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There are 406 names in this directory beginning with the letter M.
M

One million.

Mac

A brand name and registered trademark for a line of computers from Apple Inc.

MAC address

Media Access Control address. The physical address of a device connected to a network, expressed as a 48-bit hexadecimal number.


MAC protocol

Medium Access Control protocol. In a local area network, the protocol that determines which device has access to the transmission medium at a given time.

MAC sublayer

Medium Access Control sublayer. The lower sublayer of the data link layer, which uses the network's physical layer to provide services to the logical link control (LLC). The functions of the MAC sublayer vary according to the topology of the network.

MacApp

A tool for developing application programs on the Macintosh, using object-oriented Pascal.

MacBench

A benchmark from Ziff-Davis that measures the processor, floating point, disk, graphics, video, and CD-ROM performance of a MacOS, giving an idea of how well a particular system will run common Macintosh applications.

MacBinary

Macintosh files, unlike files from other computer platforms which hold data only, have a resource fork and a data fork. If Mac files are put on a non-Mac machine, the resource fork will be stripped off, rendering some files unusable. MacBinary encoding prevents loss of the resource fork when posting the file to a non-Mac platform, by attaching the resource and data forks together in a single data file. MacBinary files must be transferred using an 8-bit, binary mode. They often have .bin as a filename extension.

MacBooz

A Macintosh decompression program that can expand .zoo files.

MacCompress

The Mac version of the Compress program for DOS and UNIX. It creates files with the .Z suffix.

MacDraw

A drawing program for the Macintosh.

MacGzip

A version of gzip for Macintosh, made by SPDsoft. It compresses Mac files into gzip files; the Mac resource fork is lost unless a MacBinary translator is used first. The gunzip function decompresses .gz, .Z, .z, and .tgz files.

machinable

Readable by a computer; softcopy is machinable.

machine

A device which performs a task and is operated mechanically, electrically, or electronically. In computer terminology, “machine” refers to the computer itself.

machine address

An address that is permanently assigned to a specific storage location in a computer, by the maker of the machine.

machine code

Machine language. The language which is actually read and understood by the computer.

machine cycle

The cycle of four steps a computer's central processing unit must complete each time a machine language instruction is given: fetching the instruction from the main memory, decoding it, executing the instruction, and storing the result. “Machine cycle” also means the length of time one machine cycle takes.

machine language

(Same as machine code.) The language which is actually read and understood by the computer. Machine language consists of instructions, written in binary code, that a computer can execute directly. Each machine language statement corresponds to one machine action. An operation that requires one machine-language instruction in one computer may require several instructions in another computer.
Humans do not usually write programs in machine language, but use a programming language which the computer translates into machine language. Assembly language is the next level of programming. Each assembly-language statement corresponds to one machine-language statement, but assembly language statements are written in a symbolic code that is easier for humans to read.

machine learning

The ability of a machine to recognize patterns that have occurred repeatedly and improve its performance based on past experience.

machine-dependent program

A program that works only on one type of computer.

machine-independent program

A program that can work on many different types of computers.

machine-readable data

Data in any form that a computer can read as input. Magnetic disks, optical disks, and magnetic tapes contain machine-readable data.

Macintosh

A family of 32-bit personal computers introduced by Apple in 1984; the first widely used computers with a graphical user interface, a mouse, and windows. Rather than typing in commands, users open software and copy or delete files by clicking on icons on the screen that look like file folders, a trash can, and other things one would find in a real office. Macs quickly became popular because of their user-friendly interface. In 1994, PowerMacs, which use a PowerPC CPU, became available. The Macintosh Operating System is now called MacOS.

Macintosh clone

A Power Macintosh not made by Apple Computer.

Macintosh extensions

Software functions which can be added to the Macintosh by putting them in the Extensions folder within the System folder, including drivers and INITs. Some examples are Print Monitor, Thread Manager, Macintosh Drag and Drop, QuickTime, Audio CD Access, Apple Modem Tool.

Macintosh file

A Macintosh file has two forks: a data fork, which contains data (the same as files on other operating systems); and a resource fork, which has other attributes such as menus, icons, dialog boxes, formatting, and other codes. In some methods of converting files for transfer (such as uuencoding), the resource fork of a Macintosh file is stripped off and only the data fork is sent. BinHex and MacBinary encoding preserve the resource fork.

Macintosh user interface

The graphical user interface used by Macintosh personal computers, which is modeled after an actual desktop and has little pictures (called icons) of file folders, a trash can for deleting files, etc. Pull-down menus and draggin objects originated with the Mac. For people who are not computer experts, the Macintosh user interface makes everything much easier to learn. Parts of this interface were developed by Xerox PARC, but never released. Elements of the Macintosh user interface are now used on many other programs and operating systems, including Commodore, Amiga, Motif, OS/2 Presentation Manager, Digital Research's GEM, Hewlett-Packard's New Wave, the X Window System, RISC OS, and Microsoft Windows. Pull-down menus are used in graphical Internet browsers and on WWW pages.

Macjordomo

A Mac freeware listserver.

MacPaint

A paint program for the Macintosh computer.

macro

One instruction that represents a sequence of simpler instructions.

macro-

A prefix meaning large.

macro-assembler

A program that translates assembly language instructions into machine code and which the programmer can use to define macro instructions.

Macromedia

A software company in San Francisco, CA, which produces multimedia and digital arts tools for Microsoft Windows and Macintosh. Macromedia products include: Macromedia Director, Macromedia FreeHand, SoundEdit 16, and Fontographer.

macrotape

A larger-sized reel of magnetic tape, rather than a microtape.

MacTar

A compression program for Macintosh that creates and decompresses .tar files.

MacTCP

A Macintosh control panel which connects the computer with access to TCP/IP services.

MacTicker

A stock market program for Macintosh.

MacZoo

A Macintosh program that can decompress .zoo files.

MAD

Michigan Algorithm Decoder. One of the first extensible languages, developed at the University of Michigan.

MADAM

Manchester Automatic Digital Machine. One of the first chess-playing machines, developed by Alan M. Turing (1912-1954) in 1950. It was not very smart.

Magellan

An Internet search engine.

Magic Cookie

Magic Cookie is a file created by Microsoft Explorer and Netscape Navigator, kept in the preferences folder. The file stores data about what websites and pages within the site the user visits. This information can be used by the servers for marketing analysis, to generate mailing lists, or other uses. See cookie.

magic wand

A tool in some photo editing programs that allows the user to select an area of the image to copy, move, color, rotate, enlarge, or transform in other ways. Clicking on a pixel activates the whole area of the same color that is continuous with that pixel.

magnetic bubble memory

A kind of storage used in some lightweight portable computers. A magnetic bubble is a tiny movable magnetized cylindrical volume in a thin magnetic material that in combination with other similar volumes can be used to represent a bit of information.

magnetic disk

A hard disk or floppy disk, the primary means of data storage for a computer. Data on disks is magnetically recorded and can also be erased and re-recorded. The data is stored in concentric rings called tracks, which are further divided into numbered sectors. The disk rotates as a mechanical arm moves a read/write head back and forth. The head writes data by aligning magnetic particles on the disk's surface, and reads data by detecting the polarities of particles that have already been aligned.

magnetic field

The area around a magnetic body or a current-carrying body in which its magnetic forces can be detected. Magnetic forces have the property of attracting iron.

Magnetic Ink Character Recognition

(MICR) A character recognition system used on bank checks; special ink and characters are used, which can be magnetised for automatic reading.

magnetic tape

A data storage medium used for backup. The tape is made of a thin plastic strip with a magnetisable oxide coating on one side. To read or write, the tape drive winds the tape from one reel to another, causing it to move past a read/write head. Tapes are available in reels and cartridges of various sizes. The data is written in blocks with interblock gaps between them. To find a specific block of data on the tape the computer must read everything in front of it.

magnetic tape drive

A drive that reads and writes magnetic tape.

magneto-optical disk

A plastic or glass disk coated with a chemical (often TbFeCo) with special properties which make it rewritable. A combination of magnetic and optical methods are used to write data to the disk. A high-intensity laser heats the material up to its Curie point, the temperature at which molecules can be realigned by a magnetic field. A magnet is used to make changes in polarity which remain after cooling. The disk is read by directing a low-intensity laser at the disk and interpreting variations in its reflected light, which result from differences in polarity of the stored magnetic field.

mail bomb

Massive amounts of electronic mail sent to a single person, with malicious intent to overload the recipient’s system. Mail bombing can cause problems not only for the targeted recipient, but also for other users of the networks involved.

mail bridge

A gateway that forwards electronic mail messages between networks.

mail exploder

Part of an electronic mail system used by mailing lists. User send messages to a central address; the mail exploder delivers the messages to all individual mailboxes in its list.

mail filter

A program which can sort and process incoming email for the recipient, based on the mail headers. For example, all mail pertaining to a certain subject (as indicated by its header) could be put into a high-priority file.

mail gateway

A machine that makes a connection between two or more electronic mail systems in order to transfer messages, and translate between dissimilar systems.

mail hub

A computer which stores and/or forwards electronic mail.

mail log

An electronic mail program's record of all mail that has been sent and received.

mail merge

A way of using a computer to print customized form letters. The letter will be in one file, and a name and address list in another. Name and address information for each letter to be printed will be inserted at designated merge points. Other custom data can also be inserted at chosen points as specified by the user.

mail server

A program that sends files in response to requests sent by email.

mail transfer agent

(MTA) The program that delivers email messages. The mail transfer agent receives a message from a mail user agent (or another mail transfer agent) and either delivers it or forwards it.

mail user agent

(MUA) A program that allows the user to write and read email messages. Outgoing mail goes from the mail user agent to the mail transfer agent, and on to the addressee. Incoming messages are retrieved from the mail transfer agent. (Single-user machines more often pick up mail using POP).

Mail Users' Shell

A mail user agent for MS-DOS and Unix.

mailbot

A program which automatically delivers information via electronic mail.

mailbox

A box that holds incoming mail; a box for electronic mail is a file where mail messages are stored until the addressee opens and reads them.

mailer

A program that delivers electronic mail.

mailing list

An email discussion forum. Participants subscribe to a list, receive copies of messages sent by other members, and can email their own comments. In some mailing lists there is a moderator who receives all mail, screens it, and decides which messages to pass on. Unmoderated lists simply redirect all mail received to the list of recipients. Mailing lists may be highly technical, or social and recreational. The advantage of mailing lists over public Usenet groups is that the discussion is limited to highly interested and committed participants, and therefore more focused.

main distribution frame

(MDF). The storage space which contains the hardware for the main hub of a network.

main storage

Memory; also called main memory. The working space used by the computer to hold the program that is currently running, along with the data it needs, and to run programs and process data. The main memory is built from RAM chips. The amount of memory available determines the size of programs that can be run, and whether more than one program can be run at once. Main memory is temporary, and is lost when the computer is turned off. It is distinguished from more permanent internal memory (ROM) which contains the computer's essential programs, and storage (the disks and tapes which are used to store data).

mainframe

A “mainframe” originally meant the cabinet containing the central processor unit of a very large computer. After minicomputers became available, the word mainframe came to refer to the large computer itself. The older computers used many large vacuum tubes and generated a lot of heat, thus requiring specially air-conditioned rooms. A single computer might have hundreds of users at a time. Today, because the large vacuum tubes have given way to transistors, a desktop personal computer can have as much power as a mainframe computer that once filled a whole room. Mainframes in use now often have smaller computers as front end processors.

mainframe

This is a large and expensive computer with the ability to support hundreds or thousands of users simultaneously.

mainframe computer

A “mainframe” originally meant the cabinet containing the central processor unit of a very large computer. After minicomputers became available, the word mainframe came to refer to the large computer itself. The older computers used many large vacuum tubes and generated a lot of heat, thus requiring specially air-conditioned rooms. A single computer might have hundreds of users at a time. Today, because the large vacuum tubes have given way to transistors, a desktop personal computer can have as much power as a mainframe computer that once filled a whole room. Mainframe computers in use now often have smaller computers as front end processors.

major release

A release of new software or a software update which contains important changes.

Majordomo

A UNIX mailing list processor used to manage email discussion lists.

make

In Unix and Unix-like operating systems, “make” is a command that creates a machine-language program by compiling source files to produce a group of object files, and then linking the object files together. A makefile contains the commands that control this process.

makefile

A makefile is a script through which the programmer gives the computer instructions on how to build a particular program using the “make” command.

mal-ware or malware

Viruses, worms, Trojan horses, and other malicious programs.

male connector

A plug that fits into a “female” counterpart, or socket.

malfunction

The inability of a system or component to perform a required function; a failure.

malicious logic

Logic (hardware or software) that is purposely introduced into a system with harmful intent.

MAN

Metropolitan Area Network. A network that serves a metropolitan area. Compare LAN and WAN.

Management Information Base

(MIB). A database containing ongoing information and statistics on each device in a network, used to keep track of each device's performance and make sure all are functioning properly. MIBs are especially used with SNMP.

Management Information System

(MIS) A computer system for a business or other organization which collects and analyzes data from all departments, and is designed to provide an organization's management with up-to-date information (such as financial reports, inventory, etc.) at any time.

Management Information Systems

The study of effective systems for the development and use of information in an organization.

Manchester Automatic Digital Machine

(MADAM). One of the first chess-playing machines, developed by Alan M. Turing (1912-1954) in 1950. It was not very smart.

MANIAC

Mathematical Analyzer, Numerator, Integrator, and Computer. A high-speed computer built at the Los Alamos Scientific Laboratory in the late 1940s – early 1950s, which was used in the development of the hydrogen bomb.

mantissa

1. In a floating point number, the numeric value which is multiplied by the radix raised to the power of its exponent; for example, in 145,000 = 145 x 10^3, 145 is the mantissa, 10 is the radix, and 3 is the exponent. 2. The non-negative fractional part of a logarithm; the part of the logarithm on the right of its decimal point.

manual feed

Putting one sheet of paper into the printer at a time, by hand, instead of using the sheet feeder. The printing setup on a computer usually allows a choice between using the sheet feeder and manual feed. Manual feed is often used for large sheets of paper or nonstandard paper.

manularity

A measure of the amount of manual labor required to do a task; can be used to calculate the benefit that would result from automating the task. For example, collating a book by hand has a higher manularity than using an automatic collator.

MAPI

Messaging Application Programming Interface. A program interface that enables a user to send and receive email from within any MAPI-compliant application by means of the Microsoft Mail messaging system. If two applications are MAPI-enabled, they can share email messages with each other. Applications that can use MAPI include word processors, spreadsheets, and graphic applications. See also API.

marching ants

In paint and draw programs, when an object is selected, it is displayed on the screen with moving black and white dashes around its border. Some users call this effect “marching ants.”

Marconi, Guglielmo

An Italian inventor (1874-1937) who discovered that radio signals could be sent over long distances.

margin

The space between text and the edge of the page. Most word processors and page layout programs provide a way of adjusting the margins.

mark

1. A symbol or sign used to record something. 2. To select an item or group of items. 3. A 1 bit.

Mark 1

The first full-sized digital computer, developed in 1944 by Howard Aiken at Harvard University.

Markov chain

A random process in which the probability that a certain future state will occur depends only on the present or immediately preceding state of the system, and not on the events leading up to the present state.

Markov process

A random process similar to a Markov chain, except the states are ongoing; for example, Brownian motion.

Markov, Andrei

A Russian mathematician (1856-1922), after whom the Markov process and Markov chains were named.

markup

The process of adding coding to a text document which gives instructions for layout, type styling, placement of graphics, or other information which will be interpreted by the system used to read the document. See markup language.

markup language

A language that has codes for indicating layout and styling (such as boldface, italics, paragraphs, insertion of graphics, etc.) within a text file; for example SGML and HTML.

marquee select

In graphics programs, a way of selecting more than one item at a time. When several items are selected together, they are highlighted by a line of moving dashes around the outside which gives the impression of a theater marquee.

Martian

A joke term referring to a data packet that shows up on the wrong network, misrouted because of an error in addressing or having been sent to a nonexistent address.

MARVEL

Machine-Assisted Realization of the Virtual Electronic Library (U.S. Library of Congress).

mass storage

A large-capacity backup storage such as an external hard disk or magnetic tape.

massage

To transform a file from one form into another. Used to describe various ways of processing data or files; sometimes refers to the editing of text or graphics files.

master

A computer which controls another computer or a peripheral.

master page

A template that sets up certain design elements that will appear on every page of a printed document, such as headers, footers, logos, or borders.

math coprocessor

A circuit inside a computer that handles high-speed floating point arithmetic operations. It may be on its own separate chip, or on the CPU chip. The math coprocessor is not used with every program, but programs that contain instructions for the math coprocessor can do arithmetic operations much more quickly than programs that use only the CPU. The main use for a math coprocessor is in CAD and spreadsheet applications. Some software is designed to use a math coprocessor and will not run at all if a coprocessor is not installed. Other programs are designed to use the coprocessor if it is there and to use the CPU otherwise. The math coprocessor is also called a floating point coprocessor or floating point unit (FPU).

Mathematical Analyzer, Numerator, Integr

(MANIAC). A high-speed computer built at the Los Alamos Scientific Laboratory in the late 1940s – early 1950s, which was used in the development of the hydrogen bomb.

Mathematics Markup Language

(MathML). An XML application for including mathematical and scientific expressions on Web pages.

MathML

Mathematics Markup Language. An XML application for including mathematical and scientific expressions on Web pages.

matrix

An array of elements in rows and columns which effectively organizes data in the form of a table.

Matrox Millenium

A 64-bit PCI (Peripheral Component Interconnect) video card with 2MB or 4MB WRAM. It supports video and MPEG.

Matrox Mystique

A 64-bit PCI (Peripheral Component Interconnect) video card with 2MB or 4MB SGRAM. It supports video and MPEG.

maximize

To enlarge a window to full size, in a graphical user interface. In Windows, this is done by clicking the mouse on "maximize"; in a Macintosh file, by clicking on the little box in the upper right-hand corner. Opposite of minimize.

maximum transmission unit

(MTU). The largest unit of data that can be transmitted on any particular physical medium.

MB

1. Megabyte: 1,048,576 bytes or 1,024 kilobytes. Used to measure computer memory. Sometimes used to mean 1 million bytes or 1,024,000 bytes (1,000 kilobytes). 2. Motherboard.

Mb

megabit. 1. (Also mbit or Mbit). 1,048,576 (216) bits, or 1024 kilobits. A measurement of the capacity of memory chips. Also used to mean one million bits. See megabyte. 2. Sometimes Mb is used for megabyte.

MBone

Multicast Backbone. A network of Internet sites that supports Internet Protocol multicasting for a limited number of users. MBone provides a faster technology than the Internet for transmitting real-time audio and video programs, and for videoconferencing. The Rolling Stones made history with the first major multicast concert on the MBone.

mbps

(Also Mbps) Megabits per second (million bits per second). Used to measure the rate of information transfer.

MBps

Megabytes per second (million bytes per second).

MC

Machine Code. The language which is actually read and understood by the computer.

MC92100

Also called Scorpion. A graphics and digital video encoder chip which makes adds Internet browsing and other interactive features to a television set. The MC92100 chip can be used with existing sets or new products. It can be used with set-top boxes and DVDs. Users will be able to display multiple windows on the screen, watching television and browsing the Internet at the same time.

MCF

Meta Content Framework. An XML application proposed by Netscape Communications, which provides a standardized way to describe files or collections of data. See metadata, RDF, and XML.

MCGA

Monochrome/Color Display Adapter. A monochrome video system for early IBM PCs, which displayed very clear text but no graphics.

MCI Mail

An online service that provides electronic mail, fax, and Telex. In addition to ASCII text messages, files can be transmitted using the Xmodem, Ymodem, Kermit and Zmodem protocols, allowing the sending of binary files such as word processing documents, spreadsheets, etc. For security, mail from one MCI Mail account to another stays within the system, unlike on the Internet, where mail “hops” from one computer to another. MCI Mail also provides overnight courier delivery, receipt notification, electronic forms, and a gateway to Dow Jones News Retrieval database service.

MCSD

Microsoft Certified Solution Developer.

MCSE

Microsoft Certified Systems Engineer

MD DATA drive

A drive for Sony 140-megabyte data storage cartridges, which can also read Sony MiniDiscs.

MD5

A one-way hash algorithm used to create a message digest for digital signatures. MD5 is used with 32-bit machines and can be used when large messages have to be compressed in a secure format before a private key is used.

MDF

Main Distribution Frame. The storage space which contains the hardware for the main hub of a network.

Mead Data Central

An online service offering news and legal information.

mean time between failures

(MTBF). A figure that gives an estimate of the reliability of a piece of equipment. The higher the MTBF, the longer the equipment should last. For example, if the MTBF is 10,000 hours, the equipment should run, on the average, for 10,000 hours before failing.

mean time to failure

(MTTF). The approximate amount of time expected before a system or component will fail; see mean time between failures.

mean time to recovery

(MTTR). The average amount of time a functional unit will spend in corrective maintenance over a given period of time.

mean time to repair

(MTTR). The average amount of time needed to repair a failed unit.

meatware

Animal systems, as opposed to computer hardware or software. Used most often to compare the human biological system, controlled by its nervous system, to a computer system controlled by its central processing unit.

mechanical mouse

mechanical mouse
A mouse that operates by mechanical means; a rubber ball rolls as the mouse is moved across a tabletop or mouse pad, and the rubber ball turns vertical and horizontal wheels inside the mouse. The wheels, called encoders, have tiny metal contact points on their rims, which touch a contact bar as they turn. The contact bar sends electrical signals to the computer. The location of the mouse is established by how many times the contact points have touched the bars, the direction in which the wheels are turning, and the ratio between the number of signals from the vertical and horizontal encoders. The mechanical mouse is different from the optical mouse, which uses a beam of light to tell where it is.

medical informatics

The use of computers in medical research, medical education, and clinical medicine.

medium access control or media access co

(MAC). On a local area network, the control of which device has access to the transmission medium at a particular time.

medium access control protocol

(MAC protocol). In a local area network, the protocol that determines which device has access to the transmission medium at a given time.

medium access control sublayer

(MAC sublayer). The lower sublayer of the data link layer, which uses the network's physical layer to provide services to the logical link control (LLC). The functions of the MAC sublayer vary according to the topology of the network.

medium frequency

(MF). Electromagnetic frequencies in the range of 300 to 3000 kiloherz.

medium interface connector

(MIC). A type of connector for fiber-optic cable that uses a plug and socket and has been used with FDDI and local area networks.

MEDLARS

An online medical database from the National Library of Medicine, Bethesda, Maryland.

meg

1. Mega, or million (M). Sometimes means 1,048,576. 2. Megabyte.

mega-

1. Prefix meaning one million or 106. 2. Also used to mean 230.

megabit

(Mb, mbit or Mbit) 1,048,576 (216) bits, or 1024 kilobits. A measurement of the capacity of memory chips. Also used to mean one million bits. See megabyte.

megabyte

(MB, mb, Mbyte, M-byte) 220 bytes = 1,048,576 bytes or 1,024 kilobytes. Used to measure computer memory. Sometimes used to mean 1 million bytes or 1,024,000 bytes (1,000 kilobytes). See megabit.

megabytes

(MB, mb, Mbyte, M-byte) Each megabyte is 220 bytes = 1,048,576 bytes or 1,024 kilobytes. Megabytes are used to measure computer memory. Sometimes a megabyte means 1 million bytes or 1,024,000 bytes (1,000 kilobytes). See megabit.

megaflops

Million floating-point operations per second. A unit used to measure the performance of computers that do calculation.

megahertz

(MegaHertz , MHz). Millions of cycles per second. The unit of frequency used to measure the clock speed of a computer.

megapixel image

In graphic design, an image containing a very large number of pixels, a million or more. Megapixel images have a lot of detail and make very large files.

MEM

Microelectromechanical.

memory

Also called main memory. The working space used by the computer to hold the program that is currently running, along with the data it needs, and to run programs and process data. The main memory is built from RAM chips. The amount of memory available determines the size of programs that can be run, and whether more than one program can be run at once. Main memory is temporary, and is lost when the computer is turned off. It is distinguished from more permanent internal memory (ROM) which contains the computer's essential programs, and storage (the disks and tapes which are used to store data).

memory cache

A memory bank between the main memory and the CPU, which enables the computer to read data and execute instructions faster. The memory cache is static RAM (SRAM); main memory is dynamic RAM (DRAM). See cache and disk cache.

memory capacity

The amount of space available for storing data in memory, designated in bytes.

memory dialing

A feature of a telephone that allows numbers to be stored for quick dialing by pressing one or two buttons.

memory effects

A problem with nickel cadmium batteries in which the battery remembers how full it was when it was last charged, and doesn't go past that point the next time. Because of this the battery must be completely drained before recharging to get the longest charge.

memory expansion

Adding additional memory to a personal computer by means of expansion cards.

memory expansion option

The option of adding additional memory to a personal computer by means of expansion cards.

memory management

Strategies for providing sufficient memory to all the processes in a computer system, performed by the memory management unit (MMU).

memory management unit

(MMU). A hardware device which translates virtual addresses into physical addresses and is used to manage virtual memory.

memory protection

A system used to prevent one program from corrupting another program running at the same time, and to prevent corruption of the operating system. A hardware memory management unit and special programs are used to ensure that instructions within one program are not able to accidentally influence another program. Windows NT and most versions of UNIX have memory protection. MacOS 8 will have it.

memory resident

Remaining in memory in order to be available for immediate use.

Memphis

The original code name for Windows 97, which was later renamed Windows 98 when Microsoft realized that it was going to miss its target 1997 release date.

menu

A onscreen list from which the user may choose an operation to be performed. Items from the menu may be selected by keyboard commands or by pointing with a mouse.

menu bar

A bar across the top of the computer screen or window, which has the names of available pull-down menus, such as “File”, “Font”, “Window”, etc. Pressing the mouse on a menu bar item makes its pull-down menu appear.

menu-driven

Having an interface that uses menus, as opposed to a command-line interface.

menu-driven interface

A user interface that uses menus to communicate with the computer. Rather than having a single line where a command must be typed in, the user has a list of items to choose from, and can make selections by highlighting one. This kind of interface is easier to use than a command-line interface, but does not have all the visual elements of a graphical user interface.

message

1. In communications, a message is information transmitted via a network. 2. In object-oriented programming, a call for one of an object's methods.

Message Handling Service

(MHS). Novell messaging software.

Message Handling System

(MHS). The ISO Message-Oriented Text Interchange Standard; called X.400 by ITU-T. The OSI electronic mail system, comprised of message user agents, message transfer agents, message stores, and access units.

message sink

In a communication system, the part that receives messages.

message transfer agent

(MTA). A mail agent, used to store and transfer messages in the X.400 Message Handling System.

Messaging Application Programming Interf

(MAPI). A program interface that enables a user to send and receive email from within any MAPI-compliant application by means of the Microsoft Mail messaging system. If two applications are MAPI-enabled, they can share email messages with each other. Applications that can use MAPI include word processors, spreadsheets, and graphic applications. See also API.

Meta Content Framework

(MCF). An XML application proposed by Netscape Communications, which provides a standardized way to describe files or collections of data. See metadata, RDF, and XML.

Meta tag

An identifying tag for HTML or XML documents that can be viewed in HTML or XML source. The tag allows information such as keywords that identify content, the author’s name and other descriptive details.

meta-searcher

A regular search engine allows a user to search a single database. A meta-searcher is a front end that passes each query to multiple search engines.

MetaCard

A hypertext system for Unix and the X Window System, which is similar to HyperCard.

MetaCrawler

An Internet multisearch engine (http://www.metacrawler.com/index.html); it searches nine other search engines (Lycos, Open Text, Alta Vista, Excite, WebCrawler, InfoSeek, Inktomi, Yahoo, and Galaxy).

metadata

Data about data; for example, tags that indicate the subject of a WWW document.

metafile

A file format designed for exchanging graphical data between different application programs or different machines, often as a bitmap.

metalanguage or meta-language

A language that is used to specify the rules for other languages. XML is an example; it provides a set of rules for constructing markup languages.

metaprogram

A program used to create or modify other programs.

meter

The basic unit of length in the metric system: the distance traveled by light in a vacuum in 1/299,792,458 second; about 39.37 inches.

metric

1. Referring to the metric system, a decimal system of weights and measures based on the meter and the kilogram. 2. Any standard of measurement.

metropolitan area network

(MAN) A network that serves a metropolitan area. Compare LAN and WAN.

MF

Medium Frequency. Electromagnetic frequencies in the range of 300 to 3000 kiloherz.

MFC

1. Microsoft Foundation Classes. A class library for 32-bit Windows development (Windows 95 and Windows NT). 2. Miniature Forward Error Corrector. A hardware device that is inserted between a computer and modem to enable forward error-free communication without retransmission. The MFC encodes data for transmission, adding redundant bits. At the receiving end, the data is decoded, and errors are detected and corrected. 3. Multi-Function Center. A combination laser printer, fax, copier, scanner, fax, and message center from Brother.

MFLOPS

A benchmark that measures megaflops (million floating-point operations per second).

MHS

1. Message Handling System. The ISO Message-Oriented Text Interchange Standard; called X.400 by ITU-T. The OSI electronic mail system, comprised of message user agents, message transfer agents, message stores, and access units. 2. Message Handling Service. Novell software for messaging.

MHz

(MegaHertz or megahertz). Millions of cycles per second. The unit of frequency used to measure the clock speed of a computer.

MI/X

A free X Window server for both 680×0 and Power Macs.

MIAW

Movie in a Window. Terminology used in Macromedia Director.

MIB

Management Information Base. A database containing ongoing information and statistics on each device in a network, used to keep track of each device's performance and make sure all are functioning properly. MIBs are especially used with SNMP.

MIC

Medium Interface Connector. A type of connector for fiber-optic cable that uses a plug and socket and has been used with FDDI and local area networks.

Michael's Disk Benchmark

A simple disk I/O benchmark for Windows 95 or Windows NT, distributed as shareware.

mickey

A unit by which mouse movement is measured: 1/200th of an inch.

MICR

Magnetic Ink Character Recognition. A character recognition system used on bank checks; special ink and characters are used, which can be magnetised for automatic reading.

micro

1. 10-6, one millionth. 2. A microprocessor or microcomputer.

micro-

A prefix meaning one millionth (10-6).

microbrowser

An Internet browser designed for use with a wireless handheld device such as a mobile phone. Microbrowsers have small file sizes to accommodate the low memory available to handheld devices and the the low-bandwidth constraints of the wireless-handheld networks.

microchip

Also called microelectronic or integrated circuit. A microelectronic device comprising many miniature transistors and other electronic components on a single thin rectangle of silicon or sapphire, approximately 1/16″ to 5/8″ on a side, and 1/30″ thick. A microchip can contain dozens, hundreds, or millions of electronic components. To make a microchip, impurities are added to the supporting material, or substrate, in specific places to create P-type and N-type regions; then by projecting light onto light-sensitive chemicals, polysilicon or aluminium tracks are etched into the top 1/1000″ of the substrate to make the electronic circuits. The chips come in analog, digital and hybrid types. Compared with earlier technology, microelectronics are faster, more compact, more energy-efficient, and cheaper to manufacture. The most complete integrated circuit is a microprocessor: a computer on a single chip.

microcomputer

A computer whose CPU is a microprocessor. Also called a personal computer.

microcontroller

A microprocessor which operates as an embedded system (a computer that forms part of a larger machine of some other type).

microelectromechanical system

A system that integrates microelectronics with mechanical parts.

microelectronics

1. The branch of electronics dealing with the miniaturization of components and circuits. 2. Devices or circuits produced using microelectronics.

MicroEmacs

A simple text editor which has versions for most personal computers and for many other computers.

microfiche

A sheet of microfilm which has microimages in a grid pattern.

microfilm

A high resolution film on which photographic records are kept of documents or other material, in greatly reduced size. Microfilm makes it possible to store a great amount of material in a small amount of space.

micron

One millionth of a meter, which is about 1/25,000 of an inch. A measurement used in microelectronics.

microprocessor

A computer with its entire CPU contained on one integrated circuit.
The first microprocessor was created by Intel. The creation of microprocessors was the breakthrough that led to the development of personal computers. Microprocessors have, over time, acquired more and more of the features of large computers.

microsecond

One millionth (10-6) of a second.

Microsoft Access

A database program for Microsoft Windows that can be used to create forms, reports, and graphs.

Microsoft Basic

(MS-BASIC). Formerly called GWBasic and QBASIC. A form of BASIC from Microsoft, originally developed by Bill Gates.

Microsoft Corporation

A Redmond, WA company founded in 1975 by Bill Gates and Paul Allen.
Microsoft is the biggest supplier of operating systems and software for IBM PCs and compatibles; some Microsoft software has Macintosh versions. MS-DOS, Windows, Word, Excel, and LAN Manager are Microsoft products. Microsoft is located at http://www.microsoft.com.

Microsoft Foundation Classes

(MFC). A class library for 32-bit Windows development (Windows 95 and Windows NT).

Microsoft Internet Explorer

A graphical World-Wide Web browser from Microsoft for Microsoft Windows, Windows 95, Windows NT, and Macintosh. It can be downloaded from the Internet.

Microsoft Network

(MSN). An online information service sponsored by Microsoft, similar to America Online and CompuServe. The Microsoft network (http://www.home.msn.com/) has discussion groups, electronic mail, Internet access, and information on Microsoft products.

Microsoft Windows

User interface software with windows released by Microsoft in 1985 to run with MS-DOS.

Microsoft Windows 1

The first version of Microsoft Windows, which came out in 1985. It was able to display tiled windows.

Microsoft Windows 2

The second version of Microsoft Windows, which improved on Windows 1 by allowing overlapping windows and icons and supporting expanded memory. It was released in 1987. It was later named Windows/286.

Microsoft Windows 3.0

The first version of Microsoft Windows that gained wide popularity. It is able to manage larger amounts of memory than previous versions, and can run 16-bit DOS and Windows applications. Many applications were developed for Windows 3.0.

Microsoft Windows 3.1

An improvement on Windows 3.0, which includes multimedia capability, TrueType fonts, and Object Linking and Embedding (OLE). With the Win32s extension, Windows 3.1 can run 32-bit applications. Windows 3.1 is the stand-alone Windows; there is also Windows for Workgroups 3.1.

Microsoft Windows 3.11

The last upgrade to Windows 3.1.

Microsoft Windows 95

An operating system with graphical user interface from Microsoft, which can run 32-bit applications. Windows 95 was a major upgrade from earlier versions of Windows up to Windows 3.1, which simply provided a graphical user interface for DOS. Some features of Windows 95 are Plug and Play capability, threading, pre-emptive multitasking, and built-in networking. The user interface has icons and folders similar to Macintosh, and allows the use of long file names. The minimum requirements for a computer to run Windows 95 are an 80386 or Pentium CPU and at least 8 megabytes of RAM.

Microsoft Windows 98

An advancement over Windows 95. Windows 98 supports new technologies including FAT32, AGP, MMX, USB, DVD, and ACPI. Another new feature is the Active Desktop, which integrates the Web browser,Internet Explorer, with the operating system. To the user of Active Desktop, there is no difference between accessing a document local to the user’s hard disk and accessing a document from a Web server on the other side of the world.

Microsoft Windows for Workgroups

(WFW). A version of Windows 3.1 which is specifically designed to be used with a network.

Microsoft Windows for Workgroups 3.11

An upgrade to Windows for Workgroups 3.1 which includes 32-bit file access and the ability to send and receive faxes.

Microsoft Windows New Technology

Microsoft Windows NT. A 32-bit operating system from Microsoft for high-end workstations, servers, and networks. It has built-in networking, pre-emptive multitasking, multi-threading, memory protection, and fault tolerance. It can be used on PCs and other types of computers, including DEC Alpha. Windows NT supports the Unicode character set, which allows more characters than standard ASCII. The minimum requirements for Windows NT are an 80386 processor, and at least 12 megabytes of RAM. Windows NT has become especially popular as a server because of its extra security features.

Microsoft Windows NT

Microsoft Windows New Technology. A 32-bit operating system from Microsoft for high-end workstations, servers, and networks. It has built-in networking, pre-emptive multitasking, multi-threading, memory protection, and fault tolerance. It can be used on PCs and other types of computers, including DEC Alpha. Windows NT supports the Unicode character set, which allows more characters than standard ASCII. The minimum requirements for Windows NT are an 80386 processor, and at least 12 megabytes of RAM. Windows NT has become especially popular as a server because of its extra security features.

Microsoft Windows/286

The second version of Microsoft Windows, originally called Windows 2, which improved on Windows 1 by allowing overlapping windows and icons and supporting expanded memory. It was released in 1987.

Microsoft Windows/386

A version of Microsoft Windows that followed Windows/286, released in 1987. It added the ability to run several applications at a time, by using extended memory.

Microsoft Word

A Microsoft word processing program for DOS, Windows and Macintosh.

MicroVAX Unit of Performance

(MicroVUP). A unit of measurement of microcomputer performance. One VUP equals the performance of a VAX 11/780; the MicroVUP has been used to rate VAX workstations.

MicroVUP

MicroVAX Unit of Performance. A unit of measurement of microcomputer performance. One VUP equals the performance of a VAX 11/780; the MicroVUP has been used to rate VAX workstations.

mid-level network

The networks on the second level of the Internet hierarchy, which connect the stub networks to the backbone networks. Also called a regional network.

middle letter row

The center letter row (row of letter keys) on a keyboard.

middle-endian

Neither big nor little-endian, a middle-endian order could be 3-4-1-2.

middleware

Software that provides a link between disparate applications.

MIDI

Musical Instrument Digital Interface. A way of communicating instructions for playing music from one electronic device to another; for example, from a synthesizer to a computer to a musical instrument. MIDI includes hardware (the electronic instruments and the interface between devices) and software (the set of rules for encoding and transfer of sound information). With MIDI, a musician can use a keyboard to simulate the sounds of many different instruments, plus add special effects. A MIDI file does not store sound as a wave file does; rather, it stores information on how to create the sounds. Some of the parameters indicated by a MIDI file are pitch, loudness, timbre, and length of a note. Because MIDI instructions resemble a musical score, a MIDI file can be edited in many ways: for example, the tempo can be changed, one instrument can be changed to another, or the whole composition can be transposed to a different key. MIDI files take up less storage space than files that store actual sounds.

MIDI file

Musical Instrument Digital Interface file. A set of instructions for a computer or synthesizer to play a certain musical composition. The MIDI file does not include actual sounds, but information on how to make the sounds. The MIDI instructions include the notes played, length of notes, instruments, volume, rhythm, etc. MIDI files on the Internet can be played with the help of a media player application, such as Crescendo.

MIDI patch

One of the channels in a MIDI device. The General MIDI Standard (GMS) assigns specific instruments to specific MIDI patch locations.

MIDI sequencer

Hardware or software that is used to create, play, or edit MIDI files.

midrange computer

A minicomputer; does not include minicomputers which are single-user workstations.

milli-

Prefix meaning one thousandth or 10-3.

milliard

10^9 (Europe); equivalent to a billion in the U.S.

millimeter

One thousandth of a meter, or .039 inch.

millisecond

(ms) One thousandth of a second.

millivolt

(MV). One thousandth of a volt.

Milnet

MILitary NETwork. Milnet was originally part of ARPAnet, and was split off in 1984 as a network for the military, leaving the rest of ARPAnet as a research network.

MIMD

Multiple Instruction/Multiple Data. A kind of parallel processor in which many operations are performed on different data.

MIME

(Multipurpose Internet Mail Extensions). Extensions to the Internet mail format that allow it to carry multiple types of data (binary, audio, video, graphics, etc.) as attachments to e-mail messages.

Massachusetts Institute of Technology.

MJPEG or M-JPEG

Moving JPEG. A moving image which is made by storing each frame of a moving picture sequence in JPEG compression, then decompressing and displaying each frame at rapid speed to show the moving picture. M-JPEG does not use interframe coding as MPEG does. Sometimes called Motion JPEG.

mkdir

A UNIX command to create a directory (make directory).

MMCD

Multimedia Compact Disc. A CD-ROM that can hold 4.7 GB of data, including video.

MMF

Make Money Fast. A notorious early Usenet post encouraged people to spam a chain letter with the title Make Money Fast. MMF now refers to all similar exploitative schemes.

MMU

Memory Management Unit. A hardware device which translates virtual addresses into physical addresses and is used to manage virtual memory.

MMX

MultiMedia Extensions. Technology developed by Intel to improve multimedia performance on Intel processors. MMX makes it possible to enhance multimedia operations (video, audio, communications, and graphics) without add-on sound cards or video cards. MMX technology is based on SIMD (Single Instruction, Multiple Data) technique; to take advantage of MMX, the software used with it must be written for the MMX instructions. MMX will be used on the Intel P55C Pentium processor and P6 family processors, the Advanced Micro Devices (AMD) K6 family of processors, and the Cyrix M2 processor.

mnemonic

A memory aid; a word or expression which isdesigned to be easier to remember than what it represents. Mnemonics are used in programming; for example, assembly language instructions are mnemonics for the binary patterns of machine code.

MO disk

Magneto-optical disk. A plastic or glass disk coated with a chemical (often TbFeCo) with special properties which make it rewritable. A combination of magnetic and optical methods are used to write data to the disk. A high-intensity laser heats the material up to its Curie point, the temperature at which molecules can be realigned by a magnetic field. A magnet is used to make changes in polarity which remain after cooling. The disk is read by directing a low-intensity laser at the disk and interpreting variations in its reflected light, which result from differences in polarity of the stored magnetic field.

MO7

Magneto-Optic7. A rewritable optical disk technology that holds 6GB on a 12 cm disk. MO7 changed its name to Advanced Storage Magneto-Optical technology.

mobile telephone switching office

(MTSO). A central office for mobile telephone service, with switches and computers that connect all cell sites in a service area and keep track of all calls.

mobo

Slang for motherboard.

mockingbird

A kind of Trojan Horse that imitates a system in order to intercept communications from users logging in and thereby acquire passwords and other information.

mode

An operational state of a computer or system in which certain functions can be performed. For example, when a word processor is in insert mode, any letters typed will insert themselves wherever the cursor is, moving aside all type to the right. When the mode is switched to overwrite mode, each letter typed will replace the letter to the right of the cursor.

modem

A peripheral device that connects computers to each other for sending communications via the telephone lines. The modem modulates the digital data of computers into analog signals to send over the telephone lines, then demodulates back into digital signals to be read by the computer on the other end; thus the name “modem” for modulator/demodulator. Modems are used for sending and receiving electronic mail, connecting to bulletin board systems, and surfing the Internet. There are standards to ensure that modems made by different manufacturers can communicate with each other. Modems communicating with each other must use the same speed.

moderator

A person who receives the email messages for a moderated mailing list or newsgroup, screens all submissions, and decides which ones to pass on to the other members.

module

A self-contained functional unit which is used with a larger system. A software module is a part of a program that performs a particular task. A hardware module can be a packaged unit that attaches to a system.

moire pattern

A radiating curved pattern seen when two geometrically regular patterns (as two halftone screens) are superimposed. A moire pattern can result from scanning or rescreening a halftone, which puts a screen over another screen. Usually moire patterns are not wanted because they interfere with viewing the image. Sometimes this effect can be controlled by adjusting the angle of the halftone, or refining the image with a photo editing program. A moire pattern can also result from problems with the computer monitor.

monadic operation

An operation with only one operand (entity that is operated on).

monitor

Also called a display. A device that displays text and graphics generated by a computer. Desktop monitors are usually cathode-ray tubes, and laptop monitors are usually liquid crystal display. A monitor can be monochrome (black and white) or color. Color monitors may show either digital or analog color.

monitor port

A port that is used to connect a monitor to the computer.

monoalphabetic cipher

A cipher in which only one substitution or transposition is used.

monochrome

Monochrome means one color, and is used to refer to a black and white monitor, or a monitor that has one foreground color and one background color (such as green and black). Grayscale displays have more shading variation, but are sometimes called monochrome.

Monochrome/Color Display Adapter

(MCGA). A monochrome video system for early IBM PCs, which displayed very clear text but no graphics.

monospaced font

Also called fixed-pitch type. A font in which each character takes up the same width, like the characters on a typewriter. In a monospaced font, an i takes up as much horizontal space as an m (more blank space is left around the thin letters). The opposite is proportional spacing, (proportional-pitch type), in which each letter has a spacing proportional to its width.

MOO

Object Oriented Multi User Dungeon. MOOs use object-oriented programming to add dimension, whereas MUDs are text-based games.

MooreÕs Law

A law that states that the logic density of silicon has approximately doubled every year since the invention of the silicon chip. This means the amount of information that can be stored on a chip of the same size doubles every year. Another formulation is that the speed of new computers doubles every year and a half.

Moria

A popular Dungeons and Dragons-style simulation game, named after J.R.R. Tolkien's Mines of Moria.

morphing

A gradual animated transformation from one image into another, partially accomplished by moving certain points in the first image to corresponding points in the second image, in stages.

Morse code

A code in which each letter is represented by a pattern of dots and/or dashes, developed by Samuel Morse in the 1800s. The signals are sent by sound, light beams, or electric pulses. A dot is a signal of short duration, and a dash is a signal of longer duration. Morse code was used to send telegraph messages before the invention of the telephone and has been used in many other ways, such as emergency and wartime communications. It was originally in English, but has been adapted to other languages with different characters.

Mosaic

The first World Wide Web browser, created by the University of Illinois National Center for Supercomputing Applications (NCSA). Mosaic was the breakthrough that caused the World Wide Web to become widely used, as it was the first software that provided a multimedia graphical user interface for the Internet. It is available for UNIX, Windows, and Macintosh.

most significant bit

(MSB). In a binary number, the bit that is farthest to the left, and has the greatest weight.

most significant digit

The non-zero digit which is farthest to the left in a number, and has the greatest value.

mother board


motherboard

The main circuit board inside a computer, which contains the central processing unit, the bus, memory sockets, expansion slots, and other components. Additional boards, called daughter boards, can be plugged into the motherboard.

Motif

A graphical user interface from the Open Software Foundation, which runs on the X Window System. The main graphical user interface for UNIX.

motion path

The path that an animated object will follow (in computer animation).

Motion Picture Experts Group, Audio Laye

(MP3). A popular music download format. MP3 produces CD-quality music in a compressed file that can be transferred quickly, and played on any multimedia computer with MP3 player software.

Motorola, Inc.

A company in Schaumberg, Illinois, which manufactures semiconductors, communications devices such as cellular telephones and two-way radios, and many other electronics products. Motorola was one of the developers of the PowerPC.

Mount

Making a physical disk, or a remote file avilable for access locally.

mouse

A pointing device that is used to move a cursor on the computer screen, and make various operations possible such as typing, drawing, editing text and graphics, opening and closing files, and giving other commands. The wire connecting it to the computer or keyboard looks like a mouse's tail.
A mouse is moved over a flat horizontal surface, usually a rubber mouse pad, and its position is read by the computer. The original mouse has a button which the user clicks or holds down to place the cursor; now many models have more than one button.

mouse ahead

To input commands with the mouse faster than the computer can follow the commands. The computer will remember a few mouse moves ahead and catch up when it has the chance.

mouse around

To look around on the Internet or another network.

mouse pad

A rubber pad that sits next to the keyboard and provides a smooth surface on which to move a mouse.

mouse pointer

The little symbol on the screen that is moved with the mouse. Within text, the mouse pointer appears as a cursor, but it changes shape depending on its location on the screen and the program in use. The mouse pointer can take the form of a hand, an arrow, a cross, and other symbols. It is also called a mouse cursor.

mouse port

The computer socket provided for plugging in a mouse.

Moving JPEG

(M-JPEG). A moving image which is made by storing each frame of a moving picture sequence in JPEG compression, then decompressing and displaying each frame at rapid speed to show the moving picture. M-JPEG does not use interframe coding as MPEG does. Sometimes called Motion JPEG.

Moving Pictures Experts Group or Motion

(MPEG). 1. An ISO (International Standards Organization) group that sets standards for compressing and storing video, audio, and animation in digital form. 2. The standards set by this group. MPEG is a lossy compression method. MPEG-1 is a standard for CD-ROM video and audio. MPEG-2 is a standard for full-screen, broadcast quality video. MPEG-4 is a standard for video telephony.

Mozilla

Another name for Netscape Navigator.

MP3

MP3 stands for Motion Picture Experts Group, Audio Layer 3. A popular music download format. MP3 produces CD-quality music in a compressed file that can be transferred quickly, and played on any multimedia computer with MP3 player software. The technology creates sound files a tenth the size of standard CD music files with very little loss of sound quality. As a result, huge numbers of Internet users have taken to trading MP3 files back and forth, or posting them on download sites, often in violation of industry-owned copyrights. There are initiatives within the music industry to control the use of MP3 copies.

MP3 Player

Software that allows the user to listen to music or sound in MP3 format.

MP3 utility

A collection of tools for editing, sorting, and working with MP3s.

mpack

A UNIX compression program for MIME files.

MPC

Multimedia PC. A personal computer that has CD, sound, and graphics capabilities which meet standards specified by the MPC Marketing Council.

MPC2

The Multimedia Personal Computer (MPC) Marketing Council sets standards for multimedia computer systems. Certified products display the MPC2 symbol.

MPEG

Moving Pictures Experts Group. 1. An ISO (International Standards Organization) group that sets standards for compressing and storing video, audio, and animation in digital form. 2. The standards set by this group. MPEG is a lossy compression method. MPEG-1 is a standard for CD-ROM video and audio. MPEG-2 is a standard for full-screen, broadcast quality video. MPEG-4 is a standard for video telephony.

MPR II

Swedish low-emission standards for electromagnetic radiation. All computer monitors except the ones used in portable computers emit electromagnetic radiation (EMR). The MPR II guidelines define acceptable levels of EMR; some monitors are designed to meet these guidelines.

MPS

Multiprocessing System. A computer system that can run more than one program or set of instructions at a time, using two or more processors in the same computer, or two or more computers connected together.

MR

Modem Ready. A modem status signal indicated by a light on the modem, which means the modem is turned on and ready to operate.

ms

Millisecond — one thousandth of a second.

MS-BASIC

Microsoft Basic. Formerly called GWBasic and QBASIC. A form of BASIC from Microsoft, originally developed by Bill Gates.

MS-DOS

Microsoft Disk Operating System. A personal computer operating system from Microsoft, which is similar to IBM's PC-DOS. It is a single user system that runs one program at a time because of limited memory. Add-on memory boards can expand DOS capabilities. See also DOS.

MS-DOS application

An application designed to be run by the MS-DOS or DOS operating system. These applications can also be run under Windows and OS/2.

MSB

Most Significant Bit. In a binary number, the bit that is farthest to the left, and has the greatest weight.

MSCDEX.EXE

CD-ROM Extensions. An MS-DOS program to enable a PC to read CD-ROMs. It is loaded by AUTOEXEC.BAT. It has been used with DOS through Windows 3.1

MsgServ

An IRC bot which enables a user to leave a message for someone not currently signed on. The addressee receives the message upon login.

MSIE

MicroSoft Internet Explorer. Microsoft's popular web browser.

MSN

Microsoft Network. An online information service sponsored by Microsoft, similar to America Online and CompuServe. The Microsoft network (http://www.home.msn.com/) has discussion groups, electronic mail, Internet access, and information on Microsoft products.

MSXSL

Microsoft Extensible Style Language. Microsoft's XSL implementation. A language used in the creation of stylesheets for reading XML pages.

MTA

Message Transfer Agent. A mail agent, used to store and transfer messages in the X.400 Message Handling System.

MTBF

Mean Time Between Failures. A figure that gives an estimate of the reliability of a piece of equipment. The higher the MTBF, the longer the equipment should last. For example, if the MTBF is 10,000 hours, the equipment should run, on the average, for 10,000 hours before failing.

MTSO

(Mobile Telephone Switching Office). A central office for mobile telephone service, with switches and computers that connect all cell sites in a service area and keep track of all calls.

MTTF

Mean Time To Failure. The approximate amount of time expected before a system or component will fail; see mean time between failures.

MTTR

1. Mean Time To Recovery. The average amount of time a functional unit will spend in corrective maintenance over a given period of time. 2. Mean Time To Repair. The average amount of time needed to repair a failed unit.

MTU

Maximum Transmission Unit. The largest unit of data that can be transmitted on any particular physical medium.

mu

1. Multi-user. 2. A Greek letter used as a prefix, meaning micro- (millionth). When using only ASCII characters, it is represented by lowercase u, which looks the most like the Greek letter.

MUD

Multi-User Dungeon, Multi-User Dimension, or Multi-User Domain. A type of multi-player interactive game, played using Internet relay chat, with adventure, combat, magic, puzzles, and different locations to explore. MUDs can be played on the Internet or over a modem.

mudhead

A person who is addicted to MUD games.

MUG

Macintosh User Group.

Multi-Function Center

(MFC). A combination laser printer, fax, copier, scanner, fax, and message center from Brother.

multi-homed host

A computer that is connected to more than one physical data link. The data links it is connected to may or may not be attached to the same network.

Multi-User Dungeon

(MUD). Also called Multi-User Dimension, or Multi-User Domain. A type of multi-player interactive game, played using Internet relay chat, with adventure, combat, magic, puzzles, and different locations to explore. MUDs can be played on the Internet or over a modem.

multi-user shared hallucination

(MUSH). A type of MUD in which the players themselves can construct new rooms, or make objects and puzzles for each other.

multi-user system

An operating system that can support several people sharing the same computer at once.

multicast

Two-way communication between multiple sites, as in videoconferencing; or sending a communication from one site to a group of selected receivers. Multicasting differs from broadcasting in that a broadcast is sent to everyone who has the equipment or connection to receive it.

multicast backbone

(MBone). A network of Internet sites that supports Internet Protocol multicasting for a limited number of users. MBone provides a faster technology than the Internet for transmitting real-time audio and video programs, and for videoconferencing. The Rolling Stones made history with the first major multicast concert on the MBone.

Multichannel Multipoinbt Distribution Se

A wireless broadband technology used for Internet Access. MMDS uses both licensed and unlicensed channels that come in 6 mHz chunks, with transfer rates at 27 Mbps and 1 Gbps respectively.

Multics

Multiplexed Information and Computing Service. An early (1969) timesharing operating system, developed by MIT, GE, and Bell Laboratories, and introducing many new operating system features.

Multifinder

An enhanced version of the Macintosh Finder which added the capability of managing more than one application at a time. After this capability was no longer new on Macintoshes, the name was changed back to Finder.

multifunction peripheral

Multifunction peripherals, or MFPs, are multipurpose devices combining printing with faxing, color or black-white scanning, and phtocopying in one device. MFPs are popular among small office/home office (SOHO) owners because they are less expensive and use less space than would four separate devices. MFPs are also known as multifunction printers.

multimedia

Multimedia is communication that uses any combination of different media, and may or may not involve computers. Multimedia may include text, spoken audio, music, images, animation and video. The large amounts of data required for computer multimedia files makes CD-ROMs a good option for storage; but there are other ways of receiving multimedia communications, such as the World Wide Web. Multimedia programs are often interactive, and include games, sales presentations, encyclopedias, and more.

Multimedia Compact Disc

(MMCD). A CD-ROM that can hold 4.7 GB of data, including video.

MultiMedia Extensions

(MMX). Technology developed by Intel to improve multimedia performance on Intel processors. MMX makes it possible to enhance multimedia operations (video, audio, communications, and graphics) without add-on sound cards or video cards. MMX technology is based on SIMD (Single Instruction, Multiple Data) technique; to take advantage of MMX, the software used with it must be written for the MMX instructions. MMX will be used on the Intel P55C Pentium processor and P6 family processors, the Advanced Micro Devices (AMD) K6 family of processors, and the Cyrix M2 processor.

Multimedia Gulch

San Francisco’s challenge to Silicon Valley; a region of high-tech companies.

multimedia monitor

A monitor suitable for use with multimedia, with its own speakers.

multimedia PC

(MPC). A personal computer that has CD, sound, and graphics capabilities which meet standards specified by the MPC Marketing Council.

multimedia upgrade kit

A kit that contains hardware and software for upgrading a standard PC into a multimedia PC, including a CD-ROM drive, a sound card, speakers, cables, software, and sometimes selected multimedia CD-ROMs.

multiplatform

Usable by several types of computers or operating systems.

multiple instruction / multiple data

(MIMD). A kind of parallel processor in which many operations are performed on different data.

multiple perspective software developmen

An approach to software development which requires communication and collaboration between experts in a number of different fields.

Multiple Virtual Storage

(MVS). The most commonly-used operating system used on IBM mainframes; other operating systems are VM and DOS/VSE.

multiplex

(Short for "multiple access"). 1. A type of signal made of two or more signals are combined into a single signal to transmit over a communications channel. 2. To send two or more signals at the same time over a single communication channel.

Multiplexed Information and Computing Se

(Multics). An early (1969) timesharing operating system, developed by MIT, GE, and Bell Laboratories, and introducing many new operating system features.

multiplexer

(MUX). A hardware device that enables two or more signals to be transmitted over the same circuit by temporarily combining them into a single signal. On the receiving end, the signals are divided again by a demultiplexer.

multiplexing

A way of combining two or more signals into a single signal for transmission via a telephone wire, television broadcast, microwave, or another medium. At the receiving end, the signals are separated again by a demultiplexer. Different multiplexing technologies are time division multiplexing (TDM), frequency division multiplexing (FDM), and code division multiple access (CDMA).

multiport repeater

A central device to which several other devices connect, and which forwards signals and amplifies or refreshes the stream of data, which otherwise would deteriorate over a long distance.

multiprocessing

Using two or more processors in the same computer, or two or more computers connected together, to execute more than one program or instruction at the same time.

multiprocessing system

(MPS). A computer system that can run more than one program or set of instructions at a time, using two or more processors in the same computer, or two or more computers connected together.

multiprocessor

The ability for a system to perform more than one task.

Multipurpose Internet Mail Extensions

(MIME). Extensions to the Internet mail format that allow it to carry multiple types of data (binary, audio, video, graphics, etc.) as attachments to email messages.

multiscan monitor

A monitor that can scan at more than one speed, making it possible to work with various kinds of equipment and video modes.

multisync monitor

A monitor that is able to synchronize to different horizontal scan rates and refresh rates, which makes it possible to display images at various resolutions. Also called a multiscan monitor.

multitasking

Running more than one program at a time. When a machine has this capability, it is easy to switch between programs without having to quit, or to copy material from a file in one program to a file in another.

multithreading or multi-threading

Within a single program, processing more than one transaction at a time.

MultiTimer Pro

A Mac program that keeps track of your time as you work on a project. It can be set to start when the user starts a specific application. It stores a full record of timed sessions in a log window, which can be programmed with a per-hour rate so you know immediately how much money you have earned.

MUSE

Multiuser Shared Environment. A variation of MUD, also called multiuser simulation environment.

MUSH

Multi-User Shared Hallucination. A type of MUD in which the players themselves can construct new rooms, or make objects and puzzles for each other.

music CD

Usually means an audio CD, but can also mean a CD-ROM that contains sound files, such as an interactive music group CD-ROM.

Music Markup Language

MusicML. An XML application for incorporating musical symbols into web pages.

musical instrument digital interface

(MIDI). A way of communicating instructions for playing music from one electronic device to another; for example, from a synthesizer to a computer to a musical instrument. MIDI includes hardware (the electronic instruments and the interface between devices) and software (the set of rules for encoding and transfer of sound information). With MIDI, a musician can use a keyboard to simulate the sounds of many different instruments, plus add special effects. A MIDI file does not store sound as a wave file does; rather, it stores information on how to create the sounds. Some of the parameters indicated by a MIDI file are pitch, loudness, timbre, and length of a note. Because MIDI instructions resemble a musical score, a MIDI file can be edited in many ways: for example, the tempo can be changed, one instrument can be changed to another, or the whole composition can be transposed to a different key. MIDI files take up less storage space than files that store actual sounds.

MusicMatch

An MP3 player, ripper and encoder. MusicMatch makes it possible to play MP3s, download an MP3 to a file, and create original MP3s.

MusicML

Music Markup Language. An XML application for displaying musical notation in Web pages as easily as text. MusicML is free for non-commercial use.

MuTeX

An extension of TeX that can be used for music typesetting.

MUX

(Multiplexer). A hardware device that enables two or more signals to be transmitted over the same circuit at the same time by temporarily combining them into a single signal. On the receiving end, the signals are divided again by a demultiplexer.

mv

A UNIX command which is used to rename a file.

MV

Millivolt. One thousandth of a volt.

MVC

Model View Controller. The MVC is the paradigm behind the original highly interactive OS called the Smalltalk-80. The Smalltalk-80 OS is a mixture of text and graphics and input is primarily done with a mouse. Smalltalk was originally used for the Xerox PARC, where Steve Jobs found it and reworked it as the OS for the Macintosh; from there the highly popular interface was copied by many preceding OS's (READ: Windows!).

MVS

Multiple Virtual Storage. The most commonly-used operating system used on IBM mainframes; other operating systems are VM and DOS/VSE.

MySQL

MySQL is a true multi-user, multi-threaded SQL (Structured Query Language) database server. SQL is the most popular database language in the world. MySQL is a client/server implementation that consists of a server daemon mysqld and many different client programs and libraries. The main goals of MySQL are speed, robustness and ease of use. MySQL was originally developed because we at TcX needed a SQL server that could handle very large databases an order of magnitude faster than what any database vendor could offer to us. We have now been using MySQL since 1996 in an environment with more than 40 databases containing 10,000 tables, of which more than 500 have more than 7 million rows. This is about 50G of mission-critical data. The base upon which MySQL is built is a set of routines that have been used in a highly demanding production environment for many years. While MySQL is still in development, it already offers a rich and highly useful function set. The official way to pronounce MySQL is “My Ess Que Ell” (Not MY-SEQUEL).

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