M

M - MB - MByte (communications, computer)
Abbreviation for megabyte. One megabyte equals 1 million bytes. M is sometimes used as an abbreviation for megabit, especially when describing data rates (i.e. Mb/s or Mbit/s = megabits per second). One Megabyte equals 8 Megabits (8 bits to a byte).

MAC: Media Access Control (communications, computer)
Media Access control sublayer of the data link layer of the ISO/OSI model (international Standards Organisation, Open Systems Interconnect).

Machine Code (computer)
Program code in the form of instructions (see Machine Language).

Machine Cycle (computer)
In a microprocessor, the shortest interval within which a complete operation can occur.

Machine Instruction (computer)
Direct instructions to the computer system.

Machine Language (computer)
Program code in the form of instructions that has meaning and can be acted upon by the computer hardware and operation system employed. Object files compiled from source code are in machine language. Executable files consisting of object files linked with library files are also in machine language. It is the numeric form of specifying every bit of every instruction in a program to provide the final binary program code which the computer uses directly (from personal computers to mainframes).

Machine Readable Form (computer)
Form in which information is encoded for direct, automatic input into a computer.

Macro (computer)
Macroinstruction: program routine containing a string of standard, related keystrokes, and commands which are put into effect by a single keystroke or macro command.

Macro Position (A/V)
In Audio/Visual terms, the position on a zoom lens that allows it to be focused at very close distances from the object: used for closeups of small objects.

Magenta (computer/printing)
Subtractive primary color that reflects blue and red light, and absorbs green; one of the four process colors, sometimes called process red.

Magnetic Bubble Memory (computer/microelectronics)
Memory storage technology which uses localized magnetized regions to store information. MBM is the integrated-circuit analogy to rotating magnetic memories such as disks or tapes. Magnetic bubble memories employ materials that are easily magnetized in one direction but are hard to magnetize in the orthogonal direction. the most commonly used materials are magnetic garnets. To make a memory of these magnetic bubbles, several functions must be performed. One bit of storage is represented as the presence or absence of a bubble at a given storage rotation. Most bubble memory chips use a sophisticated path architecture for the bubble to move around in (major/minor loops). When a bubble "train" has travelled once around the major loop, all the bubbles are transferred back into the minor loops. To move bubbles along the loops, a rotating magnetic field is generated. For each rotation, each bubble moves synchronously from one path to the next. The advantages of bubble memories are desirable when a relatively small amount of secondary storage is need - a few megabits (million bits of information).

Magnetic Core (computer)
Early computer memory device that was flat, doughnut-shaped, and made from metal.

Magnetic Disk (computer)
Oxide-coated disk on which data is recorded as magnetic spots.

Magnetic Ink Character Recognition: MICR (computer)
Method of machine-reading characters made of magnetized particles.

Magnetic Integrated Circuit (computer/microelectronics)
Physical realization of one or more magnetic elements inseparably associated to perform all, or at least a major portion, of its intended function.

Magnetic Lens (computer/microelectronics)
Magnetic field with axial symmetry capable of converging beams of charged particles of uniform velocity and of forming images of objects placed in the path of such beams. Magnetic lenses are employed as condensers, and projection lenses in magnetic electron microscopes, as final focusing lenses in the electron guns of cathode-ray tubes (TV tubes), and for the selection of groups of charged particles of specific velocity in velocity spectrographs. Magnetic lenses are always converging lenses.

Magnetic Recording (A/V, computer)
Technique for storing electrical signals as a magnetic pattern on a moving magnetic surface. A time-varying current produces a corresponding time-varying magnetic field in a recording head. This field lays down a spatially varying pattern of magnetization in a strip of magnetic material moving past the head. When the pattern moves past a playback head, a time-varying electic output is generated, corresponding to the original signal.

Magnetic Sound Track (A/V)
In Film production terminology, the narrow magnetic tape that runs down one side of the film: it operates exactly like a normal audiotape. Sometimes a second stripe runs along the opposite side of the film in order to achieve the same thickness for both film edges.

Magnetic Tape (A/V, computer)
Acetate medium with an iron-oxide coating that can be magnetized. Information is stored on the tape as extremely small magnetized spots.

Magnetic Tape Unit (A/V, computer)
Device used as an information storage unit to record on and retrieve from magnetic tape.

Magnetic Thin Films (computer/microelectronics)
Sheets of magnetic material with thicknesses of a few micrometers or less, used in the electronics industry. Magnetic films can be single-crystalline, polycrystalline, or amorphous in the arrangement of their atoms. Applications include magnetic bubble memory technology, magnetoresist sensors, thin film heads, and recording media.

MagnetoOptic (communications, photonics)
Device or effect in which a magnetic field influences light frequencies.

Magnetron (communications)
Oldest of a family of crossed-field microwave electron tubes wherein electrons, generated from a heated cathode, move under the combined force of a radial electric field and an axial magnetic field. By its structure, a magnetron causes moving electrons to interact synchronously with travelling wave components of a microwave standing-wave pattern in such a manner that electron potential energy is converted to microwave energy with high efficiency. Magnetrons have been used since the 1940's as pulsed microwave radiation sources for radar tracking. Because of their compactness and the high efficiency with which they can emit short bursts of megawatt peak output power, they have proved excellent for installation in aircraft as well as in ground radar stations. In operation, a magnetron can produce a kilowatt of microwave power.

Mainframe (computer)
As a single word, the term has come to be used as a designation for medium and large-scale computer systems which contain a "main frame"; simply put it is the cabinet that houses the central processor and main memory. It is, therefore, separate from the peripheral devices and device controllers. Typically, it is the largest component in size and cost, but modern electronics have allowed great reductions, in both. The term main frame comes from the use of frame as a device to hold electronics (rack is also frequently used); and this frame, holding the electronics that do the computing might reasonably be called the main frame. In modern systems with very large main memory, some memory modules are housed in cabinets separate from the mainframe. Frequently, they are attached and thus become part of the mainframe cabinet. Multiprocessor systems with more than one central processor (CPU) are referred to as two, or three mainframe systems, in which case the mainframe refers only to the CPU and not the main memory.

Main Circuit Board (computer)
Term sometimes used to describe the circuit board that hosts the main circuits of the computer hardware, including the central processing unit: also called the Motherboard.

Make Ready (computer/printing)
Setting and testing of all the press controls just prior to starting a printing "run". Also, a make-ready copy is a final copy of artwork to be approved before processing.

Makeup (A/V)
For production talent, facial makeup used to enhance, correct, or change facial features. In film makeup, the combining of several films onto one large reel.

Male Connector (A/V, communications, computer)
Plug connector or receptacle that has pins or prongs (contrast with female connector).

MAN (communications)
Abbreviation for Metropolitan Area Network (network that spans an entire city area).

Management Information System: MIS (computer)
In general terms, a management information system is a computer-based organizational information system which provides information to support management activities and functions. The list of applications in an MIS could cover a wide variety of organizational needs, including applications which indirectly support management activities and applications which directly serve management users. Since management applications frequently need data that is best provided by a database, databases and database management software are, generally, part of an MIS.

Manchester Encoding (communications)
Digital phase encoding and signalling technique in which there is a transition in the middle of each bit time. For example, a "1" is encoded with a high level during the first half of the bit time; a "0" is encoded with a low level during the first half of the bit time.

Mandatory User Profile (computer/WindowsNT)
For Windows NT Advanced Server, a user profile created by an administrator and assigned to one or more users. A mandatory user profile cannot be changed by the user and remains the same from one logon session to the next (see personal user).

Mantissa (computer, mathematics)
First element of a number expressed in scientific notation that is multiplied by the power of 10 given in the exponent to obtain the actual number. For +1.23E3, the exponent is 3. Multiply the mantissa, 1.23 by 1,000 (10 to the third power) to obtain the result, 1230.

Macro Recorder (computer)
Function in a program that captures routine keystrokes and converts them into a macro. For example, a user turns on the recorder, calls up a menu and selects a variety of options, then turns the recorder off. The macro is assigned a key combination, which when pressed, reruns the series of selections as if they were entered at the keyboard.

Marker (computer)
Text label in a meta event with a standard MIDI file used to indicate a specific point in a musical composition. Markers are used to synchronize music with visual events.

Marquee (computer/Windows)
Dotted line used to indicate the active element in a dialog box (the element that will receive the next keystrokes from the keyboard).

MAP (computer)
Manufacturing Automation Protocol used in factory oriented networking systems.

Maser (communications)
Device for coherent amplification or generation of electromagnetic waves by use of excitation energy in resonant atomic or molecular systems. The word is an acronym for Microwave Amplification by Stimulated Emission of Radiation (see Laser).

Masks (computer/microelectronics)
Thin metals or other materials with an open pattern designed to mask off or shield selected portions of semiconductors or other surfaces during deposition processes. There are also photomasks or optical masks for contact or projection printing of wafers. These masks may use an extremely flat glass substrate with iron oxide, chromium, or emulsion coating. There are also thick film screen masks.

Masking (computing)
Masking is a process that enables one to "open a window" on desired information within a system, while suppressing or masking out the undesired information. The information items required by a computer program may be of lengths that are not matched to the usually fixed length of the storage unit in the computer memory. Therefore, either an item may require several storage units or several items may be packed into one unit. A mechanism, called masking, is necessary in order to get to the information item that is needed, without interference from other items that are stored in the same memory unit.

Mass Storage (computer)
Description applied to large capacity peripheral memory devices such as magnetic disk, magnetic tape, optical disks, etc.

Master (A/V, computer, M/M)
The controlling or primary (first) element of a system or sequence of events, such as a master recording. A MIDI master is the controlling element (such as a computer or keyboard's MIDI OUT port) in a chain of MIDI instruments. Masters for stamping CD-ROMs consist of a glass disk onto which pits are etched. These pits correspond to the digital representation of the information stored. A videotape master is the tape used to broadcast a program or create duplicate tapes for distribution.

Master Control (A/V)
In Audio/Visual terms, the nerve center for all telecasts: controls the program input, storage, and retrieval for on-the-air telecasts. Master Control also oversees the technical quality of all program material. The equivalent in telecommunications networking is sometimes referred to as the Network Control Center.

Master File (computer)
Term used to describe the controlling, permanent set of records in a database.

Master Monitor (A/V)
In Audio/Visual terms the same definition as the Line Monitor: it shows only the line-out pictures, those that go on the air or onto videotape.

Master VTR (A/V)
Videotape recorder that supplies the original program material for dubbing by the "slave" VTR/s. Also, sometimes called the Record VTR.

Math Coprocessor (computer term)
Mathematical circuit that performs high-speed floating point operations. It increases the performance of personal computing, CAD, desktop publishing applications.

Matte Key (A/V)
In Audio/Visual production, the keyed (electronically cut-in) title whose letters are filled with shades of gray or specific color.

Maximize (computer/Windows)
To enlarge an application window to fill the desktop, or a document window, to fill the application window in which it resides.

Maximize Button (computer/Windows)
Upward-pointing arrow or a Square at the right side of a window's title bar. Clicking a window's maximize button maximizes the window. When a window is already maximized, the maximize button is replaced by a restore button.

Maximum Password Age (computer/WindowsNT)
Period of time a password can be used before the system requires the user to change it.

MB (computer)
Abbreviation for Megabyte (one million bytes).

MBIG (computer/DOS/Windows)
Video image compression standard considered for adoption by ISO (International Standards Organization helping to establish Open System Interconnection standards).

MCA (computer)
A registered trademark of IBM Corporation and an abbreviation for MultiChannel Architecture. MCA was a proprietary bus structure used by the IBM PS/2-series computers to provide 32-bit address capabilities for plug-in adapter cards. Like the EISA bus standard, MCA let more than one microprocessor share the same bus, providing multiprocessing techniques for applications requiring them. Unlike EISA, the MCA plug-compatibility was proprietary and controlled only by IBM.

MCI (computer/Windows, M/M)
Media Control Interface - a high-level Application Programming Interface (API) created by Microsoft for Windows multimedia programming. MCI provides an intermediate layer between Windows. The individual function calls included in the MCI API greatly simplify the programming of simple commands such as Play, Stop, and Record.

MDK (A/V, computer, M/M)
Microsoft Multimedia Development Kit - MDK is a product designed to provide programmers and multimedia authors with the basic tools required to create multimedia titles and applications. Developing C-language applications to run under Microsoft Windows also requires the Microsoft Software Development Kit or its equivalent.

Media (A/V, communications, computer)
Material that stores or transmits data, for example, floppy disks, magnetic tape, coaxial cable, twisted pair wire, fiber optic cable. Medium is also used in computer terms to describe a substance or object storing information, usually defined as read-write or read-only. Hard disk drives and audio and videotapes have a read-write magnetic file or particle medium. Optical Drives have read-write capabilities. CD-ROMs are read-only devices using optical media. CD-WORM means CD-Write Once, Read Many times.

Media Access Control: MAC (communications)
For local area networking, the method of determining which device has access to the transmission medium at any time. CSMA/CD and Token are common access methods.

Media Access Method (communications)
For local area networking, a method for accessing usage on the physical network used by such LAN implementations as Ethernet types, Token Bus, and Token Ring types.

Medium Scale Integration: MSI (computer/microelectronics)
In microelectronic fabrication, the physical realization of a microelectronic circuit fabricated from a single semiconductor integrated circuit having circuitry equivalent to more than 10 individual gates or active circuit functions.

Medium Shot (A/V)
In Audio/Visual Production, an object seen from a medium distance. It covers any framing between long shot and close-up.

Mega (communications, computer)
Million: megahertz - MHz (frequency), megabits, megabytes (computer).

Megabit - Megabyte
One Million bits; One million bytes (byte usually contains 8 bits).

Megaflops (computer)
Term used to describe one million floating-point operations per second: it is used in benchmarks as a measure of a computer's ability to process mathematical operations.

Megahertz (communications)
One million cycles per second as a frequency measurement, it is also often used in computers as the measure for clock speed (clock crystal oscillation frequency).

MEM (computer/DOS)
DOS Command that displays memory usage and how DOS is using the available conventional, reserved, extended and expanded memory. This command can be used to check the amount of memory available on the personal computer system and the memory that is available for storing data and running programs. The command displays the conventional, reserved, extended and expanded memory that is present and available.

Memory (computer)
General term for internal storage where data, programs or other information needed by the microcomputer, or personal computer, are held. It can also be the electronic circuitry that temporarily holds data and program instructions needed by the central processing unit (CPU). Also called main, primary memory - or - main, primary, internal storage.

Memory Management (computer)
Process of allocating memory & keeping programs in memory separate from one another.

Memory Mapped I/O (computer)
Most popular microcomputers use a system known as memory-mapped I/O whereby individual character positions on the screen are mapped one-to-one to bytes in the computer's main memory.

Memory Protection (computer)
System, hardware, and software that limits or prevents access to specified areas in the central or main memory of a computer. Also, the process of keeping a program from moving into another program's domain and vice versa.

Memory Resident Program (computer/Windows)
Program that remains in the computer's memory after it is no longer running. Examples would include pop-up programs, and network software.

Memory Resident Software (computer/Windows)
Software that is loaded into memory and is available for use even when another application is active: also known as TSR (terminate, stay resident) software.

Menu (A/V, computer)
Choices from which the user determines the next set of actions to take. The design of menus in Windows is governed by the Common User Access (CUA) developed by IBM.

Menu Bar (computer/Windows)
Primary set of options offered by an application. The menu bar appears above the application's work area, directly below the title bar.

Messenger Service (computer/WindowsNT)
Sending and receiving messages sent by administrators or by the Alerter service.

Message Switching (communications)
Switching technique using a message store-and-forward system. No dedicated path is established. Rather, each message contains a destination address and is passed from source to destination through intermediate nodes. At each node, the entire message is received, stored briefly, and then passed on to the next node.

Mesh Network (communications)
Net-like communications network in which there are at least two pathways to each node. The term network means net-like as well as communications network.

Metacharacter (computer)
In computer programming language, metacharacters are characters that have some controlling role with respect to other characters with which they may be associated.

Meta Event (computer, M/M)
In MIDI terminology, non-MIDI data, like text, contained within a standard MIDI file.

M080. Meta File (computer, Windows)
Type of graphics file used by Windows and other applications. A meta file stores the objects displayed in the form of mathematical descriptions of lines and surfaces. Windows meta files using the extension WMF are a special form of meta file used only by Windows and its applications.

Metalanguage (computer)
Set of symbols and words used to describe another language (in which these symbols do not appear): the most common application is the use of program language.

Metallization (computer/microelectronics)
Selective deposition of metal film on a substrate to form conductive interconnection between integrated circuit elements and points for connections with the outside world.

M083. Metamers (computer/printing)

Colors that are spectrally different but visually identical for a given observer under specified viewing conditions.

Metallic Disk Rectifier (computer/microelectronics)
Rectifier that consists of one or more disks of metal in contact with coatings or layers of a semiconductor material. Alternating current is changed into pulsating direct current by the rectifying action that occurs at the junction interface between a metal disk and its mating semiconductor layer: types include selenium and copper-oxide rectifiers.

Metal Oxide Semiconductor: MOS (computer/microelectronics)
Metal over silicon oxide over silicone arrangement which produces circuit components such as transistors: the electrical characteristics are similar to vacuum tubes.

Meter (A/V, computer, music)
In musical terminology, the rhythmic pattern of a composition.

Metronome (A/V, computer, music)
Clock-like device emitting an audible click on each beat at an adjustable tempo. Computer-based sequencer applications often include a metronome feature that plays on the PC speaker or through a small speaker on the MIDI breakout box.

Metropolitan Area Network: MAN (communications)
Network operating in an area the size of a city. A MAN is typically smaller than a wide area network (WAN) but much larger than a local area network (LAN).

MHz - MegaHertz (communications, computer)
One million cycles per second. It is often used with reference to a computer's clock rate, which is a raw measure of its internal processing speed. For example, a 500 Mhz computer processes data internally twice as fast as a 250 Mhz computer. However, disk speed and caching play a major role in the computer's actual performance.

MIC (computer/microelectronics)
In microelectronics fabrication, abbreviation for Monolithic Integrated Circuit.

MICR (computer)
Magnetic Ink Character Recognition - special encoded characters on check and deposit slips. MICR readers detect the encoded characters and convert them into digital data.

MICR Inscriber (computer)
Device that adds magnetic characters to a document (most commonly used on checks).

Microbond (computer/microelectronics)
Physical realization of a very small fastened join between conductors or between a conductor and a microelectronic chip device.

Microchannel (computer)
Full 32-bit bus used in high-end models of IBM's PS/2 series, RS/6000 series and certain 9370 models. It is designed for multiprocessing, which allows two or more CPUs to work in parallel within the computer at the same time. Micro Channel boards are not interchangeable with PC bus boards. Micro Channel boards are designed with built-in identification that is interrogated by the operating system, thus eliminating manual switch settings that are sometimes required and the conflicts that can arise with the original PC bus. Transfers data at 20MB per second and has special modes for increasing speeds to 40 & 80MB/sec. Future enhancements were planned to create 64 bits and 160MB/sec.

Microcircuit (computer/microelectronics)
Physical realization of a hybrid or monolithic interconnected array of very small, active and passive, electronic elements.

Microcode (computer)
Permanent memory that holds elementary circuit operations the computer must perform for each machine instruction in its instruction set. It acts as a translation layer between instructions and the electronic level of the computer and enables the computer architect to more easily add new machine instructions without having to design electronic circuits.

Microcomputer (computer/microelectronics)
Term to describe a complete microprocessing system, by analogy with a minicomputer. In general terms, it is a digital computer whose central processing unit (CPU) is a microprocessor. Today's Microcomputers handle data in the form of 8-bit, 16-bit, 32-bit, and 64-bit words. Future Microcomputers will handle data in the form of 128, 256, 512, and 1024-bit words. The difference between microcomputers, minicomputers, and mainframe computers has become increasingly blurred, as contemporary microcomputers provide performance and features once only offered by mainframe computers.

Microcomputer Development System (computer/microelectronics)
Complete microcomputer system dedicated to testing and developing both the hardware and software of other microcomputer-based systems; from initial development through to the debugging of the final prototypes.

Microelectronics (computer, electronics)
Entire spectrum of electronics dealing with fabrication of sophisticated, practical systems using miniaturized electronic components. Microelectronics has developed along two basic technologies: monolithic integrated circuits and hybrid integrated circuits.

Microfiche (computer and A/V)
A 4x6 inch sheet of film that holds several hundred miniaturized document pages.

Microfilm (computer and A/V)
Continuous film strip that holds several thousand miniaturized document pages.

Microfloppy Disk (computer)
Magnetic media, 3.5" floppy disk encased in a rigid plastic shell. Developed by Sony, these disks quickly became a medium of choice. They hold more data and are much easier to store, transport and handle than their older, out-dated 5.25" counterparts.

Microinstruction (computer)
Instruction in microcode. It is the most elementary computer operation that can take place, for example, moving a bit from one register to another. It takes several microinstructions to carry out one machine instruction.

Microminiaturization (computer/microelectronics)
Process of packages an assembly of microminiature active and passive electronic elements, replacing an assembly of much larger and different parts.

Micromodule (computer/microelectronics)
Microcircuit constructed of a number of components (microwafers) and encapsulated to form a block that is still only a fraction of an inch in any dimension.

Micron (communications, computer)
One millionth of a meter. Approximately 1/25,000 of an inch. The tiny elements that make up a transistor on a chip are measured in microns. Measurements below the micro level are made in Angstroms: 10,000 Angstroms equal one micron. An Angstrom, in size, would be equivalent to biological, molecular unit structure.

Microphone (A/V, communications)
Electroacoustic device containing a transducer which is activated by sound waves and delivers essentially equivalent electric waves. Modern microphones may be classified as: (1) pressure, (2) gradient, (3) combination pressure/gradient, (4) and wave types. Pressure microphones have their electrical response caused by variations in pressure in the actuating sound wave. In a gradient microphone, the electrical response corresponds to some function of the pressure difference between two points in a sound wave. A wave microphone is one in which the response depends upon sound wave interaction. Some of the more popular types of microphones are: dynamic; electrostatic; piezoelectric; electrostrictive; carbon transducer; pressure; gradient; wave; and hot-wire.

Microphotonics (computer, photonics)
Field of engineering, design, and production in microprocessing using photons (light) rather than electrons (electricity), for computing decisions. It incorporates both the laws of electronics and of physics and produces devices that use light and electricity in compatibility (sometimes called electro-optical devices). Photonic Circuits are being designed that provide similar functionality to Electronic Circuitry, however, they are not yet capable of matching the decision-making speed of microelectronic circuits. Theoretically, microphotonic circuits would not need an electrical power source, but could function with only a light source (i.e. a light bulb).

Microprobe (computer/microelectronics)
Extremely sharp and small exploring tool head attached to a positioning handle, used for testing microelectronic circuits by establishing ohmic contact.

Microprocessor (computer)
Central processing unit (CPU) on a single chip. In order to function as a computer, it requires a power supply, clock and memory. First-generation microprocessors were Intel's 8080, Zilog's Z80, Motorola's 6800 and Rockwell International's 6502. The first microprocessor was created by Intel Corp. as a general purpose processor, developed in 1969-1971, by a design team headed by Ted Hoff (also called a logic chip).

Microprocessors (A/V)
In Audio/Visual terminology, the small, digital computers used in color cameras to set up and maintain a camera's optimal performance under a variety of production conditions.

Microprogrammable Computer
Microcomputer where the instruction set was changed with a ROM called MICROM.

Microprogramming (computer)
Technique used by designers to implement the control functions of a computer. This collection of control microprograms is sometimes called the firmware of the computer.

Microsecond (communications, computer)
One-millionth of a second.

Microsoft (computer)
Leading microcomputer software company founded in 1975 by Paul Allen and Bill Gates, two college students who wrote the first BASIC interpreter for the Intel 8080 microprocessor. They licensed it to Micro Instrumentation and Telemetry Systems to accompany its Altair 8800 microcomputer kit. By the end of 1976, more than 10,000 Altairs were sold with Microsoft's BASIC. Versions of MBASIC were licensed to Radio Shack, Apple Computer and many other hardware vendors. Eventually a version called GW-BASIC (Gee Whiz BASIC) was developed for 16-bit personal computers. Although Microsoft quickly became a leader in microcomputer programming languages, its outstanding success is due to supplying IBM with its DOS operating system and the compatible companies with the MS-DOS version. Paul Allen left and founded his own software company called Asymetrix Corporation. Microsoft's position as the supplier of the major operating system to the world's largest computer base (millions of PC-compatibles) gives it predominant influence over the future of the industry. Bill Gates is still the President and is the wealthiest individual in the world.

Micro to Mainframe Link (communications, computer)
Connection between micro and mainframe computers (usually through cabling).

Microtutor (computer)
Low-cost, self-contained microcomputer providing hands-on training on microcomputers.

Microwave (communications)
Electromagnetic waves that vibrate at 1 Ghz and above. Microwaves are the transmission frequencies used in communications satellites as well as in line-of-sight systems on earth.
Microwaves occupy a region in the electromagnetic spectrum which is bounded by radio waves on the side of longer wave lengths and by infrared waves on the side of shorter wavelengths. A microwave has a wavelength in the centimeter range. In the microwave region, a further delineation is sometimes made with such names as decimeter, centimeter, or millimeter waves. The foundation of the entire field was laid by James Clerk Maxwell in 1864, when he formulated a set of equations governing electromagnetic phenomena which became known as Maxwell's equations. A solution of these equations led Maxwell to predict the existence of electromagnetic waves when none were known to exist. The next development came when Heinrich Hertz demonstrated in 1888 an experimental proof for the existence of electromagnetic waves and verified substantially all aspects of Maxwell's predictions.

Microwave Integrated Circuit (communications, computer)
Physical realization of an electronic circuit operating at frequencies above one gigahertz (1 billion cycles per second), and fabricated by microelectronic techniques: either a hybrid or monolithic integrated circuit technology may be utilized.

Microwave Optics (communications, photonics)
Study of those properties of microwaves which are analogous to the properties of light waves in optics. The fact that microwaves and light waves are both electromagnetic waves, the major difference being that of frequency, already suggests that their properties should be alike in many respects. Different aspects of microwave optics include: rectilinear propagation; reflection and refraction; diffraction; and polarization.

Microwave Reflectometer (communications, photonics)
Form of directional coupler that is used for measuring the power flowing in both direction in a waveguide. A pair of single-detector couplers appropriately positioned on opposite sides of the waveguide can be used for this purpose, with one detector positioned to monitor transmitted power and the other detector positioned to measure power reflected back from a discontinuity in the line.

Microwave Relay (A/V)
In Audio/Visual terms, a transmission path from the remote location to the transmitter involving the use of several line-of-sight microwave units.

Microwave Solid-State Devices (communications, microelectronics)
Semiconductor devices for the generation, amplification, detection, and control of electromagnetic energy in the frequency range of about 1 to 100 Gigahertz. Devices that generate or amplify microwave energy are referred to as active microwave devices. The most prolific active solid-state microwave devices are: microwave transistors; transferred electron devices; avalanche diodes; and tunnel diodes. Devices that detect or control microwave energy are referred to as passive microwave devices. The most important passive microwave devices include: PIN diodes, varactor diodes, and point-contact and Schottky-barrier detector diodes.

Microwave Transmission Lines (communications)
Structures used for transmission of electromagnetic energy at microwave frequencies from one point to another. A transmission line may be defined more precisely as a system of material boundaries forming a continuous path from one place to another and capable of directing the transmission of electromagnetic energy along this path. Some of the more popular microwave structures include: coaxial cables; hollow-pipe waveguides; striplines; open-wire lines; and dielectric rods.

Microwave Tube (communications)
High-vacuum tube designed for operation in the frequency region from approximately 3,000 to 300,000 MHz (megahertz). Two considerations distinguish a microwave tube from vacuum tubes used at lower frequencies; the dimensions of the tube structure in relation to the wavelength of the signal that it generates or amplifies; and the time during which the electrons interact with the microwave field.

MICR Reader/Sorter (computer)
Machine that reads and sorts documents imprinted with magnetic ink characters.

MIDI (computer, M/M)
Musical Instrument Digital Interface - standard protocol for the interchange of musical information between instruments, synthesizers and computers. It defines the codes for a musical event, which includes the start of a note, its pitch, length, volume and musical attributes. It also defines codes for various button, dial and pedal adjustments used on synthesizers. MIDI is used to synchronize notes produced on several synthesizers. Its control messages can orchestrate synthesizers, each playing a part of the musical score. The basic hardware and protocol is defined by the MIDI Detailed Specifications 1.0 published and maintained by the International MIDI Association.

MIDI Cuing (computer/Windows, M/M)
Set of MIDI messages used to determine the occurrence of events other than the playing of musical notes. MIDI Cuing uses the MTC to determine when events occur in absolute rather than relative times. MMC and MSC operations us MIDI Cuing to determine when devices (such as recording, playback, or lighting devices) are to be triggered.

MIDIEX File (computer/Windows, M/M)
File consisting of raw MIDI message information without a header or other identifying elements. A MIDIEX file is usually used for saving and loading patches and other MIDI System Exclusive (SysEx) messages.

MIDI File (computer/Windows, M/M)
File with a MID extension containing MIDI song or system exclusive data and complying with IMA's specifications for Standard MIDI files. RIFF MIDI files use extension RMI.

MIDI Machine Control: MMC (computer, M/M)
Set of standard MIDI messages used to control the operation of devices such as audio tape, digital audio tape, audio CD, videotape, or videodisc recorders and playback units. The MMC specification is under development by the IMA.

MIDI Mapper (computer/Windows, M/M)
Windows applet enabling standard MIDI files written for a nonstandard synthesizer to play the proper sounds on a General MIDI synthesizer. A MIDI map created by MIDI Mapper intercepts incoming MIDI program-change messages and alters their value before sending them to the MIDI device. A completed MIDI map is called a MIDI setup.

MIDI Real Time Messages (computer, M/M)
MIDI messages such as start, stop, continue, clock, MIDI show control (MSC), MIDI time code (MTC), and song position pointer (SPP) codes. These messages are used to synchronize the MIDI message stream with other devices or production elements.

MIDI Sample Dump Standard (computer, M/M)
Standardized set of MIDI system-exclusive messages used to transfer PCM data from sampled sounds supplied on floppy disk or CD-ROM to the random access memory (RAM) in a sample-playback synthesizer.

MIDI Show Control (MSC) (computer, M/M)
Set of standardized MIDI codes used to control lighting by sending MIDI messages to a compatible controlling devices. The MSC specification is maintained by the MMA.

MIDI Time Code (MTC) (computer, M/M)
Set of MIDI synchronization messages corresponding to the SMPTE time code standard.

MIMD (computer term)
Multiple Instruction stream Multiple Data stream - a computer architecture that uses multiple processors, each processing its own set of instructions simultaneously and independently of the others (contrast with SIMD).

Millisecond (communications, computer)
One-thousandth of a second.

Minicam (A/V)
Audio/Visual production term used to describe a video camera much smaller than a studio model: it is much lighter and portable, and used for news gathering in the field.

Minicomputer
Small to medium-scale computer that functions as a single workstation, or as a multiuser system with up to several hundred terminals. A minicomputer system costs roughly from $25,000 to $250,000. Since high-end microcomputers and low-end mainframes offer price and performance in the traditional minicomputer niche, the term is beginning to have less significance. Some companies are replacing this term with small, medium and large-scale designations.

Minimize (computer/Windows)
To reduce an application window or document window to an icon. Some document windows cannot be minimized.

Minimize Button (computer/Windows)
Downward-pointing arrow at the right side of a window's title bar. Clicking a window's minimize button reduces the window to an icon.

Minimum Object Distance (A/V)
Point at which a camera is about as close as it can get and still focus on the object.

Minimum Password Length (computer/WindowsNT)
Fewest characters a password can contain (see account policy).

Minority Carrier (computer/microelectronics)
Less predominant carrier in a semiconductor: electrons are the minority in p-type semiconductors; holes are the minority in n-type semiconductors.

MIPS (computer)
Million Instructions Per Second - the execution speed of a computer. For example, one-half a MIPS or .5 MIPS is 500,000 instructions per second. A large mainframe can perform 500 to 1,000 MIPS, whereas an inexpensive microprocessor might be in the single digit MIPS range. MIPS rates are not uniform across all vendors' lines. Some rates are best-case mixes and some are averages. As a result, MIPS has been referred to as "Misinformation to Promote Sales". MIPS rate, which is tied to the computer's clock speed, is only one factor in overall performance. Bus and channel speed and bandwidth (8-bit, 16-bit, 32-bit), disk and memory speed, memory management techniques and system software also determine the total throughput of a computer system. The 8036/SX from Intel rated at 2.5 MIPS; the 80386/DX at 6 MIPS; the 486/SX at 16.5 MIPS; the 486DX at 20 MIPS; 486/DX at 40 MIPS. The "Pentium" Series of Microprocessors from Intel can compute at 200 MIPS, with clock speeds of 250 MHz, 5 millions transistors, with an internal 64-bit data bus with 32-bit address bus.

MIRROR (computer/DOS)
DOS Command that makes a mirror file of the system; makes a copy of the file partition table; and creates and maintains a delete tracking file. The first two uses allow the user to later restore the disk or partition table with the UNFORMAT command, and the last use makes undeleting files more efficient. A mirror file contains information about the file allocation table (FAT), boot record and root directory of the selected drive. DOS creates two files: MIRROR.SAV, which is hidden and contains most of the mirror file information; and MIRROR.FIL, which can be viewed in the directory listing.

Mirrored Drives (computer)
System fault tolerant technique in which a hard disk mirrors all hard disk activities.

MIS (computer)
Management Information System was the buzzword of the mid 1970s and early 1980s, when online systems were being implemented within all large organizations, and the MIS shop had control of the computing power in an organization. In the 1990's with the new found empowerment that a PC provides to individual users, companies are re-defining, reorganizing and sometimes even disconnecting and dissolving old "MIS" shops.

Mix (A/V, computer)
In audio and video technology, the combining of two or more signals representing sounds or images into a single, composite sound or image.

Mixer (A/V, communications)
Device having two or more signal inputs, usually adjustable, and one common output. It is used in audio amplifiers to combine the outputs of individual microphones and other audio-signal sources linearly and in desired proportions to produce one audio output signal. In television, a mixer serves similarly to combine the outputs of two or more television cameras or other video signal sources. The mixer stage in a superheterodyne receiver combines the incoming modulated rf (radio frequency) signal with the signal of a local rf oscillator to produce a modulated i-f (intermediate frequency) signal. Crystal diodes are widely used as mixers in radar and other microwave equipment.

Mix Bus (A/V)
Audio/Visual term for a mixing channel for audio signals. The mix bus combines sounds from several sources to produce a mixed sound signal. For video editing the rows of buttons permit the mixing of video sources, as in a dissolve and super. There are also major buses for on-the-air switching.

Mix-Down (A/V)
Final combination of sound tracks on a single or stereo tape track.

Mixed Field Tubes (A/V)
In audio/visual terms, pickup tubes employing both electrostatic and magnetic methods for guiding and focusing the electron beam. Electrostatic deflection combined with magnetic focus permits higher resolution and lower geometric distortion of the image.

Mixing (A/V)
In Audio, the combining of two or more sounds in specific proportions (volume variations) as determined by the event (show) context. In Video, the combining of various camera shots via the video switcher.

Mix-Minus (A/V)
Type of multiple audio feed missing the part that is being recorded, such as an orchestra feed with the solo instrument being recorded.

MKDIR (computer/DOS)
DOS Command that creates a subdirectory using the name provided by the user. The user can create the new subdirectory on the current drive or another drive. Subdirectory names follow the same conventions as filenames although most subdirectory names do not use an extension. MKDIR is used to create a logical structure on a hard disk to help organize access to files. If a backslash is used in front of the subdirectory names, they are added under the root directory rather than under the current directory.

mm: Millimeter (A/V, computer, M/M)
One thousandth of a meter: 25.4 mm = 1 inch.

MMA (computer, M/M)
MIDI Manufacturers Association - the MMA is a group of U.S. manufacturers of MIDI hardware and software applications. It is affiliated with the International MIDI Association whose other principal member is the Japan MIDI Association. Many of the members of the MMA are off-shore subsidiaries of Japanese manufacturers.

MMC (computer, M/M)
Multimedia Marketing Council - the MMC is a group of hardware and software suppliers establishing and maintaining specifications for the capabilities of IBM-compatible microcomputers used for multimedia applications. The specifications are intended to make PCs suitable for use with multimedia hardware and applications.

MMM (computer, M/M)
Extension for files created for display using the Multimedia Movie player. MMM files were first created with Macromind's Director application. The Microsoft Multimedia Development Kit (MDK) provides an application that can convert the Macromind Application to MMM files.

MMP (computer, M/M)
Extension for files created and used by IBM's M-Motion applications. These files use YUV encoding that can reproduce about 2 million colors using a 12-bit format (data for four pixels is stored in six bytes).

Mnemonic Code (computer)
Program language using mnemonic symbols or abbreviations: groups of letters suggesting the meaning of each of the instructions.

Mobile Radio (communications)
Radio communication in which at least one of the transmitters or receivers is installed in a vehicle and can be operated while in motion. Mobile radio is the short form of the term: Land Mobile Radio Service.

Mobility (computer/microelectronics)
In microelectronics fabrication terms, the ease with which charge carriers can move through a semiconductor. Generally, electrons and holes do not have equal mobility in a given semiconductor: mobility is higher in germanium than in silicon.

Modal (computer/Windows)
Windows dialog box that must be closed before further action can be taken by the user.

Mode (computer, M/M)
In MIDI terminology, the way a MIDI instrument responds to MIDI channel messages. In Omniphonic, the instrument responds to messages on any channel. In Polyphonic mode, the instrument will play multiple notes on one MIDI channel simultaneously. Multimode, which is not included in the MIDI specification, is used to describe a multitimbral device that can respond to more than one channel. In Monophonic mode, the instrument will play only a single note on its assigned channel. Mono and Omni modes are implemented but seldom used in professional MIDI equipment.

MODE (computer/DOS)
DOS Command that configures devices that are used on a personal computer system. It can be used to configure parallel and serial ports, redirect parallel port output to a serial port, set the device code pages, select display mode, set how fast DOS processes repeated keystrokes, and display the current configuration of all devices.

Model (computer)
In database management terms, a type of database representing a particular way of organizing information. The three primary database models are: hierarchical, network, and relational. Also, the term is used to describe an image of something that actually exists or that can theoretically exist, or mathematical representation of a real-life system.

Modeless (computer/Windows)
Window or dialog box that can be closed or minimized by the user without taking any other action. Modeless is the opposite of Modal.

Modem (communications, computer)
Modulator/De-Modulator - a device that adapts a terminal or computer to a telephone line. It converts the computer's digital pulses into frequencies within the audio range of the telephone and converts them back into pulses at the receiving side. Specialized modems are used to connect computers to a broadband local area network, which, similar to telephones, use electromagnetic waves for transmission signals. The modem handles the dialling and answering of the call and controls the transmission speed. Modems used on telephone lines transmit at speeds of 1200, 4800, 9600, 19,200, 38.400, 56,000 bits per second. The effective data rate is about 10% of bit rate; thus 300 bps is equivalent to 30 characters per second. It would take up to a full minute to fill up a text screen at 300 bps; 15 seconds at 1,200 bps, and about seven seconds at 2,400 bps. Using a modem with a personal computer requires a free serial port, and a communications program. An Answer Only Modem can answer a call but is restricted from initiating a call.

Modem Eliminator (communications, computer)
In communications, a device that allows two computers in close proximity to be hooked up without modems. In asynchronous systems, such as when the serial ports of two personal computers are connected together, a modem eliminator connects the send line on one end to the receive line on the other. In this case, a modem eliminator is the same as a null modem cable. In synchronous systems, the modem eliminator provides active intelligence with regard to synchronizing the lines.

Modular Communications System (communications, computer)
One of the fundamental principles of the Universal Communications System within a building whereby all of the physical components (outlets, cabling, connections) are modular and interconnectable, by the end user, on short notice, without having to rely on outside expertise and technical assistance. Modularity, by its own definition, means that any element of the communications system is modular, pluggable, and unpluggable, without disruption to any other element of the communications system.

Modularity (communications, computer)
Capability to partition, connect, disconnect, re-arrange, and otherwise continuously re-configure hardware, software, or system components, wherever required by the end-user.

Modular Programming (computer)
Logically self-contained and discrete part of a larger program; the complete program can thus be considered to be a collection of modules.

Modulate (A/V, communications)
To mix a voice or data signal onto a carrier for transmission. Data is modulated onto the carrier by various methods including: amplitude modulation where the height of the wave is changed; frequency modulation where the frequency is changed; or phase modulation where the phase (polarity) of the wave is changed (contrast with demodulate).

Modulation (A/V, communications)
Process of one wave interacting with another to create a third (resultant) waveform. Modulation implies bandwidth occupancy. For any signal to change in a way that cannot be predicted implies necessarily that the signal occupy a nonzero band of frequencies. For example, the spoken word occupies a band from a few hundred to several thousand hertz. Ordinary analog telephony is a good example of this modulation concept. Longitudinal sound waves generated by the spoken word constitute information-bearing signals to be communicated. The telephone transmitter, acting as a modulator, changes this acoustic energy into electric energy suitable for high-speed propagation to a distant point. At the receiving end, demodulation occurs in the telephone receiver, changing the electric signals back to pressure waves in the air. Different types of modulation include: Amplitude Modulation (AM); Angle Modulation including Frequency Modulation (FM) Phase Modulation (PM); and Pulse Modulation.

Modulator (A/V, communications)
Device or circuit by means of which a desired signal is impressed upon a higher-frequency periodic wave known as a carrier. The process is called modulation. The modulator may vary the amplitude, angle, frequency, or phase of the carrier.

Module (computer)
In microelectronic fabrication, a packaging unit displaying regularity and separable repetition. It may or may not be separable from other modules after initial assembly. Usually all major dimensions are in accordance with a prescribed set of dimensions. In software terminology, a block of code having one or more procedures for which the source code is stored in a single file. In compiled language, a code module would be compiled to a single object file.

Moiré (computer/printer)
Pronounced "mor-ray" - an objectionable pattern that results from families of curves being superimposed on one another. For example, many halftones are made up of curved patterns that can cause moire patterns when scanned into the computer. In audio/visual terms it is similar: color vibrations that occur when narrow, contrasting stripes of a design interfere with the scanning lines of the television system (called Moiré Effect).

Molecular Beam Epitaxy (computer/microelectronics)
Equipment and technology used for growing epitaxial thin films under laboratory furnace environment and atmosphere, by directing beams of atoms or molecules, created by thermal or electron beam evaporation, onto clean, heated substrates.

Molecular Electronics (computer/microelectronics)
Electronics on a molecular scale, dealing with the production of complex circuitry, in semiconductor devices, with integral elements processed by growing multi-zoned crystals in a furnace for the ultimate performance of electrical functions.

Monaural (A/V)
Synonym for monophonic or single-channel audio, usually shortened to mono.

Monitor (A/V, computer)
In audio/visual terminology, a name used to describe a video display or graphic display. In computer terms, a software package providing uniform methods for program timing, scheduling, and handling of input/output (I/O) tasks. In audio terms alone, the speaker that carries the program sound independent of the line-out. In computer terminology, monitor denotes a control program that oversees the primary allocation of resources among a set of user programs.

Monochromatic (communications, photonics)
Light waves of only one frequency, and therefore only one color.

Monochrome (A/V, computer)
Display of one foreground color and one background color; for example, black on white, white on black, blue on white. In audio/visual production it means one color; it refers to a camera or monitor that reacts only to various degrees of brightness and produces a black-and-white picture.

Monolithic (computer, microelectronics)
Term that is used to refer to the single silicon substrate in which an integrated circuit is constructed (see integrated circuit).

Monolithic Integrated Circuit (computer/microelectronics)
Physical realization of electronic circuits or sub-systems form a number of extremely small circuit elements inseparably associated on, or within, a continuous body, or a thin film of semiconductor material.

Monopulse Radar (communications)
Radar that obtains a complete measurement of the target's angular position from a single echo pulse. Together with the range measurement performed with the same pulse, the target position in three dimensions is determined completely. Usually a train of echo pulses is then employed to make a larger number of repeated measurements and produce a refined estimate, but this is not intrinsically necessary.

Monospaced Font (computer/printer)
Font in which all characters have the same width. Courier is a monospace font.

Montage (A/V)
In audio/visual production, the juxtaposition of two often seemingly unrelated shots in order to generate a third overall idea, which may not be contained in either of the two.

Monte Carlo Method (computer, mathematics)
System used in computerized random number generation and simulation, that exploits the values of the applied mathematics known as "Monte Carlo"; a method of solving problems by means of experiments with random numbers. The name (after the casino in Monaco) was first applied around 1944 to the method of solving deterministic problems by reformulating them in terms of a problem with random elements. By extension the term has come to mean any simulation problem that uses random numbers. The classic example (Buffon, 1733) is demonstrated by throwing a needle onto a ruled surface, and counting the number of times the needle crosses one of two equal spaced parallel lines.

MORE (computer/DOS)
DOS Command that displays one screen of a file or DOS command output at a time, pausing to wait for a keystroke from the user before displaying the text.

Morphing (A/V, computer, M/M)
In audio/visual and multi-media productions a recent term that describes the ability to digitize an image, then change the image, into another image (sometimes using fractal geometry), as seen in recent popular movies, with spectacular special effects.

Morphology-Integrated (computer/microelectronics)
Structural characterization of an electronic component in which the identity of the current or signal modifying areas, patters, or volumes has become lost in the integration of electronic materials; in contrast to an assembly of devices performing the same function.

Morphology-Translational (computer/microelectronics)
Structural characterization of a component in which the areas or patterns of resistive, conductive, dielectric, and active materials of the structure, can be identified in a one-to-one correspondence with devices assembled to perform an equivalent function.

MOS: Metal Oxide Semiconductor (computer/microelectronics)
Technology for producing transistors that incorporates metal over oxide over silicon layers. The Electrical characteristics are similar to vacuum tubes.

Mosaic (A/V)
In audio/visual production, visual effect in which an image is broken down into many equal-sized squares of limited brightness and color.

Motherboard (computer)
Main printed circuit board in an electronic device which contains sockets that accept additional boards. In a personal computer, the motherboard contains the bus, the microprocessor and all the chips used for controlling the peripherals that come with the system, such as the keyboard, text and graphics display, serial and parallel ports. The remaining functions, such as input/output for sound and video can be provided by adapter cards plugging into connectors on the motherboard (including many other peripherals).

Motorboating (communications)
Form of oscillation that occurs at a very low audio frequency in a system, circuit, or component. It is caused by an excessive amount of audio feedback at low frequencies. This oscillation is a succession of pulses; when these occur in a circuit that is feeding a loudspeaker, resulting in putt-putt sounds resembling those made by a motorboat.

Motorola (computer/microelectronics)
Leading manufacturer of semiconductor devices that was founded in 1928 by Paul V. Galvin in Chicago. Its first product allowed radios to operate from household current instead of batteries. By the 1960s, Motorola was a leader in communications and consumer electronics and had built its first semiconductor facility. It eventually began to move away from consumer electronics, selling off its color TV business by the mid-1970s. Although Motorola is known within the computer industry for its 68000 and 88000 series of microprocessors (Apple and Data General computers use them), much of its revenue base is obtained by selling sophisticated radio, data, and telecommunications systems, and a wide range of aerospace, automotive, and cellular telephone products.

Mouse (computer)
Puck-like object that is used as a pointing and drawing device. It is rolled across the desktop in any direction, the cursor, or pointer, moves correspondingly on the screen.

Mouse Pointer (computer/Windows)
Symbol that indicates where the next mouse click will take effect. The shape of the pointer depends on the context within which it is used. In menus and dialog boxes, it is a northwest-pointing arrow. On movable window borders, it becomes a two-headed arrow. In text boxes and word processing documents the pointer becomes the I-Beam.

Moving Target Indication (communications)
Method of presenting pulse-radar echoes in a manner that discriminates in favor of moving targets and suppresses stationary objects. The moving targets can appear as bright echoes, while ground clutter is suppressed.

MPC (computer, M/M)
Trademarked abbreviation for Multimedia Personal Computer or Multimedia PC. The MPS was originated by Microsoft Corporation and is now owned by the Multimedia Marketing Council (MMC). Computers, multimedia upgrade kits, and individual multimedia hardware components, such as audio-adapter cards, meeting a set of specifications established by the MMC may be marked with the MPC trademark.

MPEG (A/V, computer, M/M)
Moving Pictures Experts Group sets standards for moving graphic image compression.

MPU (computer)
Micro Processing Unit; alternate name for Central Processing Unit (CPU).

MPU-401 (A/V, computer, M/M)
Trademark of Roland Corporation for its MIDI adapter card for the PC. This trademark has become a de facto standard in the musical industry. "MPU-401 compatible" is a term indicating that a device serves the same purpose as an MPU-401 card or that an application uses an MPU-401 adapter card.

MSAU (communications)
Multistation Access Unit: a wiring concentrator linking several network workstations to an IBM Token Ring Network.

MSCDEX (computer/DOS/Windows)
Microsoft Compact Disc Extension. MSCDEX is a driver (MSCDEX.EXE) that is loaded as a DOS terminate and stay resident (TSR) application, not a Windows DLL. MSCEDX allows a CD-ROM to be accessed through the conventional DOS commands applicable to hard disk and floppy disk drives. MSCDEX.DRV version 2.0 or higher is required for PCs to access CD-ROM drives with HIGH Sierra or ISO-9660 directories. Version 2.2 or higher is recommended by the MPC specifications.

MS-DOS (computer/DOS)
MicroSoft-Disk Operating System - a single user operating system for PCs from Microsoft. It is almost identical to IBM's version, which is named DOS, and both versions are called DOS generically.

MS-DOS-Based Application (computer/DOS)
Application that is designed to run with MS-DOS, and therefore may not be able to take full advantage of all Windows or Windows NT features.

MSF (computer, M/M)
Multimedia (MCI) time format expressing times in Minutes, Seconds, Frames. MSF is principally used by the CDAudio commands.

MSI (computer/microelectronics)
Medium Scale Integration: medium-density logic functions (100 - 1,000 gates per chip).

MTBP (computer)
Mean Time Between Failure: standard used to evaluate a product's reliability.

MTNS (computer/microelectronics)
Metal Thick Nitride Semiconductor: similar to an MTOS device except that a thick silicon nitride or silicon nitride-oxide layer is used instead of just plain oxide.

MTOS (computer/microelectronics)
Metal Thick Oxide Semiconductor: where the oxide outside the desired active gate area is made much thicker in order to reduce problems with unwanted parasitic effects.

Multiaccess Computer
Computer system in which computational and data resources are made available simultaneously to a number of users. Users access the system through terminal devices, normally on an interactive or conversational basis.

MULTIBUS (computer)
Bus architecture from Intel Corp. that was used in a variety of industrial, military and aerospace applications. It was considered to be an advanced bus because of features, such as message passing, auto configuration, and software interrupts. MULTIBUS I was a 16-bit bus, and MULTIBUS II was a 32-bit bus architecture.

Multicast Address (computer)
An address that designates a group of entities within a domain.

Multichip Integrated Circuit (computer/microelectronics)
Hybrid integrated circuit which includes two or more SIC, MSI, or LSI chips.

Multilayer Dielectric (computer/microelectronics)
Compound, including glass and ceramic, which is applied as an insulating barrier between conductors for multi-layer and crossover work.

Multiline (communications)
Term sometimes used to describe a cable, channel or bus that contains two or more transmission paths (wires or optical fibers).

Multimedia (A/V, computer, M/M)
Computing and communication of information in more than one form and includes the use of text, audio, graphics, animation, full-motion, real-time, color video. The output may consist of text, sound, graphics, animation, video, and movies.

Multimeter (computer/microelectronics)
Common term for a volt-ohm-milliammeter, also called an analyzer or circuit analyzer. A much less common usage applies to a self-contained test instrument containing two or more single or multiscale indicating instruments that are used for simultaneously measuring two or more electrical quantities.

Multiple Range Graph (computer)
Graph that plots the values of more than one variable.

Multiplexer (A/V, communications, computer)
Device that merges several low-speed transmissions into one high-speed transmission and reverses the operation at the other end. In audio/visual terminology, a system of mirrors or prisms that directs images from several projection sources (film, slides) into one stationary television film, telecine chain, or camera.

Multiplexing (communications, computer)
Transmitting more than one signal at a time over a single link, route, or channel. In general terms, the word multiplexing implies the use of a single facility to handle simultaneously several similar but separate operations. In data communications, its value is achieved where multiplexing devices enable the transmission of several lower-speed data streams over a single, higher-speed telecommunications line. The two methods used are called: Frequency Division Multiplexing (FDM), and Time Division Multiplexing (TDM). In FDM, a high bandwidth channel is divided into several lower-frequency bands, with each band capable of carrying a channel of data. In TDM, time is divided into small slots, and each time slot is used to perform a segment of the desired operation.

Multipoint (communications)
Configuration in which more than two stations share a transmission path.

Multipoint Line (communications, computer)
Term sometimes used to describe an in-line configuration in which several terminals are connected on the same line, or cable, to one computer.

Multiprocessor (computer)
In personal computing terminology, two or more microprocessors sharing a common bus. Additional microprocessors are assigned to specific functions such as input/output (I/O) operations or high-speed video processing. Multiprocessing personal computers are most frequently employed as network file servers, but they have become more common for multimedia applications requiring high-speed animation or digital video presentation.

Multiprocessing (computer)
Simultaneous processing with two or more processors in one computer, or two or more computers that are processing together. When two or more computers are used, they are tied together with a high-speed channel and share the general workload between them. In the event one fails to operate the other takes over. In fault tolerant systems, two or more processors are built into the same cabinet. Multiprocessing is also in special-purpose computers, such as array processors, which provide concurrent mathematical processing on sets of data. Although computers are built with various overlapping features, such as executing instructions while inputting and outputting data, multiprocessing refers specifically to concurrent instruction executions.

Multiprogramming (computer)
Overlapping and interleaving the executions of more than one program, allowing many resources to be active simultaneously on one system. A single CPU (Central Processing Unit) can perform work for many different jobs by switching from one to another while being devoted at any one moment to a particular task, through the use of memory buffers that are installed on the peripheral devices that are actually doing different jobs.

Multisync Monitor (A/V, computer, M/M)
A display monitor that adjusts automatically to the synchronization frequency of the video signal it receives. It can adjust to a range of frequencies, but not all of them. The multisync monitor was popularized by NEC (Nippon Electric Company) and MultiSync is the NEC trade name.

Multitasking (computer)
Running two or more programs in one computer at the same time. Multitasking is controlled by the operating system, which loads and manages programs until finished. The number of programs that can be multitasked depends on the amount of memory available, CPU speed, width of the data and address buses (16 bit, 32 bit, etc.) capacity and speeds of peripheral resources, as well as the efficiency of the operating system.

Multithreading (computer)
The concurrent processing of transactions. It implies that transactions, or messages, can be worked on in parallel. Multithreaded programs are often written in reentrant code so that one routine can serve multiple processes at the same time.

Multitimbral (A/V, computer, M/M)
MIDI synthesizers responding to MIDI messages on multiple channels playing a different voice for each channel.

Multiuser (computer)
System and program that allows for concurrent use by more than one user. Newer generations of microprocessors are providing main bus architectures that are wide enough to provide for the simultaneous running of several programs, in parallel, on the same bus.

Multivibrator (computer/microelectronics)
Oscillator with two or more active devices, such as transistors interconnected by electrical networks. Multivibrators are classified by the manner in which the reversal-of-state action of each device is initiated and by the method of control of the time interval in each state. Different types of multivibrators include: symmetrical bistable multivibrator with two states, JFET circuit and Bipolar transistor circuit; unsymmetrical bistable circuits; monostable multivibrator; astable multivibrator; and the logic gate multivibrator.