C

C - C and/or C++ (computer) – to – Cylinder Method

C (and/or) C + + (computer)
C is a high level programming language developed at Bell Labs that is able to manipulate the computer at a low-level-like assembly language. During the last half of the 1980's, "C" had become the language of choice for developing commercial software. "C" can be compiled into machine languages for almost all computers. For example, UNIX is written in "C" and runs in a wide variety of micros, minis and mainframes. New Operating Systems from Microsoft are written in C++. C++ is an object-oriented version of "C" created by Bjarne Stroustrup that has become popular. C++ combines traditional "C" with object-oriented capabilities (now there is ‘visual’ & ‘virtual c’).

C: drive (computer)
Common designation for the hard disk in Microsoft DOS and OS/2 operating systems.

Cable (A/V, communications, computer, M/M)
Flexible metal, or fiber-optic, or group of wires. All cables used with computers and communications are insulated with plastic or rubber material.

Cable Interface Unit (communications, computer)
Electronic components in a box outside of a particular computer that sends and receives signals on the network cable.

Cable Matcher (A/V, communications, computer, M/M)
Coupling unit that matches one cable length with another (see gender-changer).

Cabletext (communications, computer)
Videotex service from Cable Television operators sent over coaxial cable (see videotex).

Cable Television (A/V)
Distribution system for broadcast signals delivered by coaxial or fiber optic cable. Also, production facilities for programs distributed on Cable TV channels and cabling.

Cache (computer, Windows)
Reserved section of memory used to improve performance. A disk cache is a reserved section of normal memory or additional memory on the disk controller board. When the disk is read, a large block of data is copied into the cache. If subsequent requests for data can be satisfied in the cache, the slower disk access is not required. If the cache is used for writing, data is queued up in memory and written to the disk in larger blocks. Memory caches are high-speed memory banks between memory and the CPU (central processing unit). Blocks of instructions and data are copied into the cache, and instruction execution and data updating are performed in the higher-speed memory. In Windows, the cache program is called "SmartDrive".

Cache Program (computer, Windows)
Program or device driver that implements a cache. In Windows it is called "SmartDrive".

Caching Controller (computer)
Disk controller with a built-in cache.


CAD (computer)
Computer Aided Design. CAD systems can be specialised workstations or high-performance personal computers using CAD software, with input devices such as graphic tablets and scanners. CAD output is the input to computer-aided manufacturing (CAM) systems for integrating design and fabrication (CAD/CAM). CAD software is available for generic use or for specialised uses, such as architectural, electrical and mechanical design. CAD software may also be highly specialised for creating products such as printed circuits and integrated circuits. CAD systems are often turnkey systems which are put together by vendors that may develop or integrate software into standard or optimised hardware. Except in a few cases, CAD systems rely extensively on graphics.

CADAM (computer)
Full featured CAD application for mainframes from IBM, which includes 3-D capability, solid modelling and numerical control. Originally developed by Lockheed for internal use, it was distributed by IBM starting in the late 1970s. In 1989, IBM purchased the Lockheed subsidiary, CADAM Inc.

CAD/CAM (computer)
Computer Aided Design/Computer Aided Manufacturing - integration of computer-aided design with computer controlled manufacturing. Products designed in the CAD system can be directly keyed into the CAM systems. For example, after a machine part is designed in CAD, the electronic image is transferred to a numerical control programming language, which generates the instructions to control the machine that makes the part.

CADD (computer)

Computer Aided Design and Drafting - CAD systems with additional features for drafting, such as dimensioning and text entry.

CAE (computer)
Computer Aided Engineering - software analysis of designs created in a computer or that are created elsewhere and entered into the computer. Different types & kinds of engineering analyses can be performed such as structural analysis and electronic circuit analysis.

Common Applications Environment - software tool/developer specified by X/Open.

CAI (computer)
Computer Assisted Instruction - early term for CBT (computer based training).

CAL (computer)
Computer Assisted Learning - same as CBT (computer based training).

Conversational Algebraic Language - timesharing language, University of California.

Calculator (computer, Windows)
Machine that provides arithmetic capabilities. It accepts input from a keypad and displays results on a readout and/or paper tape. Unlike a computer, a calculator cannot handle alphabetic data and generally provides limited output. Calculator features are offered in Windows so that the keyboard and the screen can simulate the functions of a calculator.


Calibrate (A/V, computer)
In A/V production, to preset a zoom lens to remain in focus throughout the zoom period. In computer and printing terms, to set up a scanner, monitor, printer, or image-setter so that it produces accurate and consistent results, such as predictable halftones.

Calibration (communications, computer)
Process of determining, by measurement or comparison with a standard, the correct value of each scale reading on a meter or correct value of each setting of a control knob. In a radio receiver calibration means adjusting the tuned circuits in the oscillator to make the reading of the tuning dial correspond exactly to the frequencies of incoming signals.

Call (communications, computer, DOS)
Programming statement referencing independent subroutines or programs. Call is turned into a branch instruction by the assembler, compiler, or interpreter. The routine that is called is responsible for returning to the calling program after it has finished processing.

In communications, the action taken by the transmitting station to establish a connection with the receiving station in a dial-up network.

DOS Command: Call executes a second batch file within the execution of the first batch file, and then performs the remaining commands in the first batch file.

Callback Modem (communications, computer)
Modem designed to call back a remote caller to verify identity for security purposes.

Call By Reference (computer)
Programming call to subroutine passing addresses of parameters used in the subroutine.

Call By Value (computer)
Programming call to subroutine passing actual data of parameters used in the subroutine.

Call Distribution (communications)
PBX (Private Branch Exchange/Switch) feature that can route incoming calls to the next available agent, or operator, or telephone number (*EPABX = Electronic PBX).

Calling Program (computer)
In programming, a program that initiates a call to another program.

Calling Routine (computer)
In programming, a program subroutine that initiates a call to another program routine.

CAM (computer)
Computer Aided Manufacturing - an extensive category of automated systems and techniques, including numerical control, process control, robotics and material requirements planning (MRP).

Content Addressable Memory - same as Associated Storage.

Camber (computer/microelectronics)
In microelectronics fabrication using screen printing, a slight rise or curve in the surface of the substrate.

Camcorder (A/V)
Anagram for a combined camera and recorder. The term describes a video camera and videocassette recorder combined into a single, hand-held unit. Popular camcorders record on 8-mm (or Hi-8), VHS (or VHS-C) video cassettes.

Cameo Lighting (A/V)
Technique used in A/V production where the foreground figures are lighted with highly directional light, while the background remains dark.

Camera (A/V, MultiMedia)
General name for the camera head: the lens (or lenses), the main camera with pickup tubes or charged coupled devices (CCDs), and the internal optical system, electronic accessories, and the viewfinder.

Camera Chain (A/V)
Television camera (head) and associated electronic equipment. For conventional cameras, this equipment includes the camera control unit (CCU), sync generator, and the power supply. In digitally controlled cameras, the equipment consists of the base station, or camera processing unit, and the remote control unit.

Camera Graphics (A/V)
Graphic material prepared for a television camera. The video image is created by the television camera focused on the graphic material, such as a studio card or chart.

Camera Head (A/V)
Actual television camera, which is the head of a chain of essential electronic accessories. In some ENG/EFP cameras (Electronic News Gathering/Electronic Field Production), the camera head contains all the elements of the camera chain.

Camera Left and Right (A/V)
Directions given from camera point of view: opposite of "stage left" and "stage right", which are directions given from the actor's point of view (facing the audience or camera).

Camera Light (A/V)
Small spotlight, also called eye light or inki-dinky, mounted on the front of the camera; used as an additional fill light (not to be confused with Tally Light).

Camera Ready (computer, printing)
In publishing, ready to be photographed (finished artwork) to create printing plates.

Camera Rehearsal (A/V)
Full rehearsal with cameras and other production equipment: similar to the dress rehearsal in theater.

Camera Sled (A/V)
Camera mount, consisting of a high hat (cylinder shaped camera mount) on a low angle dolly, used for low-angle dramatic shots.

Cam Head (A/V)
Special camera mounting head allowing extremely smooth pans and tilts (see fluid head).

Candela (Audio/Visual)
Term used in Audio/Visual defining a unit of measurement of the intensity of light. An ordinary wax candle generates one candela (see lumens).

Candidates (computer)
Alternative plans offered in the preliminary design phase of a project.

Canned Program (A/V, computer)
Software package that provides a fixed solution to a problem. Canned programs for applications should be analysed carefully as they usually cannot be changed or modified very much, if at all.

Canned Routine (computer)
Program subroutine that performs a specific processing task.

Canonical Synthesis (computer)
Process of designing a model of a database without redundant data items. A canonical model, or schema, is independent of the hardware and software that will process the data.

Canting Effect (A/V)
Visual effect where a scene is put on a slight tilt through disturbance of the horizon line.

Cap (A/V)
Lens Cap - rubber or metal cap placed in front of the lens to protect it from light or dust. Also, an electronic device that eliminates the picture from a camera pickup tube.

Capacitance (computer, microelectronics)
Ratio of the charge on one of the plates of a capacitor (there being an equal and opposite charge on the other plate) to the potential difference between the plates. The capacitance of a capacitor depends on the geometry of the plates and the kind of dielectric separator used, since these factors determine the charge which can be put on the plates by a unit potential difference existing between the plates.

Capacitor (computer, microelectronics)
Electronic component that holds a charge. Capacitors are created in varying sizes for use in electronic power supplies or tiny cells that are built into dynamic RAM chips. A capacitor, sometimes called a condenser, consists of two metal plates insulated from each other by a dielectric (insulator).

Capstan (A/V)
Cylinder that traps tape against a roller and moves it at a regulated speed. It includes a pulley used to control speed as well as motion through the recorder or playback unit.

Caption (A/V, computer, M/M)
Text appearing in the title bar of a window.

CAR (computer)
Computer Assisted Retrieval - systems that use computers to keep track of text documents or records stored on paper or microfilm. The computer is used to derive the location of a requested item that is manually retrieved from a shelf, bin, or microfilm library.

Card (computer)
Flat card that holds chips and other electronic components (see printed circuit board).

Card Cage (computer)
Cabinet or metal frame that holds printed circuit cards.

Card Reader (computer)
Device that reads magnetic strips on back of identification cards such as a credit card.

Cardinal Number (computer, mathematics)
Number that states how much or how many. If directory number 50 has 10 files, 50 is the ordinal and 10 is the cardinal (contrast with ordinal number).

Cardioid (A/V, communications)
Heart-shaped (cardioid) pickup pattern of a unidirectional microphone.

Cardioid Microphone (A/V)
Microphone with a heart-shaped response pattern having maximum sensitivity to sounds arriving from a 180 degree angle and some response to sounds beyond this angle. Microphones with a cardioid pattern are the most common in professional audio work.

Caret (computer, Windows)
The ^ symbol over 6 key on a keyboard - used to represent a decimal point in a number. For example ^Y can mean hold control down and press Y: in Windows, changes a mouse cursor (to look like a tiny structural steel I-beam) to be used in the text field.

Carriage (computer/printer, microelectronics)
Part of a printer or typewriter that controls the feeding of paper forms. In a standard typewriter with key arms, the carriage is the part that moves from side to side.

In microelectronics fabrication the mechanism on a screen printer to which the workholder is attached, which converts the substrate to and from the print position.

Carriage Return (computer/printer)
Computer representation of typewriter action, usually the return key, - "enter" key.

Carrier (communications, computer)
Alternating current that vibrates at a fixed frequency, used to establish a boundary, or envelope, in which a signal is transmitted. Carriers are commonly used in radio transmission (AM, FM, TV, microwave, satellite, etc.) in order to differentiate transmitting stations. For example, an FM station's channel number is actually its carrier frequency. The FM station merges (modulates) its audio broadcast (data signal) onto its carrier and transmits the combined signal over the airwaves. At the receiving end, the FM tuner latches onto the carrier frequency, filters out the audio signal, amplifies it and sends it to the speaker. Carriers are used to transmit several signals simultaneously through a wire or cable. For example, several voice, data or video signals can travel over the same line as long as each one resides within its own carrier, vibrating at a different frequency. The detector at the other end knows which one to choose.

Carriers (computer, microelectronics)
In microelectronics fabrication, holders for electronic parts which facilitate handling during processing, production, imprinting, or testing operations and protect those parts under transport.

Carrier Based (communications)
Transmission that generates a fixed frequency (carrier) to contain data being transmitted.

Carrier Frequency (communications)
Unique frequency that is used to "carry" data within its boundaries. The carrier frequency is measured in cycles per second, or Hertz (see FDM).

Carterfone Decision (communications)

Decree from FCC (Federal Communications Commission) in 1968 that permitted users to connect their own telephone equipment to the public telephone system for the first time.

Cartridge (A/V, computer)
Self-contained, removable storage module that contains disks, magnetic tape, or memory chips. Cartridges are inserted into slots in the drive, printer or computer. In A/V production it is also called a Cart. A Cart is tape recording or playback device that uses tape cartridges. An Audio cartridge is made up of a plastic case containing an endless tape loop that rewinds as it is played back.

Cartridge Font (computer, printer)
Font contained in a cartridge that physically plugged into a printer. A cartridge font was usually used by laser printers, for example in older IBM or HP LaserJet laser printers, but some dot-matrix printers also use font cartridges.

CAS (communications, computer)
Communications Application Specification - protocol from Intel for combination fax and modem board that allows personal computer users to exchange data more easily with fax machines. Introduced in 1988, Intel provided both the boards and the chips.

Cascade (computer, Windows)
Way of arranging open windows on the desktop screen so that they overlap each other, with the title bar of each window remaining visible (see Tile).

Cascading (A/V)
Movements of signals when several effects are combined on a video switcher and the signal re-enters several times. The signals move from one switching bank to the next, picking up additional effects at each video switching bank.

Cascading Menu (computer, Windows)
Menu that opens from a command on another menu.

Cascode Amplifier (communications, computer, microelectronics)
Transistor amplifier with a common emitter stage in series with a common-base stage. The input resistance and current gain are equal to the corresponding values of a single common-emitter state.

CASE (computer)
Computer Aided Software Engineering - software used in the development of information systems, including analysis, design and programming. For example, data dictionaries and diagramming tools aid in the analysis and design phases, while application generators speed up the programming phase. CASE tools provide automated methods for designing and documenting traditional structured programming techniques. The ultimate goal of CASE is to provide a language for describing the overall system that is sufficient to generate all the necessary programs.

Case Sensitive (computer)
Term defining whether an interpreter or compiler treats lowercase and uppercase letters as the same character. Most interpreters and compilers are case-insensitive. "C" Language is an exception; it is case-sensitive, and all its keywords are in lowercase. Many interpreters, such as Visual Basic, will reformat keywords to their standards: all uppercase for BASIC and a combination of upper and lowercase letters in Visual Basic.

Case Statement (computer)
Variation of the if-then-else (boolean) statement that is used when several ifs are required in a row.

Cassette (A/V, computer)
Removable cartridge containing a supply and takeup reel of magnetic tape.

Cast (A/V, computer, M/M, Windows)
In the Multimedia Movie Player, a collection of individual images displayed in playback.

Cast-based Animation (A/V, computer)
Animation methodology treating each object in an animated production as an individual graphic image (cast member) that may be independently manipulated. Modifications to the objects are controlled by a script.

Casting (computer)
In programming, the conversion of one data type into another.

Catalog (computer)
Directory of files for an application; It may also be a map, list or directory of storage space. In addition to the name of the file, the catalog record may contain the creation date, edition or version number, and expiration date. It can contain the size of the file, location in storage, and it will often maintain some usage measures such as number of accesses since creation, date of last access, etc.

Cathode (A/V, electronics)
Device that emits electrons. Electrons flow from the negatively charged cathode to the positively charged anode.

Cathode Ray (A/V, electronics)
Name given to the electrons originating at the cathodes of gaseous discharge devices. The term has now been extended to include low-pressure devices such as cathode ray tubes. Cathode rays are now used to designate electron beams originating from thermionic cathodes, whereas the term was formerly applied only to cold-cathode devices.

Cathode Ray Tube (A/V, computer, electronics)
Vacuum tube for display screen in a video terminal or TV. An electron tube in which a beam of electrons can be focused to a small area and varied in position and intensity on a surface. In common usage, the term cathode ray tube is usually reserved for devices in which the surface referred to is cathodoluminiscent, that is, luminescent under electron bombardment. The output information is presented in the form of a pattern of light. The character of this pattern is related to, and controlled by, one or more electrical signals applied to the cathode ray tube as input information. The basic elements of a cathode ray tube are: the envelope, the electron gun; and the phosphor screen.

Cathodoluminescence (A/V, electronics)
Luminescence resulting from the bombardment of a substance with an electron beam.

CATV (A/V, communications)
Community Antenna Television - original name which used a tower and antennas at the highest elevation near a community. It also can refer to the connector on a TV or VCR.

Constant Angular Velocity - devices using CAV, such as computer-hard disks and video laserdiscs, have a varying data transfer rate depending on the distance of the head from the drive spindle.

Cavity Resonator (communications, electronics)
Enclosure with conducting walls surrounding a dielectric medium, capable of resonating with electromagnetic waves. It is used as a reservoir of electromagnetic oscillations at microwave or ultra-high frequencies. The conducting walls are usually made of metal such as copper or silver, while the dielectric medium is usually air or vacuum. The enclosure has at least one aperture for coupling the electromagnetic energy between the inside and outside of the cavity.

CB (communications, radio)

Citizen's Band - frequency band for radio transmission in the 27 MHz (megahertz) range that is reserved for public use without a license.

CBEMA (computer)
Computer and Business Equipment Manufacturers Association - membership organisation founded in 1916 composed of computer vendors and business equipment manufacturers and suppliers. With over 40 members, CBEMA was concerned with the development of standards for data processing and business equipment both in the U.S. and abroad.

CBR (computer)
Computer Based Reference - reference materials to help people do their jobs quicker.

CBT (computer)
Computer Based Training - using the computer for training and instruction. CBT programs are called courseware and provide interactive training sessions for all disciplines. CBT uses graphics extensively, as well as CD ROM and DVD.

CCD (A/V, computer)
Charge-Coupled Device - an integrated circuit consisting of a linear array of semiconductor photoreceptor elements. CCDs are used to create a bit-mapped image. Each photoreceptor creates an electrical signal representing the luminance of one pixel. CCDs are primarily used in video cameras, scanners, and colour printers.

CCD Array (A/V, computer)
Row of charge coupled devices, each of which converts light into electricity.



CCIA (communications, computer)
Computer and Communications Industry Association - organisation composed of mainframe, peripheral, data communications vendors, software houses, service bureau, leasing companies and equipment repair organisations. With over 60 members, CCIA represents interests in domestic and foreign trade. Working with the NIST (National Institute of Standards and Technology), it keeps members advised on regulatory policy.

CCIS (communications)

Common Channel Interoffice Signalling - digital communications technique that transmits voice and control signals over separate channels, by time-division multiplexing the signals over the same line.

CCITT (communications)
Consultative Committee for International Telephone and Telegraphy; an international organisation for standards. It is one of four organs of the International Telecommunications Union, founded in 1865, headquarters in Geneva and comprised of over 150 member countries (see X Series protocols).

C Clamp (A/V)
Metal clamp used to attach lighting instruments to a lighting batten.

CCP (computer)
Certificate in Computer Programming - award for successful completion of examination in programming, offered by the Institute of Certification of Computer Professionals.

CCU (A/V)
Camera Control Unit - device used to control the output of a studio broadcast camera including the component signal coming from the camera (Red, Green, Blue), as well as the chrominance and luminance, and other quality control processes.

CD (A/V, computer, M/M)
Compact Disk - an audio disc that contains up to 72 minutes of hi-fi stereo sound. A CD, 4.75 inches in diameter, is like a miniature phonograph record, except that only one side of the disc contains recorded material. A CD is a direct access device, and the individual selections can be played back in any sequence. Unlike phonograph records in which the disc platter contains "carved sound", the CD is recorded in digital form as a series of tiny pits that are covered with a clear, protective plastic layer. Instead of a needle vibrating in the grooves, a laser in the CD player shines light onto the pits and picks up the reflection as binary code. Sound is converted into digital code by sampling the sound waves 44,066 times per second and converting each sample into a 16-bit number. It requires almost a million and a half bits of storage for each second of stereo hi-fi sound. The reason digital sound is so clear is that the numbers are turned into sound electronically. There's no tape hiss or needle pops and clicks to contend with. In addition, the CD can handle a wider range of volume (dynamic range), providing more realism. A soft whisper can be interrupted by a loud cannon blast. If a phonograph were pushed that far, the needle would jump out of the groove. Other forms of CDs (CD ROM, CD ROM XA, CD-I, and DVI) all stem from the audio CD. Introduced in the U.S. in 1983, sales of CDs and CD players exceeded sales of LPs and turntables in 1986. The format for CD is described in Philips N.V.'s Yellow Book. Control of Yellow Book CD-ROMs, such as starting and stopping the drive and file selection with a personal computer, requires Microsoft's MSCDEX.DRV driver.

CD (computer, DOS)
DOS Command: CD displays or changes the current directory.

CD Audio
Same as CD (Compact Disc) and DAD (Digital Audio Disc).

CD-DA (A/V, computer, M/M)
Compact Disk-Digital Audio, also called "Red Book" audio, requires compatibility with MPC specification 1.0. It enables interleaving of audio with other types of data, so recorded sound can accompany images. Playing CDs with CD-DA audio requires Microsoft's MSCDEX.DRV, version 2.2 or higher, which was not provided with Windows 3.1. It is usually supplied with the CD-ROM drive when purchased as a component of an MPC upgrade kit. The CD-DO format is defined in the International Electrotechnical Commission's (IEC) Standard BNN15-83-095.

CD+Graphics (computer, M/M)
Format in which the subchannel(s) of an audio CD contain graphic images that may be displayed on a computer or television set.

CD-I (computer, M/M)
Compact Disk Interactive - a compact disc format that holds data, audio, still video pictures and animated graphics. CD-I provides up to 144 minutes of CD-quality stereo sound, up to 9.5 hours of AM-radio-quality stereo or up to 19 hours of single channel (monophonic) audio. Developed by Philips (ND), and Sony, CD-I is designed for home and business use with CD-I players connected to TVs and personal computers starting in the early 1990s. CD-I discs feature interactive games, education, reference works. CD players incorporate at least 1MByte of memory (RAM), special pointing devices, and remote-control systems. CD-I formats are listed in Philips' Green Book.

CD+MIDI (computer, M/M)
Format in which the subchannel(s) of an audio CD contain data in standard MIDI file format that may be routed to a MIDI OUT connector and played on external MIDI synthesizers or internally by audio-adapter cards.

CD-MO (computer, M/M)
Compact Disk Magneto-Optical. Magneto-Optical CDs are capable of multiple use because they can be erased and re-recorded. The standards for CD-MOs are incorporated in Philips N.V's Orange Book 1 specification. CD-MO technology is used for high-capacity, 3.5 inch "floptical" floppy disks.

CDP (computer)
Certificate in Data Processing - award for the successful completion of an examination in hardware, software, systems analysis, programming, management and accounting, offered by the Institute of Certification of Computer Professionals.

CD ROM (computer, M/M)
Compact Disc Read Only Memory - a compact disc format that is used to hold text, graphics, and hi-fi stereo sound. The disc is almost the same as the music CD, but uses different tracks for data. The music CD player cannot play CD ROM discs, but CD ROM players, for the most part, can play CD discs and have jacks for connection to amplifiers and/or headphones. A CD ROM player is cabled to and controlled by a card that is plugged into one of the computer expansion slots. CD ROMs hold in excess of 600 MBytes of data, equivalent to about 250,000 pages of text or 20,000 medium-resolution images. CD ROMs are invaluable for large catalogues. Philips N.V.'s documentation for this standard has a yellow binding, hence the term Yellow Book. MPC Specification 1.0 requires multimedia PCs to include a CD-ROM.

CD ROM Extensions (computer, M/M)
Software for a CD ROM player on a PC running DOS. It is made up of two software modules: (1) a driver that is specialised for the CD player by its manufacturer and; (2) a RAM resident program (MSCDEX/EXE) supplied by Microsoft, executed when the computer is turned on. The CD ROM extension usually come with the CD ROM player.

CD ROM XA (computer, M/M)

CD ROM eXtended Architecture - an extension of the CD ROM standard that allows for the inclusion of various grades of medium to low-fidelity audio to be played concurrently while viewing data. Announced by Philips, Sony and Microsoft in August 1988, CD ROM XA allows for data (text and pictures) to be viewed and narrated at the same time. With up to 9 hours of AM-broadcast-quality stereo or up to 19 hours of single channel (monophonic) audio, CD ROM XA can also be used for language training. It also functions as a bridge between CD ROM and CD-I since CD ROM XA discs will play on a CD-I player. CD ROM XA uses a standard CD ROM player, but requires a CD ROM XA controller card in the computer.

CDTV (computer, M/M)
Commodore Dynamic Total Vision - proprietary audio and video CD format developed by Commodore International for its CD-1000 CDTV player, which also can play CD-DA, CD+Graphics, and CD+MIDI formats.

CD-WO (computer, M/M)
Write-Once CD or CD drive. CD-WO also is referred to as CD-ROM WO or Orange Book 2 CD and may be created in a special CD-ROM drive designed for this medium. CD-WO drives are used for pre-mastering multimedia titles, as well as archival backup of information for network file servers.

Ceefax (communications, computer)
Teletext service that was offered by the British Broadcasting Corporation.

Cell (communications, computer)
Elementary unit of storage for data (bit) or power (battery). It can also mean, in spreadsheet applications (Lotus, Excel, etc.) the intersection of a row and column. In communications a cell can represent an addressable packet of information as well as an active repeater for cellular communications (cellular phones ) (* also the elemental unit used in ATM - see ATM).

Cell Address (computer)
In a spreadsheet, the column and row coordinates of a cell.

Cell Contents (computer)
Label, value, formula, or function contained in a spreadsheet cell.

Cellular Automata (computer)
Theoretical model of a parallel computer, subject to various restrictions to make formal investigation of its computing powers easily controlled, readily worked, malleable.

Centering (computer, printing)
Placing a line of text midway between the left and right margins.

Centimetre
Unit of measurement that is 1/100th of a meter or approximately 4/10ths of an inch.

Centralized Computer System (computer)
System that does all processing at one location (see decentralized, distributed).

Centralized Data Processing (computer)
Keeping hardware, software, storage, and computer access in one location.

Centralized File Server (communications/LAN)
Single file server that serves a Local Area Network.

Centralized Processing (computer)
Processing performed in one or more computers in a single, centralized location. It implies all terminals throughout the organization are connected to the computers in the datacenter. Alternatives are termed Distributed Processing and Decentralized Processing.

Central Office (communications)
Telephone switching facility that interconnects subscribers' telephone lines to each other and to intracity (within the city) and intercity (between cities) trunk lines.

Central Processing Unit (computer)
Element of a computer that includes circuits controlling the interpretation and the execution of program instructions. (see CPU)

CENTREX (communications)
Central Office Exchange - service available from telephone companies to offer similar features as owner/operated PBXs (switches). The switching is done in the telephone company's central office rather than on the customer's premises, thus the telco still maintains management control, access, and servicing of cabling, rates, and calls.

Centronics Interface (computer, printer)
Standard 36-pin parallel interface for connecting printers and other devices to a computer. It defines the plug, socket and signals that are used in the transmission. This de facto standard was developed by Centronics Corporation, makers of the first commercially successful dot matrix printers. The Centronics printer was introduced in 1970 (Company was bought by Genicom Corp. in 1987).

Ceramic (computer, microelectronics)
Non-metallic and inorganic materials (alumina, berylia, steatite) used in microelectric substrates and component parts.

Cermet (computer, microelectronics)
Combination of ceramic, metal powders used for thin and thick film resistor fabrication.

CEPS (computer, printing)
Color Electronic Prepress Systems used in the printing and publishing industry.




CGA (computer term)
Color/Graphics Adapter - IBM video standard providing low-resolution text and graphics. It was the first graphics standard for the IBM PC and has been superseded by EGA and VGA and SVGA. CGA requires a digital RGB (red green blue) Colour Display monitor.

CGI (computer, M/M)
Computer Graphics Interface - standard format for writing graphics drivers. A graphics driver is the set of instructions that activates a graphics device, such as a printer or plotter. The CGI standard also include GDI and VDI standards.

CGM (computer)
Computer Graphics Metafile - standard for interchanging images. CGM stores images in vector graphics, but also provides a raster format. Older GDM and VDM formats are now part of CGM.

Chad (communications, computer)
Circular punched-out piece of paper from a card, paper tape, or on the borders of continuous forms. A chadded form is when the holes are cut completely through. A chadless form is when the chads are still attached to one edge of the hole (infamous now from the U.S. 2000 Presidential Election).

Chain Printer (computer, printer)
Line printer with typefaces linked together in a chain as its printing mechanism. The chain spins horizontally around a set of hammers. When a character is in front of the selected position, the hammer hits the paper into the ribbon and onto the chain character.

Chained List (computer)
Group of items in which each item contains the location of the next item in sequence.

Chaining (computer)
Linking items or records to form a chain. Each link in the chain points to the next item.

Change Agent (computer)
Role of a systems analyst in overcoming resistance to change within an organisation.

Channel (communications, computer, M/M, Windows)
In computers, a high-speed metal (gold, silver, copper, etc.) or optical fibre pathway between the computer and the control units of the peripheral devices. Channels imply independent transmission paths in which multiple channels can transfer data concurrently with each other and with other processing (IBM's MCA - micro-channel architecture). In a personal computer, the bus serves as a common, shared channel.

In communications, the pathway between two systems, computers, etc, or between a terminal and a computer. It may refer to the physical medium such as coaxial or twisted pair or fibre optic cable, or to a specific carrier frequency (subchannel) within a larger channel.

In Windows, channel can refer to a unique task ID assigned to a dynamic data exchange (DDE) conversation. Applications assign integer channel number aliases. Starting with 1 for the first DDE channel opened, the applications number sequentially thereafter. Channel is also used to identify an Input or Output (I/O) port in mini and mainframe computers. For sound, MIDI provides 16 channels, used to direct messages to a specific device: if multitimbral, one or more voices are on separately assigned channels.

Channel Bank (communications term)
Multiplexer that merges low-speed lines into one high-speed (typically T1) and vice-versa.

Channel Map (computer, M/M, Windows)
Device used to assign MIDI messages received on one of 16 MIDI channels to another channel, often on another device. The MIDI Mapper applet on Windows Control Panel, for example, created a channel map for multimedia sound applications.

Channel Program (computer)
Set of instructions executed by a high-speed peripheral channel. The instruction in the program that initiates the input/output operation indicates where the channel program resides. The channel executes the channel program independently, allowing other operations to take place in the computer.

Character (computer, communications)
One of a set of alpha, numeric or graphic symbols, each character being represented by a unique binary code. One character is representative and generally equal to one byte ( 8 bits ).

Character (A/V)
Person appearing in a production; usually defined by clarifying and intensifying specific physiological traits (behaviour, clothing, looks, moves) and psychological traits (feelings,, schemes, thinking, etc.).

Character Cell (computer)
Matrix of dots that is used to form a single character on a display screen or printer. For example, an 8 x 16 character cell is made up of 16 horizontal rows each containing eight dots. Character cells are displayed and printed contiguously; therefore the design of each letter, digit, or special symbol within the cell must include surrounding blank spaces.

Character Code (computer, communications)
Digital code applied to data for input into computers (for example, ANSI, ASCII, EBCDIC).

Character Data (computer)
Alphanumeric data or text - as opposed to specifically Numeric Data.

Character Field (computer)
Data field (in databases) that holds alphanumeric characters (versus only numeric).

Character Generator (A/V, computer)
Circuitry that converts data characters into dot patterns for a display screen. Or a device which creates text characters that are superimposed onto video frames: also can be called a special effects generator.

Character Graphics (computer)
Set of special symbols strung together just like letters of the alphabet to create graphics.

C154. Character Printer (computer)
Printer that prints one character at a time, such as a daisy wheel or dot matrix printer.




Character Recognition (computer)

Technology of using machines to automatically identify human-readable symbols, most often alphanumeric characters, and then to express their identities in machine-readable codes. The ability of a machine to recognise printed text (see OCR or MICR).

Character Set (computer, communications)
Group of unique symbols and codes. For example, the ASCII character set contains 128 characters numbered from 0 to 127: the English Language set is 26 symbols from A to Z.

Character String (computer)
Group of alphanumeric characters - as opposed to numeric data string.

Character Terminal (computer)
Display screen without graphics capability.

Characteristic (computer, mathematics)
In logarithms and floating point, a number that indicates where the decimal point is placed.

Characteristic Curve (computer, electronics)
Curve that shows the relationship between two changing values.

Characters Per Inch: CPI (computer, printing)
Expression of the amount (density) of data stored on magnetic tape. It was also sometimes used to describe traditional measurement used for typewriters called "pitch", or the number of characters that could fit in an inch (contrast with "point" which is the size of the characters in a printer font setting).

Charged Coupled Device: CCD (A/V, computer, M/M)
Imaging devices used in some cameras instead of a camera pickup tube. Within the device, image sensing elements translate the optical image into a video signal. It has the advantage of small size. CCDs are semiconductor devices wherein a charge is stored in a spatially defined depletion region (potential well) at the surface of a semiconductor, and moved about the surface by transferring this charge to similar adjacent wells. A charge-coupled device must be continuously clocked or refreshed to maintain its usefulness.

Chat (computer, communications, internet)
Term used to describe an interactive discussion between one or more individuals, using their computer, keyboard, screen, and connected through communications using a modem or other communications interface, to a private, or group, or public "Chat Room" on the Internet.

CHCP (computer, DOS)
DOS Command: CHCP changes the current code page or displays the current code pages. The code pages can be changed to use a different character set that provides characters from a foreign language.

CHDIR (computer, DOS)
DOS Command: CHDIR displays or changes the current directory.

Cheat (A/V)
Angle a performer or object toward a camera, not directly noticeable to an audience.
In computers it is colloquial vernacular for a sneak way around a game level or function.
Check Bits (computer)
Bits that are used for error checking purposes. The bits hold a number which has been calculated from a segment of data that has been transmitted or stored (see CRC, parity).

Check Box (computer, Windows)
Windows dialog-box object - square box and associated caption. An X is created or erased (toggled) by alternate clicks on the box with the mouse or an assigned "hot" key.

Check Digit (computer)
Used to ensure that account numbers are correctly entered into the computer. Check digits are added to account numbers before the numbers are actually assigned and used. Using a special formula, the check digit is calculated from the original account number and is added to and maintained as part of the number at all times, usually as the last digit of the number. When the account number is keyed into the computer, a validation routine in the data entry program recalculates the check digit and compares it to the check digit entered. If the account number is erroneous or the digits are transposed when entered, the calculated check digit will not be equal to the check digit that was entered.

Check Sum (computer)
Total numeric value of a block of data that is used for error checking purposes. Both numeric and alphabetic fields can be used in calculating a check sum, since the binary content of the data can be added. Just as a check digit tests the accuracy of a single number, a check sum tests an entire set of data transmitted or stored. Check sums can detect single bit errors and some multiple bit errors.

Checkpoint/Restart (computer)
Method of recovering from a system failure. A checkpoint is a copy of the computer's memory that is periodically saved on disk along with the current register settings (last instruction executed, etc.). In the event of a power failure, or hardware or software failure, the last checkpoint serves as a recovery point. When the problem has been fixed, the restart program copies the last checkpoint into memory, resets all the hardware registers and starts the computer from that point. Any transactions in memory after the last checkpoint was taken until the power failure occurred will still be lost.

Child (computer, Windows)
In Windows, an abbreviation for a MIDI child window. In general, Child is used in programming for an object related to, but lower in hierarchical level than a parent object. In database management, the data that is dependent on its parent.

Chip (computer, microelectronics)
Packaged integrated circuit, approximately 1/16th to 1/2 inch square and about 1/30th of an inch thick. They hold from 50 to several million electronic components (transistors, resistors, etc.). The terms chip, integrated circuit and microelectronic are synonymous.

Chip and Wire (computer, microelectronics)
Hybrid technology exclusively employing face-up-bonded chip devices interconnected to the substrate in a conventional manner, by flying wires.

Chip Architecture (computer, microelectronics)
Design or structure of an IC (Integrated Circuit) chip, incorporating arithmetic logic unit, registers, and control-bus pathway configuration.


Chip Capacitors (computer, microelectronics)
Discrete devices which introduce capacitance into an electronic circuit, made in tiny wedge or rectangular shapes to be oven-fired onto hybrid circuits.

Chip Component (computer, microelectronics)
Unpackaged circuit element (active or passive) used in hybrid microelectronics. Besides ICs (Integrated Circuits), the term includes diodes, transistors, resistors, and capacitors.

Chip Set (computer, microelectronics)
Group of chips designed to work together to perform a function.

CHKDSK (computer, DOS)
DOS Command: CHKDSK was a utility for checking the status of a disk. It also reported the amount of memory currently available.

Choke (computer, electronics)
Inductor used in a low-pass filter where useful output is a direct current (filter for a power rectifier).

Choose (computer, Windows)
Pick an item that begins an action in Windows Networking. Often, the user must choose a command on a menu to perform a task, and choose an icon to start an application.

Chopper (communications, electronics)
Electromechanical component that synchronously switches a signal circuit. By extension, the term chopper is also applied to photoelectric, electronic, and transistor circuits adapted to perform the same function as a mechanical chopper. An older, related device, is an optical shutter arranged to sequentially pass and interrupt, or chop, a light beam.

Chopping (communications, electronics)
Interrupting an electric current or beam of light at regular intervals. Chopping is used to change a dc signal into an ac signal that can be more readily amplified.

Chorus (A/V, computer, M/M)
Electronic effect that combines multiple copies of a sound to create the illusion of multiple instruments playing simultaneously.

Chroma (A/V)
Saturation (or vibrancy) of colour (in a video signal, monitor, printing process).

Chroma Key (A/V, computer, M/M)
Colour or key of a video signal omitted when sending genlocked signals to a television set or VCR. The chroma key can then be replaced by a computer-generated overlay, much like weather maps are shown on television. Chroma Keying is a special key effect that usually uses the colour deep blue or deep green for the background over which the keying occurs.

Chroma Key Card (A/V, computer, M/M)
Studio card similar to a regular key card, except that the background for the white lettering is blue instead of black.


Chrome (A/V, computer, printing)

Colour transparency process such as: Kodachrome, Ektachrome, Agfachrome, Fujichrome.

Chrominance (A/V)
Term used in television broadcasting to describe the signal (a subcarrier of the basic black-and-white signal) containing the colour information in a composite video signal. Chrominance has two components: hue (tint) and saturation (the degree to which colour is diluted by white light). Chrominance is also called chroma and abbreviated as C.

Chrominance Channel (A/V)
Colour (chroma) channels within a colour camera. A separate chrominance channel is responsible for each primary colour signal when using RGB component techniques.

Chrominance Signal (A/V)
Portion of the colour television signal containing the colour information.

Chunk (computer, Windows)
Part of a RIFF or MIDI file assigned to a particular function. A chunk may be treated as a single element by an application. Chunks are the basic elements of a RIFF file.

Church, Alonzo

A twentieth century mathematician and logician, and one of the founders of computer science. Church invented the lambda-calculus and posited a version of the Church-Turing thesis.

CICS (computer)
Customer Information Control System - sometimes pronounced "kicks" - it is a transaction processor monitor program from IBM that provides transaction processing in IBM's batch-oriented VM and MVS operating systems. A CICS session controls the transmission between many applications and the users interacting with them. It implements the upper layers (4,5,6) of SNA and provides the Logical Unit (LU) necessary for SNA (System Network Architecture) operation.

CIE (A/V, computer, printing)
International Colour standard based on definitions and measurements of the Commission Internationale de l'Eclairage.

CIM (computer)
Computer Integrated Manufacturing - integrating of office and accounting functions with automated factory systems. Point of sale, billing, machine tool scheduling and ordering are all part of CIM.

Cine-Oriented Image (A/V, computer)
Film-image orientation like that of movie film, which runs parallel to the outer edge of the medium (film). Contrast with comic-strip oriented image.

Ciphertext (communications, computer)
Information, text, data encoded (encrypted) for security purposes.

Circuit (communications, computer, microelectronics)
Interconnection of a number of devices in one or more closed paths to perform a desired electrical or electronic function. A set of electronic components performing functions in an electronic system. Types of circuits include: alternating current, direct current, coupled circuits, electric transients, electric network, integrated, magnetic, open circuit, parallel, series, series-parallel, short circuit, solid-state, etc. An electronic circuit is a circuit where the equilibrium of the electrons in some of the components is upset by a means other than an applied voltage. In solid-state circuits, electron equilibrium is upset by intentionally introduced irregularities in the crystals.

Generically, a communications channel.

Circuit Analyzer (computer, microelectronics)
Device that tests the validity of an electronic circuit.
In communications, the same as a data line monitor.

Circuit Board (computer, microelectronics)
Same as a printed circuit board.

Circuit Breaker (computer, electronics)
Protective device that opens a circuit upon sensing an overload of current. Circuit breakers can be reset and used repeatedly as opposed to fuses that "blow" or break, and must be replaced.

Circuit Card (computer, electronics)
Same as a printed circuit board.

Circuit Switching (communications)
Temporary connection of two or more communications channels. Users have full use of the circuit until the connection is terminated. Contrast with message switching, which stores messages and forwards them later, and contrast with packet switching, which breaks up a message into packets and routes each packet through the most expedient path.

CISC (computer)
Complex Instruction Set Computer - pronounced "sisk". Computers that have large instructions. CISC machines have from two to three hundred instructions, which are built into microcode. Contrast with RISC (reduced instruction set computing).

Cladding (communications, photonics)
Plastic or glass sheath that is fused to and surrounds the core of an optical fiber. It keeps the light waves inside the core and adds strength to it. The cladding is covered with a protective outer jacket (PVC based - and on larger cables, Kevlar wrapped and fiberglass wrapped).

Clamping Circuit (communications, electronics)
Electronic circuit that effectively functions as a switch to connect a signal point to a fixed reference voltage or current level, either at a specific time interval or at some prescribed amplitude level of the signal itself.

Classify (computer)
Categorise information (data) according to characteristics that make it useful.

Clean Room (computer, microelectronics)
Workstation or area within which steps are taken to protect incomplete circuit fabrication from dust and contamination. Within a Clean Room, the air is highly filtered in order to keep out impurities.

Clear (computer, microelectronics)
Also called Reset - to restore a memory element or flip-flop to a "standard" state, forcing the Q terminal to logic "0".

Clearance (computer, microelectronics)
Shortest distance between the outer edges of images applied in sequence.

Clear Memory (computer)
Reset all RAM and hardware registers to a zero or blank condition. Rebooting the computer may or may not clear memory, but turning the computer off and on again guarantees that memory is cleared (sometimes waiting a minute or two before turning back on).

Clef (A/V, Music, M/M)
In musical notation, a symbol representing the range of notes falling on the staff lines on which it appears. The most common clefs are the treble or G clef and the bass clef. Some instruments, such as the viola, use the alto clef.

Click (computer)
Select an object by pressing the mouse button when the cursor is pointing to the required menu option or icon, or location on a page of text, or "double clicking" on a file or program.

Click Track (computer, M/M)
Metronome-like sounds recorded on one track of a multi-track audio recording to indicate the tempo of the recording when making multiple-track recordings in sequential fashion.

Client (communications, computer/Windows)
The device or application receiving data from a server device or application. The data may be in the form of a file received from a network file server; an object from an OLE server; or values from a DDE server assigned to client variables.

An individual or organisation contracting for systems analysis.

In a client/server network, a program on the personal computer or workstation that allows that node to communicate with the server.

Client/Server (communications, computer)
In a communications network, the client is the requesting machine and the server is the supplying machine. It implies that software is specialised at each end. For example, in a network-ready database system, the user interface would reside in the workstation, and the storage and retrieval functions would reside in the server.

Client/Server Protocol (communications)
Communications protocol that provides a structure for requests between a workstation (client) and a server in a network. It refers to Layer 7 in the ISO/OSI Model.

Clip (A/V)
Compress the white and/or black picture information, or prevent the video signal from interfering with the "sync" (synchronisation) signals.

Clip Art (computer, M/M)
Set of images used to illustrate word processing and desktop publishing documents. These illustrations are already produced by professional artists for public use. Computerised clip art is stored on disk and used to enhance a graph or document.

Clipboard (computer, Windows)
Windows temporary storage location for text and graphic objects. The Clipboard is the go-between in all copy, cut, and paste operations. Contents of Clipboard can be viewed and saved using the Program Manager Clipboard applet (see copy, cut, and paste). The Clipboard View displays the contents of the Clipboard; the contents can be saved in a disk file or retrieved from a previously save Clipboard file.

ClipBook (computer, Windows)

Permanent storage of information to be saved and shared with others. This differs from Clipboard, which only temporarily stores information. The ClipBook Page is permanently saved. Information on a ClipBook page can be copied back onto the Clipboard and then pasted into documents. Clipbook pages can be shared on the network. Clipbook Services supports the ClipBook Viewer application, allowing remote ClipBooks.

Clip Lights (A/V)
Small internal reflector bulbs that are clipped to pieces of scenery or furniture.

Clipper (A/V)
Knob on a video switcher that selects whitest portion of the video source, clipping out the darker shades; it produces high-contrasting blacks and whites for keying and matting.

Clipping (A/V, electronics)
Electrical circuit that, when activated, automatically cuts variations in the signal above 100 percent white or at the level that the circuit is set to clip.

Clipping Circuit (communications, electronics)
Electronic circuit that prevents transmission of any portion of an electrical signal exceeding a prescribed amplitude. The clipping circuit operates by effectively disconnecting the transmission path for the portion of the signal to be clipped.

Clock (computer, M/M)
The basic timing device in a computer. The most common clock frequencies for 80486-based computers were 33 MHz and 66 MHz. For 80386-based computers the most common clock frequencies were 25 MHz and 33 MHz. For Pentium (Intel) based computers the clock frequencies can be 100, 150, 250, 350, 500 MHz. In MIDI, clock messages provide the basic synchronisation between instruments in a chain. The master MIDI provides the clock signals.

Clock/Calendar (computer)
Internal time clock and day/month/year calendar that is kept continuously active with a battery backup system. Its output allows software to remind users of appointments, to determine the age of a transaction and to automatically activate tasks at specified times.

Clock Doubling (computer)
Term used to describe the 80x86 CPU chips that were created by Intel. The chips doubled the frequency of the clock for internal, central-processing unit operations while maintaining the original clock frequency for other functions. This capability provided an improvement in computer-processing speed without requiring DRAM chips.



Clock Input (computer, microelectronics)
Terminal on a flip-flop whose condition or change of condition controls the admission of data into a flip-flop through the synchronous inputs and thereby controls the output state of the flip-flop. The clock signal performs two functions: it permits data signals to enter the flip-flop; after entry it directs the flip-flop to change its state accordingly.

Clock Pulse (computer)
Signal that is used to synchronise the operations of an electronic system. Clock pulses are continuous, precisely spaced changes in voltage.

Clock Speed (computer)
Internal timing and speed of the computer. The clock circuit uses the fixed vibrations generated from a quartz crystal to deliver a steady stream of pulses to the processor. A faster clock will speed up all processing operations provided the computer circuits can handle the increased speed. For example, the same processor running at 500 MHz is twice as fast internally as one running at 250 MHz.

Clock Time (A/V)
Also called schedule time; the time at which a program starts and ends.

Clone (computer)
Identical copy of another device. Personal Computer clones are able to run the same software as the original machine, but do not necessarily look identical. Although clones imply 100% compatibility, that is not always the case.

Close (computer, Windows)
Remove the document window or application window from the desktop screen. A document can be saved or abandoned in a document window before closing the application.

Closed Architecture (computer)
System whose specifications are not public (Contrast with open architecture). A personal computer design that limits add-on devices to those that can be plugged into the back of that particular machine.

Closed Circuit Television: CCTV (A/V, communications)
Video communications in which signal is transmitted from the point of origin only to those specific receivers that have access by previous arrangement. This private nature of closed circuit television distinguishes it from broadcasting, where all receivers, in a given area, have access to the signals.

Closed Shop (computer)
Environment where only data processing staff are allowed access to the computer systems.

Closed System (computer)
System that does not accept interconnection to foreign terminals or devices.

Close-Up (A/V)
Object or any part of an object seen at close range and framed tightly. The close-up can be extreme (big close-up), or rather loose (medium close-up).

Closure (A/V)
Term for psychological closure; mentally filling in spaces on an incomplete picture.

Clothing (A/V)
Regular clothes worn "on camera", rather than a costume.

CLS (computer, DOS)
DOS Command: CLS cleared all the information from the screen when working at the command prompt line.

Cluster (computer)
Two or more sectors of a disk drive treated as a group. With current versions of DOS, the standard cluster size for hard disks is 2,048 bytes, made up of four 512-byte sectors. The cluster size determines the minimum disk space taken up by a file. For instance, a short 302-byte text file consumes 2,048 bytes, leaving 1,746 bytes unusable. The unusable bytes are called "slack". Also known as an "allocation unit".

Cluster Controller (computer)
Control unit that manages several peripheral devices, such as terminals or disk drives.

Clustered Bar Graph (computer)
Bar graph comparing several different but related sets of data.

CLUT (A/V, computer)
Hardware or Software Look-Up Table containing colour mixing information (i.e. palette).

CLV (computer)
Constant Linear Velocity - recording technique used with CD-ROM (and other devices) specifying that the velocity of the media at the point of read or write remain constant, regardless of the distance from the spindle. CLV devices have a constant data transfer rate. To achieve CLV, the rotational speed of the spindle motor must be inversely proportional to the distance of the read or write point on the media from the spindle. Video laserdisc drives were produced in CLV and Constant Angular Velocity modes.

CMI (computer)
Computer Managed Instruction - use of computers to organize an instructional program for students. It helps create text materials, tracks the results and monitors student progress.

CMIP (communications, computer)
Common Management Information Protocol - standard endorsed by the ISO/OSI that defines the functions for network monitoring and control.

CML (computer, microelectronics)
Current Mode Logic - logic in which transistors operate in the unsaturated mode as distinguished from most other logic types which operated in the saturation region. This logic has very fast switching speeds and low logic swings. Also called ECL or MECL.

CMOS (computer, microelectronics)
Complementary Metal Oxide Semiconductor - type of integrated circuit widely used for processors and memories. CMOS uses PMOS and NMOS transistors (P-type and N-type channel semiconductors) in complement that results in requiring less power to operate.

CMOT (communications, computer)
CMIP over TCP/IP - abbreviated version of the CMIP protocol for TCP/IP networks, designed to smooth transition to ISO/OSI.

CMS (communications, computer)
Conversational Monitor System - software the provides interactive communications for IBM VM operating system, allowing a user or programmer to launch applications from a terminal and interactively work with them. The CMS counterpart in MVS is called TSO. Contrast with ESCS, which provides batch communications for VM.

Call Management System - call accounting package from AT&T for its PBXs.

CMY (A/V, computer/printer)
Cyan, Magenta, Yellow - the colour mixing system used to print colours.
(conversely, RGB - red, green, blue - used in cameras)

CMYK (A/V, computer/printing)
Four colour process inks used in printing, composed of Cyan, Magenta, Yellow, and Black.
(conversely, RGB - red, green, blue - used in camera pick-up tubes)

CO (communications)
Central Office - local telephone company switching station that covers a geographic area such as a town or part of a city.

Coaxial Cable (communications)
High-capacity, concentric axial, cable used in communications and video, with an impedance of 75 ohms (called coax). It contains an insulated solid wire (copper) surrounded by a solid, foil, or braided metallic shield (copper or aluminium) which is wrapped in an external cover (jacket). Although similar in appearance, there are several types of coaxial cable, each designed with a different width and impedance for a particular purpose (baseband, broadband). Coax provides a much higher bandwidth than twisted pair wiring (telephone type), but a lower bandwidth than Fiber Optic cable.

COBOL (computer)
Common Business Oriented Language - high level business programming language that has been the primary business application language on mainframes and minicomputers. COBOL is a compiled language and was one of the first high level languages developed. Formally adopted in 1960, it stemmed from a language called Flowmatic in the mid- 1950s. COBOL required more writing than other languages, but ended up being more readable as a result.

CODASYL (computer)
Conference on Data Systems Languages - organisation that was devoted to the development of computer languages. Founded in 1959, it was made up of individuals and institutions that contribute their own time and effort. COBOL was a product of CODASYL.

Code (communications, computer)
In computer terms, an abbreviation for Source Code. Text entered into a computer program that is used to create an application. Code consists of instructions and their parameters; functions and their arguments; objects and their events; properties and methods; constants, variable declarations and assignments; expressions and comments. Any representation of one set of data for another: also, encoding for security purposes.

Code Template (computer)
Self-contained groups of modules and resources performing a group of standard functions. Code templates may be incorporated, usually with little or no modification, into other applications requiring these functions.

Codec (communications)
Coder - Decoder - electronic circuit that converts voice, text, video, into digital code and also decodes from digital code back to original form using techniques such as pulse code modulation and delta modulation. Analog-to-Digital and Digital-to-Analog (A/D, D/A) converters uses a form of a codec.

Coder (communications, computer)
Person assigning special codes to data. Also, a junior or trainee programmer who writes simple programs or writes the code for a larger program designed by someone else.

Coercion (computer)
In computer programming language, a mechanism for automatically converting from one data type to another in expressions. Coercion is also used to describe the assignment of an expression of one mode to a variable of another.

Co-Fire (computer, microelectronics)
Place circuits onto an un-fired ceramic and firing both circuits & ceramic simultaneously.

COGO (computer)
Coordinate Geometry - language used for solving civil engineering design challenges.

Coherence (computer, photonics)
Property of light; constant phase relationships maintained between different parts of the light beam.

Coherence Length (computer, photonics)
Distance light propagates before coherence is lost: A measure of the degree of coherence.

Cohesion (computer, microelectronics)
Measure of the inner "strength" of a program, module, or circuit.

Coincidence Amplifier (computer, electronics)
Electronic circuit that amplifies only that portion of a signal present when another enabling or controlling signal is simultaneously applied. The controlling signal may be such that the amplifier functions during a specified time interval, called time selection, or such that it functions between specified voltage or current levels.

Cold Site (computer)
Term used to describe an environmentally suitable empty shell within which an individual or company can install their own computer system.

Collaborative Software (computer)
Educational and other software that allows users on networked or linked computers to participate in a cooperative and competitive way, in an on-line activity.


Collapse (computer, Windows)
To "hide" additional directory levels below a selected directory in File Manager.

Collating Sequence (computer)
Ordering assigned to a set of items. If two subsets of a set of items are ordered as defined by the collating sequence, then they can easily be merged into a single, ordered set. An example would be the collating of a set of updated records into a master file of records. This requires both sets of records be sorted on a key in the same sequence (ascending or descending order).

Collator (computer)
Utility program that merges records from two or more files into one file. Also a large photocopier peripheral that collates copy pages into sets once they are copied.

Collector (computer, electronics)
Output side of a bipolar transistor; the same as drain in a MOS transistor.

Collector Junction (computer, microelectronics)
Semiconductor junction in a transistor between the collector and base regions.

Collimated Beam (computer, photonics)
Wide, parallel beam of light.

Collision (communications, computer)
Problem that occurs when two messages are sent at the same moment in time on a contention based local area network. Also, the problem that occurs when two records have the same disk address in a computer system (see CSMA / CD, Ethernet, Local Area Network) .

Collocator (computer, microelectronics)
In semiconductor fabrication, a device used to collect substrates from a screen printer and deposit them, in rows, onto a conveyor & dryer belt - also called a furnace belt.

Colour (A/V, computer, M/M)
Perception of the different wavelengths of light. It is possible to create almost all visible colours using two systems of primary colours. Transmitted colours use red, green and blue (RGB), and reflected colours use cyan (light blue), magenta (purplish-red) and yellow (CMY). Colour displays/cameras use RGB (capture) and colour printers use CMYK (copy) (K is for Black).

Colour Balance (A/V, computer, printing)
Combination of Cyan, Magenta, and Yellow that produces a neutral gray.

Colour Bars (A/V)
Standard used by the TV industry for alignment of cameras and videotape recordings. It can be a test signal, that typically contains six basic colours: blue, cyan, green, magenta, red, and yellow. Colour bars are used to verify chrominance encoding functions of colour TV systems.

Colour Burst (A/V)
In colour systems, a burst of a subcarrier frequency serving as a colour synchronizing signal to establish a frequency and phase reference for the chrominance signal.


Colour Cast (A/V, computer, printing)
Modification of a hue by the addition, often unintentional, of a trace of another hue.

Colour Compatibility (A/V, printing)
Colour signals that can be perceived as black-and-white pictures on monochrome television sets. Generally used to mean that the colour scheme has enough brightness/contrast for monochrome reproductions, with a good greyscale contrast.

Colour Correction (A/V, computer, printing)
Photographic or electronic process used to compensate for the deficiencies of the process inks and the colour separation process: also, any colour change requested by the client.

Colour Cycling (computer, printing)
In computer graphics, a technique that simulates animation by continuously changing colours rather than moving the objects. Also called colour lookup table animation.

Colour Gamut (A/V, computer, printing)
Range of colours that can be formed by all possible combinations of colorants in any colour reproduction system.

Colour Graphics (computer, printing)
Ability to display graphic images in colours.

Colorizing (A/V, computer)
Creation of colour patterns or colour areas through a colour generator (without a camera). Also, term used to describe the addition of colour to existing or older black and white images or films, by computers, frame-by-frame (digitized), to create a new copy that is a colour version of the original black and white master. In all cases, the black and white masters remain, and are not tampered with. Each frame of a black and white master is digitized (off of the master), improved or cleaned-up first, and then a new colour master (digital) is created from the regenerated and re-processed, black and white digital master.

Colour Key (computer, printing)
Off-Press overlay colour proof method used by 3M Corporation.

Colour Keying (A/V term)
Technique for superimposing a video image onto another. For example, to float a person over a landscape, the person's image is placed onto a colour background, such as blue. The person and landscape images are scanned together. Then, the landscape is made to appear in the resulting image wherever background (blue) exists in the person image. The landscape is cancelled wherever the person appears (no background).

Colour Model (computer, printing)
Metaphor that enables a person to imagine what a coloured space looks like.

Colour Palette (computer, Windows)
In Windows, a means of establishing a foreground or background colour by selecting a colour displayed with the mouse. The Colour Palette then converts the selection to the standard Windows red/green/blue (RGB) colour format.

Colour Printer (computer, printing)

Printer that prints in colour using dot matrix, electrophotographic, Cycolor, electrostatic, ink jet, thermal-transfer, dye diffusion, dye sublimation techniques.

Colour Proof (computer, printing)
Representation of the final printed piece, used for checking colour accuracy.

Colour Processor (A/V)
Electronic video accessory used to control the colour response of the picture.

Colour Subcarrier (A/V)
Carrier signal that is added to the monochrome signals to convey colour information.

Colour Separation (computer, printing)
Process of making films from a colour original (one for each of the process colours), from which printing plates can be made.

Colour Sequence (computer, printing)
Order in which inks are applied, usually Black, Cyan, Magenta, and Yellow.

Colour Space (computer, printing)
Mathematical abstraction that describes a domain of visible or produce-able colours.

Colour Temperature (A/V, computer, microelectronics)

Relative reddishness or bluishness of light, measured in degrees Kelvin. The normal colour temperature for indoor lighting is 3,200 Kelvin; for outdoors, 5,600 Kelvin. The temperature (measured in degrees Kelvin) to which an object would have to be heated before it radiates a given colour; the higher the colour temperature, the bluer the light. For comparison purposes the following lists some reference approximations:

Reference Fahrenheit Celsius Kelvin

Absolute Zero (helium liquifies) - 459.7 (F) - 273.2 (C) + 000.0 (K)
Lowest World Temperature - 126.0 (F) - 088.0 (C) + 185.2 (K)
Water Freezing Temperature + 032.0 (F) + 000.0 (C) + 273.2 (K)
Human Body Temperature + 098.6 (F) + 037.0 (C) + 310.0 (K)
Highest U.S. Temperature + 134.0 (F) + 057.0 (C) + 330.0 (K)
Water Boiling Temperature + 212.0 (F) + 100.0 (C) + 373.2 (K)
Aluminium Melting Temperature +1219.0 (F) + 659.0 (C) + 932.0 (K)
Iron Melting Temperature +2795.0 (F) +1535.0 (C) +1808.0 (K)
Rocket Exhaust Temperature +5500.0 (F) +3037.0 (C) +3300.0 (K)
Tungsten Melting Temperature +6098.0 (F) +3370.0 (C) +3643.0 (K)
Carbon Boiling Temperature +7592.0 (F) +4199.0 (C) +4472.0 (K)
Surface of the Sun +9890.0 (F) +5476.0 (C) +5749.0 (K)




Colorant (computer, printing)
Dyes and pigments used to colour materials.

Colorimeter (A/V, photonics)
Optical measuring devices that respond to colour in a manner similar to the human eye.

Colorimetry (A/V, computer, printing)
Science of measuring and specifying colours.

Column (computer)
Vertical set of data or components, as compared to row, which is a horizontal set.

COM (computer)
Computer Output Microfilm - devices that create microfilm or microfiche directly from the computer. COM units can be standalone or online to the computer and receive input the same as data sent to a printer; already formatted with page headers, numbers, etc. Using methods that take a picture of an image generated on a CRT, or by using lasers that write images directly, COM units create a film image of each page of a report. Additional graphics, such as lines and logos, may also be added.

COM File (computer, DOS)
Microsoft DOS and OS/2 machine language program ready to run.

COM Port (computer)
Connection on a computer, usually COM1, COM2, COM3, where the cable for a serial printer or another serial communications device, such as a modem, is plugged in.

COM1 (computer)
Label assigned to serial port #1 on a PC. DOS versions support COM1 and COM2, while higher versions support COM1 - COM4. OS/2 supports eight COM ports. COM1, COM2, COM3, COM4 would represent a computer's first, second, third, and fourth serial ports. Not all computers have all four serial ports.

Comb Filter (A/V)
Circuit used in some Monitor/Receivers and in most VCRs and Camcorders to improve the separation of the luminance and chrominance output signals, which, when recombined, results in a sharper picture. It can be used to double the output signals, then when recombined, even though it is the same information, it will appear sharper and clearer.

Combinatorics (computer, mathematics)
Study of methods of counting how many objects there of a certain type, or how many different ways there are of doing something. Items being counted are drawn from a finite system that has some structure, and the process of counting requires a detailed analysis of that structure.

Combo Box (computer, Windows)
Windows object combining text and list box into a single element. The list portion of a drop-down combo box appears when a down-arrow to the right of the text box is clicked.




Comet Tailing (A/V)
Occurrence where a camera pickup tube is unable to process extremely bright highlights that are reflected off polished surfaces or bright lights in a very dark scene. The effect looks like red or blue, or silverized vapour trails, tailing the bright object.

Comic Strip Oriented Mode (A/V, computer)
Film image that runs the length of the film like a comic strip.

Comma Delimited (computer)
Record layout separates data fields with a comma; surrounds character data with quote marks.

Command (computer)
Order given to the computer by the end-user, also called command-driven and menu-driven. Also, a programming language directive, as opposed to a function.

Command Button (computer/Windows)
Windows object causing an event when clicked. Command buttons are ordinarily gray rectangles with rounded corners surrounded by a border: a dialog box element. Clicking a command button causes Windows to take action, such as accepting the setting that has been specified in the dialog box.

Command Driven (computer)
Program that accepts commands as typed-in phrases. Command-driven programs are hard to learn, but may offer more flexibility than menu-driven programs. Once learned, command-driven programs are often faster to use, because the user can state a request quickly and succinctly with a rapid set of known keystrokes (see menu-driven).

Command File (computer)
Service program or utility, that may contain control statements and automatically run programs whenever it is invoked.

Command Language (computer)
Language accepting a limited number of commands, such as a query language, job control languages (JCL): conversely, programming is a general purpose language.

Command Line Interface: CLI (computer, DOS)
Operating system interface in which commands are issued to the operating system by typing them in at, for example, a DOS prompt.

Command Line Parameter (computer)
Word, filename, or group of characters that modifies the effect of a DOS command. For example, in the command DOS=HIGH,UMB - HIGH and UMB are parameters. This command loads DOS in reserved memory (High) and UMB retains the link to Upper Memory Blocks (if any are available).

Command Menu (computer)
List of commands in an application program.

Command Mode (computer)
One of several options for entering commands.


Command Message (computer, M/M, Windows)
In Media Control Interface terminology, a symbolic constant, usually in hexadecimal format, defining a specific MCI command (such as Pause) to be executed by a device.

Command Processor (computer)
System program that accepts a limited number of user commands and converts them into the machine commands required by the operating system.

Command String (computer, M/M, Windows)
Media Control Interface term defining a specific MCI command (such as Pause) to be executed by a device. A command string is expressed as a string of English words describing the command to be executed, such as "Play CDAudio".

Command Tree (computer)
Hierarchical diagram showing choices from a main menu and the associated submenus.

COMMAND.COM (computer, DOS)
Command processor for Microsoft DOS (or OS/2 in real mode), it creates the user interface by displaying the screen prompts, accepting the typed-in commands and executing them. Other command processors, or shell programs, can be substituted for COMMAND.COM in order to provide a different user interface.

Comment (computer)
Explanatory material in source code. A comment isn't to be interpreted or compiled into a final application. In Visual Basic they are preceded by an apostrophe (') but can also be created by preceding with REM at the line beginning. Comments in "C" Language are enclosed within pairs of /*...*/ and in Pascal Language between curly braces {...}.

Commercial Software (computer)
Software that is designed and developed for sale to the general public.

Commodore (computer)
The Commodore 64 was a home computer introduced in 1982 by Commodore Business Machines, Inc, which included 64K of RAM, color graphics (16 colors) and three independent tone generators. In 1986, the Commodore 128 was introduced. It ran Commodore 64 software and, with the addition a Z80 (Zilog) board, it ran CP/M (Control Program for Microprocessors) software such as WordStar and dBase II. The 128D, introduced in 1987, added a detached keyboard and a built-in disk. Over 10 million Commodore 64s and 128s were sold world-wide.

Common Carrier (communications)
A government-regulated organisation that provides telecommunications services for public use, such as AT&T, the local telco, MCI, Sprint, etc.

Communications (computer, communications, telecommunications)
Electronic transfer of information . Data Communications used to refer to digital transmission, and telecommunications used to refer to analog transmission. This demarcation is rapidly disappearing with the advent of digital voice, data, video, and full-motion colour, multi-media applications. The term was originally used for corporate public relations and information departments, however, the term is now also beginning to represent all forms of communications.

Communications Access Method (communications, computer)
Access Methods that transfer information between hosts, remote terminals, other computers. These routines prepare the information for transmission by placing the data into frames with the appropriate control information for the frames (OSI layers 3,4,5).

Communications Act, USA, 1934
Establishment of the Federal Communications Commission (FCC) in 1934, the regulatory body for interstate and foreign telecommunications. Its mission is to provide high quality services at reasonable cost to everyone in the U.S. on a non-discriminatory basis.

Communications Channel
Also called a circuit or line, it is a pathway over which information is transferred between two devices that are remotely separated. It may refer to the entire physical medium, such as a public or private telephone line, optical fibre, coaxial cable, or twisted pair cabling. It may also refer to the specific carrier frequency transmitted within the medium, such as in a microwave or satellite channel, or in a broadband local area network.

Communications Controller
Peripheral control device that connects several communications lines to a computer and performs the actual transmitting and receiving as well as various message coding and decoding activities. Communications controllers are typically nonprogrammable devices designed for specific protocols and communications tasks. A front end processor, on the other hand, can be programmed for a variety of protocols and network conditions.

Communications Control Unit (communications, computer)
Term used to describe a wide variety of units which control the transmission and reception of information in computer communication networks and include front-end processors, concentrators, message or data switches, remote terminal controllers and simple multiplexers.

Communications Network
Communications channels that interconnect terminals and computers;

Communications channels that support interconnection and management software;

Types: Local Area (LAN), Bldg., Enterprise, Metropolitan (MAN), Wide Area (WAN).

Communications Parameters (communications, computer)
Settings that affect the way in which information is transmitted and received over a serial port (i.e., bit rate, data bits, parity, stop bits).

Communications Program (communications, computer)
Software that manages the information movement between computers and terminals. In mainframes and large minicomputers, it is made up of access methods, network control programs, and program monitors, which reside in the computer and front end processor, and collectively handle hundreds or thousands of users. In a personal computer communications program, it manages the transmission of information to and from the computer's serial port. It includes several error checking protocols to ensure against loss of data in noisy transmission lines and also provides simple ASCII transmission for local transfers. It can emulate various dumb terminals ("green-screens") for communicating to mini/mainframe networks.

Communications Protocol
Set of hardware and software standards for transmitting data between terminals and computers. There are many layers of protocols that may be used depending on the type of computer systems and networks (See OSI and OSI model).

Communications Satellite
Radio relay station in orbit, 22,300 miles above the equator. It travels at the same rate of speed as the earth (geosynchronous), so that it appears stationary. It contains many communications channels that receive analog and digital signals from earth stations. All signals are transmitted within a carrier frequency. The signals are amplified and then transmitted back to earth, covering either a small geographical area (spot beam) or up to a third of the earth's surface (sometimes called the satellite footpath). The next generation of communications satellites are being positioned in polar orbits such as LEOS / MEOS satellite systems. These are lower orbits (800 to 1,200 miles). They are smaller, more powerful, more economical.

Communications Server (communications, computer)
Computer in a Local Area Network (generally), managing access to external networks. It may manage a pool of modems and/or provide gateways to dissimilar networks.

Communications Settings (computer, Windows)
Special settings that tell Windows how to send information using a serial device such as a modem or printer (see serial port).

COMP (computer, DOS)
DOS Command: COMP compares two files and reports the differences. The COMP command is better than DISKCOMP to compare files on two disks when the files were not copied to the disk with the DISKCOPY command. This is because the files may be stored in different locations on each disk, which DISKCOMP will report but COMP will not, assuming the contents of the files are identical. The default output the COMP command produces, displays the offset (number of bytes from the beginning where there is a difference), and the hexadecimal value of the two different characters. This command stops comparing two files when it finds more than ten differences.

Compact Disk Read Only Memory (CD-ROM) (computer)
Optical data storage technology using disc formats similar to audio compact discs.

Compandor (communications)
Compressor/exPandor - device that improves the signal for AM radio transmission. On outgoing transmission, it raises the amplitude of weak signals and lowers the amplitude of strong signals. On incoming transmission, it restores the signal to its original form.

Comparator (computer)
Device that compares two quantities and determines their equality.

Compare (computer)
Fundamental capability of computers. By comparing one set of data with another, computers can locate, analyse, select, reorder and make decisions. After comparing, they can indicate whether the data were equal or which set was greater or less than the other.



Compare Operation (computer)
Operation in which the computer compares two data items and performs alternative operations based on the comparison.

Comparator Circuit (communications, electronics)
Electronic circuit that produces an output voltage or current whenever two input levels simultaneously satisfy predetermined amplitude requirements. A comparator circuit may be designed to respond to continuously varying (analog) or discrete (digital) signals, and its output may be in the form of signalling pulses which occur at the comparison point, or in the form of discrete direct-current levels.

Compatible (computer)
Personal computer that can run software designed, in most cases, for the IBM PC.

Compatibility (A/V, communications, computer)
Term normally applied to a computer program to describe the ease with which it can be converted from one system to another. Two compilers or language translators (but usually different computers) are said to have compatibility if source programs written for a compiler on one computer will compile and execute successfully on the other. Similarly, two versions of the same compiler (on the same computer) are said to maintain compatibility if a source program written for one version of the compiler will successfully compile and execute using the other version. If compatibility extends in only one direction, it is said to have upward compatibility (older to newer), or downward compatibility (new to older- but seldom occurs).

Compatibility Mode (computer)
Special feature of a computer and/or operating system that allows it to run programs written for a different system. Programs usually run slower in compatibility mode.

Compilation (computer)
Compiling of a program (see compiler).

Compile (computer)
Create executable or object (machine-language) files from source (readable) code.

Compile Time (computer)
Time that it takes to translate a program from source language into machine language. The link editing time may also be included in the compile time.

Compiler (computer)
Software program that translates a high-level programming language such as BASIC and C into machine language. A compiler usually generates assembly language first and then translates the assembly language into machine language (machine language = binary code).

Compiler Language (computer)
High level language translated into machine language before the program is executed.

Compiler, Incremental (computer)
Technique within which the compiler generates code for a statement or group of statements as received, independent of the code to be generated later for other statements. This compilation process is closely related to that used in batch-processing operations.

Compiler, Syntax-Directed (computer)
General purpose compiler supporting a family of languages by providing syntactic rules for language analysis in the form of data, typically in tabular form, rather than building the specific algorithm for a particular language into the computer. Syntax-directed compilers also form the basis for compiler-compilers, which are specialised processors that generate compilers.

Complement (computer, mathematics)
Number derived by subtracting a number from a base number. For example, the tens complement of 8 is 2. In set theory, complement refers to all objects in one set that are not in another set. Complements are used in digital circuits, because it is faster to subtract by adding complements than by performing true subtraction. The binary complement of a number is created by reversing all bits and adding 1. The carry from the high-order position is eliminated.

Complementary Metal Oxide Semiconductor (CMOS) (computer, microelectronics)
Semiconductor device that does not require a large amount of power to operate. CMOS is found in devices that require low power consumption, such as notebook computers.

Complex Amplitude (computer, photonics)
Description of wave amplitude and phase by one complex value. When waves interfere, their complex amplitudes add up.

Complexity Editing (A/V)
Arranging shots that primarily, though not exclusively, help to intensify the screen event.

Complex Instruction Set Computing (CISC) (computer)
Central Processing Unit (CPU) design that contains a large number of instructions.

Compliant Bond (computer, microelectronics)
Bond which uses an elastically or plastically de-formable member to import the required energy to the lead frame; the metal part of a solid state device package which achieves electrical connection between the die and other parts of the systems.

Component (computer, electronics)
Packaging consisting of one or more circuits made up of devices, which can be part of another system or subsystem. An element of a larger system. A hardware component can be a device as small as a transistor or as large as a disk drive as long as it is part of a larger system. Software components are routines or modules within a larger system.

Component Part (computer, electronics)
Term sometimes used to denote a passive device (as opposed to an active device).

Component Placement Equipment (computer, microelectronics)
Automatic systems for sorting and placing components onto hybrid circuit substrates consisting of: indexing conveyor, sorter, placement heads, missing component detector, programmable electro-pneumatic control, and options to handle special requirements.

Component Video (A/V)
In component video, the red, green and blue signals remain in their original state (sometimes called primitive), and the image is crisper than composite video. Component video can also be represented by Y (luminance), and C (chrominance).
Composite Blanking (A/V)
Complete blanking signal composed of both line-rate and field-rate blanking signals.

Composite Sync (A/V)
Combined line-rate and field-rate synchronising pulses including field equalisation pulses.

Composite Video (A/V)
Video-only portion of NTSC TV signal. The colour picture signal plus blanking and all synchronising signals. In composite video, the red, green and blue colour signals are mixed; the image is not as crisp as RGB (primitive red, green, blue colour transmitted separately). Some PCs have composite video output that connects directly to a Television set.

Compound (computer)
Set of instructions, or a statement requiring more than one keyword to complete.

Compound Device (computer, M/M, Windows)
In multimedia applications, a device requiring a device element, usually a file, to completely describe the destination of an MCI command.

Compound Document (computer)
Originally, a text file containing text and graphics. Now, compound documents can also contain voice and video (multimedia). Also, a file or representation of the contents of a file created by two or more applications, usually, in Windows, by the OLE protocol. An example is a WordPerfect for Windows document containing Clip-Art from WordPerfect's Presentations software. The elements of the document created by a foreign application may be embedded in the compound document, becoming an integral component of that document. Alternatively, these elements may be linked to a file from another application and simply have a reference to the file and the application that created it.

Compound File (computer)
File having multiple, individual (logical) files or elements within a physical file, each reading as an individual file. RIFF & Microsoft SQL Server files are compound files.

Comprehensive (computer, printing)
Preliminary version of a design, often created for client input or approval (a comp).

Compressed Font (computer, printing)
Font whose characters are narrower than normal for its point size. Switching from a normal-width font to a compressed font allows more words to be printed on one line.

Compression (communications)
Reduction at one level of a signal with respect to gain at another level of the same signal. Also, reduction of an original data file to a compacted state requiring less disk storage.

Compressor (computer, communications)
(1) Device that diminishes range between strongest and weakest transmission signals.
(2) Routine or program that compresses data (see data compression).




CompuServe (computer)
Major information utility service company that offered program packages, text editors, encyclopedia references, games, and a software exchange, as well as banking, travel reservations, and legal advice.

Computational Complexity (computer, mathematics)
Determination of the intrinsic difficulty of mathematically posed problems arising in computer sciences and many other disciplines. The study of complexity has led to more efficient algorithms than those previously known or suspected.

Compute (computer)
Perform mathematical operations or general computer processing.

Computer
Machine that processes information according to instructions stored internally either temporarily or permanently. The computer, itself, is called hardware. The instructions that tell it what to do are called software. A set of instructions that performs a particular task is called a program, or software program, or application software program.

Computer Architecture
Design of a computer system. It sets the standard for all devices that connect to it and all the software that runs on it. Its design is based on the type of programs that will run (business, scientific, etc.) and the number of them that must be run concurrently. The design specifies how much memory is needed and how it will be managed. It specifies how concurrency is handled and how big the internal bus must be that transfers data between memory and the processor. It also specifies the word size, or number of bits processed in the registers at one time. If a computer is designed from scratch, its native language, or instruction set, must be created, stipulating what functions the computer performs and how instructions must be written to activate them. This is the foundation of the computer. It determines how people will communicate, or interface with it.

Computer Aided Design/Computer Aided Manufacturing: CAD/CAM)
Use of computers to create two and three dimensional pictures of manufactured products.

Computer Aided Software Engineering (CASE)
Software that provides an automated means of designing systems.

Computer Assisted Instruction: CAI
Use of computers to present drills, practice exercises, and tutorial sequences to a student, and to engage the student in a dialog about the substance of the instruction. CAI is one element of computer assistance in the process of learning and teaching.

Computer Browser Service (computer/Windows)
Maintenance of an up-to-date list of computers and providing the list to applications when requested, in the Windows networking operating systems. It provides the computer lists displayed in the Select Computer and Select Domain dialog boxes, and for Windows Advanced Server only, the lists in the Server Manager window.





Computer Centre
Area or department that houses the computer systems and related equipment, in a centralised computing environment. A control section is usually provided that accepts work from, and releases output to, the different user departments.

Computer Conferencing (communications, computer)
Method of sending, receiving, and storing typed messages within a network of users.

Computer Designer
Individual that designs the electronic structure of a computer.

Computer Fraud and Abuse Act
Act passed by the U.S. Congress in 1984, to fight computer crime.

Computer Games
Wide variety of recreational and educational uses of computers. For recreation they may offer more potential variety and sophistication than TV or handheld games. For education, they can provide an incomparable motivational tool.

Computer Generated Hologram: CGH (computer, photonics)
Hologram created by a digital computer, rather than being created photographically.

Computer Graphics
Term used to describe the input, construction, storage, retrieval, manipulation, alteration, and analysis of objects, and their pictorial representation using computers. Computer graphics, in general, can include both off-line input of drawings or photographs of objects via scanners, digitizers, cameras, or pattern recognition devices, and output of drawings on paper or film with plotters and film recorders.

Computer Industry
Collection of business enterprises which supply computer equipment and computer related services and supplies. The evolution of electronic technology and the invention, in the 1950s, of the stored program computer, led to the development of what is now known as the computer industry. The principal industry segments include: communications; hardware; media; services; and software.

Computer Language
Programming language, machine language, or the language of the computer industry.

Computer Literacy
Understanding of computers and information systems, which includes a working vocabulary about computer and information system components, the fundamental principles of computer processing and a perspective for how non-technical people can take advantage of the world of computer technology. Computer literacy does not deal with how the computer works (digital circuits) but does imply knowledge of how the computer does its work (inputs, processes, outputs). It also includes a basic understanding of systems analysis and design, application programming, and systems programming.

Computer Music
Term used to describe two complementary types of computer output: computer-composed music involving composition; and computer-realised music involving the conversion into electronic sound of a score which may or may not have been composed on a computer.

Computer Name (computer/Windows)
Unique name of up to 15 uppercase characters that identifies a computer to the network. The name cannot be the same as any other computer or domain name in the network.

Computer Networks (communications, computer)
Resource sharing networks of computers. Computer Networks sometimes, but not always, include information networks such as the sharing of library resources. The rate at which computer networks are now proliferating throughout the world indicates that they are becoming a powerful force in both the public and private sectors.

Computer On a Chip
Single chip that contains the CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory) and I/O (Input/Output) control unit. Computers on a chip are used for applications ranging from toy features to space station functions.

Computer Output Microfilm (COM)
Computer output produced as very small images on sheets or rolls of film.

Computer Power
Effective performance of a computer. Computer power can be expressed in Millions of Instructions Per Second (MIPS), Clock Speed ( 50 MHz, 100, 250 MHz, 500 MHz) and in Word or Bus Size ( 8-bit, 16-bit, 32-bit, 64-bit, 128-bit etc.). As with automobile horsepower, however, such specifications are only guidelines. The real power of a computer system is net throughput, which is how long it takes to get a job done. A Software package is called "powerful" if it contains a large number of features and functions.

Computer Programmer
Person who designs, writes, tests, and implements programs.

Computer Registry (computer/Windows)
Database repository for information about a computer's configuration.

Computer Science
Study of systems analysis and design, system software design, and system programming. Computer science is concerned with information processes, structures, procedures that enter into representation of such processes, and with their implementation in computing systems. It is also concerned with relationships between information processing and classes of tasks that give rise to them. Computer science does not concern itself with information science, the study of information and its uses. Computer science also does not generally concern itself with computer and systems engineering.

Computer Security
Preservation of computing resources against abuse or unauthorised use, especially the protection of data from accidental or deliberate damage, disclosure, or modifications. Safeguards are both technical and administrative. Threats are both external (physical) and internal (logical) to the computer system.






Computer Security Act, USA
Signed on January 8th, 1988 by the Reagan Administration, the Computer Security Act:

a) Establishes a central authority for developing guidelines for protecting unclassified,
but sensitive information stored in government computers;

b) Requires each government agency to formulate a computer security plan, tailored to its own circumstances and based on the guidelines;

c) Mandates that each government agency provide training for its computer employees on the threats and vulnerabilities of its computer systems;

d) Ensures that the National Security Agency and other defence-related government agencies not control computer security standards in civilian agencies of government.

Computer Services Organisation
Organisations that offer information processing, software and/or professional computing services. It can be a service bureau that provides timesharing and batch processing services, a software house, a Value Added Reseller (VAR) or consulting firm.

Computer Storage Technology
Techniques, equipment, organisation for providing the memory capability required by computers in order to store instructions and data for processing at high electronic speeds.

Computer System
System made up of the CPU (Central Processing Unit), all the peripheral devices connected to it (printers, screens, keyboards, plotters, scanners, etc.), and its operating system (DOS, UNIX, etc.). Computer systems fall into categories called microcomputers (personal computers and workstations), minicomputers, and mainframe computers (roughly small, medium and large).

Computing
Performing computer and/or arithmetic operations.

Computing Services
Department that manages computer resources for an organisation. Also can be called Information Services, Informatics, or Management Information Systems.

COMSAT (communications)
Communications Satellite Corporation - private organisation that launches and operates satellites, created by an act of Congress in 1962. In 1965, it launched the Early Bird, the first commercial satellite to retransmit signals from a geosynchronous orbit. COMSAT provides satellite capacity to international carriers such as AT&T, MCI, RCA, and others. It owns part of the International Telecommunications Satellite Corporation (INTELSAT), and is also part owner of the International Maritime Satellite Corporation (INMARSAT) (communications for ships and offshore oil rigs).

Concatenate (concatenation)
Link structures together. To append one file to another. In speech synthesis, phenomes (k, sh, ch, etc.) are concatenated to produce meaningful and intelligible sounds.


Concentrator (communications, computer)
Device joining several channels into one. A concentrator is similar to a multiplexer, but it does not spread or distribute or delineate signals back out on the other end.

Concurrent Operation (computer)
Multitasking, multiprocessing, and parallel processing. Concurrency suggests two or more computer functions running simultaneously in real time (in parallel, at the same time).

Concurrent Processing (computer)
Simultaneous execution of more than one sequential program on a computer or network of computers. The individual, sequential programs are called processes. Two processes are considered concurrent only if they interact in some way. This interaction may range from cooperation (exchange of information) to competition for scarce resources (processor, memory, printer, etc.). Concurrent processing is achieved on a single computer, or single processor, by interleaving the execution of the individual processes.

Concurrent Programming (computer)
Term used to describe the development of programs that specify the parallel execution of several tasks. Such programs are used in systems with multiple processors that may be executing simultaneously. Examples include multiprocessing systems, computer networks, and computer configurations with separate I/O (input/output) processors. Concurrent programming may also be used to describe single processors that provide logical parallelism, such as in multi-user systems that may run on, and control, several hardware processors, and are composed of both physical and logical parallel sub-systems.

Condenser Microphone (A/V)
Microphone whose diaphragm consists of a condenser plate that vibrates with the sound pressure against another fixed condenser plate, called the backplate.

Condition Code (computer)
Group of program conditions (such as carry, borrow, overflow, etc.) that are particularly relevant to instruction set executions.

Con/Dryer (computer, microelectronics)
In microelectronics fabrication, the process equipment that is designed to receive screen printed substrates and dry the ink on the substrate while conveying them down the assembly line.

Conditional Branch (computer)
In programming, an instruction that directs the computer to another part of the program based on the results of a compare operation.

Conditional Replace (computer)
Word processing function that asks the user whether to replace text each time the program finds a particular item, or word, or group of identified text.

Conditional Statement (computer)
In programming, a language statement, such as an IF, THEN, ELSE, WHEN statement, which tests a condition and branches to a subroutine based on the results of that test.


Conditioning (communications)
Improvement made in the signalling characteristics of leased communications lines or channels, or those used in switched telephone networks: includes extra costs for a private telecommunications line that can improve performance by reducing distortion, and by amplifying weak signals.

Conductor (communications, computer, electronics)
Material that can carry electrical current, as opposed to an insulator.

Conduction (computer, electronics)
Electrical conduction may be defined as the passage of an electric charge.

Conduction Band (computer, electronics)
Electronic energy band of a crystalline solid which is partially occupied by electrons.

CONFIG.SYS (computer, DOS)
Configuration file customising DOS and OS/2 to a particular hardware environment. CONFIG/SYS resides in the root directory and is examined upon startup. It is primarily used to initiate the drivers for peripheral devices that have been added to the system. Device drivers have a .SYS extension. For example, to add a driver NEWDISK/SYS, the line DEVICE=NEWDISK.SYS would be added to the CONFIG.SYS file.

Configuration (computer)
Interconnected components that make up a whole system, such as an Audio/Visual System, Communications System, Computer System, Multi-Media system, etc. To configure a system is to choose from a variety of options to create a customised system.

Configuration File (computer)
File that contains information about a specific user, program, computer, or file.

Confirmation Message (computer, Windows)
Message displayed by Windows when specifying a destructive action, asking if there is certainty to proceed (safety measure). For example, Windows displays a confirmation message when told to delete a file.

Connected User (computer/Windows)
User accessing a computer or a resource across the network.

Connection Time (communications, computer)
Time a user at a terminal is logged-on to a computer system or service bureau.

Connector (A/V, communications, computer)
Cable or wiring plug that enables two devices to the connected together.

In database management, a link or pointer between two data structures.

In flowcharting, a symbol used to break a sequence and resume the sequence elsewhere, It is usually a small circle with a number or other identification written in it.



Console (A/V, computer)
Main operator terminal on a large computer system. Front panel of a computer system.
In Audio/Visual terminology it can mean a monitor, camera control unit, or video editing suite.

Constant (computer)
Term used to describe a value that remains unchanged during a calculation. In computer programming it can mean a variable name assigned to a permanent value by the source code. When declared, the value of a constant cannot be changed while an application is running. Also, any data with fixed values within a program.

Consultant (A/V, communications, computer)
Independent specialists that can act as technical support or in an advisory capacity; or that can perform specialised functions such as systems analysis, network configuration, system design services. Consultants can provide short or long term help to clients and end-users to formulate requirements and produce either generalised or detailed information, documentation, or specifications from which the client can then make choices on hardware, software, or systems, in the marketplace. Consultants are often used as advisers on projects, either for selected elements, or over the entire development cycle.

Consultative Committee on International Telegraphy and Telephone (CCITT)
Agency of the United Nations involved in development of communications standards.

Contact (A/V, computer, microelectronics)
In Audio/Visual, a person who knows about an event and can assist the A/V production team during a remote telecast. In microelectronic fabrication, a metal strip or socket that touches a corresponding metal strip in order to make a connection that allows current to pass, often made of precious (also called "noble") metals to avoid corrosion.

Contact Potential Difference (computer, microelectronics)
Potential difference that exists across the space between two electrically connected metals. Also, potential difference between the bulk regions of a junction of two semiconductors.

Contact Printing (computer, microelectronics)
In microelectronics fabrication, print mode in screen printing where the entire substrate contacts the bottom surface of the screen during the print cycle.

Contaminant (computer, microelectronics)
Impurity present in a material that affects one or more properties of the material.

Contention (communications, computer)
Condition when two devices attempt to use a single resource at the same moment in time. Contention can be solved by using priority schemes; the simplest being the first-come-first-serve strategy. All processes contending for a resource must be remembered so that they will, in turn, be able to use it.

Contention Network (communications, computer)
Network in which workstations compete for the channel, or path, to send a message.

Contention Resolution (communications, computer)
Process of resolving which of a number of devices gains access first as in the CSMA/CD scheme used in Baseband, Local Area Networks (CSMA - Carrier Sense Multiple Access/Collision Detection).

Context Sensitive Help (computer)
Help screens that provide specific information about the condition or mode the program is in at the time help is sought.

Context Sensitivity (computer)
Software feature that allows a user to access information about the application or command the user is currently using.

Contextual Search (computer)
Search for records or documents based upon the text contained in them as opposed to searching on key fields, or by file name.

Context Switching (computer)
In a multitasking environment, to turn control over to another program under direction of the operating system. A program's context is its current state.

To stop working in an application and go work in another under direction of the user.

Contiguous (computer)
Adjacent to or touching - as opposed to fragmented.

Continuity Check (communications, computer)
Test of a line, channel or circuit to determine pathways from beginning to end.

Continuity Editing (A/V)
Preserving of visual continuity from shot to shot.

Continuous Carrier (communications)
Frequency that transmits even when information is not being sent over the channel.

Continuous Forms (computer, printer)
Paper forms made as a series of sheets joined together with perforated edges. Some of these forms are fed through a printer with sprockets that interlock with the holes on either sides of the sheets.

Continuous Tone (computer, printing)
Images that are represented, not by pure black and white, but by a series of evenly graduated tones, as in a photograph; sometimes called a "contone".

Continuous Wave Radar (communications)
Radar in which the transmitter output is uninterrupted, in contrast to pulse radar, where the output consists of short pulses.

Continuous Word System (computer)
Speech recognition system that can understand sustained human speech, so that users can speak normally when using the system.

Contrast (A/V, computer, printing)
Measure of the range of light and dark values in an image. This difference between the brightest and darkest spots in a picture is often measured by reflected light, in foot candles, expressed in a ratio. The maximum contrast ratio for traditional analogue colour cameras is 30 : 1.

Control (computer, M/M, Windows)
In MIDI, device on a keyboard or a panel altering the expression of sound; also, called a controller. Controllers may be continuous (modulation wheel) or on-off (sustain).

Control Ball (computer)
Mouse-type device (track ball), that does not need desk-space to move around on.

Control Block (computer)
Segment of disk/memory containing a group of codes for identification/control purposes.

Control Break (computer)
Change of data category which is used to trigger a subtotal in a report. For example, if data is subtotalled by state, a control break occurs when NJ changes to NM.

Suspension of a computer operation that is sometimes accomplished by pressing the CTRL and BREAK keys simultaneously.

Control Bus (communications, computer)
Bus carrying control signals that regulate system operation within the computer.

Control Character (computer)
Special character triggering some action on a display screen, printer, or communications line. Control characters, such as a line feed, carriage return, and escape, may or may not be printable. Tab and Insert are other examples of control characters.

Control Code (computer)
One or more characters that are used to control a device, such as a display screen or printer. Control codes often begin with an Escape character. There is an endless number of codes used to control electronic devices. The first 32 characters of the ASCII character code were (are) used for controlling communications devices and printers.

Control Head (A/V)
VCR (video cassette recorder) recording head responsible for recording and reproducing a control signal that keeps the video head synchronised with the tracks on the video tape.

Control Key (computer)
Special key on the keyboard which is depressed with some other key (CTRL or CTL). It is used to command the computer, and its effect is determined by the software.

CONTROLINI (computer, Windows)

File containing definitions for Windows built-in colour schemes and patterns, as well as any custom colours that may have been created.

Control-L (A/V, computer)

Method used by Sony Corporation and some other VCR and camcorder producers to remotely control video products (see LANC).

Control Menu (computer, Windows)
Menu appearing on every application that runs in a window and on some non-Windows applications. Icons, some dialog boxes, and windows within an application workspace also have Control menus. For applications running in a Window and for icons and dialog boxes, Control-menu commands move, change the size of, and close windows. For non-Windows applications, The Control-menu commands transfer information and performs other functions (also known as System menu).

Control Menu Box (computer, Windows)
Icon that opens Control Menu for the window. It is always at the left of the title bar.

Control Menu Icon (computer, Windows)
In Windows, an Icon used to open the Control Menu. On an application window, the Control menu is a long dash; on a document window, it is a shorter dash.

Control Panel (computer)
Upper portion of an application screen; it consists of status, entry, and prompt lines.

Control Program (computer term)
Software that controls the operation of, and has highest priority, in a computer. Operating systems (like DOS), network operating systems (like Novell's NOS) and network control programs (NCPs) are examples (contrast with Application Programs).

Control Room (A/V, communications, computer)
In A/V, a room adjacent to a studio in which the director, technical director, the audio engineer, and the lighting technician perform various production functions. In a building network, the control room can be the location where communicated information can be routed to other parts of the building and exterior to the building to other networks.

Control Room Directing (A/V)
Simultaneous coordination of two or more cameras, the switching systems, audio, and other production elements.

Control Structure (computer)
Pattern for controlling the flow of logic in a program.

Control-S (A/V, computer)
Wired, video component control system developed by Sony for its VCRs and camcorders. Control-S duplicates the functions of a conventional infra-red remote control device by a standard control signal protocol. It is often used to supervise multiple monitors in group presentations because it can be daisy-chained through Control-In and Out ports.

Control Total (computer)
Method for ensuring accuracy of processed information. It can be a total of several fields of data in a file, including fields not normally used in calculations. At various stages in the processing, the control total can be recalculated and compared with the original. If any data is lost or changed, the mismatch will signal an error.




Control Track (A/V)
Areas of the videotape used for recording the synchronisation information (sync spikes), which is essential for videotape editing: for example, the synch pulse recorded on videotape that guides the recorder transport speed and playback.

Control Unit (computer)
Within a processor, the circuitry that locates, analyses and executes each instruction in the program. A control unit or controller can also be hardware that controls peripheral devices such as disks or printers or screens. Upon signalling from the CPU (Central Processing Unit), it performs the physical data transfers between memory and the device. In single-chip computers, a built-in control unit accepts keyboard input and provides output to a display. Personal computer control units are contained on a single printed circuit board (PCB). In clustered systems or larger systems, control units can be on one or more printed circuit boards, or they may reside in a stand-alone device or cabinet.

Control Variable (computer)
Variable that keeps track of the process iterations. Its value is incremented or decremented, and compared to a constant to test the end of the process, or loop.

Controlled Rectifier (communications, electronics)
Three terminal semiconductor junction device with four regions of alternating conductivity type (p-n-p-n), also called a thyristor. This switching device has a characteristic such that, once it conducts, the voltage in the circuit in which it conducts most drop below a threshold before the controlled rectifier regains control. These devices are useful as high-current switches and may be used to drive electromagnets and relays.

Conventional Memory (computer/DOS/Windows)
Memory of up to one megabyte in a Personal Computer. The first 640K was used for DOS. The first 640 KB (640,000 bytes) of memory on any computer that uses the 8086, 80286, 80386, 80386SX, or 80486 microprocessor was called conventional (or standard) memory. A personal computer can have three types of memory: conventional, extended and expanded. Understanding what each type of memory is and what it is used for can help users to configure the memory that is in their system and set up program information files for running applications. Conventional memory was used to store the MS-DOS operating system as well as most programs that run under MS-DOS. Certain device drivers, network software, and other memory-resident programs can also use conventional memory. Conventional memory is the most essential, for running DOS and Windows. Without at least 500 KB of conventional memory, a user could even start Windows.

Conventional Programming (computer)
Programming that uses a procedural language.

Convergence (A/V, computer, communications, multi-media)
In colour television, the meeting or crossing of the three RGB (Red, Green, Blue) electron beams at the shadow mask of a kine tube (picture tube), so that the red beam strikes only the red phosphors, the green beam strikes only the green phosphors, and the blue beam strikes only the blue phosphors.

In multi-media and computers, a new term being used to describe the integration and coming together of all forms of media and information (voice, data, video, audio, graphics, television, etc.) within one device or workstation that will provide both the management and movement of all information, to everyone, at any time.

Conversation (computer, Windows)
Interactive dialog between user and computer and implies a question/answer type of session. In DDE operations, the collection of Windows messages that are passed between two different applications, the client and server, during interprocess communications.

Converter (communications, computer)
Device that changes one set of codes, modes, sequences, frequencies, to another.
Devices that changes electrical current from 60 Hz to 50 Hz and vice versa.

Convertible Camera (A/V)
Camera adaptable for studio or field work: either a studio camera that can be stripped down to be portable or an ENG/EFP (Electronic News Gathering/Electronic Field Production) camera that can accept certain accessories to become a studio camera.

Cookie (A/V, computer, communications, internet)
Any cutout pattern that, when placed in front of a spotlight, produces a shadow pattern. The cookie, usually made from a thin, cutout metal sheet, is inserted into a pattern projector (from Greek - cucalorus or kukaloris, meaning the breaking up of light).

In communications/internet, an applet or short program that is exchanged between a personal computer and a host server that allows the host server to recognise that particular computer each time it connects to the host - they accumulate in the PCs temporary internet directory.

Cooperative Processing (computer)
Sharing of workload among two or more computers such as a minicomputer and a PC.

Coordinate (computer)
Intersection of two or more planes: end points in 2 dimensional vector graphics, cells in a spreadsheet, bits in memory - all are identified by the intersection of rows and columns.

Coordinating (computer)
Organising the process of analysing and planning a new system by pulling together the various individuals, schedules, and tasks that contribute to the analysis.

Coprocessor (computer term)
Secondary processor to speed up operation by handling some of the main CPU workload. A special chip designed for high-speed numeric calculation. A coprocessor can be added to a computer to speed operations of some applications. Historically, Intel coprocessors included the 8087 (for the original PC), the 80287 for ATs, and the 80387 for 80386-based computers. The Intel 80486 and Pentium chips had built-in numerical, or "math" coprocessors.

Copy (computer, Windows)
Duplicate of original. In digital electronics, all copies are identical. In Windows, to put a copy of the selected text or item on the Clipboard so that it can be transferred to another location. Windows applications use the Copy command to perform this task.

COPY (computer, DOS)
DOS Command: copies files to another location, or combines several files into one.



Copy Protection (computer)
Resistance to unauthorised copying of software. Copy protection is only of value if there is no succeeding method of copy busting. Copy protection attempts, in the PC environment, have been abandoned since, in order to manage a hard disk, there must be the utility for disk copying available and made easy for end-users.

Copyrighted Software (computer)
Software registered as copyright, not to be copied without permission from the authors.

Core Memory (computer)
In early computer systems, a round magnetic doughnut element used to represent one bit in a core storage system. Computer Memory used to be referred to as core.

Core Storage (computer)
Non-volatile memory that used to hold magnetic charges in very small cores about 1/16th inch, in diameter: the direction of the magnetic flux determined the state at "0" or "1".

Corner Reflector Antenna (communications)
Directional antenna consisting of the combination of a reflector comprising two conducting planes forming a dihedral angle and a driven radiator or dipole which usually is in the bisecting plane. It is widely used both singly and in arrays, gives good signal gain in comparison to cost, and covers a relatively wide band of frequencies.

Corrosion (computer, microelectronics)
In semiconductor fabrication, a defect on aluminum metallization, usually a white crystalline growth.

Corruption (computer)
Damage or alteration to information or programs due to hardware or software failure.

COS (communications, computer)
Corporation for Open Systems - nonprofit international research and development consortium founded in 1986 and dedicated to assuring acceptance of an open network architecture in world markets. It is made up of some 75 information technology companies and user organisations that provide development, service, and support for systems that conform to the international standards, which include OSI (Open System Interconnection), ISDN (Integrated Services Digital Network), ATM (asynchronous transfer mode).

Cosmetic Defect (computer)
Variation from the conventional appearance of an item, such as a slight change in color; not necessarily detrimental to performance.

Costume (A/V)
Special clothes worn by an actor to depict a certain character or period of time.

Cost/Benefit Analysis (communications, computer)
Study to project the costs and benefits of a new information system, or to evaluate an existing system as to its efficiency and effectiveness. Costs include people and machine resources as well as operational costs to run the systems. Tangible benefits are derived by estimating cost savings of both human and machine resources. Intangible benefits, such as improved services and employee relations, may ultimately provide the largest payback, however, these intangibles are much more difficult to quantify and to justify ( i.e., TCO = total cost of ownership).

Counter (computer)
In programming, a variable that is used to keep track of any countable element. The language determines the number of counters (variables) available to a programmer. In electronics, a circuit that counts pulses and generates an output at a specific time. The device is capable of changing states in a specified sequence upon receiving appropriate input signals. The output of the counter indicates the number of pulses which have been applied. A counter is made from flip-flops and some gates. The output of all flip-flops are accessible to indicate the exact count at all times (see Divider).

Counter, Binary (computer)
Interconnection of flip-flops having a signal input so arranged to enable binary counting. Each time a pulse appears at the input, the counter changes state and tabulates the number of input pulses for readout in binary form.

Counter, Ring (computer)
Special form of counter sometimes referred to as a Johnson or shift counter, which has very simple wiring and operates very fast. It forms a loop, or circuit, of interconnected flip-flops so arranged that only one is "0". As input signals are received, the positioning of the "0" state is moved, in sequence, from one flip-flop to another, around the loop until they are all "0". Once they are all "0", then the first state goes to "1", and this moves in sequence from one flip-flop to another, until all are "1".

Count-In (A/V, computer, M/M)
Term used in musical sequencing. Count-in provides one or two measures of metronome clicks, or drum beats, establishing the rhythm prior to recording a performance with a MIDI instrument and a sequencer application.

Counting Circuit (communications, computer)
One of several types of functional circuits used in switching or digital data-processing systems, such as dial telephone systems and digital computers. The general function of a counting circuit is to receive and count repeated current or voltage pulses, which represent information arriving from some other circuit within the same switching system, or from an external source.

Country (computer, DOS)
DOS Command: COUNTRY sets the country conventions used by DOS for such things as date & time, case conversions, currency, sorting, folding formats and decimal separators. If this command is not used, DOS uses the United States as the default. Since the country is selected during the DOS/Windows installation, this command is already entered. It would only be needed again, if there were a change in the country DOS uses from the original setting.

Coupled Circuits (computer, electronics)
Two or more electric circuits are said to be coupled if energy can transfer electrically or magnetically from one to another. If electric charge, or current, or rate of change of current in one circuit produces electromotive force or affects the voltage between nodes in another circuit, the circuits are coupled.

Coupler (A/V)
Video accessory that combines two or more video signals into one.


Coupling (computer)
Measure of strength of the relationship between program modules.

Courseware (computer)
Software application program used for educational and training purposes.

Cover Shot (A/V, production)
Sometimes referred to as a "protection" shot, meaning an extra shot recorded by the photographer just in case it was not done right the first time. The term "cover" is also used by some people as a synonym for establishing shot (see establishing shot).

Covert Channel (communications, computer)
Transfer of information that violates a computer security system. A covert storage channel refers to depositing information in a memory or storage location that can be accessed by different security clearances. A covert timing channel is the manipulation of a system resource in such a way that it can be detected by another process.

CP/M (computer)
Control Program for Microprocessors - single user operating system developed by Digital Research Inc. (Gary Kildall, creator), in the early 1980s to run on microprocessors. Although unsophisticated by 2003 standards, it was a major contributor to personal computing. Microsoft's DOS (Disk Operating System) was modelled after CP/M.

CPE (communications)
Customer Premises Equipment - communications equipment within customer's premises.

CPF (computer)
Control Program Facility - Operating System for IBM System/38 minicomputers. CPF included an integrated relational database that was part of the overall architecture.

C533. CPI (computer, printing)
Characters Per Inch - density of characters on a magnetic tape or number of printed characters in one inch produced from a printer.

CPM (computer)
Critical Path Method - project management planning and control technique implemented on computers. The critical path is the series of tasks in the project that have no built-in slack time. Any task in the critical path that takes longer than expected will lengthen the total time of the project.

CPS (computer, printing)
Characters Per Second - speed of a serial printer or speed of data transfer between devices, or over a communications channel. CPS can be equivalent to bytes per second.

CPU (computer)
Central Processing Unit - computing part of the computer. Also called the processor, it is made up of the control unit and the ALU (Arithmetic Logic Unit). A personal computer CPU can be contained on a single microprocessor. A minicomputer CPU can be distributed over several printed circuit boards. A mainframe CPU can be distributed over many printed circuit boards. The CPU, clock, main memory make up a computer. A complete computer system requires the addition of control units, input, output and storage devices and an operating system. The terms CPU and processor imply the use of main memory since data must be stored in memory in order to be processed.

CPU Time (computer)
Amount of time it takes for the CPU to execute a set of instructions and explicitly excludes waiting time for input and output to occur. The CPU time is always less than the total duration of time for a data processing job to be completed from start to finish.

CR (computer, printing)
Carriage Return - return (enter) key on a keyboard or the actual code that is generated when the key is pressed. In ASCII code, a CR has a numeric value of 13.

Crab (A/V)
Sideways motion of the camera crane dolly base.

Cradle Head (A/V)
Cradle-shaped camera mounting allowing smooth up-and-down tilts and horizontal pans.

Crane (A/V)
Camera dolly that resembles an actual crane in both appearance and operation. The crane can lift the camera from close to the studio floor to over ten feet above it. Also, to move the boom of the camera crane up or down - also called a boom.

Crash (computer)
Unplanned program halt due to hardware or software failure (see abend, head crash).

Crawl (A/V)
Graphics that move slowly up the screen; for manual insertions, sometimes mounted on a drum, or crawl. An up-and-down movement of credits can be called a Roll, and a horizontal movement can be called a Crawl.

Crazing (computer, microelectronics)
Minute cracks on or near the surface of materials such as ceramic.

CRC (communications, computer)
Cyclic Redundancy Check - error checking technique used to ensure the accuracy of transmitting digital information over a communications channel. The transmitted information messages are divided into predetermined lengths which, used as dividends, are divided by a fixed divisor. The remainder of the calculation is appended and sent with the message. At the receiver, the computer recalculates the remainder. If it does not match the transmitted remainder, an error is detected.

Crescendo (A/V, music)
Musical term indicating a gradual increase in the volume of playing.

Critical Path Method (CPM) (computer)
Diagrammatic network-based technique, similar to Program Evaluation and Review Technique (PERT), used as an aid in systematic management of complex projects. CPM was introduced in 1957 by du Pont. Its use adds another step to a project, and it requires updating as conditions change, but experience has shown that the effort can be a good investment in completing a project.

CROM (computer)
Control Read-Only Memory - a ROM microprogrammed to decode control logic.

Cromalin (computer, printing)
Popular off-press colour proof from duPont Corporation.

Crop (A/V, computer, printing)
Select part of an image, discarding the rest.

Crossover Network (A/V, communications)
Selective network used to divide the audio frequency output of an amplifier into two or more bands of frequencies. The frequency separation is employed to feed two or more loudspeakers, each operating in a restricted frequency band and thereby operating more efficiently and with less distortion. Most crossover networks used in high fidelity audio systems are designed for crossover frequencies somewhere between 400 and 2,000 cycles.

Crosstalk (A/V, computer, communications)
Electrical interference between two signals, often related. Cross-talk occurs in cables carrying more than one signal and in audio mixers (left and right stereo audio signals can get mixed up). Cross-talk is specified in dB-, the larger the negative number the better.

Cross Assembler (computer)
Assembler that generates machine language on one computer for a different computer. It is used to develop microprocessor-based programs used in specialised applications, which are either too small or are incapable of handling the development software.

Cross Compiler (computer)
Compiler generating machine language on one computer for use on a different computer.

Cross Fade (A/V)
In Audio, transition method where a preceding sound is faded out and following sound is faded in simultaneously. The sounds overlap temporarily. In Video, transition method where a preceding picture is faded to black and the following picture is faded in from black.

Cross Hatch (A/V)
Test pattern consisting of vertical and horizontal lines used for converging colour monitors.

Cross Keying (A/V)
Key lighting from both sides of the camera. The key lights from one side act as fill for the key lights from the other side.

Cross Tabulate (computer)
Analyse and summarise information. Cross tabulation is used to summarise the details in a database file into totals for a spreadsheet.

Crowbar (computer, microelectronics)
DC power supply protective circuit that shorts the dc (direct current) output to ground whenever an overload condition occurs.


CRT (A/V, computer)
Cathode Ray Tube - the vacuum tube used as a display screen in a video terminal or television, composed of an electron gun aimed at a screen coated with phosphors that glow when hit by the electrons. The term is often used to refer to the entire terminal.

Cryotron (computer, electronics)
Current-controlled switching device based on superconductivity in computer circuits. In its simplest form, the device has two electrodes of a superconducting material (lead), separated by an insulating film. For the electrodes to become superconducting, they have to be cooled to almost absolute zero (0 Kelvin = -273 Celsius = -460 Fahrenheit).

Cryptography (communications, computer)
Various methods of creating secret code or cyphers. It is the only practical method for protecting information transmitted through accessible communications networks such as telephone, satellite, and microwave systems. Cryptographic procedures can also be used for message authentication, personal identification, and digital verification.

Cryptology (communications, computer)
Codewriting has been common and universal since Greek and Roman times. By the 1500's it was one of the essential arts of diplomacy and war. At that time, both the British and the Spanish governments had whole departments that specialised in making and breaking ciphers.

1/ Polygraphie, by Johannes Trithemius, was published in the late 1500's. It is one of the Western World's finest treatise on Codebreaking.

2/ De Furtivus Literarum Notis, by Porta, is a text that all Elizabethan era spies knew by heart.

3/ Nomenclatures; long lists of word substitutions were widely used and very popular. In a particular coded message, the word highland might be substituted for england, and carnations for canons. Sometimes they included simple substitution alphabets, where a letter, number, or symbol replaced a letter of the alphabet, one for one (i.e. monophonic substitution code). The letters of the English alphabet occur in fixed ratios, E being the most common letter and X being the least common letter. One can create what is called a contact chart of the code symbols and letter pairs.

4/ Brute Force attack is a well known method used to codebreak. A brute force attack by an array of computers can utilise algorithms that run through a cybertext billions of times a second, trying all patterns in order of likelihood. It is just a matter of time + computer power.

CSMA/CD (computer, communications)
Carrier Sense Multiple Access/Collision Detection: baseband access method that uses a collision-detection scheme. When a device wants to gain access to the network, it checks to see if the network is free. If not, it waits a random time before retrying. If the network is free and two devices attempt to gain access at exactly the same time, they both back off to avoid collision and each wait a random amount of time before retrying.

CSU (communications)
Channel Service Unit - communications device the connects inhouse lines to external digital circuits. The CSU terminates the line and provides signal regeneration and remote testing, while a DSU (Data Service Unite) converts data into the required format.

CTS (communications, computer)
Clear To Send - RS-232 signal sent from a receiving station to a transmitting station that indicates that it is ready to accept information (see RTS).

CTTY (computer, DOS)
DOS Command: CTTY redirects the default input and output from the keyboard and screen to another device.

CUA (computer, Windows)
Common User Access - element of IBM Systems Application Architecture (SAA) specification establishing a set of standards for user interaction with menus, dialog boxes, and other interactive portions of an application. The CUA was first implemented in Windows and OS/2 and has been an integral part of these graphical user interfaces (GUIs) since their beginning.

Cube Flip (A/V)
Also called cube-spin: visual effect where freeze frames appear to be glued on a cube.

Cue (A/V, M/M)
In Audio/Visual production, a signal to start, pace, or stop any type of production activity or talent action. In music, a musical or sound effect element occurring in synchronization with a visual event in a multimedia, television or motion picture production.

Cue Card (A/V)
Large card containing copy, held next to the camera lens by floor personnel.

Cue Track (A/V)
Area of videotape used for audio information as in-house identification or the SMPTE (Society of Motion Picture and Television Engineers) address code. It can also be used for a second audio track.

CUI (computer)
Character based User Interface - user interface that employs the character, or text mode of the computer. It typically refers to typing in commands (see GUI).

Current (computer, electronics)
Present activities or the latest version or model.

Flow of electrons within a wire or circuit, measured in amperes (amps).

Current Cell (computer)
Cell currently available for use in a spreadsheet. Also called the active cell.

Current Directory (computer, Windows)
Disk directory the system is presently working in. Unless otherwise specified, all commands that deal with disk files imply the current directory. In Windows, the directory that is currently highlighted in the Directory Tree or whose directory window is the active window.

Current Drive (computer)
Disk drive currently being used by the computer system. Also called the default drive.

Current Loop (communications)
Transmission system that detects the presence or absence of current as 1s and 0s rather than voltage levels. This presence or absence is used to represent transmitted data.

Current Measurement (computer, electronics)
Measurement of the flow of electric current. The unit of measurement, the ampere (amp), is defined in the system of electromagnetic units through its electromagnetic reaction.

Current Statement (computer)
Statement or instruction executed at a particular instance in time. In dubbing operations or interpreted applications, such as Visual Basic, the current statement is the next statement executed by the interpreter when program operation is resumed.

Current Window (computer, Windows)
Application window or document window that is currently being worked in. The current window is the one to which Windows applies the next keystrokes, or cursor control.

Cursor (computer)
Symbol that is the contact point between user and data. In text systems, the cursor is a blinking rectangle or underline. In graphics, it can take any shape (arrow, square, brush, etc.) and usually changes as it is moved into different parts of the screen.

Pen or puck-like devices used with a graphics tablet. As the tablet cursor is moved across the tablet, the screen cursor moves correspondingly. (see mouse).

Cursor Keys (computer)
Keys that move the cursor on a display screen, which include the up, down, left and right arrow, home, end PgUp and PgDn keys. In addition to cursor keys, a mouse or tablet cursor also moves the cursor on the screen.

Customised Software (computer)
Software designed for a particular customer, rather than packages that are available off-the-shelf for a particular industry, such as insurance or banking. Software packages, such as spreadsheets & database management systems, although canned, off-the-shelf packages themselves, can be enhanced to create customised solutions to a user's requirements.

Cut (A/V, computer, Windows)
In Audio/Visual Production, the instantaneous change from one shot (image) to another. A Director's signal to interrupt the current action (used during rehearsal). In Windows, to move text from a document into a temporary storage area called the Clipboard.

Cut And Paste (computer)
Move a block of text from one part of a document to another or from one file to another.

Cut Bar (A/V)
Button or small metal bar that activates the mixing A/V buses alternately. The effect is cutting between two pre-set shots (images).

CUT Mode (communications, computer)
Control Unit Terminal mode - a mode that allows an IBM 3270 type terminal to have a single session with the mainframe. Micro to mainframe software emulates the mode to communicate with the mainframe (see DFT mode).

Cutoff Frequency (A/V, communications)
Sound frequency at which an audio high-pass or low-pass filter no longer allows the signal to pass through it.

Cyan (A/V, computer, printing)
Subtractive primary colour, and one of the four process colour inks (sometimes called "process blue"); cyan absorbs red light, and reflects or transmits blue and green.

Cybernetics (computer)
Comparative study of human and machine processes in order to understand their similarities and differences. It often refers to machines that imitate human behaviour (see Artificial Intelligence or AI, and Robot).

Cyberspace (computer)
Early name for Virtual Reality that projects the user into a three dimensional space generated by a computer. Implementations can include the use of an electronic glove and a head-mounted stereoscopic display, which allow users to point to and manipulate illusionary objects in their view (contemporary term is "Virtual Reality").

Cycle (communications, computer)
Single event repeated. In a carrier frequency, one cycle is one complete wave.

Cycle Stealing (computer)
CPU (Central Processing Unit) design technique that periodically "grabs" machine cycles from the main processor usually by some peripheral control unit, such as a DMA (direct memory access) device. In this way, processing and peripheral operations can be performed concurrently or with some degree of overlap.

Cycle Time (computer)
Time interval between start of once cycle and start of the next cycle. It can also mean the time required to change the information in a set of registers (also called the state transition time).

Cycles Per Second (communications, computer)
Number of times an event or set of events is repeated in one second (see Hertz).

Cyclic Redundancy Check (CRC) (communications)
Commonly used method for error detection involving the addition of one or more bits, called redundancy bits, to the information-carrying bits of a character or stream of characters. These redundancy bits do not carry any information; they are merely used to determine the correctness of the bits carrying the information. Parity Check is a common method used, as well. Parity may be even or odd, meaning that the sum of the "one" bits of any character, including parity bit, will always be even or odd, depending upon which arrangement is chosen.

Cycolor (computer, printing)
Printing process that prints full tonal images like photographs. It uses a special film that is coated with light-sensitive microcapsules, called cyliths, that contain leuco dyes. The film is exposed to the colour image that is being printed, resulting in a latent image of hard and soft cyliths. The latent image donor film is transferred onto a special Cycolor paper by being squeezed together through pressure rollers, thus releasing the dyes from the film onto the paper. The paper is then briefly heated, and the result is a full-colour image that can, quite accurately, resemble the original photograph.

Cylinder (computer)

Aggregate of all tracks that reside in the same location on every disk surface. On multiple-platter disks, the cylinder is the sum total of every track with the same track number on every surface. On a floppy disk, a cylinder comprises the top and corresponding bottom track. When storing data, the Operating System fills up an entire cylinder before moving to the next one. The access arm remains stationary until all tracks on the cylinder are read or written to.

Cylinder Method (computer)
Organising data on a magnetic disk, vertically, which minimises seek time.