Microsoft Press computer dictionary fifth edition phần 8 doc

read1 real mode 440 R read 1 n. The action of transferring data from an input source into a computer’s memory or from memory into the CPU (central processing unit). Compare write 1 . read 2 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 write 2 . read-after-write n. A feature of certain data storage devices, such as tape drives, in which the device reads data immediately after it is written as a means of verifying data integrity. reader n. See card reader. Reader n. See Microsoft Reader. read error n. An error encountered while a computer is in the process of obtaining information from storage or from another source of input. Compare write error. 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 notification n. An e-mail feature providing feed- back to the sender that a message has been read by the recipient. 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. A file attribute, stored with a file’s directory entry, 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-only memory n. See ROM. read-only terminal n. See RO terminal. read/write adj. Able to be both read from and written to. Abbreviation: R/W. Compare read-only. read/write channel n. See input/output channel. read/write head n. See head. 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 specify- ing a physical location in memory. See also physical address. Compare relative address, virtual address. RealAudio n. Streaming audio technology developed by RealNetworks, Inc., for distributing radio and FM-quality sound files over the Internet in real time. RealAudio is based on two components: client software for decompress- ing the sound on the fly and server software for delivering it. The client software is free, distributed either as a down- loadable program or as part of browser software. See also RealPlayer, RealVideo, stream, streaming. reallocate n. A function in C that allows the programmer to request a larger portion of heap memory than was previ- ously assigned to a particular pointer. See also dynamic memory allocation, heap (definition 1). reallysafe palette n. A color look-up table (CLUT) con- sisting of 22 colors from the 216-color websafe palette that are completely consistent when viewed with all Web browsers on all major computer platforms. The reallysafe palette arose from an experiment that indicated that most of the colors of the websafe palette shift to some degree in different viewing environments. See also browser CLUT, websafe palette. 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. read real-mode mapper real-time conferencing 441 R 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 number n. 1. A number that can be represented in a number system with a given base, such as the decimal system, by a finite or infinite sequence of digits and a radix point. For example, 1.1 is a real number, as is 0.33333 See also irrational number. Compare complex number, imaginary number. 2. A data type, in a programming language such as Pascal, that is used for storing, to some limit of precision, values that include both integer and frac- tional parts. See also double-precision, single-precision. Compare floating-point number, integer. RealPlayer n. An Internet media player and browser plug-in developed by RealNetworks, Inc., that supports playback of RealAudio and RealVideo, as well as certain other formats, after installation of appropriate plug-ins. The current version allows RealPlayer users to surf for media content directly from the player or through a Web browser. See also RealAudio, RealVideo. Real Soon Now adv. Soon, but not really expected to be as soon as claimed. One might say, for example, that a commercial program will have some desired feature Real Soon Now if several versions ago the vendor knew of the need for the feature and has done nothing. Acronym: RSN. real storage n. The amount of RAM memory in a system, as distinguished from virtual memory. Also called: physical memory, physical storage. See also virtual memory. RealSystem G2 n. An open, standards-based platform for delivery of streaming audio and video over the Internet and other TCP/IP networks developed by RealNetworks, Inc. RealSystem G2 was introduced by RealNetworks in its audio and video players, servers, and development tools in 1998. Among other features, RealSystem G2 scales to different bandwidths, includes streaming that adjusts delivery to available bandwidth, and supports SMIL (Synchronized Multimedia Integration Language) for multimedia presentations. See also RealPlayer, RealVideo, SMIL, streaming. RealSystem Producer n. A software application developed by RealNetworks that converts most types of video and sound files into RealMedia formats for use as streaming media over the Internet or within a corporate intranet. RealSystem Server n. Software developed by RealNet- works to enable a server to broadcast streaming media. Several versions of RealSystem Server are available, designed to meet needs ranging from small intranet servers to large proxy servers. 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 percep- tion of time or those in which computer operations pro- ceed at the same rate as a physical or external process. Real-time operations are characteristic of aircraft guid- ance systems, transaction-processing systems, scientific applications, and other areas in which a computer must respond to situations as they occur (for example, animat- ing 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 clock n. In PCs, a circuit or other hardware element that provides the system with real-world time. Upon startup of the system, the real-time clock puts the date and time in memory, where it can then be systematically incre- mented by the BIOS. A real-time clock generally has a battery that is separate from the rest of the system, so it’s not dependent upon the system’s power source. This is not the same thing as a system clock, which synchronizes the processor. Acronym: RTC. See also clock (definition 2). real-time conferencing n. See teleconferencing. Real-Time Control Protocol record1 442 R Real-Time Control Protocol n. A scalable transport control protocol that works with the Real-Time Protocol (RTP) to monitor real-time transmissions to multiple par- ticipants over a network—for example, during videocon- ferencing. The Real-Time Control Protocol, or RTCP, transmits packets of control information at regular inter- vals and is used to determine how well information is being delivered to recipients. Acronym: RTCP. See also Real-Time Protocol, Real-Time Streaming Protocol, Resource Reservation Setup Protocol. real-time operating system n. An operating system designed for the needs of a process-controlled environ- ment. A real-time operating system recognizes that responses must be made and tasks handled instantly, with no lag time. Real-time operating systems are typically used as embedded systems in devices and applications requiring time-critical reaction, such as telecommunications, air traffic control, and robotic functions. Acronym: RTOS. See also real-time system. Real-Time Protocol n. An Internet-standard network transport protocol used in delivering real-time data, includ- ing audio and video. The Real-Time Protocol, or RTP, works with both unicast (single sender, single recipient) and multicast (single sender, multiple recipients) services. RTP is often used in conjunction with the Real-Time Control Protocol (RTCP), which monitors delivery. Acronym: RTP. See also Real-Time Control Protocol, Real-Time Streaming Protocol, stream. real-time streaming n. The process of delivering a streaming media file via a specialized streaming media server using real-time streaming protocol (RTSP). With real-time streaming, the file itself actually plays on the streaming media server, even though it is viewed on the computer that opened the file. Real-time streaming transmits at a higher bandwidth than HTTP streaming. It is often used to broadcast live events, such as concerts or keynote conference addresses. See also HTTP streaming. Real-Time Streaming Protocol n. A control protocol for the delivery of streamed multimedia data over Internet Protocol (IP) networks. The Real-Time Streaming Proto- col, or RTSP, was developed by Columbia University, Pro- gressive Networks, and Netscape and has been submitted as a proposed standard to the IETF (Internet Engineering Task Force). RTSP is designed to deliver real-time, live, or stored audio and video efficiently over a network. It can be used either for groups of recipients or for on-demand delivery to a single recipient. Acronym: RTSP. See also Advanced Streaming Format, Real-Time Protocol, Resource Reservation Setup Protocol, stream. real-time system n. A computer and/or a software system that reacts to events before the events become obso- lete. For example, airline collision avoidance systems must process radar input, detect a possible collision, and warn air traffic controllers or pilots while they still have time to react. RealVideo n. The streaming technology developed by RealNetworks, Inc., for distributing video over intranets and the Internet. RealVideo transmits video from a server in encoded (compressed) form. The video and accompa- nying sound are viewed on the client end with the help of a software player. RealVideo works with both IP and IP multicasting and, as with RealAudio, does not require transmission of complete files before playback can begin. See also RealAudio, RealPlayer, streaming. reboot vb. To restart a computer by reloading the operating system. See also boot 2 , cold boot, warm boot. receipt notification n. An e-mail feature providing feed- back 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. Receive Data n. See RXD. 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. record 1 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 record record2 red-green-blue 443 R unit of elements, or the elements can be accessed individu- ally. See also array, data structure, type 1 (definition 1). record 2 vb. To retain information, usually in a file. record format n. See record structure. record head n. The device in a tape machine that places data on the tape. In some tape machines, the record head is combined with the read head. record layout n. The organization of data fields within a record. See also record 1 . record length n. The amount of storage space required to contain a record, typically given in bytes. See also record 1 . 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 record 1 . record number n. A unique number assigned to a record in a database in order to identify it. A record number can identify an existing record by its position (for example, the tenth record from the beginning of a database), or it can be assigned to the record to serve as a key (for example, the number 00742 assigned to the tenth record from the beginning of the database). See also record 1 . record structure n. An ordered list of the fields that compose a record, together with a definition of the domain (acceptable values) of each field. See also record 1 . recover vb. 1. To return to a stable condition after some error has occurred. A program recovers from an error by stabilizing itself and resuming execution of instructions without user intervention. 2. To put back into a stable condition. A computer user may be able to recover lost or damaged data by using a program to search for and sal- vage whatever information remains in storage. A database may be recovered by restoring its integrity after some problem has damaged it, such as abnormal termination of the database management program. recoverable error n. An error that can be successfully managed by software. For example, when the user enters a number when a letter is required, the program can simply display an error message and prompt the user again. recovery n. The restoration of lost data or the reconcilia- tion of conflicting or erroneous data after a system failure. Recovery is often achieved using a disk or tape backup and system logs. See also backup. Recreational Software Advisory Council n. An independent, nonprofit organization established in the fall of 1994 by a group of six trade organizations, led by the Soft- ware Publishers Association. The Council’s goal was to create a new, objective content-labeling rating system for recreational software and other media such as the Internet. Acronym: RSAC. rectangle ad n. An Internet ad format that is larger than a traditional banner ad and is generally inserted directly into page content for greater visibility. rectifier n. A circuit component that passes current flowing in one direction but stops current flowing in the other direction. Rectifiers are used to convert alternating current to direct current. recto n. The right-hand page of two facing pages. A recto is characteristically an odd-numbered page. Compare verso. recursion n. The ability of a routine to call itself. Recur- sion enables certain algorithms to be implemented with small, simple routines, but it does not guarantee speed or efficiency. Erroneous use of recursion can cause a program to run out of stack space during execution, causing the program, and sometimes the entire system, to crash. See also call 1 (definition 2), routine. Recycle Bin n. A folder in Windows 9x, Windows CE, Windows NT, Windows 2000, and Windows XP represented by an icon on the screen resembling a basket deco- rated 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 Delete key; until then, the user can retrieve it. Com- pare Trash. Red Book n. 1. The standards documents of the U.S. National Security Agency entitled “Trusted Network Interpretation of the Trusted Computer System Evalua- tion Criteria (NCSC-TG-005)” and “Trusted Network Interpretation (NCS-TG-011).” These documents define a system of ratings from A1 (most secure) to D (nonse- cure), indicating the ability of a computer network to pro- tect sensitive information. Compare Orange Book (definition 1). 2. A specifications book written by the Sony Corporation and Philips Corporation and endorsed by ISO, covering audio compact discs. Compare Green Book, Orange Book (definition 2). 3. Telecommunications standards published by the CCITT. red-green-blue n. See RGB. record redirection reformat 444 R 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. redirector n. Software on a client computer that inter- cepts requests for information and, when appropriate, directs them to the network. Redirectors can either be built into the client operating system or be part of an added net- working package. 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). reduce vb. In a graphical user interface, to decrease the size of a window. A user can reduce a window either by clicking the appropriate button in the title bar or by clicking the mouse on the border of the window and dragging the border toward the middle of the window. See also maximize, minimize. Reduced Instruction Set Computing n. See RISC. redundancy n. Using one or more servers on a Web site to perform identical tasks. If one of the servers crashes, another server assumes its tasks. Redundancy ensures that the Web site will continue to function if one of the servers stops working. redundancy check n. See CRC, LRC. redundant code n. Code that duplicates a function per- formed elsewhere—for example, code to sort a list that has already been sorted. 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. reengineering vb. 1. With regard to software, changing existing software to strengthen desirable characteristics and remove weaknesses. 2. With regard to corporate management, using information technology principles to address the challenges posed by a global economy and to consoli- date management of a rapidly expanding work force. 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. refactoring n. An optimization process in object-oriented programming intended to improve the design or structure of a program without changing its functionality. The goal of refactoring is to make the program clearer and easier to work with—in part by removing duplication, abstracting common behaviors, and refining class hierarchies—and to improve the extensibility and reusability of existing code. reference 1 n. A data type in the C++ programming language. A reference must be initialized with a variable name. The reference then becomes an alias for that variable but actually stores the address of the variable. reference 2 vb. To access a variable, such as an element in an array or a field in a record. reference parameter n. A parameter in which the address of a variable, rather than the explicit value, is passed to the called routine. See also parameter. reference type n. A data type that is represented by a reference (similar to a pointer) to the type’s actual value. If a reference type is assigned to a variable, that variable references (or “points to”) the original value. No copy is made. Reference types comprise classes, interfaces, delegates, and boxed value types. See also data type, value type. reflecting software n. See reflector. reflective liquid-crystal display n. A liquid crystal display that is not equipped with edge light or backlight to enhance readability but rather depends on reflecting ambi- ent 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 for- wards any e-mail sent to it to the multiple recipients cur- rently 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 refresh registry 445 R reuse a disk that already contains programs or data, effec- tively destroying the existing contents. refresh vb. 1. To retrace a video screen at frequent inter- vals, 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. refreshable adj. In programming, referring to a program module capable of being replaced in memory without affecting processing of the program or the information being used by the program. 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 main- tain 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. See also refresh (definition 1). REGEDIT n. See Registry Editor. regenerate vb. See rewrite. regeneration buffer n. See video buffer. regenerator n. See repeater. region n. 1. An area dedicated to or reserved for a particular purpose. 2. In video programming, a contiguous group of pixels that are treated as a unit. On the Apple Macin- tosh, for example, a region is an area in a grafPort that can be defined and manipulated as an entity. The visible working area within a window is an example of a region. See also grafPort. region code n. Codes on DVD movie titles and DVD- ROM drives that prevent playback of certain DVDs in certain geographical regions. Region codes are part of the DVD specification. See also CSS, DeCSS. region fill n. In computer graphics, the technique of fill- ing a defined region on the screen with a selected color, pattern, or other attribute. See also region (definition 2). 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). registered file type n. File types that are tracked by the system registry and are recognized by the programs you have installed on your computer. See also file type. 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. See the illustration. F0Rgn 04.EPS Registration marks. registry n. A central hierarchical database in Windows 9x, Windows CE, Windows NT, and Windows 2000 used to store information necessary to configure the system for one or more users, applications, and hardware devices. The Registry contains information that Windows continu- ally references during operation, such as profiles for each user, the applications installed on the computer and the types of documents each can create, property sheet set- tings 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 Reg- istry is common to the several Windows platforms, there Registry Editor relative address 446 R are some differences among them. Also called: system registry. See also hierarchical database, .ini, input/output port, property sheet, Registry Editor. Registry Editor n. An application under Windows that allows the user to edit the entries in the registry. Acronym: REGEDIT. See also registry. 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. relation n. A structure composed of attributes (individual characteristics, such as name or address, corresponding to the columns in a table) and tuples (sets of attribute values describing particular entities, such as customers, corresponding to the rows in a table). Within a relation, tuples cannot be repeated; each must be unique. Further, tuples are unordered within a relation; interchanging two tuples does not change the relation. Finally, if relational theory is to be applicable, the domain of each attribute must be atomic— that is, a simple value, rather than a structure such as an array or a record. A relation in which the domains of all attributes are atomic is said to be normalized or in first normal form. See also normal form (definition 1). relational algebra n. A collection of rules and operators that permits relations (tables) to be manipulated. Rela- tional algebra is usually described as having the following operators: SELECT, PROJECT, PRODUCT, UNION, INTERSECT, DIFFERENCE, JOIN (or INNER JOIN), and DIVIDE. In a relational database, relational algebra is used to develop procedures to build new relations based on the existing relations. relational calculus n. In database management, a non- procedural method for manipulating relations (tables). There are two families of relational calculus: domain calculus and tuple calculus. The two families of relational calculus are mathematically equivalent to each other and to relational algebra. Using either family, one can formu- late a description of a desired relation, based on the existing relations in the database. 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. relational database management system n. See relational database. relational expression n. An expression that uses a relational operator such as “less than” or “greater than” to compare two or more expressions. A relational expression resolves to a Boolean (true/false) value. See also Boolean, relational operator. relational model n. A data model in which the data is organized in relations (tables). This is the model implemented in most modern database management systems. relational operator n. An operator that allows the programmer to compare two (or more) values or expressions. Typical relational operators are greater than (>), equal to (=), less than (<), not equal to (<>), greater than or equal to (>=), and less than or equal to (<=). See also relational expression. relational structure n. The record organization used in the implementation of a relational model. 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 relative coordinates reliability 447 R 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 recalculat- ing the coordinates of each corner with reference to the origin. See the illustration. Compare absolute coordinates. F0Rxx05 .eps Relative 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 cinematogra- phy, 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 path n. A path that is implied by the current working directory. When a user enters a command that refers to a file, if the full pathname is not entered the current working directory becomes the relative path of the file referred to. Compare full path. relative pointing device n. A cursor-control device, such as a mouse or a trackball, in which the movement of an on- screen cursor is linked to the movement of the device but not to the position of the device. For example, if a user picks up a mouse and puts it down in a different location on a desk, the position of the on-screen cursor does not change because no movement (rolling) is detected. When the user rolls the mouse again, the cursor moves to reflect the mouse movement against the surface of the desk. Relative pointing devices differ from absolute pointing devices, such as graphics tablets, in which the device’s location within a defined area is always associated with a predefined on- screen position. See also relative coordinates, relative movement (definition 1). Compare absolute pointing device. relative URL n. Short for relative uniform resource loca- tor. 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. Acronym: RELURL. See also file extension, URL. RELAX NG n. An XML schema language based on Tree Regular Expressions for XML (TREX) and Regular Lan- guage Description for XML (RELAX). RELAX NG supports XML namespaces, uses XML syntax, maintains the information set of the XML document, and provides unre- stricted support for mixed or unordered content. relay 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. release 1 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 alpha 2 , beta 2 . release 2 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. reliability n. The likelihood of a computer system or device continuing to function over a given period of time and under specified conditions. Reliability is measured by different performance indexes. For example, the reliability of a hard disk is often given as mean time between failures (MTBF): the average length of time the disk can be expected to function without failing. See also MTBF, MTTR. Point at relative coordinate (2,3) from the point below x-axis y-axis Origin Reference point reliability, availability, serviceability remote login 448 R reliability, availability, serviceability n. Acronym: RAS. See high availability. reload 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 inter- rupted. 2. To retrieve a new copy of the Web page cur- rently visible in a Web browser. relocatable address n. In programming, an address that is to be adjusted to reflect the actual place in memory into which a program is loaded for execution. In “Get the byte located 12 bytes from this instruction,” the address is relocatable; in “Get the byte located at address 255,” the address is not relocatable. This convention is comparable to describing the “address” of a parked car as “level 2, row G” on one day and “level 5, row B” on another. relocatable code n. A program written in such a way that it can be loaded into any part of available memory rather than having to be placed in one specific location. In relocatable code, address references that depend on the program’s physical location in memory are calculated at run time so that program instructions can be carried out correctly. See also reentrant code. relocate n. To move programs and blocks of memory about within available space so as to use memory resources flexibly and efficiently. A relocatable program can be loaded by the operating system into any part of available memory rather than into only one specific area. A relocatable block of memory is a portion of memory that can be moved around by the operating system as required; for example, the system might collect several available, relocatable blocks of memory to form one larger block of the size requested for use by a program. RELURL n. See relative URL. remailer n. A service that will forward e-mail while con- cealing the e-mail address of the originator of the message. Remailers may be used by individuals who wish to retain their privacy or avoid unsolicited commercial e-mail (UCE). Remailers may also be used to hide the identities of individuals and businesses sending spam or malicious or fraudulent e-mail. remark n. See comment, REM statement. remote 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 LAN (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. Acronym: RAS. See also remote access. remote administration n. The performance of system administration–related tasks via access from another machine in a network. Remote Application Programming Interface n. A Remote Procedure Call (RPC) mechanism that enables an application running on a desktop computer to make function calls on a Windows CE–based device. The desktop computer is known as the Remote Application Program- ming Interface (RAPI) client, and the Windows CE device is known as the RAPI server. RAPI runs over Winsock and TCP/IP. Acronym: RAPI. See also remote procedure call. Remote Authentication Dial-In User Service n. See RADIUS. remote communications n. Interaction with a remote computer through a telephone connection or another communications line. remote computer system n. See remote system. Remote Data Objects n. An object-oriented data access tool featured in Visual Basic 4 and later. Remote Data Objects have no native file format of their own; they can be used only with databases complying with the most recent ODBC standards. This feature is popular for its speed and minimal coding requirements. Acronym: RDO. See also ODBC, Visual Basic. Remote Installation Services n. Software services that allow an administrator to set up new client computers remotely, without having to visit each client. The target clients must support remote booting. Acronym: RIS. 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 Inter- remote monitoring replace 449 R net, remote login is done primarily by rlogin and telnet. See also rlogin 1 (definition 1), telnet 1 . remote monitoring n. See RMON. remote network monitoring n. See RMON. Remote PC n. See remote system. 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. remote terminal n. A terminal that is located at a site removed from the computer to which it is attached. Remote terminals rely on modems and telephone lines to communicate with the host computer. See also remote access. Compare remote system. 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. rename 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. render vb. To produce a graphic image from a data file on an output device such as a video display or printer. rendering 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. The degree of realism can range from opaque, shaded poly- gons to images approximating photographs in their com- plexity. See also ray tracing. RenderMan Shading Language n. A C-like graphics and rendering language developed by Pixar. repaginate vb. To recalculate the page breaks in a document. Repeat 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. repeat counter n. A loop counter; typically, a register that holds a number representing how many times a repetitive process has been or is to be executed. Repeat delay n. A delay for the amount of time that elapses before a character begins repeating when you hold down a key. repeater 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 reference model and regenerates the signal. repeating Ethernet n. See repeater. repeat key n. On some keyboards, a key that must be held down at the same time as a character key to cause the character key’s key code to be sent repeatedly. On most computer keyboards, however, a repeat key is not needed because a key automatically repeats if held down for longer than a brief delay. Compare typematic. RepeatKeys n. A feature of Windows 9x and Windows NT that allows a user to adjust or disable the typematic keyboard feature so as to accommodate users with restricted mobility, who may activate typematic by accident because they have trouble lifting their fingers from the keys. See also typematic. Compare BounceKeys, FilterKeys, MouseKeys, ShowSounds, SoundSentry, StickyKeys, ToggleKeys. 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. Acronym: RSI. See also carpal tunnel syn- drome, ergonomic keyboard, wrist support. replace 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 [...]... zero R 461 S S-100 bus n A 100-pin bus specification used in the design of computers built around the Intel 80 80 and Zilog Z -80 microprocessors System designs using the Motorola 680 0, 680 00, and Intel iAPx86 family of microprocessors have also been built around the S-100 bus S-100 computers were extremely popular with early computer enthusiasts They had an open architecture, which permitted the configuration... highly responsive, they execute quickly, thereby reducing system overhead Also called: serverlet See also applet, CGI Client pull Send doc1 doc1 Send doc2 doc2 doc1 doc2 Server service bureau n 1 A company that provides various services related to publishing, such as prepress production, desktop publishing, typesetting, imagesetting, and optical scanning of graphics 2 An organization that provides data... for the research and development department at many software and computer companies See also applet, Java Virtual Machine satellite computer n A computer that is connected to another computer, with which it interacts over a communications link As its name indicates, a satellite computer is of lesser “stature” than the main, or host, computer; the host controls either the satellite itself or the tasks... protocol, OSPF 2 See raster image processor RISC86 n A “hybrid” microprocessor technology in which CISC (Complex Instruction Set Computing) instructions are translated into RISC (Reduced Instruction Set Computing) instructions for processing RISC86 is designed to support the 80 x86 CISC architecture while providing the speed gains characteristic of RISC technology RISC86 was developed by NexGen and is implemented... sensor or a microphone Analog-to-digital converters are used in computers to sample analog signals as voltages and convert them to the binary form a computer can process The two primary characteristics of this type of sampling are the sampling rate (usually expressed in samples per second) and the sampling precision (expressed in bits; 8- bit samples, for instance, can measure an input voltage accurate... home use See also radio frequency, RFI revert 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... Acronym for Systems Application Architecture An IBM-developed standard for the appearance and operation of application software that will give programs written for all IBM computers—mainframe computers, minicomputers, and personal computers—a similar look and feel SAA defines how an application interfaces with both the user and the supporting operating system True SAA-compliant applications are compatible... X Window System ROM emulator n Short for read-only memory emulator A special circuit containing RAM memory that is connected to a target computer in place of the target computer s ROM chips A separate computer writes the contents into the RAM, and then the target computer reads the RAM as if it were ROM ROM emulators are used to debug ROM-resident software without the high cost and delay of manufacturing... more compressed text or data files When a user runs the program, it uncompresses the compressed files and stores them on the user’s hard drive See the illustration segmented instruction addressing n See segmented addressing architecture segmented memory architecture n See segmented addressing architecture 471 S self-modifying code sensor glove CANARY is a BIRD has logview.exe FEATHERS F0Sgn 08. eps logvu.exe... RISC microprocessors can perform Families of RISC chips include Sun Microsystems’ SPARC, Motorola’s 88 000, Intel’s i860, and the PowerPC developed by Apple, IBM, and Motorola See also architecture, SPARC Compare CISC RIP n 1 Acronym for Routing Information Protocol An Internet protocol, defined in RFC 10 58, that defines the exchange of routing table information Through RIP, each router on a network sends . mode is the only mode possible in the 80 86 processor and is the only operating mode supported by MS-DOS. In contrast, the protected mode offered in the 80 286 and higher microprocessors provides. database. relational expression n. An expression that uses a relational operator such as “less than” or “greater than” to compare two or more expressions. A relational expression resolves to. Micro- systems’ SPARC, Motorola’s 88 000, Intel’s i860, and the PowerPC developed by Apple, IBM, and Motorola. See also architecture, SPARC. Compare CISC. RISC86 n. A “hybrid” microprocessor technology

Định dạng
Số trang	64
Dung lượng	0,93 MB