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L1 cache n. A memory cache built into i486 and higher-level processors to help improve processing speed. The L1 cache, typically containing 8 KB, can be read in a single clock cycle, so it is tried first. The i486 contains one L1 cache; the Pentium contains two, one for code and one for data. Also called: level 1 cache, on-chip cache. See also cache, i486DX, Pentium. Compare L2 cache.
L2 cache n. A memory cache consisting of static RAM on a motherboard that uses an i486 or higher-level processor. The L2 cache, which typically contains 128 KB to 1 MB, is faster than the system DRAM but slower than the L1 cache built into the CPU chip. Also called: level 2 cache. See also cache, dynamic RAM, i486DX, static RAM. Compare L1 cache.
L2TP n. See Layer Two Tunneling Protocol.
L8R adv. Abbreviation for later, as in See you later, an expression often used in e-mail or Usenet groups as a closing remark.
label n. An identifier. A label can be a physical item, such as a stick-on tag used to identify disks and other computer equipment, or an electronic label added to floppy disks or hard disks. It can also be a word, symbol, or other group of characters used to identify a file, a storage medium, an element defined in a computer program, or a specific item in a document such as a spreadsheet or a chart. See also identifier.
label edge router n. See MPLS.
label prefix n. In a spreadsheet, a character at the beginning of a cell entry that identifies the entry to the program as a label.
label switching n. See MPLS.
label switch path n. See MPLS.
label switch router n. See MPLS.
LACP n. Acronym for Link Aggregation Control Protocol. See link aggregation.
lag n. The time difference between two events. In electronics, a lag is a delay between a change in input and a change in output. On computer displays, a lag is a fading brightness left on the phosphor coating of the screen after an image changes. See also persistence.
LAN n. Acronym for local area network. A group of computers and other devices dispersed over a relatively limited area and connected by a communications link that enables any device to interact with any other on the network. LANs commonly include PCs and shared resources such as laser printers and large hard disks. The devices on a LAN are known as nodes, and the nodes are connected by cables through which messages are transmitted. See also baseband network, broadband network, bus network, client/server architecture, collision detection, communications protocol, contention, CSMA/CD, network, peer-to-peer architecture, ring network, star network. Compare WAN.
landscape mode n. A horizontal print orientation in which text or images are printed sideways that is, the width of the image on the page is greater than the height. Compare portrait mode.
landscape monitor n. A monitor that is wider than it is high. Landscape monitors are usually about 33 percent wider than they are high roughly the same proportion as a television screen. Compare full-page display, portrait monitor.
LANE n. Acronym for LAN Emulation. See ATM (definition 1), communications protocol, LAN.
LANGID n. See language identifier.
language n. See programming language.
language-description language n. See metalanguage.
language identifier n. A standard international numeric abbreviation for a country or geographical region. A language identifier is a 16-bit value that consists of a primary language identifier and a secondary language identifier. Acronym: LANGID. See also locale identifier.
language processor n. A hardware device or a software program designed to accept instructions written in a particular language and translate them into machine code. See also compiler (definition 2), interpreter.
language translation program n. A program that translates statements written in one programming language into another programming language (usually from one high-level language into another). See also high-level language.
LAN Manager n. An older LAN (local area network) technology developed by Microsoft and distributed by Microsoft, IBM (as IBM LAN Server), and other original equipment manufacturers. Superseded by TCP/IP networking protocols in Windows 9x, LAN Manager implemented the NetBEUI protocol and was notable for its small stack size. It was used to connect computers running the MS-DOS, OS/2, or UNIX operating systems to allow users to share files and system resources and to run distributed applications using a client/server architecture. See also client/server architecture, LAN, NetBEUI.
LANtastic n. A network operating system from Artisoft designed to support both peer-to-peer and client/server networks consisting of PCs running a mix of MS-DOS and Windows operating systems.
laptop n. A small, portable personal computer that runs on either batteries or AC power, designed for use during travel. Laptops have flat LCD or plasma screens and small keyboards. Most can run the same software as their desktop counterparts and can accept similar peripherals, such as sound cards, internal or external modems, floppy disks, and CD-ROM drives. Some laptops are designed to be plugged into a docking station, effectively making them desktop computers. Most have connectors for plugging in external keyboards and full-sized monitors. Older laptops weighed as much as 15 pounds; current laptops can weigh as little as 5 pounds without peripherals. While notebook is the current term for ultralight portable computers, these machines are also commonly referred to as laptops. See also portable computer. Compare subnotebook computer.
large model n. A memory model of the Intel 80x86 processor family. The large model allows both code and data to exceed 64 kilobytes, but the total of both must generally be less than 1 megabyte. Each data structure must be less than 64 kilobytes in size. See also memory model.
large-scale integration n. A term describing a chip on which circuit elements number in the thousands. Acronym: LSI. See also integrated circuit. Compare medium-scale integration, small-scale integration, super-large-scale integration, ultra-large-scale integration, very-large-scale integration.
laser or LASER n. Acronym for light amplification by stimulated emission of radiation. A device that uses certain quantum effects to produce coherent light, which travels with greater efficiency than noncoherent light because the beam diverges only slightly as it travels. Lasers are used in computer technology to transmit data through fiberoptic cables, to read and write data on CD-ROMs, and to place an image on a photosensitive drum in laser printers.
laser engine n. See printer engine.
laser printer n. An electrophotographic printer that is based on the technology used by photocopiers. A focused laser beam and a rotating mirror are used to draw an image of the desired page on a photosensitive drum. This image is converted on the drum into an electrostatic charge, which attracts and holds toner. A piece of electrostatically charged paper is rolled against the drum, which pulls the toner away from the drum and onto the paper. Heat is then applied to fuse the toner to the paper. Finally, the electrical charge is removed from the drum, and the excess toner is collected. By omitting the final step and repeating only the toner-application and paper-handling steps, the printer can make multiple copies. The only serious drawback of a laser printer is that it offers less paper-handling flexibility than do dot-matrix printers. Both multipart forms and wide-carriage printing, for example, are better handled by line printers or dot-matrix printers. See also electrophotographic printers, nonimpact printer, page printer. Compare dot-matrix printer, ion-deposition printer, LCD printer, LED printer.
laser storage n. The use of optical read/write technology with metallic discs for information storage. See also compact disc.
LaserWriter 35 n. The standard set of 35 PostScript fonts for the Apple LaserWriter family of laser printers. See also laser printer, PostScript font.
last in, first out n. A method of processing a queue in which items are removed in inverse order relative to the order in which they were added that is, the last in is the first out. Acronym: LIFO. See also stack. Compare first in, first out.
last mile n. The connection (which may in fact be more or less than one mile) between an end user s system and that of a service provider, such as a telephone company. The last mile connection historically has referred to the twisted-pair copper wires used between a home and the telephone company. While this definition remains accurate, last mile is now often used more broadly to refer to the link between an end user s system and the high-speed Internet access technology of a service provider, such as an ISP (Internet service provider). Thus, for modem users accessing the Internet through voice-grade lines, the last mile is still equivalent to the phone company s twisted-pair copper wiring. However, because standard modem transmission over voice-grade lines is sometimes frustratingly slow, other last mile solutions have been designed to provide greater speed and bandwidth. These include coaxial cable (used in cable TV), fiber optics, or a radio link (such as a cellular telephone or a point-to-point link). DSL and ISDN are methods for providing high-speed last-mile data service through twisted-pair copper wires. See also DSL, ISDN, twisted-pair wiring. Compare local loop.
latch n. A circuit or circuit element used to maintain a particular state, such as on or off, or logical true or false. A latch changes state only in response to a particular input. See also flip-flop.
late binding n. See dynamic binding.
latency n. The time required for a signal to travel from one point on a network to another. See also ping1 (definition 1).
LaTeX1 or LATEX n. A document preparation system based on TeX, developed by Leslie Lamport. By using simple, intuitive commands for text elements such as headers, LaTeX lets the user focus more on document content than document appearance. See also header (definition 1), TeX.
LaTeX2 vb. To process a LaTeX file. See also LaTeX1.
launch vb. To activate an application program (especially on the Macintosh) from the operating system s user interface.
Launcher n. In Mac OS, a program that organizes frequently used applications and programs and that allows the user to execute them with a single mouse click.
layer n. 1. The protocol or protocols operating at a particular level within a protocol suite, such as IP within the TCP/IP suite. Each layer is responsible for providing specific services or functions for computers exchanging information over a communications network (such as the layers in the ISO/OSI reference model) and information is passed from one layer to the next. Although different suites have varying numbers of levels, generally the highest layer deals with software interactions at the application level, and the lowest governs hardware-level connections between different computers. See the table. See also ISO/OSI reference model, protocol stack, TCP/IP. 2. In communications and distributed processing, a set of rules and standards that handles a particular class of events.
ISO/OSI layer Focus Application (highest level) Program-to-program transfer of information Presentation Text formatting and display, code conversion Session Establishing, maintaining, and coordinating communication Transport Accurate delivery, service quality Network Transport routes, message handling and transfer Data-link Coding, addressing, and transmitting information Physical Hardware connections
layer 4 switching n. In Network Address Translation (NAT), a function that handles incoming packets and changes the IP address and destination port to transfer them to the proper server within the private network, and then readdresses return packets leaving the private network. Because layer 4 switching controls the address on packets moving in both directions, the internal network remains transparent to the client. See also LVS, NAT.
layered architecture n. The division of a network model into multiple discrete layers, or levels, through which messages pass as they are prepared for transmission. In a layered architecture, protocols at each layer provide specific services or functions and rely on protocols in the layers above and below them for other needed services. See also protocol.
layered interface n. In programming, one or more levels of routines lying between an application and the computing hardware and separating activities according to the type of task the activities are designed to carry out. Ultimately, such an interface makes it easier to adapt a program to different types of equipment. See the illustration. Layered interface.
layering n. In computer graphics, the grouping of logically related elements in a drawing. Layering enables a program user to view, and work on independently, portions of a graphic instead of the entire drawing.
Layer Two Tunneling Protocol n. An industry-standard Internet tunneling protocol that provides encapsulation for sending Point-to-Point Protocol (PPP) frames across packet-oriented media. For IP networks, Layer Two Tunneling Protocol traffic is sent as User Datagram Protocol (UDP) messages. In Microsoft operating systems, this protocol is used in conjunction with Internet Protocol security (IPSec) as a virtual private network (VPN) technology to provide remote access or router-to-router VPN connections. Layer Two Tunneling Protocol is described in RFC 2661. Acronym: L2TP. See also IPSec, Point-to-Point Protocol, tunnel, User Datagram Protocol.
layout n. 1. The overall plan or design of a document system. See also page layout. 2. In programming, the order and sequence of input and output. 3. In computer design, the arrangement of circuits and other components of the system.
lazy evaluation n. A programming mechanism that allows an evaluation action to be performed only when needed and only to a certain extent. Lazy evaluation allows a program to handle data objects such as extremely large tables and lists in a timely and effective manner.
LBA n. See logical block addressing.
LCC n. See leaded chip carrier, leadless chip carrier.
lcd n. In some FTP clients, the command that changes the current directory on the local system. See also FTP client.
LCD n. See liquid crystal display.
LCD printer n. Short for Liquid Crystal Display printer. An electrophotographic printer similar to a laser printer and often incorrectly labeled as one. LCD printers use a bright light source, typically a halogen lamp. Also called: liquid crystal shutter printer. See also electrophotographic printers, nonimpact printer, page printer. Compare ion-deposition printer, laser printer, LED printer.
LCD projector n. Short for Liquid Crystal Display projector. A type of data projector that uses electricity to turn the pixels representing a projected image off or on. Unlike the newer DLP projectors, LCD projectors are able to display shades of color (gray scale) by controlling the amount of electricity used to turn a particular pixel on or off. See also gray scale, liquid crystal display. Compare DLP projector.
LCP n. See Point-to-Point Protocol.
LDAP n. See Lightweight Directory Access Protocol.
lead1 n. In electronics, the metallic connector of certain components such as resistors and capacitors.
lead2 n. In typography, the amount of vertical space between two lines of text.
leaded chip carrier n. A method of mounting chips on boards. A leaded chip carrier has leglike pins for connecting it to the board. The chip makes contact with the board through surface mount technology in which the leads are soldered to the surface rather than into predrilled holes. Somewhat confusingly, a leaded chip carrier goes by the same acronym (LCC) as a leadless chip carrier. Acronym: LCC. Compare leadless chip carrier.
leader n. A row of dots, hyphens, or other such characters used to lead the eye across a printed page to related information. Leaders can be created by many word processors and other programs.
leading n. The space, expressed in points, between lines of type, measured from the baseline (bottom) of one line to the baseline of the next. The term is derived from the traditional typesetting practice of inserting a thin bar of lead between lines of metal type. See the illustration. See also point. Leading. Ordinary text is typically set with leading one or two points greater than the point size of the type.
leading edge n. The initial part of an electronic signal. If a digital signal switches from off to on and then back to off, the transition from off to on is the leading edge of the signal.
leading zero n. A zero that precedes the most significant (leftmost) digit of a number. One or more leading zeros may be used as fill characters in a field containing numeric input. Leading zeros have no significance in the value of a number.
lead ion battery n. An energy storage device that is based on the conversion of chemical to electrical energy as ions flow from one terminal to another through an acid medium in which lead and copper are suspended. This type of battery is used in laptop and notebook computers.
leadless chip carrier n. A method of mounting chips on boards. A leadless chip carrier has contacts, rather than leglike pins, for connecting it to the board. The chip simply rests in a socket that has contacts on its base for completing the connection, and the chip is clamped in place so that the contacts are secure. Acronym: LCC. See also PLCC. Compare DIP (definition 1), pin grid array.
leaf n. Any node (location) in a tree structure that is at the farthest distance from the root (primary node), no matter which path is followed. Thus, in any tree, a leaf is a node at the end of a branch one that has no descendants. See also root, subtree, tree.
leapfrog attack n. A method used by hackers to make an attack difficult to trace back to the source. In a leapfrog attack the hacker uses a User ID stolen from another source or routes information through a series of hosts to hide their identity and obscure the origin of the attack. Also called: network weaving.
leapfrog test n. A diagnostic routine, used for testing disk or tape storage, that repeatedly copies itself onto the storage medium.
leap year n. A potential problem for some systems that follow an erroneous algorithm for calculating leap years. There are three rules for calculating leap years: (1) A year is a leap year if it is divisible by 4, but (2) not if it is divisible by 100, unless (3) it is also divisible by 400. Thus, 1900 was not a leap year, but 2000 was.
leased line n. See dedicated line (definition 1).
least significant bit n. In a sequence of one or more bytes, the low-order (usually rightmost) bit of a binary number. Acronym: LSB. See also low-order. Compare most significant bit.
least significant character n. The low-order, or rightmost, character in a string. Acronym: LSC. See also low-order. Compare most significant character.
least significant digit n. The low-order, or rightmost, digit in the normal representation of a number. Acronym: LSD. See also low-order. Compare most significant digit.
LED n. See light-emitting diode.
LED printer n. Short for light-emitting diode printer. An electrophotographic printer similar to LCD and laser printers. The significant difference between LED and laser or LCD printers is in the light source; LED printers use an array of light-emitting diodes. See also electrophotographic printers, light-emitting diode, nonimpact printer, page printer. Compare ion-deposition printer, laser printer, LCD printer.
left justification n. In typesetting, word processing, and desktop publishing, the process of aligning text evenly along the left margin of a column or page. The right edge of the text is ragged. See also justify (definition 1), rag. Compare full justification, right justification.
left-justify vb. To justify, as text, along the left. See also justify (definition 1), rag. Compare right-justify.
legacy adj. Of or pertaining to documents, data, or hardware that existed prior to a certain time. The designation refers particularly to a change in process or technique that requires translating old data files to a new system.
legacy data n. Data acquired by an organization that was compiled by another organization. The acquiring organization thus receives the existing information as a legacy from the information s prior owner.
legacy system n. A computer, software program, network, or other computer equipment that remains in use after a business or organization installs new systems. Compatibility with legacy systems is an important consideration when a new version is installed. For example, will a new spreadsheet software release be able to read the existing business records without expensive and time-consuming conversion to a new format? Legacy systems in many organizations are based on mainframe computers, which may be either augmented or slowly replaced by client/server architectures. See also mainframe computer. Compare client/server architecture.
legend n. Text that describes or explains a graphic, usually printed below the graphic. On a graph or map, the legend is the key to the patterns or the symbols used.
Lempel Ziv compression n. A data compression method designed by Abraham Lempel and Jakob Ziv in 1977 and 1978. Lempel Ziv compression is based on the substitution of certain values for repeated data. It is implemented in two basic forms: LZ77, which is based on values that point to the positions of repeating data, and LZ78, which builds a dictionary and uses the dictionary index to point to repeating data. An enhanced version of LZ78, known as LZW, is implemented in well-known file formats, such as GIF and TIF. See also .lzh, LZW compression.
length n. The number of linear units of storage space occupied by an object, such as a file on disk or a data structure in a program, typically measured in bits, bytes, or blocks.
LEO n. See low-Earth-orbit satellite.
LER n. See MPLS.
less than adj. See relational operator.
less than or equal to adj. See relational operator.
letterbomb n. An e-mail message that is intended to impair the recipient s computer use. Some sequences of control characters can lock up a terminal, files attached to the message may contain viruses or Trojan horses, and a sufficiently large message can overflow a mailbox or crash a system. See also control character, e-mail(definition 1), mailbox, Trojan horse, virus.
letter quality adj. Pertaining to or being a level of print quality on dot-matrix printers that is better than draft quality. As the name implies, letter quality is supposed to be crisp and dark enough for use in business letters. See also print quality. Compare draft quality, near-letter-quality.
letter-quality printer n. Any printer that produces output high enough in quality to be acceptable for business letters. See also daisy-wheel printer, laser printer.
level 1 cache n. See L1 cache.
level 2 cache n. See L2 cache.
lexicographic sort n. A sort that arranges items in the order in which they would appear if listed in a dictionary. A lexicographic sort puts numbers, for instance, where they would be if they were spelled out; for example, 567 would fall in the Fs. Compare alphanumeric sort.
lexicon n. 1. The words of a language and their definitions. 2. In programming, the identifiers, keywords, constants, and other elements of a language that make up its vocabulary. The ways in which these vocabulary elements can be put together is the syntax of the language. Compare syntax.
LF n. See linefeed.
LHARC n. A freeware file-compression utility program developed by Haruyasu Yoshizaki and introduced in 1988. With LHARC, the contents of one or more files can be compressed into a singular, smaller file, with the extension .lha. A copy of the program is required to uncompress these files. LHARC can also embed a small program with the compressed information and save everything in a single file, called a self-extracting archive, with an .exe extension. As a result, the recipient of the compressed file does not need a separate utility program to uncompress the file. See also freeware, PKZIP, utility program.
library n. 1. In programming, a collection of routines stored in a file. Each set of instructions in a library has a name, and each performs a different task. 2. A collection of software or data files.
library routine n. In programming, a routine stored in a collection of routines (a library) that can be used by any program that can link into the library. See also function library, library (definition 1).
license agreement n. A legal contract between a software provider and a user specifying the rights of the user regarding the software. Usually the license agreement is in effect with retail software once the user opens the software package. See also End-User License Agreement.
licensing key n. A short character string that serves as a password during the installation of licensed commercial software. The use of licensing keys is a security device aimed at reducing illegal duplication of licensed software.
LIFO n. See last in, first out.
ligature n. In typography, a single character created from two joined letters that replaces the two separate letters. Because ligatures are not included with all digital fonts, their use may cause text problems in font substitution situations.
light-emitting diode n. A semiconductor device that converts electrical energy into light, used, for example, for the activity lights on computer disk drives. Light-emitting diodes work on the principle of electroluminescence and are highly efficient, producing little heat for the amount of light output. Acronym: LED.
light guide n. A structure, such as a fiberoptic filament, designed to transmit light over distances with minimal attenuation or loss.
lightmap n. A basic lighting scheme used in 3D computer game rendering and other digital animation applications. A lightmap generates a precalculated 3D grid for lighting all objects in a game but cannot be adjusted for player-initiated changes within the scene.
light pen n. An input device consisting of a stylus that is connected to a computer s monitor. The user points at the screen with the stylus and selects items or chooses commands either by pressing a clip on the side of the light pen or by pressing the light pen against the surface of the screen (the equivalent of performing a mouse click). See also absolute pointing device. Compare touch screen.
light source n. 1. The device that provides the luminescence (for example, a bulb or laser) in any technology based on the use and interpretation of light, such as a scanner or CRT. 2. In computer graphics, the imaginary location of a source of light, which determines the shading in an image.
lightwave system n. A system that transmits information by means of light.
Lightweight Directory Access Protocol n. A network protocol designed to work on TCP/IP stacks to extract information from a hierarchical directory such as X.500. This gives users a single tool to comb through data to find a particular piece of information, such as a user name, an e-mail address, a security certificate, or other contact information. Acronym: LDAP. See also CCITT X series.
Lightweight Internet Person Schema n. In Lightweight Directory Access Protocol directories, a specification for the retrieval of such information as names and e-mail addresses. Acronym: LIPS. See also Lightweight Directory Access Protocol.
LIM EMS n. Acronym for Lotus/Intel/Microsoft Expanded Memory Specification. See EMS.
limit check n. In programming, a test that checks specified information to verify that it is within acceptable limits. See also array.
limiting operation n. Any routine or operation that constrains the performance of a larger process in which it is included; a bottleneck.
line n. 1. Any wire or wires, such as power lines and telephone lines, used to transmit electrical power or signals. 2. In communications, a connection, usually a physical wire or other cable, between sending and receiving (or calling and called) devices, including telephones, computers, and terminals. 3. In a SONET network, a segment that runs between two multiplexers. See also SONET. 4. In word processing, a string of characters displayed or printed in a single horizontal row. 5. In programming, a statement (instruction) that occupies one line of the program. In this context, the common reference is to a program line or a line of code.
line adapter n. A device, such as a modem or network card, that connects a computer to a communications line and converts a signal to an acceptable form for transmission.
line analyzer n. A monitoring device used to verify the integrity of a communications line and to assist in troubleshooting.
linear adj. 1. Having the characteristics of a line. 2. Proceeding sequentially. For example, a linear search is one that moves from A to B to C. 3. In mathematics and electronics, having a direct and proportional relationship among characteristics or variables. For example, the output of a linear amplifier is directly proportional to the input. See also linear programming.
linear addressing architecture n. An architecture that allows a microprocessor to access any individual memory location by means of a single address value. Thus, each memory location within the entire range of addressable memory has a unique, specified address. See also flat address space, segmented address space.
linear bus n. See bus network.
linear inferences per second n. See LIPS (definition 2).
linear list n. A simple ordered list of elements in which each element except the first immediately succeeds one other element, and each except the last immediately precedes one other. Compare linked list.
linear memory n. See flat memory.
linear programming n. The process of creating programs that find optimal solutions for systems of equations (composed of linear functions) in which the terms given are not sufficient to derive a straightforward solution.
linear search n. A simple, though inefficient, search algorithm that operates by sequentially examining each element in a list until the target element is found or the last item has been completely processed. Linear searches are primarily used for very short lists. Also called: sequential search. See also search algorithm. Compare binary search, hash search.
linear structure n. A structure in which items are organized according to strict rules of precedence. In a linear structure, two conditions apply: if X precedes Y and Y precedes Z, then X precedes Z; and if X precedes Y and X precedes Z, then either Y precedes Z or Z precedes Y.
line-based browser n. A Web browser whose display is based on text rather than graphics. A popular line-based browser is Lynx. See also Lynx, Web browser.
line cap n. The way in which a line segment is terminated when the segment is printed, especially on a PostScript-compatible printer. See the illustration. See also line join. Line cap. The dots represent the mathematical endpoints of a specified line.
line chart n. A business graphic in which values from one or more sets of data are connected by lines. See the illustration. Line chart.
line concentration n. The funneling of multiple input channels into a smaller number of output channels. See also concentrator.
line conditioner n. A device for filtering electrical power to compensate for brownouts, suppress power surges, and act as a buffer between a power line and the computer (or other piece of equipment). Line conditioners contain transformers, capacitors, and other circuitry that help regulate the quality of power to ensure that electrical flow is constant. See also brownout, UPS.
line conditioning n. See conditioning, line conditioner.
line drawing n. A drawing made up of solid lines without shading or other features that suggest mass or contouring.
line driver n. A device used to increase transmission distance by amplifying a signal before placing it on the line or passing it along the line. See also short-haul.
line editor n. A text-editing program that numbers each line of text, working with the document on a line-by-line rather than on a word-by-word basis. See also editor.
linefeed n. A control character that tells a computer or printer to advance one line below the current line without moving the position of the cursor or print head. Acronym: LF.
line join n. The way in which two line segments are connected when they are printed, especially on a PostScript-compatible printer. See the illustration. See also line cap. Line join. Three styles of line join.
line level n. The strength of a communications signal at a given point on the line, measured in decibels (a multiple of the base-10 logarithm of the ratio between two values) or nepers (the natural logarithm of the ratio between two values).
line load n. 1. In communications, a measure of the usage of a communications line expressed as a percentage of the maximum capacity of the circuit. 2. In electronics, the amount of current carried by a line.
line noise n. Spurious signals in a communications channel that interfere with the exchange of information. In an analog circuit, line noise may take the form of a pure audio tone, static, or signals leaked from another circuit. In a digital circuit, line noise is any signal that makes it difficult or impossible for the device at the receiving end of the circuit to interpret the transmitted signal accurately. See also channel.
line number n. 1. A number assigned by a line editor to a line of text and used to refer to that line for purposes of viewing, editing, or printing. The line numbers are sequential. See also line editor. 2. In communications, an identifying number assigned to a communications channel.
line printer n. Any printer that prints one line at a time as opposed to one character at a time (as with many dot-matrix printers) or one page at a time (as with some dot-matrix and most laser printers). Line printers typically produce the familiar 11-by-17-inch fanfold computer printouts. They are high-speed devices and are often used with mainframes, minicomputers, or networked machines rather than with single-user systems.
line regulator n. See voltage regulator.
line segment n. A portion of a line, defined by its beginning and ending points.
lines of code n. A measure of program length. Depending on circumstances, a line of code can be each line in the program (including blank lines and comments), each line containing actual code, or each statement. See also statement.
line spacing n. See leading.
line speed n. See baud rate, data rate.
lines per minute n. A measurement of printer speed, the number of lines of characters printed in one minute. Acronym: LPM.
line style n. In desktop publishing, printing, and high-end word processing, the form and quality of a line, such as a dotted line, a double line, or a hairline. See also hairline.
line surge n. A sudden, transient increase in the voltage or current carried by a line. A nearby lightning strike, for example, can cause a surge in power lines that can damage electrical equipment. Delicate types of equipment such as computers are often protected from line surges by surge suppressors placed in the power lines.
line voltage n. The voltage present in a power line. In North America, line voltage is approximately 115 volts alternating current (VAC).
line width n. The length of a line of type measured from the left margin to the right margin on a piece of paper or on a computer screen. On a typewriter, line width is usually measured in terms of the number of monospace alphanumeric characters that can fit on the line; on a computer monitor or printer, line width is normally measured in inches, centimeters, points, or picas. See also pica (definition 2), point1 (definition 1).
linguistics n. The analytic study of human language. Close ties exist between linguistics and computer science because of the mutual interest in grammar, syntax, semantics, formal language theory, and natural-language processing.
link1 vb. 1. To produce an executable program from compiled modules (programs, routines, or libraries) by merging the object code (assembly language object code, executable machine code, or a variation of machine code) of the program and resolving interconnecting references (such as a library routine called by a program). See also linker. 2. To connect two elements in a data structure by using index variables or pointer variables. See also index (definition 1), pointer (definition 1).
link2 n. See hyperlink.
linkage editor n. See linker.
link aggregation n. A technique for combining two or more Ethernet connections into one logical link, or trunk, between two devices. It is used to increase the bandwidth capacity of connections and to make these connections more resilient. The IEEE 802.3ad specification standardizes this process among different vendors using the Link Aggregation Control Protocol (LACP). Also called: bonding, trunking. See also IEEE 802.x.
Link Aggregation Control Protocol n. See link aggregation.
Link Control Protocol n. See Point-to-Point Protocol.
link edit vb. See link1 (definition 1).
linked list n. In programming, a list of nodes or elements of a data structure connected by pointers. A singly linked list has one pointer in each node pointing to the next node in the list; a doubly linked list has two pointers in each node that point to the next and previous nodes. In a circular list, the first and last nodes of the list are linked together. See also array, key (definition 2), list, node (definition 1), pointer (definition 1). Compare linear list.
linked object n. An object that is inserted into a document but still exists in the source file. When information is linked, the new document is updated automatically if the information in the original document changes. If you want to edit the linked information, double-click it and the toolbars and menus from the original program appear, allowing you to edit it in its native format. If the original document is on your computer, changes that you make to the linked information will also appear in the original document. See also OLE, package, source document.
linked stylesheet n. A stylesheet existing separately from the HTML documents to which it is linked. A linked stylesheet may be used for sets of Web pages or entire Web sites requiring a uniform appearance. Since the style is defined once and linked to associated Web pages, the entire site can be changed by modifying a single stylesheet file. Compare inline stylesheet.
linker n. A program that links compiled modules and data files to create an executable program. A linker can also have other functions, such as creating libraries. See also library, link1 (definition 1), program creation.
linkrot n. A condition affecting inadequately maintained Web pages that results in outdated, inoperative links to other Web pages.
link time n. 1. The length of time required to link a program. See also link1 (definition 1). 2. The period during which a program is being linked. See also compile time (definition 2), link(definition 1), run time (definition 1).
link-time binding n. Assignment of a meaning to an identifier (such as a subroutine label) in a program at the time that various files of compiled code are linked together to form an executable program, rather than when the source code is compiled or when the program is run. Compare compile-time binding, run-time binding.
Linotronic n. Any in the series of high-quality typesetting devices known as Linotronic laser imagesetters, which can print at resolutions such as 1270 and 2540 dots per inch (dpi). These devices are commonly attached to PostScript raster image processors (RIPs) so that desktop publishing applications can typeset directly from a microcomputer. See also imagesetter, PostScript, raster image processor.
Linpack n. A benchmarking routine that solves 100 simultaneous equations in a test of CPU, floating-point processor, and memory access speeds. See also benchmark, central processing unit, floating-point processor.
Linux n. A version of the UNIX System V Release 3.0 kernel developed for PCs with 80386 and higher-level microprocessors. Developed by Linus Torvalds (for whom it is named) along with numerous collaborators worldwide, Linux is distributed free, and its source code is open to modification by anyone who chooses to work on it, although some companies distribute it as part of a commercial package with Linux-compatible utilities. The Linux kernel works with the GNU utilities developed by the Free Software Foundation, which did not produce a kernel. It is used by some as an operating system for network servers and in the 1998/1999 timeframe began to gain increased visibility through support from vendors such as IBM and Compaq. See also free software, GNU, kernel, UNIX.
Linux Virtual Server n. See LVS.
Linux World Expo n. The world s largest trade show for designers, engineers, and businesses using the Linux operating system.
Lion worm n. A UNIX shellscript worm first detected in early 2001 that infects Linux servers using Berkeley Internet Name Domain (BIND) tools. After it has used a BIND exploit to infect a machine, Lion steals password files and other critical information and transmits them to the hacker. Lion then installs hacking tools and replaces critical files, hiding itself and opening multiple back doors for further compromise. The Lion worm was apparently launched in early 2001 by a group of Chinese hackers with a specific political agenda. In references to this worm, Lion may also be spelled as 1i0n .
LIPS n. 1. Acronym for Language Independent Program Subtitling. A system developed by the GIST group (C-DAC, India) and used by Indian Television for nationwide broadcast of programs with multilingual subtitles in teletext mode. This system was judged the best design in the VLSI (Very Large Scale Integration) design contest in the VLSI 93 International Conference. Three versions of this application-specific integrated circuit (ASIC) with different features were implemented in Xilinx 3K and 4K series FPLAs (field programmable logic arrays). See also field-programmable logic array, gate array, very-large-scale integration. 2. Acronym for linear inferences per second. A measure of speed for some types of artificial-intelligence machines and expert systems. See also artificial intelligence, expert system. 3. See Lightweight Internet Person Schema.
liquid crystal display n. A type of display that uses a liquid compound having a polar molecular structure, sandwiched between two transparent electrodes. When an electric field is applied, the molecules align with the field, forming a crystalline arrangement that polarizes the light passing through it. A polarized filter laminated over the electrodes blocks polarized light. In this way, a grid of electrodes can selectively turn on a cell, or a pixel, containing the liquid crystal material, turning it dark. In some types of liquid crystal displays, an electroluminescent panel is placed behind the screen to illuminate it. Other types of liquid crystal displays are capable of reproducing color. Acronym: LCD. See also supertwist display, twisted nematic display.
liquid crystal display printer n. See LCD printer.
liquid crystal shutter printer n. See LCD printer.
LISP n. Short for List Processing. A list-oriented programming language developed in 1959 60 by John McCarthy and used primarily to manipulate lists of data. LISP is heavily used in research and academic circles and is considered the standard language for artificial-intelligence research. See also artificial intelligence. Compare Prolog.
list n. A multielement data structure that has a linear (first, second, third, . . .) organization but that allows elements to be added or removed in any order. Queues, deques, and stacks are simply lists with restrictions on adding and removing elements. See also deque, element (definition 1), linked list, queue, stack.
list box n. A control in Windows that enables the user to choose one option from a list of possibilities. The list box appears as a box, displaying the currently selected option, next to a button marked with a down arrow. When the user clicks the button, the list appears. The list has a scroll bar if there are more options than the list has room to show.
listing n. A printed copy of program source code. Some compilers and assemblers produce optional assembly listings during compilation or assembly. Such listings of code often have additional information such as line numbers, nested block depth, and cross-reference tables. See also assembly listing.
list processing n. The maintenance and manipulation of multielement data structures. This involves adding and deleting elements, writing data into elements, and traversing the list. List processing is the basis of the artificial-intelligence programming language LISP. See also LISP, list, node (definition 1).
LISTSERV n. One of the most popular commercial mailing list managers, marketed by L-SOFT International in versions for BITNET, UNIX, and Windows. See also mailing list, mailing list manager.
literal n. A value, used in a program, that is expressed as itself rather than as a variable s value or the result of an expression. Examples are the numbers 25 and 32.1, the character a, the string Hello, and the Boolean value TRUE. See also constant, variable.
lithium ion battery n. An energy storage device based on the conversion of chemical to electrical energy in dry chemical cells. Despite the higher cost, the laptop industry is quickly adopting lithium ion batteries because of their increased storage capacity over both nickel cadmium and nickel metal hydride batteries, in response to the demand for greater power brought on by higher processor speeds and the use of devices such as CD-ROM drives. Compare nickel cadmium battery, nickel metal hydride battery.
little endian adj. Of, pertaining to, or being a method of storing a number so that the least significant byte appears first in the number. For example, given the hexadecimal number A02B, the little endian method would cause the number to be stored as 2BA0. The little endian method is used by Intel microprocessors. Also called: reverse byte ordering. Compare big endian.
live1 adj. 1. Of or relating to real-world data or a program working with it, as opposed to test data. 2. Of or relating to audio or video that is transmitted from one site to another as it is being produced, as opposed to being recorded before broadcast time. See also synchronous transmission. 3. Capable of being manipulated by a user to cause changes in a document or part of a document.
live2 n. Used to identify a Web site that has been published to a Web server and can be browsed by site visitors. Also called: going live.
Live3D n. A Netscape proprietary Virtual Reality Modeling Language (VRML) plug-in for Web browsers that allows users to view and interact with a virtual-reality world. See also VRML.
liveware n. A slang term for people, to distinguish them from hardware, software, and firmware. Also called: wetware.
LLC n. Acronym for Logical Link Control. In the IEEE 802.x specifications, the higher of two sublayers that make up the ISO/OSI data link layer. The LLC is responsible for managing communications links and handling frame traffic. See also IEEE 802.x, MAC.
Lmhosts file n. A local text file that lists the names of network hosts (sometimes called NetBIOS names) to IP addresses for hosts that are not located on the local subnet. See also IP address, systemroot.
load1 n. 1. The total computing burden a system carries at one time. 2. In electronics, the amount of current drawn by a device. 3. In communications, the amount of traffic on a line.
load2 vb. To place information from storage into memory for processing, if it is data, or for execution, if it is program code.
load-and-go adj. In reference to a routine, able to begin execution immediately, once loaded. The term is commonly used in reference to compilers and the machine code they generate.
load balancing n. 1. In distributed processing, the distribution of activity across two or more servers in order to avoid overloading any one with too many requests from users. Load balancing can be either static or dynamic. In the former, the load is balanced ahead of time by assigning different groups of users to different servers. In the latter, software refers incoming requests at runtime to whichever server is most capable of handling them. 2. In client/server network administration, the process of reducing heavy traffic flows either by dividing a busy network segment into multiple smaller segments or by using software to distribute traffic among multiple network interface cards working simultaneously to transfer information to a server. 3. In communications, the process of routing traffic over two or more routes rather than one. Such load balancing results in faster, more reliable transmissions.
loaded line n. A transmission cable fitted with loading coils, usually spaced about a mile apart, that reduce amplitude distortion in a signal by adding inductance (resistance to changes in current flow) to the line. Loaded lines minimize distortion within the range of frequencies affected by the loading coils, but the coils also reduce the bandwidth available for transmission.
loader n. A utility that loads the executable code of a program into memory for execution. On most microcomputers, the loader is an invisible part of the operating system and is automatically invoked when a program is run. See also loader routine, load module.
loader routine n. A routine that loads executable code into memory and executes it. A loader routine can be part of an operating system or it can be part of the program itself. See also loader, overlay1 (definition 1).
load module n. An executable unit of code loaded into memory by the loader. A program consists of one or more load modules, each of which can be loaded and executed independently. See also loader.
load point n. The beginning of the valid data area on a magnetic tape.
load sharing n. A method of managing one or more tasks, jobs, or processes by scheduling and simultaneously executing portions of them on two or more microprocessors.
load shedding n. In electrical systems, the process of turning off power to some electronic equipment in order to maintain the integrity of the power supply to other connected devices. See also UPS.
lobby page n. A page of information about the broadcast that is displayed in the viewer s browser before the broadcast begins. It can contain a title, subject, host s name, information about the broadcast, and a countdown to the time of the broadcast.
local adj. 1. In general, close at hand or restricted to a particular area. 2. In communications, a device that can be accessed directly rather than by means of a communications line. 3. In information processing, an operation performed by the computer at hand rather than by a remote computer. 4. In programming, a variable that is restricted in scope, that is, used in only one part (subprogram, procedure, or function) of a program. Compare remote.
local area network n. See LAN.
local bus n. A PC architecture designed to speed up system performance by allowing some expansion boards to communicate directly with the microprocessor, bypassing the normal system bus entirely. See also PCI local bus, VL bus.
local bypass n. A telephone connection used by some businesses that links separate buildings but bypasses the telephone company.
locale identifier n. A 32-bit value that consists of a language identifier and a sort identifier. In code, a locale identifier (LCID) identifies the primary language and any secondary language of a specific locale. Acronym: LCID. See also language identifier.
localhost n. The name that is used to represent the same computer on which a TCP/IP message originates. An IP packet sent to localhost has the IP address 127.0.0.1 and does not actually go out to the Internet. See also IP address, packet (definition 1), TCP/IP.
localization n. The process of altering a program so that it is appropriate for the geographic area in which it is to be used. Localization involves the customization or translation of the separated data and resources required for a specific region or language. For example, the developers of a word processing program must localize the sorting tables in the program for different countries or languages because the correct order of characters in one language might be incorrect in another. L10N is a common abbreviation for Localization, where the L in Localization is followed by 10 letters and ends with the letter N.
localized version n. A version of a program that has been translated into another language. Also called: international version.
local loop n. The (end) portion of a telephone connection that runs from the subscriber to the local telephone exchange. See also last mile.
local memory n. In multiprocessor systems, the memory on the same card or high-speed bus as a particular processor. Typically, memory that is local to one processor cannot be accessed by another without some form of permission.
local newsgroups n. Newsgroups that are targeted toward a geographically limited area such as a city or educational institution. Posts to these newsgroups contain information that is specific to the area, concerning such topics as events, meetings, and sales. See also newsgroup.
local reboot n. A reboot of the machine that one is directly working on, rather than of a remote host. See also reboot.
LocalTalk n. An inexpensive cabling scheme used by AppleTalk networks to connect Apple Macintosh computers, printers, and other peripheral devices. See also AppleTalk.
local user profile n. A user profile that is created automatically on the computer the first time a user logs on to a computer. See also mandatory user profile, roaming user profile, user profile.
local variable n. A program variable whose scope is limited to a given block of code, usually a subroutine. See also scope (definition 1). Compare global variable.
location n. See address1 (definition 1).
location-based service n. A service provided to a wireless mobile device based on the device s location. Location-based services can range from simple services, such as listing nearby restaurants, to more complex features, such as connecting to the Internet to monitor traffic conditions and find the least congested route to a destination.
lock n. 1. A software security feature that requires a key or dongle in order for the application to run correctly. See also dongle. 2. A mechanical device on some removable storage medium (for example, the write-protect notch on a floppy disk) that prevents the contents from being overwritten. See also write-protect notch.
locked file n. 1. A file on which one or more of the usual types of manipulative operation cannot be performed typically, one that cannot be altered by additions or deletions. 2. A file that cannot be deleted or moved or whose name cannot be changed.
locked volume n. On the Apple Macintosh, a volume (storage device, such as a disk) that cannot be written to. The volume can be locked either physically or through software.
lockout n. The act of denying access to a given resource (file, memory location, I/O port), usually to ensure that only one program at a time uses that resource.
lock up n. A condition in which processing appears to be completely suspended and in which the program in control of the system will accept no input. See also crash1.
log n. A record of transactions or activities that take place on a computer system. See logarithm.
logarithm n. Abbreviated log. In mathematics, the power to which a base must be raised to equal a given number. For example, for the base 10, the logarithm of 16 is (approximately) 1.2041 because 101.2041 equals (approximately) 16. Both natural logarithms (to the base e, which is approximately 2.71828) and common logarithms (to the base 10) are used in programming. Languages such as C and Basic include functions for calculating natural logarithms.
log files n. A computer file that records requests received by online applications or the number of hits a Web page receives. Log files are useful in analyzing the technical performance of a Web site, redesigning Web site navigation, and revising marketing strategies used by e-businesses.
logic n. In programming, the assertions, assumptions, and operations that define what a given program does. Defining the logic of a program is often the first step in developing the program s source code. See also formal logic.
logical adj. 1. Based on true and false alternatives as opposed to arithmetic calculation of numeric values. For example, a logical expression is one that, when evaluated, has a single outcome, either true or false. See also Boolean algebra. Compare fuzzy logic. 2. Conceptually true to a particular design or idea for example, network transmissions travel in a circle around a logical ring, even though the ring shape itself is not physically apparent. Compare physical.
logical block addressing n. A technique in which the cylinder, head, and sector locations on a hard disk are converted to 24-bit addresses for data storage and retrieval. Logical block addressing is used with SCSI drives and is also a feature of Enhanced IDE (EIDE) disk drives, on which it breaks through the earlier 528-MB IDE limit and allows support for drives up to 8.4 GB in capacity if 24-bit logical address space is used. Address conversion is performed by an EIDE drive s disk controller, but also requires support from the BIOS and the computer s operating system. Acronym: LBA. See also EIDE, SCSI.
logical decision n. Any decision that can have one of two outcomes (true/false, yes/no, and so on). Compare fuzzy logic.
logical device n. A device named by the logic of a software system, regardless of its physical relationship to the system. For example, a single floppy disk drive can simultaneously be, to the MS-DOS operating system, both logical drive A and drive B.
logical drive n. See logical device.
logical error n. See logic error.
logical expression n. See Boolean expression.
logical file n. A file as seen from a conceptual standpoint, without reference to and as distinct from its physical realization in memory or storage. For example, a logical file might consist of a contiguous series of records, whereas the file might be physically stored in small pieces scattered over the surface of a disk or even on several disks. A logical file might also consist of some subset of columns (fields) and rows (records) extracted from a database. In this case, the logical file (or view) is only that information required by a particular application program or user.
Logical Link Control n. See LLC.
logical memory n. A correlation between physical memory of the computer system and an address range that is accessible to devices. The hardware abstraction layer (HAL) provides this correlation (or mapping). See also map.
logical network n. A way to describe the topology, or layout, of a computer network. Referring to a logical (rather than physical) topology describes the way information moves through the network for example, in a straight line (bus topology) or in a circle (ring topology). The difference between describing a network as logical or physical is sometimes subtle because the physical network (the actual layout of hardware and cabling) doesn t necessarily resemble the logical network (the path followed by transmissions). A logical ring, for example, might include groups of computers cabled octopus-like to hardware collection points which, in turn, are cabled to one another. In such a network, even though the physical layout of computers and connecting hardware might not visually resemble a ring, the logical layout followed by network transmissions would, indeed, be circular. See also bus network, ring network, star network, token ring network, topology. Compare physical network.
logical operator n. An operator that manipulates binary values at the bit level. In some programming languages, logical operators are identical to Boolean operators, which manipulate true and false values. See also Boolean operator, mask.
logical record n. Any unit of information that can be handled by an application program. A logical record can be a collection of distinct fields or columns from a database file or a single line in a text file. See also logical file.
logical schema n. See conceptual schema.
logic analyzer n. A hardware device that facilitates sophisticated low-level debugging of programs. Typical features include the ability to monitor bus signals during execution, to halt execution when a given memory location is read or written to, and to trace back through some number of instructions when execution is halted for any reason. See also debugger.
logic array n. See gate array.
logic board n. Another name for motherboard or processor board. The term was used in conjunction with older computers to distinguish the video board (analog board) from the motherboard. See also motherboard.
logic bomb n. 1. A logic error in a program that manifests itself only under certain conditions, usually when least expected or desired. The term bomb implies an error that causes the program to fail spectacularly. See also logic error. 2. A type of Trojan horse that executes when certain conditions are met, such as when a user performs a specific action. 3. See Year 2000 problem. 4. See fork bomb.
logic chip n. An integrated circuit that processes information, as opposed to simply storing it. A logic chip is made up of logic circuits.
logic circuit n. An electronic circuit that processes information by performing a logical operation on it. A logic circuit is a combination of logic gates. It produces output based on the rules of logic it is designed to follow for the electrical signals it receives as input. See also gate (definition 1).
logic diagram n. A schematic that shows the connections between computer logic circuits and specifies the expected outputs resulting from a specific set of inputs.
logic error n. An error, such as a faulty algorithm, that causes a program to produce incorrect results but does not prevent the program from running. Consequently, a logic error is often very difficult to find. See also logic, semantics, syntax.
logic gate n. See gate (definition 1).
logic operation n. 1. An expression that uses logical values and operators. 2. A bit-level manipulation of binary values. See also Boolean operator.
logic programming n. A style of programming, best exemplified by Prolog, in which a program consists of facts and relationships from which the programming language is expected to draw conclusions. See also Prolog.
logic-seeking printer n. Any printer with built-in intelligence that lets it look ahead of the current print position and move the print head directly to the next area to be printed, thus saving time in printing pages that are filled with spaces.
logic symbol n. A symbol that represents a logical operator such as AND or OR. For example, the symbol + in Boolean algebra represents logical OR, as in A + B (read, A or B, not A plus B ).
logic tree n. A logic specification method that uses a branching representation. Each of the tree s forks represents a decision point; the ends of the branches denote actions to be taken.
login n. See logon.
log in vb. See log on.
Logo n. A programming language with features that are heavily drawn from LISP. Logo is often used to teach programming to children and was developed originally by Seymour Papert at MIT in 1968. Logo is considered an educational language, although some firms have sought to make it more widely accepted in the programming community. See also LISP, turtle, turtle graphics.
logoff n. The process of terminating a session with a computer accessed through a communications line. Also called: logout.
log off vb. To terminate a session with a computer accessed through a communications line usually a computer that is both distant and open to many users. Also called: log out. Compare log on.
logon n. The process of identifying oneself to a computer after connecting to it over a communications line. Also called: login.
log on vb. To gain access to a specific computer, a program, or a network by identifying oneself with a username and a password. Also called: log in. Compare log off.
logon script n. A file assigned to certain user accounts on a network system. A logon script runs automatically every time the user logs on. It can be used to configure a user s working environment at every logon, and it allows an administrator to influence a user s environment without managing all aspects of it. A logon script can be assigned to one or more user accounts. Also called: login script. See also user account.
logout n. See logoff.
log out vb. See log off.
LOL n. Acronym for laughing out loud. An interjection used in e-mail, online forums, and chat services to express appreciation of a joke or other humorous occurrence. See also ROFL.
Long data type n. A fundamental data type that holds large integers. A Long variable is stored as a 32-bit number ranging in value from 2,147,483,648 to 2,147,483,647.
long filenames n. A feature of most current PC operating systems, including the Macintosh, Windows 9x, Windows NT, Windows 2000, and OS/2. Long filenames allow a user to assign a plain-text name to a file, rather than limiting possible names to just a few characters. Names can be over 200 characters long, include uppercase and lowercase letters, and have spaces between characters. Compare 8.3.
long-haul adj. Of, pertaining to, or being a type of modem that is able to transmit over long distances. Compare short-haul.
longitudinal redundancy check n. See LRC.
LonWorks n. An open standard for network automation created by the Echelon Corporation and supported by the LonMark Interoperability Association. LonWorks, introduced in 1991, can be used in building, transportation, industrial, and home applications to implement a distributed control network.
lookup n. A function, often built into spreadsheet programs, in which a previously constructed table of values called a lookup table is searched for a desired item of information. A lookup table consists of rows and columns of data. A lookup function examines the table either horizontally or vertically and then retrieves the data that corresponds to the argument specified as part of the lookup function.
loop1 n. 1. A set of statements in a program executed repeatedly, either a fixed number of times or until some condition is true or false. See also DO loop, FOR loop, infinite loop, iterative statement. 2. A pair of wires that runs between a telephone central office and customer premises.
loop2 vb. To execute a group of statements repeatedly.
loop check n. See echo check.
loop configuration n. A communications link in which multiple stations are joined to a communications line that runs in a closed loop. Generally, data sent by one station is received and retransmitted in turn by each station on the loop. The process continues until the data reaches its final destination. See the illustration. See also ring network. Loop configuration.
loophole n. In programming, a logical failure to account for all possible situations. See also bug (definition 1), logic error.
loop invariant n. A condition that remains true while a loop iterates.
loop structure n. See iterative statement.
lo-res adj. See low resolution.
loss balancing n. Amplification of a signal or value to compensate for loss during a transmission or translation of a value.
lossless compression n. The process of compressing a file such that, after being compressed and decompressed, it matches its original format bit for bit. Text, code, and numeric data files must be compressed using a lossless method; such methods can typically reduce a file to 40 percent of its original size. Compare lossy compression.
lossy compression n. The process of compressing a file such that some data is lost after the file is compressed and decompressed. Video and sound files often contain more information than is apparent to the viewer or listener; a lossy compression method, which does not preserve that excess information, can reduce such data to as little as 5 percent of its original size. Compare lossless compression.
lost cluster n. A cluster (disk storage unit) marked by the operating system as being in use but not representing any part of any chain of stored segments of a file. A lost cluster usually represents debris resulting from incomplete data housekeeping, as might result from the ungraceful exit (messy or abrupt termination) of an application program.
Lotus 1-2-3 n. An electronic spreadsheet product introduced in 1983 by Lotus Development Corporation. Notable for its inclusion of graphing and data-management (database) capabilities in addition to spreadsheet functionality, Lotus 1-2-3 is important in the history of the personal computer because it was one of the first killer apps that convinced businesses to buy and use a PC. Lotus Development was purchased by IBM in 1995. See also killer app.
Lotus cc:Mail n. See cc:Mail.
Lotus Domino n. A groupware application that transforms Lotus Notes into an application and messaging server. See also Lotus Notes.
Lotus Notes n. A groupware application introduced in 1988 by Lotus Development Corporation and now owned by IBM. Lotus Notes combines e-mail, calendar management, group scheduling, contact and task management, newsgroup access, and Web browsing capability (through the integration of Microsoft Internet Explorer) in one client application. Lotus Notes also offers search capabilities across multiple formats and file types on a network or the Web.
low-Earth-orbit satellite n. A communications satellite put into orbit no higher than 500 miles above the earth s surface. A low-Earth-orbit satellite, or LEO, circles the planet in 90 minutes to 2 hours. LEOs allow for use of smaller dishes and handheld devices, so they are well-suited for interactive conferencing. However, because a LEO remains above the local horizon for about only 20 minutes, large numbers of these satellites, in several different orbits, are required to maintain service. Acronym: LEO. Compare geostationary orbit satellite.
lowercase adj. In reference to letters, not capital for example, a, b, c. Compare uppercase.
low frequency n. The portion of the electromagnetic spectrum between 30 kilohertz (kHz) and 300 kHz. This range of frequencies is used for several types of radio communication, including the longwave broadcast band in Europe and Asia.
low-level language n. A language that is machine dependent or that offers few control instructions and data types. Each statement in a program written in a low-level language usually corresponds to one machine instruction. See also assembly language. Compare high-level language.
low memory n. On computers running MS-DOS, the first 640 kilobytes of RAM. This RAM is shared by MS-DOS, device drivers, data, and application programs. Also called: conventional memory. Compare high memory.
low-order adj. Carrying the least weight or significance; typically, the rightmost element in a group. For example, the rightmost bit in a group of bits is the low-order bit. Compare high-order.
lowpass filter n. An electronic circuit that allows all frequencies below a specified frequency to pass through it. Compare bandpass filter, highpass filter.
low resolution adj. Abbreviated lo-res. Appearing in relatively coarse detail, used in reference to text and graphics in raster-oriented computer displays and printing. Low-resolution printing is comparable to draft-quality dot-matrix output printed at 125 dots per inch or less. See also resolution. Compare high resolution.
LPM n. See lines per minute.
LPMUD n. A type of multiuser dungeon (MUD), typically combat related, that contains its own object-oriented programming language for the creation of new areas and objects in the virtual world. See also MUD.
LPT n. Logical device name for a line printer, a name reserved by the MS-DOS operating system for up to three parallel printer ports designated LPT1, LPT2, and LPT3. The first port, LPT1, is usually the same as the primary MS-DOS hard-copy output device PRN (the logical device name for the printer). The letters LPT were originally used to stand for line print terminal.
LRC n. Acronym for longitudinal redundancy check. A procedure used to check the accuracy of data stored on magnetic tape or transmitted over a communications line. See also parity bit. Compare VRC.
ls n. A UNIX command that instructs the server to return a list of files and subdirectories in the current directory or the directory specified in the command. Because many FTP sites are built on UNIX systems, this command can also be used on those sites. See also FTP site, UNIX.
LS-120 n. Acronym for Laser Storage-120. A floppy disk drive developed by Imation Corporation that uses proprietary laser storage 120-megabyte (MB) media as well as standard 1.44 MB 3.5-inch floppy media. The LS-120 disk drive is capable of storing 120 MB of data on a single 3.5-inch floppy disk and is compatible with other floppy disk formats. LS-120 drives are ATAPI (AT Attachment Packet Interface) compliant so several different drives can use the same EIDE controller. Also called: Super Disk.
LSB n. 1. See least significant bit. 2. Acronym for Linux Standard Base. A standard developed to aid in Linux software development by providing a uniform foundation for all versions of the operating system. The Linux model provided by the LSB provides a stable platform for developers to create software that may be used with any version of the operating system, while leaving companies the ability to add other features on top of the base.
LSC n. See least significant character.
LSD n. See least significant digit.
LSI n. See large-scale integration.
LSP n. See MPLS.
LSR n. See MPLS.
LU n. Acronym for logical unit. In an IBM SNA network, a point denoting the beginning or end of a communications session. See also SNA.
Luddite n. A person opposed to technological advances, especially those designed to replace human skill and experience with automated machinery. The first Luddites were bands of textile workers in Nottinghamshire, England, who protested the use of new large-scale machinery, which they blamed for low wages and high unemployment. The origin of the term has never been verified, but the most popular theory is that the name derives from Ned Ludd, an apprentice knitter who destroyed his knitting frame with a hammer to protest beatings by his master. See also technophobe. Compare technophile.
LUG n. Acronym for Linux Users Group. See user group.
luggable computer n. The first portable computers, produced in the early to mid-1980s. These early units, all of which had built-in CRT-based displays, weighed over 20 pounds and were the size of a medium suitcase hence their name. See also portable computer.
luminance n. 1. A measure of the amount of light radiated by a given source, such as a computer display screen. 2. The perceived brightness component of a given color, as opposed to its hue or its saturation. See also HSB. Compare illuminance.
luminance decay n. See persistence.
luminosity n. The brightness of a color based on a scale from black to white on your monitor.
Lunar calendar n. Predominant calendar type used in Israel among Hebrew speakers, in Islamic cultures, and in most of Asia. Lunar calendars calculate months based on lunar phases.
lurk vb. To receive and read articles or messages in a newsgroup or other online conference without contributing to the ongoing exchange.
lurker n. A person who lurks in a newsgroup or other online conference. See also lurk. Compare netizen.
LVS n. Acronym for Linux Virtual Server. A high- performance open source server that handles connections from clients and passes them on to a cluster of real servers. LVS receives incoming packets and forwards them to the proper back-end server. LVS is typically used to build scalable Web, mail, or other network services. Also called: ipvs. See also layer 4 switching.
Lycos n. A Web search engine and directory that provides summaries of pages matching search requests. In addition, the Lycos site offers categorized directories of sites, reviews of selected sites, and services for finding names, viewing maps, and so on.
Lynx n. A text-only Web browser program for UNIX platforms.
.lzh n. The file extension that identifies archive files compressed with the Lempel Ziv and Haruyasu algorithm. See also compressed file, Lempel Ziv compression, LHARC.
LZW compression n. A compression algorithm named after Abraham Lempel and Jakob Ziv (creators of Lempel Ziv compression) and LZW designer Terry Welch that makes use of repeating strings of data in its compression of character streams into code streams. It is also the basis of GIF compression. See also GIF, Lempel Ziv compression.
EAN: 2147483647
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