R&D ~ registration marks
A/B Switch box ~ America On-line AMI BIOS ~ Arithmetic Operation ARP ~ AVI Backbone ~ Bit Image Bit Map ~ Boot Disk Boot Drive ~ Bytes Per Inch C++ ~ Carrier Frequency carrier system ~ certification CGI ~ Chooser extension cipher ~ Clipper Chip clock ~ color color bits ~ communications satellite communications server ~ computer security CON ~ copy copy program ~ cycle time daemon ~ defragmentation demand paging ~ digitize DikuMUD ~ disk disk buffer ~ Document Style Semantics and Specification Language document window ~ dynamic Web page Easter egg ~ erase erase head ~ ezine F2F ~ finger2 firewall ~ font suitcase footer ~ FYI Game Control Adapter ~ GUI HAL ~ hot key1 hot key2 ~ Hz i486DX ~ internal modem internet ~ ISO 9660 ISO/OSI model ~ just-in-time K1 ~ knowledge base L1 cache ~ LU luggable computer ~ LZW compression MAC ~ MILNET mime ~ msec MTBF ~ MYOB named anchor ~ network drive Network File System ~ number crunching object ~ overwrite mode P5 ~ PC/XT keyboard PDA ~ pipeline processing piracy ~ preventive maintenance preview ~ pwd quasi-language ~ QWERTY keyboard R&D ~ registration marks Registry ~ RFI RF shielding ~ run-time library SAA ~ server error server push-pull ~ soft return software ~ style sheet stylus ~ System T1 ~ ToggleKeys token ~ typography UART ~ uupc V.120 ~ view2 viewer ~ VxD w3 ~ WinG WINS ~ WWW X.25 ~ X Windows Yahoo! ~ yotta- Z39.50 standard ~ Zulu time
R&D
n. Acronym for research and development.
rack-mounted
adj. Built for installation in a metal frame or cabinet of standard width (typically 19 inches or 23 inches) and mounting arrangements.
RAD
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).
RADIUS
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).
RAID
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).
RAM
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.
RAS
n. See remote access server, Remote Access Service.
raster
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.
rasterization
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.
read1
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.
read2
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.
README
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.
read-only
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.
read/write
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.
RealAudio
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.
reallocate
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.
real-time
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.
reboot
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.
receive
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.
recompile
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.
record1
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).
record2
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.
redirection
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.
redlining
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.
redraw
n. See refresh (definition 1).
reduced instruction set computing
n. See RISC.
redundancy check
n. See CRC, LRC.
reengineer
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.
reference2
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.
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.
reformat***
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.
refresh
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.)
REGEDIT
n. See also Registry. See registry editor.
register
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).
registration
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.
A/B Switch box ~ America On-line AMI BIOS ~ Arithmetic Operation ARP ~ AVI Backbone ~ Bit Image Bit Map ~ Boot Disk Boot Drive ~ Bytes Per Inch C++ ~ Carrier Frequency carrier system ~ certification CGI ~ Chooser extension cipher ~ Clipper Chip clock ~ color color bits ~ communications satellite communications server ~ computer security CON ~ copy copy program ~ cycle time daemon ~ defragmentation demand paging ~ digitize DikuMUD ~ disk disk buffer ~ Document Style Semantics and Specification Language document window ~ dynamic Web page Easter egg ~ erase erase head ~ ezine F2F ~ finger2 firewall ~ font suitcase footer ~ FYI Game Control Adapter ~ GUI HAL ~ hot key1 hot key2 ~ Hz i486DX ~ internal modem internet ~ ISO 9660 ISO/OSI model ~ just-in-time K1 ~ knowledge base L1 cache ~ LU luggable computer ~ LZW compression MAC ~ MILNET mime ~ msec MTBF ~ MYOB named anchor ~ network drive Network File System ~ number crunching object ~ overwrite mode P5 ~ PC/XT keyboard PDA ~ pipeline processing piracy ~ preventive maintenance preview ~ pwd quasi-language ~ QWERTY keyboard R&D ~ registration marks Registry ~ RFI RF shielding ~ run-time library SAA ~ server error server push-pull ~ soft return software ~ style sheet stylus ~ System T1 ~ ToggleKeys token ~ typography UART ~ uupc V.120 ~ view2 viewer ~ VxD w3 ~ WinG WINS ~ WWW X.25 ~ X Windows Yahoo! ~ yotta- Z39.50 standard ~ Zulu time