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This section of the site is dedicated to helping to build a better understanding of the term 'Data Communication'. Listed from A-Z is a glossery of terms involved in computing, and the Internet. Click on a each individual link to visit each individual letter.



n. Acronym for research and development.



adj. Built for installation in a metal frame or cabinet of standard width (typically 19 inches or 23 inches) and mounting arrangements.



n. Acronym for rapid application development. A method of building computer systems in which the system is programmed and implemented in segments, rather than waiting until the entire project is completed for implementation. Developed by programmer James Martin, RAD uses such tools as CASE and visual programming. See also CASE, visual programming.


radio button

n. In graphical user interfaces, a means of selecting one of several options, usually within a dialog box. A radio button appears as a small circle that, when selected, has a smaller, filled circle inside it. Radio buttons act like the station selector buttons on a car radio. Selecting one button in a set deselects the previously selected button, so one and only one of the options in the set can be selected at any given time. In contrast, check boxes are used when more than one option in the set can be selected at the same time. Compare check box.


radio frequency

n. Abbreviated RF. The portion of the electromagnetic spectrum with frequencies between 3 kilohertz and 300 gigahertz. This corresponds to wavelengths between 30 kilometers and 0.3 millimeter. See also radio (definition 1).



n. Acronym for Remote Authentication Dial-In User Service protocol. A proposed Internet protocol in which an authentication server provides authorization and authentication information to a network server to which a user is attempting to link. See also authentication, communications protocol, server (definition 2).



n. Acronym for redundant array of independent disks (formerly redundant array of inexpensive disks). A data storage method in which data, along with information used for error correction, such as parity bits or Hamming codes, is distributed among two or more hard disk drives in order to improve performance and reliability. The hard disk array is governed by array management software and a disk controller, which handles the error correction. RAID is generally used on network servers. Several defined levels of RAID offer differing trade-offs among access speed, reliability, and cost. See also disk controller, error-correction coding, Hamming code, hard disk, parity bit, server (definition 1).



n. Acronym for random access memory. Semiconductor-based memory that can be read and written by the central processing unit (CPU) or other hardware devices. The storage locations can be accessed in any order. Note that the various types of ROM memory are capable of random access, but cannot be written to. The term RAM, however, is generally understood to refer to volatile memory that can be written to as well as read. Compare core, EPROM, flash memory, PROM, ROM (definition 2).


RAM cache

n. Cache memory that is used by the system to store and retrieve data from the RAM. Frequently accessed segments of data may be stored in the cache for quicker access compared with secondary storage devices such as disks. See also cache, RAM.


RAM card

n. An add-in circuit board containing RAM memory and the interface logic necessary to decode memory addresses.


RAM chip

n. A semiconductor storage device. RAM chips can be either dynamic or static memory. See also dynamic RAM, RAM, static RAM.


RAM disk

n. Short for random access memory disk. A simulated disk drive whose data is actually stored in RAM memory. A special program allows the operating system to read from and write to the simulated device as if it were a disk drive. RAM disks are extremely fast, but they require that system memory be given up for their use. Also, RAM disks usually use volatile memory, so the data stored on them disappears when power is turned off. Many portables offer RAM disks that use battery-backed CMOS RAM to avoid this problem. See also CMOS RAM. Compare disk cache.


random access

n. The ability of a computer to find and go directly to a particular storage location without having to search sequentially from the beginning location. The human equivalent of random access would be the ability to find a desired address in an address book without having to proceed sequentially through all the addresses. A computer's semiconductor memory (both RAM and ROM) provides random access. Certain types of files stored on disk under some operating systems also allow random access. Such files are best used for data in which each record has no intrinsic relationship to what comes physically before or after it, as in a client list or an inventory. Also called direct access. See also RAM, ROM. Compare indexed sequential access method, sequential access.



n. See remote access server, Remote Access Service.



n. A rectangular pattern of lines; on a video display, the horizontal scan lines from which the term raster scan is derived.


raster graphics

n. A method of generating graphics that treats an image as a collection of small, independently controlled dots (pixels) arranged in rows and columns. Compare vector graphics.


raster image

n. A display image formed by patterns of light and dark or differently colored pixels in a rectangular array. See also raster graphics.



n. The conversion of vector graphics (images described in terms of mathematical elements, such as points and lines) to equivalent images composed of pixel patterns that can be stored and manipulated as sets of bits. See also pixel.


RCA connector

n. A connector used for attaching audio and video devices, such as stereo equipment or a composite video monitor, to a computer's video adapter. See also composite video display. Compare phono connector.



n. The action of transferring data from an input source into a computer's memory or from memory into the central processing unit (CPU). Compare write1.



vb. To transfer data from an external source, such as from a disk or the keyboard, into memory or from memory into the central processing unit (CPU). Compare write2.



n. A file containing information that the user either needs or will find informative and that might not have been included in the documentation. README files are placed on disk in plain-text form (without extraneous or program-specific characters) so that they can be read easily by a variety of word processing programs.



adj. Capable of being retrieved (read) but not changed (written). A read-only file or document can be displayed or printed but not altered in any way; read-only memory (ROM) holds programs that cannot be changed; a read-only storage medium, such as CD-ROM, can be played back but cannot be used for recording information. Compare read/write.


read-only attribute

n. In Windows and OS/2, a file attribute, stored with a file's directory, indicating whether or not a file may be changed or erased. When the read-only attribute is off, the file can be modified or deleted; when it is on, the file can only be displayed.



adj. Abbreviated R/W. Able to be both read from and written to. Compare read-only.


read/write memory

n. Memory that can be both read from and written to (modified). Semiconductor RAM and core memory are typical read/write memory systems. Compare ROM (definition 2).


real address

n. An absolute (machine) address specifying a physical location in memory. See also physical address. Compare relative address, virtual address.



n. Web software that streams prerecorded or live audio to a client, such as a Web browser, by decompressing it on the fly so that it can be played back to the Web browser user in real time.



n. A function in C that allows the programmer to request a larger portion of heap memory than was previously assigned to a particular pointer. See also dynamic memory allocation, heap (definition 1).


real mode

n. An operating mode in the Intel 80x86 family of microprocessors. In real mode, the processor can execute only one program at a time. It can access no more than about 1 MB of memory, but it can freely access system memory and input/output devices. Real mode is the only mode possible in the 8086 processor and is the only operating mode supported by MS-DOS. In contrast, the protected mode offered in the 80286 and higher microprocessors provides the memory management and memory protection needed for multitasking environments such as Windows. See also 8086, privileged mode. Compare protected mode, virtual real mode.


real-mode mapper

n. An enhancement for Windows 3.x systems that allows 32-bit file system access. The real-mode mapper provides a 32-bit disk access interface to the DOS device driver chain. Acronym: RMM.



adj. Of or relating to a time frame imposed by external constraints. Real-time operations are those in which the machine's activities match the human perception of time or those in which computer operations proceed at the same rate as a physical or external process. Real-time operations are characteristic of transaction-processing systems, aircraft guidance systems, scientific applications, and other areas in which a computer must respond to situations as they occur (for example, animating a graphic in a flight simulator or making corrections based on measurements).


real-time animation

n. Computer animation in which images are computed and updated on the screen at the same rate at which the objects simulated might move in the real world. Real-time animation allows dynamic involvement by the user because the computer can accept and incorporate keystrokes or controller movements as it is drawing the next image in the animation sequence. Arcade-style animation (such as in a flight simulator program) makes use of real-time animation in translating game plays into on-screen actions. In contrast, in animation done in virtual time, image frames are first calculated and stored and later replayed at a higher rate to achieve smoother movement. See also animation, bit block.


real-time operating system

n. An operating system designed or optimized for the needs of a process-control environment. See also real-time system.



vb. To restart a computer by reloading the operating system. See also boot2, cold boot, warm boot.


receipt notification

n. An e-mail feature providing feedback to the sender that a message has been received by the recipient.



vb. To accept data from an external communications system, such as a local area network (LAN) or a telephone line, and store the data as a file.


rec. newsgroups

n. Usenet newsgroups that are part of the rec. hierarchy and whose names have the prefix "rec." These newsgroups cover topics devoted to discussions of recreational activities, hobbies, and the arts. See also newsgroup, traditional newsgroup hierarchy, Usenet. Compare comp. newsgroups, misc. newsgroups, news. newsgroups, sci. newsgroups, soc. newsgroups, talk. newsgroups.



vb. To compile a program again, usually because of changes that needed to be made in the source code in response to error messages generated by the compiler. See also compile.



n. A data structure that is a collection of fields (elements), each with its own name and type. Unlike an array, whose elements all represent the same type of information and are accessed using an index, the elements of a record represent different types of information and are accessed by name. A record can be accessed as a collective unit of elements, or the elements can be accessed individually. See also array, data structure, type1 (definition 1).



vb. To retain information, usually in a file.


record locking

n. A strategy employed in distributed processing and other multiuser situations to prevent more than one user at a time from writing data to a record. See also record1.


Recycle Bin

n. A folder in Windows 95, represented by an icon on the screen resembling a basket decorated with the recycling logo. To remove a file, the user drags its icon to the Recycle Bin. However, a file in the Recycle Bin is not actually deleted from the disk until the user opens the Recycle Bin, selects the file, and presses the Del key; until then, the user can retrieve it. Compare Trash.


Red Book

n. 1. The standards documents of the U.S. National Security Agency entitled "Trusted Network Interpretation of the Trusted Computer System Evaluation Criteria (NCSC-TG-005)" and "Trusted Network Interpretation (NCS-TG-011)." These documents define a system of ratings from A1 (most secure) to D (nonsecure), indicating the ability of a computer network to protect sensitive information. Compare Orange Book (definition 1). 2. A specifications book written by the Sony and Philips corporationsand endorsed by ISO, covering audio compact discs. Compare Green Book, Orange Book (definition 2). 3. Telecommunications standards published by the CCITT.



n. The process of writing to or reading from a file or device different from the one that would normally be the target or the source. For example, the MS-DOS or OS/2 command dir >prn redirects a directory listing from the screen to the printer. Compare pipe.



n. A feature of a word processing application that marks changes, additions, or deletions made to a document by a coauthor or editor. The purpose of redlining is to produce a record of the changes made to a document during the course of its development.



n. See refresh (definition 1).


reduced instruction set computing

n. See RISC.


redundancy check

n. See CRC, LRC.



vb. To rethink and redefine processes and procedures. In the context of computer systems, to reengineer means to change the way work is done in order to maximize the benefits of new technology.


reentrant code

n. Code written so that it can be shared by several programs at the same time. When a program is executing reentrant code, another program can interrupt the execution and can then start or continue execution of that same code. Many operating-system routines are written to be reentrant so that only one copy needs to reside in memory to serve all executing applications. See also relocatable code.



vb. To access a variable, such as an element in an array or a field in a record.


reflective liquid-crystal display

n. A liquid crystal display that is not equipped with edge or back lighting to enhance readability but rather depends on reflecting ambient light, making it difficult to read in brightly lit environments such as the outdoors. Also called reflective LCD.


reflective routing

n. In wide area networks, the process of using a reflector to distribute data, thereby reducing the load of the network server. See also reflector.



n. A program that sends messages to a number of users upon receipt of a signal from a single user. A common type of reflector is an e-mail reflector, which forwards any e-mail sent to it to the multiple recipients currently on its list. See also multiple recipients. Compare mail reflector.



vb. 1. In applications, to change the look of a document by altering stylistic details, such as font, layout, indention, and alignment. 2. In data storage, to prepare for reuse a disk that already contains programs or data, effectively destroying the existing contents.



vb. 1. To retrace a video screen at frequent intervals, even if the image does not change, so as to keep the phosphors irradiated. 2. To recharge dynamic random access memory chips (DRAMs) so that they continue to retain the information stored in them. Circuitry on the memory board automatically performs this function. See also refresh cycle.


refresh cycle

n. The process in which controller circuitry provides repeated electric pulses to dynamic random access memory chips in order to renew the stored electric charges in those locations that contain binary 1. Each pulse is one refresh cycle. Without constant refreshing, dynamic semiconductor RAM loses any information stored in it--as it does when the computer is turned off or when the power fails. See also dynamic RAM, static RAM.


refresh rate

n. In reference to video hardware, the frequency with which the entire screen is redrawn to maintain a constant, flicker-free image. On TV screens and raster-scan monitors, the electron beam that lights the phosphor coating on the inner surface of the screen typically refreshes the entire image area at a rate of about 60 hertz, or 60 times per second. (Interlaced monitors, which redraw alternate lines during each sweep of the electron beam, actually refresh any particular line only 30 times per second. Because odd and even lines are refreshed on successive sweeps, however, the effective refresh rate is 60 times per second.)



n. See also Registry. See registry editor.



n. A set of bits of high-speed memory within a microprocessor or other electronic device, used to hold data for a particular purpose. Each register in a central processing unit is referred to in assembly language programs by a name such as AX (the register that contains the results of arithmetic operations in an Intel 80x86 processor) or SP (the register that contains the memory address of the top of the stack in various processors).



n. The process of precisely aligning elements or superimposing layers in a document or a graphic so that everything will print in the correct relative position. See also registration marks.


registration marks

n. Marks placed on a page so that in printing, the elements or layers in a document can be arranged correctly with respect to each other. Each element to be assembled contains its own registration marks; when the marks are precisely superimposed, the elements are in the correct position.



or registry n. A central hierarchical database in Windows 95 and Windows NT used to store information necessary to configure the system for one or more users, applications, and hardware devices. The Registry contains information that Windows 95 and Windows NT continually reference during operation, such as profiles for each user, the applications installed on the computer and the types of documents each can create, property sheet settings for folders and application icons, what hardware exists on the system, and which ports are being used. The Registry replaces most of the text-based .ini files used in Windows 3.x and MS-DOS configuration files, such as AUTOEXEC.BAT and CONFIG.SYS. Although the Windows 95 Registry is similar to the one in Windows NT, there are some differences, such as how they are stored on disk. Also called System Registry. See also hierarchical database, .ini, input/output port, property sheet, registry editor.


registry editor

n. An application under Windows 95 that allows the user to edit the entries in the Registry. Acronym: REGEDIT. See REGEDIT.


regression analysis

n. In statistics, an analysis of the degree to which variations in an independent variable affect a dependent variable (a variable whose value depends on the value of another variable). See also multiple regression.


regression testing

n. Complete retesting of a modified program, rather than a test of only the modified routines, to ensure that no errors have been introduced with the modifications.


relational database

n. A database or database management system that stores information in tables--rows and columns of data--and conducts searches by using data in specified columns of one table to find additional data in another table. In a relational database, the rows of a table represent records (collections of information about separate items) and the columns represent fields (particular attributes of a record). In conducting searches, a relational database matches information from a field in one table with information in a corresponding field of another table to produce a third table that combines requested data from both tables. For example, if one table contains the fields EMPLOYEE-ID, LAST-NAME, FIRST-NAME, and HIRE-DATE, and another contains the fields DEPT, EMPLOYEE-ID, and SALARY, a relational database can match the EMPLOYEE-ID fields in the two tables to find such information as the names of all employees earning a certain salary or the departments of all employees hired after a certain date. In other words, a relational database uses matching values in two tables to relate information in one to information in the other. Microcomputer database products typically are relational databases. Compare flat-file database, inverted-list database.


relative address

n. A location, as in a computer's memory, that is specified in terms of its distance (displacement or offset) from a starting point (base address). A relative address is typically computed by adding an offset to the base--in everyday terms, this is similar to creating the address 2001 Main Street, in which the base is the 2000 block of Main Street and the offset is 1, which specifies the first house from the beginning of the block. Also called indirect address.


relative coordinates

n. Coordinates that are defined in terms of their distance from a given starting point, rather than from the origin (intersection of two axes). For example, from a starting point on the screen, a square defined by relative coordinates can be drawn as a series of lines, each representing a displacement in distance and direction from the end of the preceding point. The entire square can be redrawn at another location simply by changing the coordinates of the starting point rather than by recalculating the coordinates of each corner with reference to the origin. Compare absolute coordinates.


relative movement

n. 1. Motion whose distance and direction are relative to a starting point. For example, when a mouse pointer is moved on the screen, the coordinates of its new position are relative to the previous location of the pointer. See also relative coordinates, relative pointing device. 2. In computer graphics and cinematography, the movement of one object in relation to another, such as the movement of horse A from the perspective of horse B on a racetrack.


relative URL

n. Short for relative Uniform Resource Locator. A form of URL in which the domain and some or all directory names are omitted, leaving only the document name and extension (and perhaps a partial list of directory names). The indicated file is found in a location relative to the pathname of the current document. See also file extension, URL. Compare: Absolute URL.



n. A switch activated by an electrical signal. A relay allows another signal to be controlled without the need for human action to route the other signal to the control point, and it also allows a relatively low-power signal to control a high-power signal.



n. 1. A particular version of a piece of software, most commonly associated with the most recent version (as in "the latest release"). Some companies use the term release as an integral part of the product name (as in Lotus 1-2-3 Release 2.2). 2. A version of a product that is available in general distribution. Compare beta2.



vb. 1. To relinquish control of a block of memory, a device, or another system resource to the operating system. 2. To formally make a product available to the marketplace.



vb. 1. To load a program into memory from a storage device again in order to run it, because the system has crashed or the program's operation was otherwise interrupted. 2. To retrieve a new copy of the Web page currently visible in a Web browser.



adj. Not in the immediate vicinity, as a computer or other device located in another place (room, building, or city) and accessible through some type of cable or communications link.


remote access

n. The use of a remote computer.


remote access server

n. A host on a local area network that is equipped with modems to enable users to connect to the network over telephone lines. Acronym: RAS.


Remote Access Service

n. Windows software that allows a user to gain remote access to the network server via a modem. See also remote access. Acronym: RAS.


remote administration

n. The performance of system administration-related tasks via access from another machine in a network.


remote login

n. The action of logging in to a computer at a distant location by means of a data communications connection with the computer that one is presently using. After remote login, the user's own computer behaves like a terminal connected to the remote system. On the Internet, remote login is done primarily by rlogin and telnet. See also rlogin1 (definition 1), telnet1.


remote procedure call

n. In programming, a call by one program to a second program on a remote system. The second program generally performs a task and returns the results of that task to the first program. Acronym: RPC.


remote system

n. The computer or network that a remote user is accessing via a modem. See also remote access. Compare remote terminal.


removable disk

n. A disk that can be removed from a disk drive. Floppy disks are removable; hard disks usually are not. Also called exchangeable disk.


REM statement

n. Short for remark statement. A statement in the Basic programming language and the MS-DOS and OS/2 batch file languages that is used to add comments to a program or batch file. Any statement beginning with the word REM is ignored by the interpreter or compiler or the command processor. See also comment.



n. A command in most file transfer protocol (FTP) clients and in many other systems that allows the user to assign a new name to a file or files.



vb. To produce a graphic image from a data file on an output device such as a video display or printer.



n. The creation of an image containing geometric models, using color and shading to give the image a realistic look. Usually part of a geometric modeling package such as a CAD program, rendering uses mathematics to describe the location of a light source in relation to the object and to calculate the way in which the light would create highlights, shading, and variations in color. Realism can range from opaque, shaded polygons to images approximating photographs in their complexity. See also ray tracing.



vb. To recalculate the page breaks in a document.



n. A command in Microsoft Word that causes all information contained in either the last command dialog box or the last uninterrupted editing session to be repeated.



n. A device used on communications circuits that decreases distortion by amplifying or regenerating a signal so that it can be transmitted onward in its original strength and form. On a network, a repeater connects two networks or two network segments at the physical layer of the ISO/OSI model and regenerates the signal.


repetitive strain injury

n. An occupational disorder of the tendons, ligaments, and nerves caused by the cumulative effects of prolonged repetitious movements. Repetitive strain injuries are appearing with increasing frequency among office workers who spend long hours typing at computerized workstations that are not equipped with safeguards such as wrist supports. See also carpal tunnel syndrome, wrist support. Acronym: RSI.



vb. To put new data in the place of other data, usually after conducting a search for the data to be replaced. Text-based applications such as word processors typically include search-and-replace commands. In such operations, both old and new data must be specified, and search-and-replace procedures may or may not be sensitive to uppercase and lowercase, depending on the application program. See also search1, search and replace.


Request for Discussion

n. A formal proposal for a discussion concerning the addition of a newsgroup to the Usenet hierarchy, the first step in a process that ends with a call for votes. See also traditional newsgroup hierarchy, Usenet. Acronym: RFD.


reset button

n. A device that restarts a computer without turning off its power. Compare big red switch.



vb. To make an object or space larger or smaller. Also called scale.



n. 1. The fineness of detail attained by a printer or a monitor in producing an image. For printers that form characters from small, closely spaced dots, resolution is measured in dots per inch, or dpi, and ranges from about 125 dpi for low-quality dot-matrix printers to about 600 dpi for some laser and ink-jet printers (typesetting equipment can print at resolutions of over 1000 dpi). For a video display, the number of pixels is determined by the graphics mode and video adapter, but the size of the display depends on the size and adjustment of the monitor; hence the resolution of a video display is taken as the total number of pixels displayed horizontally and vertically. See the following table. See also high resolution, low resolution. k:\compdict\database\3050.doc 2. The process of translation between a domain name address and an IP address. See also DNS.



n. 1. Any part of a computer system or a network, such as a disk drive, printer, or memory, that can be allotted to a program or a process while it is running. 2. An item of data or code that can be used by more than one program or in more than one place in a program, such as a dialog box, a sound effect, or a font in a windowing environment. Many features in a program can be altered by adding or replacing resources without the necessity of recompiling the program from source code. Resources can also be copied and pasted from one program into another, typically by a specialized utility program called a resource editor.


resource file

n. A file that consists of resource data and the resource map that indexes it. See also resource (definition 2), resource fork.


resource fork

n. One of the two forks of an Apple Macintosh file (the other being the data fork). The resource fork of a program file contains reusable items of information that the program can use during the course of execution, such as fonts, icons, windows, dialog boxes, menus, and the program code itself. A user-created document typically stores its data in the data fork, but it can also use its resource fork for storing items that might be used more than once in the document. For example, in a HyperCard stack, the data that constitutes each card, or record, in the stack is stored in the data fork; digitized sounds and icons that might be used more than once are stored in the resource fork. The use of such resources makes program development easier because resources can be developed and altered independently of the program code. See also HyperCard, resource (definition 2). Compare data fork.


response time

n. 1. The time, often an average, that elapses between the issuance of a request and the provision of the data requested (or notification of inability to provide it). 2. The time required for a memory circuit or storage device to furnish data requested by the central processing unit (CPU).



n. The act of restoring a file or files. See also backup, recovery.



vb. To copy files from a backup storage device to their normal location, especially if the files are being copied to replace files that were accidentally lost or deleted.


Return key

n. A key on a keyboard that is used to terminate input of a field or record or to execute the default action of a dialog box. On IBM Personal Computers and compatibles, this key is called ENTER. The corresponding key on a typewriter causes the carriage holding the paper to return to the starting position to begin a new line; hence the name. See also Enter key.


reverse engineering

n. A method of analyzing a product in which the finished item is studied to determine its makeup or component parts, typically for the purpose of creating a copy or a competitive product--for example, studying a completed ROM chip to determine its programming or studying a new computer system to learn about its design.


reverse path forwarding

n. A technique that makes routing decisions through a TCP/IP network by using the source address of a datagram rather than the destination address. Reverse path forwarding is used in broadcast and multicast applications because it reduces redundant transmissions to multiple recipients. See also datagram, TCP/IP. Acronym: RPF.


reverse video

n. The reversal of light and dark in the display of selected characters on a video screen. For example, if text is normally displayed as white characters on a black background, reverse video presents text as black letters on a white background. Programmers commonly use reverse video as a means of highlighting text or special items (such as menu choices or the cursor) on the screen.



vb. To return to the last saved version of a document. Choosing this command tells the application to abandon all changes made in a document since the last time it was saved.


Revisable-Form-Text DCA

n. A standard within Document Content Architecture (DCA) for storing documents in such a way that the formatting can be changed by the receiver. A related standard is Final-Form-Text DCA. See also DCA. Compare Final-Form-Text DCA. Acronym: RFTDCA.



vb. To wind a magnetic tape spool or cassette to its beginning.


rewritable digital video disc

n. Technology for recording data on disks that have the same storage capacity as digital video discs (DVDs) but can be rewritten like compact disc-rewritable (CD-RW) devices. See also digital video disc, PD-CD drive.



vb. To write again, especially in situations where information is not permanently recorded, such as RAM or a video display. Also called refresh, regenerate. See also dynamic RAM.



n. Acronym for Restructured Extended Executor. A structured programming language used on IBM mainframes and with OS/2 Version 2.0. REXX programs invoke application programs and operating system commands.



n. Acronym for Request for Comments. A document in which a standard, a protocol, or other information pertaining to the operation of the Internet is published. The RFC is actually issued, under the control of the IAB, after discussion and serves as the standard. RFCs can be obtained from sources such as InterNIC.



n. Acronym for radio frequency interference. Noise introduced into an electronic circuit, such as a radio or television, by electromagnetic radiation produced by another circuit, such as a computer.


RF shielding

n. A structure, generally sheet metal or metallic foil, designed to prevent the passage of radio frequency (RF) electromagnetic radiation. RF shielding is intended to keep RF radiation either inside a device or out of a device. Without proper RF shielding, devices that use or emit RF radiation can interfere with each other; for example, running an electric mixer might cause interference on a television. Computers generate RF radiation and, to meet Federal Communications Commission (FCC) standards, must be properly shielded to prevent this RF radiation from leaking out. The metal case of a PC provides most of the needed RF shielding. Devices meeting FCC type A standards are suitable for business use. Devices meeting the more stringent FCC type B standards are suitable for home use. See also radio frequency, RFI.



n. Acronym for red-green-blue. A model for describing colors that are produced by emitting light, as on a video monitor, rather than by absorbing it, as with ink on paper. The three kinds of cone cells in the eye respond to red, green, and blue light, respectively, so percentages of these additive primary colors can be mixed to get the appearance of any desired color. Adding no color produces black; adding 100 percent of all three colors results in white. See also CMYK, RGB monitor. Compare CMY.


RGB monitor

n. A color monitor that receives its signals for red, green, and blue levels over separate lines. An RGB monitor generally produces sharper and cleaner images than those produced by a composite monitor, which receives levels for all three colors over a single line. See also RGB. Compare composite video display.


Rich Text Format

n. An adaptation of DCA (Document Content Architecture) that is used for transferring formatted text documents between applications, even those applications running on different platforms, such as between IBM and compatibles and Apple Macintoshes. See also DCA. Acronym: RTF.


right click

vb. To make a selection using the button on the right side of a mouse or other pointing device. Doing so in the Windows 95 environment typically brings up a pop-up menu with options applicable to the object over which the cursor is positioned. See also mouse, pointing device.


right justification

n. In typesetting, word processing, and desktop publishing, the process of aligning text evenly along the right margins of a column or page. The left edge of the text is ragged. See also justify (definition 1), rag. Compare full justification, left justification.



vb. To align lines of text and other display elements so that the right edges form a smooth line. See also align (definition 1), rag. Compare left-justify.


ring network

n. A local area network in which devices (nodes) are connected in a closed loop, or ring. Messages in a ring network pass around the ring from node to node in one direction. When a node receives a message, it examines the destination address attached to the message. If the address is the same as the node's, the node accepts the message; otherwise, it regenerates the signal and passes the message along to the next node in the ring. Such regeneration allows a ring network to cover larger distances than star and bus networks. The ring can also be designed to bypass any malfunctioning or failed node. Because of the closed loop, however, adding new nodes can be difficult. See also token passing, token ring network. Compare bus network, star network.



n. Acronym for reduced instruction set computing. A microprocessor design that focuses on rapid and efficient processing of a relatively small set of simple instructions that comprises most of the instructions a computer decodes and executes. RISC architecture optimizes each of these instructions so that it can be carried out very rapidly--usually within a single clock cycle. RISC chips thus execute simple instructions more quickly than general-purpose CISC (complex instruction set computing) microprocessors, which are designed to handle a much wider array of instructions. They are, however, slower than CISC chips at executing complex instructions, which must be broken down into many machine instructions that RISC microprocessors can perform. Families of RISC chips include Sun Microsystems' SPARC, Motorola's 88000, Intel's i860, and the PowerPC developed by Apple, IBM, and Motorola. See also architecture, SPARC. Compare CISC.



n. 1. A protocol used to log in to a networked computer in which the local system automatically supplies the user's login name. See also communications protocol, logon. Compare telnet1. 2. A UNIX command in BSD UNIX that enables a user to log in to a remote computer on a network using the rlogin protocol. See also BSD UNIX.



vb. To connect to a networked computer using the rlogin protocol.



adj. Able to function or to continue functioning well in unexpected situations.



Acronym for rolling on the floor, laughing. An expression, used mostly in newsgroups and online conferences, to indicate one's appreciation of a joke or other humorous circumstance. Also called ROTFL.


role-playing game

n. A game that is played online such as a MUD, in which participants take on the identities of characters that interact with each other. Often these games have a fantasy or science fiction setting and have a set of rules that all players need to follow. See also MUD.



n. A return to a previous stable condition, as when the contents of a hard disk are restored from a backup after a destructive hard disk error.



n. 1. Acronym for read-only memory. A semiconductor circuit into which code or data is permanently installed by the manufacturing process. The use of this technology is economically viable only if the chips are produced in large quantities; experimental designs or small volumes are best handled using PROM or EPROM. 2. Acronym for read-only memory. Any semiconductor circuit serving as a memory that contains instructions or data that can be read but not modified (whether placed there by manufacturing or by a programming process, as in PROM and EPROM). See also EEPROM, EPROM, PROM.



adj. Having upright rather than slanted characters in a typeface. See also font family. Compare italic.



n. Acronym for read-only memory basic input/output system. See BIOS.



n. The main or uppermost level in a hierarchically organized set of information. The root is the point from which subsets branch in a logical sequence that moves from a broad focus to narrower perspectives. See also leaf, tree.


root account

n. On UNIX systems, the account having control over the operation of a computer. The system administrator uses this account for system maintenance. Also called superuser. See also system administrator.


root directory

n. The point of entry into the directory tree in a disk-based hierarchical directory structure. Branching from this root are various directories and subdirectories, each of which can contain one or more files and subdirectories of its own. For example, in the MS-DOS operating system the root directory is identified by a name consisting of a single backslash character (\). Beneath the root are other directories, which may contain further directories, and so on.


root name

n. In MS-DOS and Windows, the first part of a filename. In MS-DOS and earlier versions of Windows, the maximum length of the root name was eight characters; in Windows NT and later versions of Windows, the root name may be as long as 255 characters. See also 8.3, extension (definition 1), filename, long filenames.


ROT13 encryption

n. A simple encryption method in which each letter is replaced with the letter of the alphabet 13 letters after the original letter, so that A is replaced by N, and so forth; N, in turn, is replaced by A, and Z is replaced by M. ROT13 encryption is not used to protect messages against unauthorized readers; rather, it is used in newsgroups to encode messages that a user may not want to read, such as sexual jokes or spoilers. Some newsreaders can automatically perform ROT13 encryption and decryption at the touch of a key.



vb. 1. To turn a model or other graphical image so that it is viewed at a different angle. 2. To move bits in a register to the left or to the right. The bit that moves out of the end position rotates to the newly vacated position at the opposite end of the register. Compare shift.


routable protocol

n. A communications protocol that is used to route data from one network to another by means of a network address and a device address. TCP/IP is an example of a routable protocol.



n. An intermediary device on a communications network that expedites message delivery. On a single network linking many computers through a mesh of possible connections, a router receives transmitted messages and forwards them to their correct destinations over the most efficient available route. On an interconnected set of local area networks (LANs) using the same communications protocols, a router serves the somewhat different function of acting as a link between LANs, enabling messages to be sent from one to another. See also bridge, gateway.



n. Any section of code that can be invoked (executed) within a program. A routine usually has a name (identifier) associated with it and is executed by referencing that name. Related terms (which may or may not be exact synonyms, depending on the context) are function, procedure, and subroutine. See also function (definition 3), procedure, subroutine.



n. A series of items arranged horizontally within some type of framework--for example, a continuous series of cells running from left to right in a spreadsheet; a horizontal line of pixels on a video screen; or a set of data values aligned horizontally in a table. Compare column.



n. Short for reprogrammable PROM. See EPROM.


RS-232-C standard

n. An accepted industry standard for serial communications connections. Adopted by the Electrical Industries Association, this Recommended Standard (RS) defines the specific lines and signal characteristics used by serial communications controllers to standardize the transmission of serial data between devices. The letter C denotes that the current version of the standard is the third in a series. See also CTS, DSR, DTR, RTS, RXD, TXD.


RSA encryption

n. Short for Rivest-Shamir-Adleman encryption. The patented public key encryption algorithm, introduced by Ronald Rivest, Adi Shamir, and Leonard Adleman in 1978, on which the PGP (Pretty Good Privacy) encryption program is based. See also PGP, public key encryption.



Acronym for read the manual. See RTFM.



vb. To execute a program.


run time

n. 1. The time period during which a program is running. See also compile time, dynamic allocation, dynamic binding, link time. 2. The amount of time needed to execute a given program.



adj. Occurring after a program has begun to be executed, such as evaluation of variable expressions and dynamic allocation of memory.


run-time error

n. A software error that occurs while a program is being executed, as detected by a compiler or other supervisory program.


run-time library

n. A file containing one or more prewritten routines to perform specific, commonly used functions. A run-time library, used primarily in high-level languages such as C, saves the programmer from having to rewrite those routines.