MICROSOFT Computer Dictionary, Fifth Edition

Microsoft Computer Dictionary, Fifth Edition

into and out of memory. Enabling devices to take temporary control of the system bus for data transfer and bus mastering frees the CPU for other work. This in turn improves performance in tasks, such as video replay and multiple-user queries to large databases, that require simultaneous data access and intensive processing. The technology known as direct memory access (DMA) is a well-known example of bus mastering. See also bus, controller, direct memory access. Compare PIO.

bus mouse

n. A mouse that attaches to the computer’s bus through a special card or port rather than through a serial port. See also mouse. Compare serial mouse.

bus network

n. A topology (configuration) for a LAN (local area network) in which all nodes are connected to a main communications line (bus). On a bus network, each node monitors activity on the line. Messages are detected by all nodes but are accepted only by the node(s) to which they are addressed. A malfunctioning node ceases to communicate but does not disrupt operation (as it might on a ring network, in which messages are passed from one node to the next). To avoid collisions that occur when two or more nodes try to use the line at the same time, bus networks commonly rely on collision detection or token passing to regulate traffic. See the illustration. Also called: bus topology, linear bus. See also collision detection, contention, CSMA/CD, token bus network, token passing. Compare ring network, star network.

Bus network. A bus network configuration.

bus system

n. The interface circuitry that controls the operations of a bus and connects it with the rest of the computer system. See also bus.

bus topology

n. See bus network.

button

Microsoft Computer Dictionary, Fifth Edition

n. 1. A graphic element in a dialog box that, when activated, performs a specified function. The user activates a button by clicking on it with a mouse or, if the button has the focus, by hitting the Return or Enter key. 2. On a mouse, a movable piece that is pressed to activate some function. Older mouse models have only one button; newer models typically have two or more buttons.

button bomb

n. A button on Web pages with the image of a bomb.

button help

n. Help information displayed via the selection of buttons or icons. Applications such as the World Wide Web, multimedia kiosks, and computer-aided instruction often use button help icons to ease system navigation.

bypass

n. In telecommunications, the use of communication pathways other than the local telephone company, such as satellites and microwave systems.

byte

n. Short for binary term. A unit of data, today almost always consisting of 8 bits. A byte can represent a single character, such as a letter, a digit, or a punctuation mark. Because a byte represents only a small amount of information, amounts of computer memory and storage are usually given in kilobytes (1024 bytes), megabytes (1,048,576 bytes), or gigabytes (1,073,741,824 bytes). Abbreviation: B. See also bit, gigabyte, kilobyte, megabyte. Compare octet, word.

bytecode

n. An encoding of a computer program that a compiler produces when the original source code is processed. This encoding is in an abstract, processor-independent form that cannot be directly executed by most CPUs but is highly suitable for further analysis (for example, compiler optimization), for processing by interpreters (for example, executing Java applets within Web browsers), or for use in generation of binary instructions for the target computer’s CPU. Intermediate bytecode production is a feature of the compilers for the Pascal and Java programming languages. See also central processing unit, compiler (definition 2), interpreter, Java, Java applet, Pascal.

BYTE Information Exchange n. See BIX.

byte-oriented protocol

n. A communications protocol in which data is transmitted as a string of characters in a particular character set, such as ASCII, rather than as a stream of bits as in a bit-oriented protocol. To express control information, a byte-oriented protocol relies on control characters, most of which are defined by the coding scheme used. The asynchronous communications protocols commonly used with modems and IBM’s BISYNC protocol are byte-oriented protocols. Compare bit-oriented protocol.

bytes per inch

n. The number of bytes that fit into an inch of length on a disk track or a tape. Acronym: BPI.

C: C - Cycolor

C

n. A programming language developed by Dennis Ritchie at Bell Laboratories in 1972. It is so named because its immediate predecessor was the B programming language. Although C is considered by many to be more a machine-independent assembly language than a high-level

Microsoft Computer Dictionary, Fifth Edition

language, its close association with the UNIX operating system, its enormous popularity, and its standardization by the American National Standards Institute (ANSI) have made it perhaps the closest thing to a standard programming language in the microcomputer/workstation marketplace. C is a compiled language that contains a small set of built-in functions that are machine dependent. The rest of the C functions are machine independent and are contained in libraries that can be accessed from C programs. C programs are composed of one or more functions defined by the programmer; thus C is a structured programming language. See also C++, compiled language, library, Objective-C, structured programming.

C++

n. An object-oriented version of the C programming language, developed by Bjarne Stroustrup in the early 1980s at Bell Laboratories and adopted by a number of vendors, including Apple Computer, Inc. and Sun Microsystems, Inc. See also C, Objective-C, object-oriented programming.

C2

n. A security class of the U.S. Department of Defense Trusted Computer System Evaluation Criteria (DOD 4200.28.STD). C2 is the lowest level of security in the U.S. National Computer Security Center’s hierarchy of criteria for trusted computer systems, requiring user logon with password and a mechanism for auditing. The C2 level is outlined in the Orange Book. See also Orange Book (definition 1).

CA

n. See certificate authority.

.cab

n. File extension for cabinet files, which are multiple files compressed into one and extractable with the extract.exe utility. Such files are frequently found on Microsoft software (for example, Windows 9x) distribution disks.

cabinet

n. The box in which the main components of a computer (CPU, the hard drive, floppy and CDROM drives, and expansion slots for peripheral devices, such as monitors) are located. See also CPU, expansion slot.

cable1

n.A collection of wires shielded within a protective tube, used to connect peripheral devices to a computer. A mouse, a keyboard, and a printer might all be connected to a computer with cables. Printer cables typically implement a serial or a parallel path for data to travel along. See the illustration.

Microsoft Computer Dictionary, Fifth Edition

Cable.

cable2

adj. Pertaining to the cable television (CATV) distribution system. For example, a cable modem is a modem that sends and receives digital data through a connection to a cable TV system. Because cable TV is a broadband service, it can carry data (such as an Internet connection) at a very high speed. See also CATV.

cable connector

n. The connector on either end of a cable. See also DB connector, DIN connector, RS-232-C standard, RS-422/423/449.

cable matcher

n. A device that allows the use of a cable that has slightly different wire connections from those required by the devices to which it is attached.

cable modem

n. A modem that sends and receives data through a coaxial cable television network instead of telephone lines, as with a conventional modem. Cable modems, which have speeds of 500 kilobits per second (Kbps), can generally transmit data faster than current conventional modems. However, cable modems do not operate at the same rate upstream (when sending information) and downstream (when receiving information). Upstream rates vary from about 2 Mbps to 10 Mbps, downstream rates from about 10 Mbps to 36 Mbps. See also coaxial cable, modem.

cable telephony

n. Telephone service provided over a cable TV connection rather than over traditional telephone lines. Although service is delivered over cable rather than telephone wire, the end user perceives no difference between cable telephony and normal telephone service. Proponents of cable telephony see it as part of the eventual integration of Internet, television, and telephone services into a single communication/entertainment unit.

cable television n. See CATV.

cabling diagram

n. A plan that shows the path of cables that attach computer system components or peripherals. Cabling diagrams are particularly important for explaining the connection of disk drives to a disk controller.

cache

Microsoft Computer Dictionary, Fifth Edition

n. A special memory subsystem in which frequently used data values are duplicated for quick access. A memory cache stores the contents of frequently accessed RAM locations and the addresses where these data items are stored. When the processor references an address in memory, the cache checks to see whether it holds that address. If it does hold the address, the data is returned to the processor; if it does not, a regular memory access occurs. A cache is useful when RAM accesses are slow compared with the microprocessor speed because cache memory is always faster than main RAM memory. See also disk cache, wait state.

cache card

n. An expansion card that increases a system’s cache memory. See also cache, expansion board.

Cache-Coherent Non-Uniform Memory Access n. See ccNUMA.

cache farm

n. A group of servers that save copies of Web pages to caches to fulfill successive requests without calling the pages up repeatedly from the Web server. In essence, the servers are dedicated to caching. By saving Web pages where they can be accessed without increasing traffic on the Web site, the cache farm allows higher-performance Web access for the end user and a reduction in network congestion and volume. See also cache.

cache memory n. See cache.

cache poisoning

n. Deliberate corruption of Internet Domain Name System (DNS) information through alteration of data that equates host names with their IP addresses. Misleading information of this type, when cached (saved) by one DNS server and later passed to another, exposes DNS servers to attacks in which data sent from one host to another can be accessed or corrupted. Cache poisoning has been used to redirect network requests from a legitimate server to an alternate Web site. See also DNS.

CAD

n. Acronym for computer-aided design. A system of programs and workstations used in designing engineering, architectural, and scientific models ranging from simple tools to buildings, aircraft, integrated circuits, and molecules. Various CAD applications create objects in two or three dimensions, presenting the results as wire-frame “skeletons,” as more substantial models with shaded surfaces, or as solid objects. Some programs can also rotate or resize models, show interior views, generate lists of materials required for construction, and perform other allied functions. CAD programs rely on mathematics, often requiring the computing power of a highperformance workstation. See also CAD/CAM, I-CASE.

CAD/CAM

n. Acronym for computer-aided design/computer-aided manufacturing. The use of computers in both the design and manufacture of a product. With CAD/ CAM, a product, such as a machine part, is designed with a CAD program and the finished design is translated into a set of instructions that can be transmitted to and used by the machines dedicated to fabrication, assembly, and process control. See also CAD, I-CASE.

CADD

n. A system of hardware and software similar to CAD but with additional features related to engineering conventions, including the ability to display dimension specifications and other notes. Acronym: CADD. See also CAD.

caddy

Microsoft Computer Dictionary, Fifth Edition

n. A plastic carrier that holds a CD-ROM and is inserted into a CD-ROM drive. Some PCs, especially older models, have CD-ROM drives that require the use of a caddy. Most current CDROM drives do not require a caddy.

CAE

n. Acronym for computer-aided engineering. An application that enables the user to perform engineering tests and analyses on designs created with a computer. In some instances, capabilities such as logic testing that are generally attributed to CAE applications are also part of CAD programs, so the distinction between CAD and CAE is not a hard-and-fast one. See also CAD, I-CASE.

CAI

n. Acronym for computer-aided (or computer-assisted) instruction. An educational program designed to serve as a teaching tool. CAI programs typically use tutorials, drills, and question- and-answer sessions to present a topic and to test the student’s comprehension. CAI programs are excellent aids for presenting factual material and for allowing students to pace their learning speed. Subjects and complexity range from beginning arithmetic to advanced mathematics, science, history, computer studies, and specialized topics. Also called: CAL, CAT, computeraided learning, computer-aided teaching, computer-assisted learning, computer-assisted teaching, computer-augmented learning. See also I-CASE. Compare CBT, CMI.

CAL

n. 1. Acronym for computer-assisted (or computer-augmented) learning. See CAI. 2. Acronym for Common Application Language. An object-oriented communications language for controlling home-networking products. CAL, originally part of the CEBus (Consumer Electronic Bus) standard for home automation, can be implemented with various communication protocols, homenetworking standards, and home electronic products. See also CEBus, home automation.

calculator

n. Broadly, any device that performs arithmetic operations on numbers. Sophisticated calculators can be programmed for certain functions and can store values in memory, but they differ from computers in several ways: they have a fixed set of commands, they do not recognize text, they cannot retrieve values stored in a data file, and they cannot find and use values generated by a program such as a spreadsheet.

calendar program

n. An application program in the form of an electronic calendar, commonly used for highlighting dates and scheduling appointments. Some calendar programs resemble wall calendars, displaying dates in blocks labeled with the days of the week; others display dates day by day and enable the user to enter appointments, notes, and other memoranda. A day-of-the-week type of calendar program could, for example, be used to find out that Christmas 2003 will be on a Saturday. Depending on its capabilities, such a program might cover only the current century, or it might cover hundreds of years and even allow for the change (in 1582) from the Julian to the Gregorian calendar. A calendar/scheduler program might show blocks of dates or, like an appointment book, single days divided into hours or half hours, with room for notes. Some programs allow the user to set an alarm to go off at an important point in the schedule. Other programs can coordinate the calendars of different people on the same network so that a person entering an appointment into his or her calendar also enters the appointment into a colleague’s calendar.

call1

n. In a program, an instruction or statement that transfers program execution to some section of code, such as a subroutine, to perform a specific task. Once the task is performed, program execution resumes at the calling point in the program. See also calling sequence.

call2

Microsoft Computer Dictionary, Fifth Edition

vb. 1. To establish a connection through a telecommunications network. 2. To transfer program execution to some section of code (usually a subroutine) while saving the necessary information to allow execution to resume at the calling point when the called section has completed execution. Some languages (such as FORTRAN) have an explicit CALL statement; others (such as C and Pascal) perform a call when the name of a procedure or function appears. In assembly language, there are various names for a CALL instruction. When a subroutine call occurs in any language, one or more values (known as arguments or parameters) are often passed to the subroutine, which can then use and sometimes modify these values. See also argument, parameter.

callback or callback security

n. A security feature used to authenticate users calling in to a network. During callback, the network validates the caller’s username and password, hangs up, and then returns the call, usually to a preauthorized number. This security measure usually prevents unauthorized access to an account even if an individual’s logon ID and password have been stolen. See also authentication, preset-to callback, remote access server.

callback modem

n. A modem that, instead of answering an incoming call, requires the caller to enter a touch-tone code and hang up so that the modem can return the call. When the modem receives the caller’s code, it checks the code against a stored set of phone numbers. If the code matches an authorized number, the modem dials the number and then opens a connection for the original caller. Callback modems are used when communications lines must be available to outside users but data must be protected from unauthorized intruders.

calling sequence

n. In a program when a subroutine call occurs, an agreement between the calling routine and the called routine on how arguments will be passed and in what order, how values will be returned, and which routine will handle any necessary housekeeping (such as cleaning up the stack). The calling sequence becomes important when the calling and called routines were created with different compilers or if either was written in assembly language. Two common calling sequences are the C calling sequence and the Pascal calling sequence. In the C calling sequence, the calling routine pushes any arguments included in the call on the stack in reverse order (right to left) and performs any stack cleanup; this permits a varying number of arguments to be passed to a given routine. In the Pascal calling sequence, the calling routine pushes any included arguments on the stack in the order in which they appear (left to right), and the called routine is expected to clean up the stack. See also argument, call1, stack.

CALL instruction

n. A type of programming instruction that diverts program execution to a new area in memory (sequence of directives) and also allows eventual return to the original sequence of directives.

CALS

n. Acronym for Computer-Aided Acquisition and Logistics Support. A U.S. Department of Defense standard for electronic exchange of data with commercial suppliers.

CAM

n. 1. Acronym for computer-aided manufacturing. The use of computers in automating the fabrication, assembly, and control aspects of manufacturing. CAM applies to the manufacture of products ranging from small-scale production to the use of robotics in full-scale assembly lines. CAM relates more to the use of specialized programs and equipment than it does to the use of microcomputers in a manufacturing environment. See also CAD/CAM, I-CASE. 2. See Common Access Method.

camera-ready

Microsoft Computer Dictionary, Fifth Edition

adj. In publishing, of or pertaining to the stage at which a document, with all typographic elements and graphics in place, is suitably prepared to be sent to a printing service. The printing service photographs the camera-ready copy and then uses the photograph to make plates for printing. Some applications are advertised as being able to bring documents to the camera-ready stage, eliminating the need for manual layout and pasteup of elements onto boards.

campuswide information system

n. Information and services distributed on a college or university campus through computer networks. Campuswide information system services typically include student and faculty directories, calendars of campus events, and access to databases. Acronym: CWIS.

cancel

n. A control character used in communication with printers and other computers, commonly designated as CAN. It usually means that the line of text being sent should be canceled. In ASCII, which is the basis of character sets used by most microcomputers, this is represented internally as character code 24.

cancelbot

n. Short for cancel robot. A program that identifies articles in newsgroups based on a set of criteria and cancels the distribution of those articles. Although the criteria for cancellation is set by the owner of the cancelbot, most cancelbots exist to identify and eliminate spam messages posted to dozens or hundreds of newsgroups. See also spam.

cancel message

n. A message sent to Usenet news servers indicating that a certain article is to be canceled, or deleted, from the server. See also article, news server, Usenet.

candidate key

n. A unique identifier for a tuple (row) within a relation (database table). The candidate key may be either simple (a single attribute) or composite (two or more attributes). By definition, every relation must have at least one candidate key, but it is possible for a relation to have more than one candidate key. If there is only one candidate key, it automatically becomes the primary key for the relation. If there are multiple candidate keys, the designer must designate one as the primary key. Any candidate key that is not the designated primary key is an alternate key. See also key (definition 2), primary key.

canned program

n. See canned software.

canned routine

n. A previously written routine that is copied into a program and used as is, without modification. See also library routine.

canned software

n. Off-the-shelf software, such as word processors and spreadsheet programs.

canonical form

n. In mathematics and programming, the standard or prototypical form of an expression or a statement.

canonical name

n. An object’s distinguished name presented with the root first and without the LDAP attribute tags (such as: CN=, DC=). The segments of the name are delimited with forward slashes (/). For example, CN=MyDocuments,OU=MyOU,DC=Microsoft,DC=Com is presented as microsoft.com/MyOU/MyDocuments in canonical form. See also Lightweight Directory Access Protocol.

Microsoft Computer Dictionary, Fifth Edition

capacitance

n. The ability to store an electric charge. Capacitance is measured in farads. A capacitance of 1 farad will hold 1 coulomb of charge at a potential of 1 volt. In practical use, a farad is an extremely large amount of capacitance; typical capacitors have values of microfarads (10-6 ) or picofarads (10-12 ). See also capacitor.

capacitor

n. A circuit component that provides a known amount of capacitance (ability to store an electric charge). A capacitor typically consists of two conductive plates separated by an insulating (dielectric) material. If other factors remain constant, capacitance increases as the plates are made larger or brought closer together. A capacitor blocks direct current but passes alternating current to an extent that depends on its capacitance and on the frequency of the current. See also capacitance.

capacity

n. The amount of information a computer or an attached device can process or store. See also computer.

caps

n. Short for capital letters. Compare lowercase.

Caps Lock key

n. A toggle key that, when on, shifts the alphabetic characters on the keyboard to uppercase. The Caps Lock key does not affect numbers, punctuation marks, or other symbols. See the illustration.

Caps Lock key.

capstan

n. On a tape recorder, a polished metal post against which a turning rubber wheel (called a pinch roller) presses to move a length of magnetic tape placed between the wheel and the post. The capstan controls the speed of the tape as it moves past the recording head. See also pinch roller.

capture

vb. In communications, to transfer received data into a file for archiving or later analysis.

capture board

n. See video capture card.

capture card

n. See video capture card.

Microsoft Computer Dictionary, Fifth Edition

Carbon

n. Code name for the Application Program Interfaces (API) and shared libraries used to write applications for Macintosh OS X. Since Macintosh OS X is an entirely different system rather than an update of the previous Macintosh OS, Carbon bridges the gap between the systems, allowing developers to rewrite their programs to OS X without rewriting the code for the entire application. Carbon allows OS X native applications to run under earlier versions of the Macintosh OS without modification but with OS X advantages.

carbon copy n. See cc.

carbonize

vb. To update a Macintosh application for OS X. Although older versions of Macintosh applications will run under OS X, only those that have been carbonized will be able to use OS X– specific advantages.

carbon ribbon

n. A ribbon used with impact printers, especially daisy-wheel printers, and with typewriters for highest-quality output. A carbon ribbon is made of a thin strip of Mylar coated on one side with a carbon film. Characters printed with a carbon ribbon are extremely crisp and free from the fuzziness that can be associated with an inked cloth ribbon. Also called: film ribbon, Mylar ribbon. See also daisy-wheel printer. Compare cloth ribbon.

card

n. 1. A printed circuit board or adapter that can be plugged into a computer to provide added functionality or new capability. These cards provide specialized services, such as mouse support and modem capabilities, that are not built into the computer. See also adapter, board, printed circuit board. 2. In programs such as the HyperCard hypertext program, an on-screen representation of an index card on which information can be stored and “filed” (saved) for future reference. See also hypertext. 3. A manila card about 3 inches high by 7 inches long on which 80 columns of data could be entered in the form of holes punched with a keypunch machine. The punched holes corresponded to numbers, letters, and other characters and could be read by a computer that used a punched-card reader. Also called: punched card. See also card reader (definition 2).

card cage

n. An enclosure area for holding printed circuit boards (cards). Most computers have an area with protective metal and mounting brackets where cards are installed. The term originally came from an external box that held rack-mounted cards or peripherals and resembled a cage.

carder

n. A person who engages in online credit card fraud. Specifically, a carder steals credit card numbers, either to purchase merchandise (often computer-related) from Web-based stores or to trade the stolen numbers with like-minded individuals—again, over the Internet. Carders generally obtain credit card numbers through conventional means, such as “trashing” (searching through trash) or calling individuals and posing as bank officers. See also hacker (definition 2).

cardinal number

n. A number that indicates how many items there are in a set—for example, “There are 27 names on that list.” Compare ordinal number.

card punch

n. See keypunch.

card reader