabytes (MB) by the data transfer rate in KBps. A 5-MB file equals 5000 KB. Divide this by 150 KBps to arrive at 33 seconds of running video.bits per second See bps. bit stream transmission (n.) The transmission of characters at a fixed rate of speed. No stop and start elements are used, and no pauses exist between bits of data in the stream.black box (n.) An electronic circuit or assembly that can be isolated from a system in order to perform a special function, such as controlling an external peripheral.blanking interval 1. (n.) In a video display, the short duration at the end of a scan line when the signal is suppressed and the beam repositions. 2. (n.) The time it takes a video player to locate the next frame to display. See illustration.blanking interval between scan linesblending (n.) The combination of two pixels in the context of a graphic.block 1. (n.) In CD-ROM or CD-i, the user data portion of a logical sector. 2. (n.) Any group of bits transmitted as a unit or packet. It contains control delimiters at the beginning and end, a header, the data stream, and check characters used for error correction.block check character See BCC.block error correct (v.) To add 276 bytes of error correction code to the end of each block of data during premastering of a CD-ROM, allowing errors in the user data block to be corrected.Blue Book (n.) The format used by compact discs that are designed for laser disc players.blue screen (n.) A solid blue background used in the process of shooting video with special lighting so that the background may be "keyed" out, leaving only the subject, which may be placed over any background of the compositor's choice. This is the technique used by television weather reporters, who appear with a map juxtaposed behind them.BMP (n.) A three-character MS-DOS extension at the end of a file name that identifies the file contents as a bitmapped pattern. A graphics format (filename.bmp).BNC (n.) Bayonet-Neill-Concelman; a round connector attached to the end of a coaxial cable and used in video applications. It is pushed onto the receptacle and then locked by twisting clockwise. BNC connectorsboard (n.) Short for "printed circuit board," an internal plug-in unit with printed-circuit wiring and components. It may either control some essential function of the computer's central processor or provide a special feature such as telecommunications, audio, or video control and display. Also known as a card.Boolean operator (n.) A qualifying term that refines a definition; examples include AND (items that include both terms that appear in a query), NOT (items that contain one term but not another), and OR (items that are derived from either class defined). In general, it is a variable that can accept only true or false values.Boolean search (n.) A type of search for information in which qualifiers such as "and," "or," and "not" are used.boot (v.) To start a computer and prepare it to process commands by loading the operating system.boot record (n.) Under the ISO 9660 standard, the record that identifies the location of a boot file on a CD-ROM. This file contains an operating system that can be loaded.boot sequence (n.) The sequence whereby a microprocessor receives instructions from ROM to check its circuits and then to try to load files from a disk drive. It initially tries the A: (floppy) drive, and if the necessary files are not found, it tries to read from the first hard disk drive (C:).bot (n.) Contraction of robot; a term most often found in multiuser dungeons (MUDs) and chats (IRCs). It refers to a character that is not a person, but rather a collection of responses from a computer program.bounce 1. (v.) To mix two or more audio tracks into one. Also called ping-ponging. 2. (v.) To return a piece of e-mail because of a delivery error.bps (n.) Bits per second; a measurement that reflects the speed at which data is sent over transmission lines. It should not be confused with a baud rate, which is a measurement of signal elements that may include more than one bit at high speeds.Bps (n.) Bytes per second; a rate of data transfer, not to be confused with bps, which refers to bits per second. branch 1. (v.) To leap from one location in a program to another based on programmed responses to user input.branching point (n.) An optional path which a user may choose, given two or more directions or destinations.BRender (n.) A three-dimensional API provided by Argonaut, a British game developer.BRI (n.) Basic rate interface; one of the common interfaces used in integrated services digital network (ISDN). It consists of two bearer B-channels at 64 kilobits per second (Kbps), full-duplex, along with a data D-channel at 16 Kbps. The B-channels can accommodate videoconferencing, voice, or facsimile data, while the D-channel handles private data. The BRI "U" interface uses two wires, while the BRI "T" interface uses four wires.bridge (n.) A connecting device between two or more subnetworks, or LANs, that are running similar cabling and protocols. It uses the bottom two layers of the OSI model to create an extended network on which workstations on different subnetworks can share data. bridge disc (n.) A technique for storing data on a CD-ROM XA disc that allows the data to be played back on several platforms. A Photo-CD can be played on a CD-i or Photo-CD player, and also on a 2x multiple session CD-ROM drive.bridge/router (n.) A sophisticated networking device that performs the functions of a bridge, a router, or both simultaneously. It can route multiple protocols, such as TCP/IP and XNS, while bridging other traffic.broadband (n.) Broadband transmission is often in the range of 1 megahertz (MHz) or more, and it can accommodate multiple channels. At the minimum, it is used to describe bandwidth capability greater than voice, which telecommunications standards have set at 4 kilohertz (kHz). ISDN is considered a broadband medium. Cable television employs broadband techniques to send multiple channels over a single cable.Broadband Integrated Services Digital Network See B-ISDN.broadcast (v.) To transmit television and radio programs through the air. In network applications, it means to forward a message to all destinations.broadcast quality (adj.) Loosely defined, this describes the level of quality that television stations will transmit, adhering to the NTSC format in the United States. This format calls for 525 lines of video at a rate of 60 fields per second, with the appropriate levels of brightness and color (luma and chroma).browse (v.) To scan networked information with no particular target in mind.browser (n.) Software that allows a user to search through information on a server; commonly refers to universal client applications, such as Netscape Navigator or Microsoft Internet Explorer. It is the name used by Eastman Kodak on Photo-CD discs for the database program that lets users search for images by keyword or title.BSC (n.) Binary synchronous communication, or "bisync"; an industry- standard IBM communications protocol that is character- or byte-oriented. A defined set of control characters is used to synchronize the transmission of binary-coded data between two stations, both of which must be synchronized prior to data transmission.B-spline (n.) A basic spline from which an approximated curve is derived, typically used in the creation of wire-frame models for a dimensional figure. torus formed by a bicubic B-spline surfacebubble memory (n.) Memory technology that uses magnetic bubbles that are generated from a single-crystal sheet. It is nonvolatile and requires very low power levels.buffer 1. (n.) Memory space that temporarily stores a small amount of data to help compensate for differences in the transfer rate of data from one device to another. It can also be used to store small bits of data that may be used repeatedly (such as a digitized beep or other sound). Most CD-ROM drives have buffers. 2. (n.) A storage space where data is held temporarily until it is passed to or from a host computer or peripheral device.bug (n.) An error in a computer program or a problem with the system.build (n.) An interim version of software in which bugs are resolved and features refined prior to release.Bulletin Board System See BBS.bump map (n.) A texture map that may be applied to the surface of a three-dimensional image to simulate natural surfaces, patterns, or imperfections.bundled title (n.) A CD-ROM that is packaged with hardware components, peripherals, or entire systems and is not priced separately.burst (n.) In reference to color television reception, a signal which provides a reference for the 3.58-megahertz (MHz) oscillator. The signal is sent during the video blanking interval.burst error (n.) An error that contains a group of consecutive bits, often due to scratches on the surface of a CD-ROM.bus 1. (n.) A connection or path between a central processing unit (CPU) and the input/output devices, or the connection between two processors. Types of buses that have been used in IBM-compatibles include ISA, VESA, and PCI. The Nubus system was used on older Macintosh computers. In 1995, Apple Computer replaced the Nubus with the 64-bit PCI bus in selected Power Macintosh models. 2. (n.) A signal or power-transmitting conduit that allows two or more lines to be connected and their signals mixed.button (n.) A graphic component of an interface that represents some embedded function. When clicked, buttons can branch the user to another location in the program.buyout music (n.) Audio tracks that are sold with a license that allows the purchaser to duplicate and use them in productions without paying royalties.bypass mode (n.) An operating mode on ring networks, such as FDDI and token ring, in which an interface is removed, or bypassed, from the ring.byte (n.) A measurable number of consecutive binary digits that are usually treated as a unit. Bytes of eight bits usually represent either one character or two numerals. A computer's storage capacity or memory is figured in kilobytes (KB). One kilobyte is equal to 1024 (210) bits.byte aligned (n.) Information stored in memory that is located an exact multiple of eight bits from the starting point.bytes per second See Bps.C (n.) A high-level, procedural programming language that runs faster than other high-level languages because it allows embedding of instructions. It is highly portable to platforms for which there is a C compiler.cable 1. (n.) All types of wires and cords used to transmit signals or connect equipment. Cables may contain single or multiple wires and may be shielded to reduce interference. Most cables allocate at least one wire to be used as a ground. Coaxial cable is used for video applications. 2. (adj.) Describes local television service delivered over cable rather than broadcast through the air.cable modem (n.) A device that enables a user to connect a computer with a special circuit board to existing coaxial cable provided by a cable TV network and access digital services inserted into the vertical blanking interval of a television signal. Each interval is able to carry the amount of data approximately equivalent to a 9600 baud modem. Transmission is one-way from the cable provider and is not interactive unless a modem on a telephone line is connected simultaneously.cable tap (n.) In an Ethernet network, a device that connects a transceiver to the main cable.cable television See CATV.cache (n.) A temporary block of computer memory that is allocated for frequent or rapid data access.caching (n.) The use of memory or disk storage to speed data processing by storing data that will be accessed later.CAD/CAM (n.) Computer-aided design/computer-aided manufacturing; software applications used by engineers for the graphic design of components and systems. Once components are built, they may be manipulated on screen and evaluated. CAM applications extrapolate manufacturing specifications from the CAD designs and may control manufacturing processes.CADD Computer-aided design and drafting.caddy (n.) The case or cartridge that protects CD-ROM discs while they are inserted in the drive. Late model drives are typically caddiless, and the disc rests in an open tray.CAI Computer-aided instruction. See CBT. CAL Computer-aided learning See CBT.call (v.) In computer programming, to invoke a procedure or subroutine, and to transfer control to it. Ordinarily, control is returned to the program at the instruction immediately following the point from which the call was made.CAM Computer-aided manufacturing. See CAD/CAM. camcorder (n.) Contraction of camera/recorder; portable videotaping gear. The usual formats are VHS and 8mm, along with their higher resolution versions, S-VHS and Hi-8. VHS-C is a compact version of VHS.capacitance 1. (n.) The degree to which a substance or device conducts or passes electricity. 2. (n.) The ability to store an electric charge, measured in farads. capacitor (n.) One of the components in a circuit that stores voltage, like a holding tank. The charge is released later as it is triggered.capstan (n.) A roller or spindle that controls the speed and movement of magnetic tape through a recorder or player. See illustration.capstancard (n.) A printed circuit board. See board.carriage return See CR.carrier sense multiple access with collision detection See CSMA/CD.carrier signal (n.) A constant sine wave that can be modulated with a second signal that contains data. The high-pitched tone that a modem emits is an audible carrier signal. Changes, or modulation, in the amplitude, frequency, or phase of the carrier can convey information.cascade (v.) To connect numerous multiple-port devices in order to expand the number of ports or available I/O lines.cast 1. (n.) The actors who appear in a production. 2. (adj.) Describes the overemphasis of one hue or tint in an image.Category 4 (n.) A standard for wiring that must be met when connecting networks with a bandwidth of 20-megabits per second (Mbps) and 16-Mbps token ring networks. Category 3 (n.) A standard for wiring that must be met when connecting 10-megabit per second (Mbps) 10BASE-T Ethernet and 4-Mbps token ring networks.cathode-ray tube See CRT.CATV (n.) Cable television; local television service that is delivered over cable rather than broadcast through the air. It was defined as Community Antenna Television before the installation of cable.CAV (n. or adj.) Constant angular velocity; a type of videodisc player that spins the disc at a constant speed regardless of the position of the reading head, so that tracks nearer the center pass under the reading head more slowly than the tracks nearer the perimeter. Each frame is separately addressable. The standard speed for CAV discs is 1800 rpm (NTSC) or 1500 rpm (PAL), and the disc makes one revolution for each frame. The maximum program duration is approximately 30 minutes per side on a 12-inch disc.C-band (n.) A high-frequency spectrum used for satellite transmission. Uplink is at 6 gigahertz (GHz); downlink is at 4 GHz.CBI (n.) Computer-based instruction. See CBT. CBL (n.) Computer-based learning. See CBT. CBT (n.) Computer-based training; the use of computers to facilitate learning. Also called computer-aided instruction (CAI), computer-aided learning (CAL), computer-based instruction (CBI), and computer-based learning (CBL).CCD (n.) Charge coupled device; a light-detecting component used by digital cameras.CCIR (n.) Consultative Committee for International Radio; in addition to the name of the committee, refers to the 625-line TV system used in Western Europe.CCIR-656 (n.) A recommendation of the CCIR that is the standard for digital component electrical interfaces. It defines synchronizing signals and blanking, and parallel and serial interface specifications.CCIR-601 (n.) A recommendation of the CCIR that is the standard for digital component video. It specifies color difference coding (Y,R-Y,B-Y) and the 4:2:2 format. CCITT (n.) Comit Consultatif International de Tlgraphique et Tlphonique (International Telephone and Telegraph Consultative Committee); a worldwide standards organization that defines communications protocols. The recommendations enable global compatibility for voice, data, and video transmission over telecommunications devices. The CCIT has been replaced by the ITU. CCITT Group III (n.) A compression standard used for facsimile transmission.CCITT Group IV (n.) A compression standard widely used for storing images on optical disc. It is based on a two-dimensional compression scheme in which every scan line is the reference line for the next scan line, and only the changes or deltas are stored.CCL (n.) Connection Control Language; a set of commands used to identify and manage data connections.CD (n.) Compact disc; usually refers to a compact audio disc, a 4.75-inch (12 cm) optical disc containing information encoded digitally in the CLV format. This format is popular for high fidelity music that offers a 90+ decibel signal/noise ratio and 74 minutes of digital sound. The standard for this format is the Red Book. The official designation is CD-DA (compact disc-digital audio). The following illustration shows the evolution of compact discs and the relationship between different types of compact discs. See illustration on following page. CD-A (n.) Compact disc-audio. See CD-DA. CD-DA (n.) Compact disc-digital audio. See CD. CDDI (n.) Copper Distributed Data Interface; the implementation of Fiber Distributed Data Interface (FDDI) network protocols using twisted pair copper wiring.CDEV (n.) Control panel device; a piece of system code used in the Macintosh OS to extend functionality. (Pronounced see-dev.)CD-i (n.) Compact disc-interactive; developed in 1991 by Philips, this CD-ROM format holds audio, digital data, still graphics, and MPEG video. These discs adhere to the Green Book standard. An infrared remote control device, a mouse, or a track ball allows users to interact with the content on the disc by clicking a cursor over hot spots on the video display. CD-i audio levels (n.) Levels of audio encoding that are part of the Green Book specification. Level A is a method of recording audio that offers fidelity comparable to that of standard CD audio, but it compresses the data to about half as much space on disc. Level B is used in both the CD-i and CD-ROM XA formats, a method of recording audio that offers medium fidelity but that is more highly compressed than level A. Level C is used in both the CD-i and CD-ROM XA formats, a method of recording audio that offers fidelity sufficient for speech. It is highly compressed.CDMA (n.) Code Division Multiple Access; a method of concurrent transmission whereby packets of data are coded to differentiate them from other packets. This is related to TDMA, a popular, but slower transmission technique.CDPD (n.) Cellular Digital Packet Data; the standard for 19 200 bits per second (bps) data communications over unused analog cellular voice channels.CD Plus (n.) A CD-ROM format from Sony and Philips that plays Red Book audio, written on the first tracks, and also includes graphics and data files readable by a microcomputer on later tracks. Windows 95 supports the CD Plus format. CD + G (n.) Compact disc + graphics; developed by Warner New Media, this format is not readable by standard CD-ROM players. It is a CD format that includes extended graphics capabilities as well as some limited video graphics written to the CD subcode area. The primary use is for karaoke, in which the lyrics of a song are displayed and the music without vocals is played to accompany the person who sings the song.CD + MIDI (n.) Compact disc + Musical Instrument Digital Interface; developed by Warner New Media, this CD format adds Musical Instrument Digital Interface (MIDI) information to the digital audio data. CD-R (n.) Compact disc-recordable; developed in 1990 by Philips and Sony, this standard is called the Orange Book. It permits the writing of CD-Audio, CD-ROM, CD-ROM XA, and CD-i block structures to a CD-ROM blank by a CD recorder. The primary applications are for prototype production discs, or "one-offs," and for archiving data. In 1992, a second generation of CD recorders became standard, and they were capable of "multisession," or writing to a disc on more than one occasion. To read a multisession disc, readers must be able to identify a complex Table of Contents, but not all readers can do this. The original ISO 9660 logical file structure does not handle multisession discs because it was created before their invention. CD-R layersCD-ROM (n.) Compact disc-read-only memory; a 4.75-inch disc onto which optical memory storage is encoded. CD-ROMs hold about 620 megabytes of data. The standards for this format are called the Yellow Book. The logical level standard is called ISO 9660. The UNIX extension is called the Rock Ridge proposal. CD-ROM drive (reader, player) (n.) Any playback device for data encoded on CD-ROMs. Compared to an audio CD player, it performs more error correction. Usually controlled by a computer to read text, graphic, video, and audio files, it also reads the Red Book audio format. See illustration on following page.CD-ROM extensions (n.) Software routines that connect MS-DOS with specific CD-ROM drivers and compatible computers to read discs in the ISO 9660 and High Sierra formats.CD-ROM upgrade kit (n.) A package with software, interface card, cables, and the drive for installation in a computer. CD-ROM XA (n.) Compact disc-read-only memory extended architecture; an extension of the Yellow Book standard, generally consistent with the ISO 9660 format. It is designed to add better audio (ADPCM) compression along with the ability to stream interleaved video with audio for multimedia applications.CDTV (n.) Commodore Dynamic Total Vision; an interactive multimedia system designed for consumer use. It reads programs on special CD-ROM discs.laser beam path on a CD-ROM playerCD-WO (n.) Compact disc-write once; another name for CD-recordable (CD-R).cell 1. (n.) In spreadsheets, the point where a row and a column intersect. 2. (n.) In animation, a transparent piece of film onto which images are drawn. 3. (n.) In data transmission, a packet of information containing 53 bytes of address information combined with data.Cello (n.) The trademark name for a freeware Internet browser. Cello allows access to the World Wide Web, Gopher, and FTP. It does not, however, accommodate e-mail messages to newsgroups.cellular (adj.) Describes a means of dividing an area into regions, or cells, so that each region becomes a network in which every point exists within the range of a central transmission facility.Cellular Digital Packet Data See CDPD.central processing unit See CPU.Centronics parallel (n.) A standard 36-pin parallel interface that permits the connection of printers and other peripherals to a computer. CERN (n.) Conseil European pour la Recherche Nuclaire (European Particle Physics Laboratory); the Swiss research center at which the World Wide Web was developed.CGA (n.) Color Graphics Adapter; one of the IBM PC graphics standards. CGI (n.) Common Gateway Interface; a standard that defines the automatic creation of forms and responses on the Web in the form of HTML documents. CGI scripts convert data input by a visitor to a Web site into a page of information, and they are used to allow access to a database or to accept an order from users.CGM (n.) Computer Graphics Metafile; an object-oriented graphic file format used by many software applications.channel (n.) Either of two independent signals in a stereo audio system, designated right and left. Most audio, video, and computer playback devices provide separate channels for these signals.chapter (n.) Each independent segment on a videodisc. chapter cue (n.) A signal in the vertical blanking interval of a master tape identifying the first frame of a new chapter. On a videodisc pressed from this master, a chapter stop is encoded on the corresponding disc frame.chapter number (n.) The number displayed on the screen that identifies videodisc chapters.chapter stop (n.) Codes embedded in videodiscs to signal the break between two separate chapters, allowing access to a specific chapter.character user interface See CUI.chat (n.) An online forum for real-time, text-based discussion by participants who are logged on simultaneously.check disc (n.) A prototype videodisc or compact disc produced prior to quantity replication to confirm the accuracy and integrity of the data.checksum (n.) A number representing the sum of a set of data bytes. It is sent with the data set, and error correction schemes use it to determine whether the data has been accurately received.child directory (n.) In MS-DOS, the directory that resides within a parent directory in the logical format.chip (n.) A silicon wafer onto which circuit paths are etched or printed photographically in layers, connecting active and passive devices within the solid structure. See illustration on following page. chroma key (n.) A video effect created by shooting objects against a monochrome background, the color of which is "keyed" out so it can be replaced with images from another source. Foreground objects appear to be juxtaposed over the new background in the composition. This color-based video matting (overlay) technique drops all areas of a selected color (usually blue) from the foreground image, and it substitutes corresponding areas of the new background.chrominance (chroma) (n.) The color and saturation information in a video signal. Luminance must be present to make it visible. Low chroma levels appear to be washed out and high levels are too vivid, causing bleeding between different colors. See luminance.chunk (n.) A block of a type of data that is used in TIFF and RIFF standards. chip formatsChyron 1. (n.) A manufacturer of video character generators. 2. (n.) A word applied in the computer industry to any character generator or to lettering on the screen.CinePak (n.) A video compression algorithm that was developed by SuperMac and was previously referred to as Compact Video. CIRC (n.) Cross-Interleaved Reed-Solomon Code; the first level of error correction that is used in every compact disc (CD), and the only one that is used for audio CDs. It consists of two Reed-Solomon Codes interleaved crosswise.circuit switching (n.) A network configuration in which a continuous connection is established between two devices, providing uninterrupted flow of information, as opposed to packet switching.CISC (n.) Complex instruction set computing; a method of processing in which complex instructions are used at the assembly language level.CIX (n.) Commercial Internet Exchange; a group of Internet service providers who provide a backbone service free from acceptable use policies (AUPs) and dedicated to commercial use.cladding (n.) A material that surrounds the core of a fiber-optic cable, providing insulation and protection.clean boot (n.) The process of bypassing the config.sys and autoexec.bat files on startup.cleanroom (n.) A room in which semiconductors are manufactured and CDs are pressed. It is maintained virtually dust-free to reduce particle contamination.Clear To Send See CTS.click (v.) To press and release a mouse button rapidly, usually over a hot spot or icon on the screen in a graphical user interface (GUI).client (n.) In the "client/server" model, the system that initiates requests to the server, database, or processing engine. The client uses its own intelligence to further process the results for display.client/server (n.) A network architecture that distributes computing responsibility between a front-end and a back-end program. Prior to client/server, the burden of data processing was placed on either the client (early PC environments) or the server (a typical mainframe). In the client/server model, clients share data and processing functions with the server.clip art (n.) Illustrations or artwork files that are made available for use in productions and projects. Catalogs of clip art categorized by subject are widely distributed, and users who purchase them are typically granted permission to use the images without copyright infringement.clipboard (n.) A memory location in which data that is selected and copied or cut from a document resides until it is pasted or cleared; a form of memory buffer available in most GUIs.clipping (n.) The process of operating a device in a nonlinear amplitude region and producing distortion so that peaks of waveforms are cut off. Clipped waveforms consist mostly of odd harmonics.clock speed (n.) The shortest amount of time that is required for a central processing unit (CPU) to perform a single instruction. A computer clock generates regular timing pulses in a range from 25-200 megahertz (MHz).clone (n.) A computing system based on the IBM design that runs software such as Microsoft DOS and Windows.closed architecture (n.) A system with software and hardware that is compatible with only one manufacturer or developer, which may not be freely extensible. By contrast, open architecture uses open standards for compatibility.cluster (n.) A logical storage unit on a hard disk, floppy, or other media.CLUT (n.) Color look-up table; a selection of colors assigned a digital value and held in a table. A program decodes a color picture for display by matching the code stored for each pixel with the associated color value in the look-up table. This process is also called "indexed color." color look-up table componentsCLV (n.) Constant linear velocity; a type of videodisc player with variable rotation speed, so that all data sectors pass under the reading head at the same rate. The disc rotates faster when the head is closer to the center of the disc, and more slowly as the head moves away from the center of the disc. Referred to as "extended-play" discs, they will play twice as long per side as CAV discs, or up to one hour. Some of the control features of a CAV disc are lost in the CLV format, such as freeze-frame capability. Compact discs of all types spin at a constant linear velocity and exhibit a constant sector size.CMOS (n.) Complimentary metal-oxide semiconductor; a MOS device containing both N-channel and P-channel MOS active elements. CMOS is one of two basic processes (MOS and bipolar) used to fabricate integrated circuits.CMYK (adj.) Describes a type of color representation based on the cyan (C), magenta (M), yellow (Y), and black (K) inks used in color printing. The first three inks form all available colors using subtractive color mixing, while black is used to add tonal range and to define edges.coaxial cable (n.) A standard video cable with a single center conductor surrounded by insulation and an outer conductor made of woven metal. If the cable is run underground or exposed to water, it is enclosed by another layer of insulation. It is referred to as "coax."code (n.) Any representation of information using numbers, letters, or symbols.CODEC (n.) Compression-decompression or compressor-decompressor. This may be either a software-only, or a hardware-assisted scheme that is used to process digital video and/or audio files. The amount of data required to represent moving pictures with sound is reduced by a CODEC, which normally discards redundant data on compression. Some of the more widely used CODECS are Indeo, MPEG, and CinePak.Code Division Multiple Access See CDMA.coded order (n.) In video compression, the order in which frames are stored and decoded, not necessarily the same as the order in which they are displayed.coherent light (n.) A light beam that is made up of a single frequency where the light waves are in phase. It is emitted from a laser or light-emitting diode.color balance (n.) The process of matching the strength of red, green, and blue signals to make an accurate white color from the mixture.color bars (n.) A video test signal consisting of solid blocks of the three primary colors and their combinations, referred to as "bars." Most frequently, the SMPTE version is used.color cycling (n.) An animation technique in which a special effect is created by swapping colors in and out of a color look-up table (CLUT).Color Graphics Adapter See CGA.color look-up table See CLUT.color map (n.) A set of relationships in a table format that defines RGB color components to be displayed based on graphic data from a computer.color model (n.) A means of defining the color of an image with components in three or four dimensions. The most frequently used models include RGB (red, green, and blue light), HLS (hue, lightness, and saturation), HSV (hue, saturation, and value) and CMYK (cyan, magenta, yellow, and black).color perception (n.) The sensation of hues created by the human eye as it defines the frequencies of electromagnetic waves. The graph below illustrates the color perceived by each bandwidth in the spectrum, measured in nanometers. the color spectrum nanometerscolorYCC (n.) Developed by Eastman Kodak for Photo-CD, a device-independent color encoding process. Each color pixel is separated into two 8-bit chroma components and one 8-bit luma component, for a total of 24 bits. The process can also convert RGB color to YCC, and vice versa. It provides image compression and high resolution for video or print graphics.Comit Consultatif International de Tlgraphique et Tlphonique See CCITT.Command key (n.) On a Macintosh keyboard, a special key that has a flower-shaped diagram and performs functions when combined with other keys. Common functions are global menu choices:Command-A Select AllCommand-C Copy material to clipboardCommand-F Find Command-G Find againCommand-I Get infoCommand-M Make aliasCommand-N New folder or documentCommand-O OpenCommand-P PrintCommand-Q Quit from applicationCommand-S Save file to current folderCommand-V Paste from clipboardCommand-W Close file or folderCommand-X Cut to clipboardCommand-Z Undo last command or typingcommand line (n.) In operating systems that require keyboard characters for instructions, such as MS-DOS or UNIX, this display line prompts the user to input keyboard instructions. Commercial Internet Exchange See CIX.Commodore Dynamic Total Vision See CDTV.Common Gateway Interface See CGI.Common Intermedia Format (n.) A video conferencing standard with a resolution of 352 288 pixels.Common Object Request Broker Architecture See CORBA.Common User Access Architecture See CUA Architecture.compact disc See CD.compact disc digital audio See CD-DA.compact disc-interactive See CD-i.compact disc + graphics See CD + G.compact disc + Musical Instrument Digital Interface See CD + MIDI.compact disc-read-only memory See CD-ROM.compact disc-read-only memory extended architecture See CD-ROM XA.compact disc recordable See CD-R.compact disc-write once See CD-WO.compact video (n.) Developed by SuperMac, this is a CODEC can compress QuickTime movies in 320 240 resolution at high frame rates for CD-ROM playback.companding (n.) The process of compressing data for transmission, and expanding it on reception.compatibility (n.) Related to compact discs, the extent to which different types of discs can be read by different types of di