MICROSOFT Computer Dictionary, Fifth Edition

Microsoft Computer Dictionary, Fifth Edition

n. See RLE.

run-length limited encoding

n. A fast and highly efficient method of storing data on a disk (usually a hard disk) in which patterns in the bits representing information are translated into codes rather than being stored literally bit by bit and character by character. In RLL encoding, changes in magnetic flux are based on the number of zeros that occur in sequence. This scheme allows data to be stored with fewer changes in magnetic flux than would otherwise be needed for the number of data bits involved and results in considerably higher storage capacity than is possible with older technologies, such as frequency modulation (FM) and modified frequency modulation (MFM) encoding. Abbreviation: RLL encoding. Compare frequency modulation encoding, modified frequency modulation encoding.

running foot

n. One or more lines of text in the bottom margin area of a page, composed of one or more elements such as the page number, the name of the chapter, and the date. Also called: footer.

running head

n. One or more lines of text in the top margin area of a page, composed of one or more elements such as the page number, the name of the chapter, and the date. Also called: header.

RUNOFF

n. A very early text editor/text formatting program, developed by J. E. Saltzer at M.I.T. for the CTSS (Compatible Time-Sharing System) operating system in the mid-1960s, in order to format his Ph.D. thesis. RUNOFF was the ancestor of many other text processors, including TeX, and the UNIX programs roff, nroff, and troff.

run-time

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

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.

runtime

n. See common language runtime.

run-time binding

n. Assignment of a meaning to an identifier (such as a variable) in a program at the time the program is executed rather than at the time the program is compiled. Compare compile-time binding, link-time binding.

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.

run-time version

n. 1. Program code that is ready to be executed. Generally, this code has been compiled and can operate without error under most user command sequences and over most ranges of data sets.

Microsoft Computer Dictionary, Fifth Edition

2. A special release that provides the computer user with some, but not all, of the capabilities available in the full-fledged software package.

R/W

adj. See read/write.

RXD

n. Short for Receive (rx) Data. A line used to carry received serial data from one device to another, such as from a modem to a computer. Pin 3 is the RXD line in RS-232-C connections. See also RS-232-C standard. Compare TXD.

RZ

n. See return to zero.

S: S-100 bus - System V

S-100 bus

n. A 100-pin bus specification used in the design of computers built around the Intel 8080 and Zilog Z-80 microprocessors. System designs using the Motorola 6800, 68000, 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 of systems with a wide range of add-on expansion boards.

SA

n. Identifier for Intel’s line of RISC-based microprocessors for portable and embedded devices. See also StrongARM.

SAA

n. 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 at the source level (before being compiled) with any SAA-compliant operating system—provided the system is capable of furnishing all the services required by the application.

Sad Mac

n. An error indication that occurs on Apple Macintosh computers when the system fails the initial diagnostic test. A Sad Mac is a picture of a Macintosh with a frowning face and X’s for eyes, with an error code beneath the picture.

safe mode

n. In some versions of Windows, such as Windows 95, a boot mode that bypasses startup files and loads only the most basic drivers. Safe mode allows the user to correct some problem with the system—for example, if the system fails to boot or the registry has become corrupted. See also boot1.

salt

n. Random data used to supplement encryption schemes. A salt value allows two identical packets of data to be encrypted into two different packets of ciphertext using the same key by changing the salt value with each packet. Also called: salt string, salt value.

Samba

n. A popular freeware program that provides file and print services, authentication and authorization, name resolution, and service announcement (browsing). As a file server, Samba

Microsoft Computer Dictionary, Fifth Edition

enables the sharing of files, printers, and other resources on a UNIX Samba server with Windows clients over a network. Based on the Server Message Block (SMB) protocol, Samba originally was developed as a Network File System (NFS) for UNIX by Andrew Tridgell. See also NFS, SMB.

sampling

vb. 1. In statistics, gathering data from a representative subset of a larger group (called a population)— for example, determining a country’s presumed voting pattern by polling a demographic cross section of voters. Other uses of this type of sampling might include checking the accuracy and efficiency of computerized transactions by reviewing every hundredth transaction or predicting traffic volumes by measuring traffic flow in a few strategic streets. There are many statistical procedures for estimating how accurately a given sample reflects the behavior of a group as a whole. 2. The conversion of analog signals to a digital format; samples are taken at periodic intervals to measure and record some parameter, such as a signal from a temperature 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 to 1/256 of the measured range).

sampling rate

n. The frequency with which samples of a physical variable, such as sound, are taken. The higher the sampling rate (that is, the more samples taken per unit of time), the more closely the digitized result resembles the original. See also sampling (definition 2).

sampling synthesizer

n. A device designed to reproduce sounds, at differing frequencies, based on a digitized sound stored in read-only memory. For example, a recorded piano note, digitized and stored in memory, is used by the synthesizer to create other piano-like notes.

samurai

n. A hacker employed by a company or organization to manage network security or conduct legal cracking operations. A samurai uses the skills of a hacker to meet the legitimate needs of an employer.

SAN

n. See storage area network.

sandbox

n. 1. Java Virtual Machine security area for downloaded (remote or untrusted) applets, an area in which such applets are confined and prevented from accessing system resources. Confinement to the sandbox prevents downloaded applets from carrying out potentially dangerous operations, maliciously or otherwise. They have to “play” inside the sandbox, and any attempt to “escape” is thwarted by the Java Security Manager. 2. Slang for the research and development department at many software and computer companies. See also applet, Java Virtual Machine.

sans serif

adj. Literally, “without stroke”; describes any typeface in which the characters have no serifs (the short lines or ornaments at the upper and lower ends of the strokes). A sans serif typeface usually possesses a more straightforward, geometric appearance than a typeface with serifs and typically lacks the contrast between thick and thin strokes found in serif faces. Sans serif typefaces are used more frequently in display type, such as headlines, than in blocks of text. Compare serif1.

SAOL

Microsoft Computer Dictionary, Fifth Edition

n. Acronym for Structured Audio Orchestra Language. Part of the MPEG-4 standard, SAOL describes a set of tools for producing computer music, audio for computer games, streaming Internet sound or music, and other multimedia applications. SAOL is a flexible computer language for describing music synthesis and integrating synthetic sound with recorded sound in an MPEG- 4 bit stream. See also bit stream, MPEG-4, streaming (definition 1).

SAP

n. See Service Advertising Protocol.

SAPI

n. Acronym for Speech Application Programming Interface. A feature in Windows 9x and Windows NT that allows applications to include speech recognition or convert text to speech. Also called: Speech API. See also voice recognition.

SAS

n. See single attachment station.

SASL

n. Acronym for Simple Authentication and Security Layer. An authentication support mechanism for use with connection-based protocols. SASL allows a client to request identification from a server and negotiate use of an added security layer for authentication during subsequent client/server interaction.

satellite

n. See communications satellite.

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 the satellite performs. See also remote communications.

satellite dish

n. A parabolic (dish-shaped) reflector and antenna that is used for transmitting and receiving signals between the ground and earth satellites. Satellite dishes are commonly used for receiving television transmissions.

saturated mode

n. The state in which a switching device or amplifier is passing the maximum possible current. A device is in saturated mode when increasing the control signal does not result in output of additional current.

saturation

n. 1. In a switching device or amplifier, the fully conducting state. At saturation, the device is passing the maximum possible current. The term is most commonly used with reference to circuits containing bipolar or field-effect transistors. 2. In color graphics and printing, the amount of color in a specified hue, often specified as a percentage. See also HSB.

save

vb. To write data (typically a file) to a storage medium, such as a disk or tape.

SAX

n. Acronym for Simple API for XML. An event-driven application program interface (API) used to interpret an XML file. SAX works with an XML parser, providing an interface between the parser and an XML application. SAX is used as an alternative to the more complex object-based Document Object Model (DOM) interface. See also DOM.

Microsoft Computer Dictionary, Fifth Edition

scalability

n. A measure of how well a computer, service, or application can grow to meet increasing performance demands. For server clusters, it is the ability to incrementally add one or more systems to an existing cluster when the overall load of the cluster exceeds its capabilities. See also server cluster.

scalable

adj. Of or relating to the characteristic of a piece of hardware or software or a network that makes it possible for it to expand—or shrink—to meet future needs and circumstances. For example, a scalable network allows the network administrator to add many additional nodes without the need to redesign the basic system.

scalable font

n. Any font that can be scaled to produce characters in varying sizes. Examples of scalable fonts are screen fonts in a graphical user interface, stroke fonts (such as Courier) and outline fonts common to most PostScript printers, TrueType fonts, and the method for screen font definition used in Macintosh System 7. In contrast, most text-based interfaces and printing devices (such as daisy-wheel printers) offer text in only one size. See also outline font, PostScript font, screen font, stroke font, TrueType.

scalable parallel processing

n. Multiprocessing architectures in which additional processors and additional users can easily be added without excessive increases in complexity and loss of performance. Acronym: SPP.

Scalable Processor Architecture n. See SPARC.

Scalable Vector Graphics n. See SVG.

scalar

n. A factor, coefficient, or variable consisting of a single value (as opposed to a record, an array, or some other complex data structure). Compare vector.

scalar data type

n. A data type defined as having a predictable and enumerable sequence of values that can be compared for greater-than/less-than relationships. Scalar data types include integers, characters, user-defined enumerated data types, and (in most implementations) Boolean values. Some debate exists as to whether or not floating-point numbers can be considered a scalar data type; although they can be ordered, enumeration is often questionable because of rounding and conversion errors. See also Boolean expression, enumerated data type, floating-point number.

scalar processor

n. A processor designed for high-speed computation of scalar values. A scalar value can be represented by a single number.

scalar variable n. See scalar.

scale1

n. A horizontal or vertical line on a graph that shows minimum, maximum, and interval values for the data plotted.

scale2

Microsoft Computer Dictionary, Fifth Edition

vb. 1. To enlarge or reduce a graphic display, such as a drawing or a proportional character font, by adjusting its size proportionally. 2. To alter the way in which values are represented so as to bring them into a different range—for example, to change linear feet to quarter inches on a blueprint drawing of a house. 3. In programming, to determine the number of digits occupied by fixed-point or floating-point numbers. See also fixed-point notation, floating-point number.

scaling

n. In computer graphics, the process of enlarging or reducing a graphical image—scaling a font to a desired size or scaling a model created with a CAD program, for example. See also CAD.

scan

vb. 1. In television and computer display technologies, to move an electron beam across the inner surface of the screen, one line at a time, to light the phosphors that create a displayed image. 2. In facsimile and other optical technologies, to move a light-sensitive device across an imagebearing surface such as a page of text, converting the light and dark areas on the surface to binary digits that can be interpreted by a computer.

scan code

n. A code number transmitted to an IBM or compatible computer whenever a key is pressed or released. Each key on the keyboard has a unique scan code. This code is not the same as the ASCII code for the letter, number, or symbol shown on the key; it is a special identifier for the key itself and is always the same for a particular key. When a key is pressed, the scan code is transmitted to the computer, where a portion of the ROM BIOS (read-only memory basic input/output system) dedicated to the keyboard translates the scan code into its ASCII equivalent. Because a single key can generate more than one character (lowercase a and uppercase A, for example), the ROM BIOS also keeps track of the status of keys that change the keyboard state, such as the Shift key, and takes them into account when translating a scan code. Compare key code.

scan head

n. An optical device found in scanners and fax machines that moves across the subject being scanned, converts light and dark areas to electrical signals, and sends those signals to the scanning system for processing.

scan line

n. 1. One of many horizontal lines of a graphics display screen, such as a television or rasterscan monitor. 2. A single row of pixels read by a scanning device.

scanner

n. An optical input device that uses light-sensing equipment to capture an image on paper or some other subject. The image is translated into a digital signal that can then be manipulated by optical character recognition (OCR) software or graphics software. Scanners come in a number of types, including flatbed (scan head passes over a stationary subject), feed (subject is pulled across a stationary scan head), drum (subject is rotated around a stationary scan head), and handheld (user passes device over a stationary subject).

scan rate

n. See refresh rate.

scatter diagram

n. A graph consisting of points whose coordinates represent values of data, often used to illustrate a correlation between one or more variables and a test group. See the illustration. Also called: point chart, point diagram.

Microsoft Computer Dictionary, Fifth Edition

Scatter diagram.

schedule

vb. To program a computer to perform a specified action at a specified time and date.

scheduler

n. An operating-system process that starts and ends tasks (programs), manages concurrently running processes, and allocates system resources. Also called: dispatcher.

scheduling algorithm

n. An algorithm that governs the proper timing of a sequence of events in an operating system or application. For example, an effective motion graphics scheduling algorithm would be able to retrieve the graphic objects, process them, and display them without causing stutter or disruptions. See also algorithm.

schema

n. A description of a database to a database management system (DBMS) in the language provided by the DBMS. A schema defines aspects of the database, such as attributes (fields) and domains and parameters of the attributes.

schematic

n. A diagram that shows a circuit’s components and the connections between them using lines and a set of standard symbols to represent various electronic components. See the illustration.

Schematic.

Microsoft Computer Dictionary, Fifth Edition

Schottky diode

n. A type of diode (device that passes current in one direction) in which a semiconductor layer and a metal layer are brought into contact. It is characterized by very fast switching speeds. Also called: hot carrier diode, Schottky barrier diode.

scientific notation

n. A floating-point method of representing a number, especially a very large or very small one, in which numbers are expressed as products consisting of a number between 1 and 10 multiplied by a power of 10. Scientific notation commonly uses the letter E in place of “times 10,” as in 5.0E3, meaning 5.0 times 10 to the third power, or 103. See also floating-point notation.

sci. newsgroups

n. Usenet newsgroups that are part of the sci. hierarchy and begin with “sci.” These newsgroups are devoted to discussions of scientific research and applications, except for computer science, which is discussed in the comp. newsgroups. See also newsgroup, traditional newsgroup hierarchy, Usenet. Compare comp. newsgroups, misc. newsgroups, news. newsgroups, rec. newsgroups, soc. newsgroups, talk. newsgroups.

scissoring n. See clip.

scope

n. 1. In programming, the extent to which an identifier, such as a constant, data type, variable, or routine, can be referenced within a program. Scope can be global or local. Scope can also be affected by redefining identifiers, such as by giving the same name to both a global variable and a local variable. See also block1(definition 3), global, local. 2. In electronics, slang for oscilloscope. See also oscilloscope.

score

n. When referring to a spelling checker, a score is a number that indicates how much a replacement word differs from the original misspelled word. A low score indicates that the misspelled word was changed slightly, while a high score indicates that the word was changed a great deal.

SCP

n. Acronym for Simple Control Protocol. A lightweight peer-to-peer networking protocol for devices that have limited processing and memory resources and operate over limited-bandwidth networks such as powerline carrier (PLC) systems. Products using SCP can interoperate with products using the Universal Plug and Play (UPnP), CEBus, and Home Plug & Play (HPnP) standards. Developed by a team of companies including Microsoft and General Electric, SCP enables the interaction between UPnP devices, devices based on Internet Protocol (IP), and non- IP-capable devices such as coffeemakers and alarm clocks. SCP, which was designed as a stand-alone protocol, can be used in residential, commercial, industrial, and utility applications. See also UPnP networking.

SCR

n. See silicon-controlled rectifier.

scrambler

n. A device or program that reorders a signal sequence in order to render it indecipherable. See also encryption.

scrap

n. An application or system file maintained for storing data that has been marked for movement, copying, or deletion. See also clipboard (definition 1).

Microsoft Computer Dictionary, Fifth Edition

scrapbook

n. 1. A file in which a series of text and graphical images can be saved for subsequent use. 2. A Macintosh system file that can hold a number of text and graphical images for later use. Compare clipboard (definition 1).

scratch1

n. A memory region or file used by a program or operating system to hold work in progress temporarily. Created and maintained usually without the end user’s knowledge, the scratch is needed only until the current session is terminated, at which time the data is saved or discarded. Also called: scratch file. See also temporary file. Compare scrap.

scratch2

vb. To erase or discard data.

scratch file

n. See scratch1.

scratchpad

n. 1. A temporary storage area used by a program or operating system for calculations, data, and other work in progress. See also scratch1, temporary file. 2. A high-speed memory circuit used to hold small items of data for rapid retrieval. See also cache.

scratchpad memory n. See cache.

scratchpad RAM

n. Memory used by a central processing unit (CPU) for temporary data storage. Also called: scratchpad, scratchpad memory. See also central processing unit, register.

scream

vb. To operate at very high speed. For example, a modem that can transfer data several times faster than the one it replaced or a computer with a very high clock speed could be said to “scream.”

screamer

n. Slang for a piece of computer equipment that operates at a very high speed. Generally, “screamers” are the newest versions of a particular piece of equipment, such as a PC with the latest, fastest microprocessor, or are comprised of multiple components that increase the operating speed over standard models, such as a PC that has a huge amount of RAM (Random Access Memory), a high-performance video board, a superfast CD-ROM drive, and the latest microprocessor. However, as technology evolves and new, faster devices are introduced, yesterday’s screamer rapidly becomes today’s snail.

screen angle

n. The angle at which the dots in a halftone screen are printed. A correct angle will minimize blur and other undesirable effects, such as moiré patterns. See also color separation (definition 1), halftone, moiré.

screen buffer

n. See video buffer.

screen dump

n. A duplicate of a screen image; essentially, a snapshot of the screen that is either sent to a printer or saved as a file.

Microsoft Computer Dictionary, Fifth Edition

screen flicker n. See flicker.

screen font

n. A typeface designed for display on a computer monitor screen. Screen fonts often have accompanying PostScript fonts for printing to PostScript-compatible printers. See also derived font, intrinsic font. Compare PostScript font, printer font.

screen frequency n. See halftone.

screen grabber

n. See grabber (definition 3).

screen name

n. A name under which an America Online user is known. The screen name may be the same as the user’s real name. See also America Online.

screen phone

n. A type of Internet appliance combining a telephone with an LCD display screen, a digital fax modem, and a computer keyboard, with ports for a mouse, printer, and other peripheral devices. Screen phones can be used as regular telephones for voice communications and can also be used as terminals to gain access to the Internet and other online services.

screen pitch

n. A measurement of a computer monitor’s screen density, representing the distance between phosphors on the display. The lower the number, the more detail can be displayed clearly. For example, a .28-dot-pitch screen has better resolution than one with .32. See the illustration. See also phosphor.

Screen pitch.

screen saver

n. A utility that causes a monitor to blank out or display a certain image after a specified amount of time passes without the keyboard being touched or the mouse being moved. Touching a key or moving the mouse deactivates the screen saver. Screen savers were originally used to prevent images from becoming permanently etched on a monitor’s screen. Although modern monitors are not susceptible to this problem, screen savers remain popular for their decorative and entertainment value. See the illustration.