Glossary [M]

Term	Description
Macro	A series of commands, keyboard or mouse actions that are recorded and performed automatically when a certain key is pressed or a certain command is entered.
Main board	See Motherboard.
Master Boot Record	See MBR.
Math Coprocessor	See Coprocessor.
MBR	Master Boot Record. When a hard drive is partitioned, the Master Boot Record is written to the first sector on the hard drive. It contains the Partition Table and other information needed by the BIOS to access the hard drive.
MCA Bus	Micro Channel Architecture. A very proprietary bus developed by IBM that had a bus speed of 10 MHz and could use multiple bus mastering devices. There were 16 and 32 bit versions and MCA expansion cards were configured using software (a reference disk and an option disk).
Meg	See Megabyte.
Megabyte	Abbreviated MB, a megabyte is equal to 1024 Kilobytes, or 1,048,576 bytes. A computer systems memory is measured in megabytes.
Megahertz	Abbreviated MHz, a system's clock speed is measured in Megahertz or millions of cycles per second. The speed of computer devices or chips associated or synchronized with the system clock will be measured in MHz. e.g.: CPUs and system Bus.
Memory	Refers to actual chips on the motherboard, expansion cards and devices that can hold information or data for processing.
Memory Address	The computer assigns numbers or addresses to physical memory locations on boot up to keep track of the information that the CPU has access to. This process is referred to as Memory Mapping.
Memory Cache	See Cache.
Memory Mapping	See Memory Address.
Menu Bar	When a window is open, the Menu Bar is just below the Title Bar and displays the names of an applications pull down menus that provide access to the different functions and features of that particular program.
Microchip	See Integrated Circuit Chip.
Microprocessor	See Central Processing Unit.
MIDI	Musical Instrument Digital Interface. This is a standard that has been developed for transferring sound created by musical instruments to digital information stored on a computer.
MIPS	Millions of Instructions Per Second. The approximate number of commands that can be carried out in one second. A CPU's power is sometimes measured in MIPS for comparison to another CPU.
MMX	An enhancement to the Pentium Processor that added instructions meant to speed up the I/O needed for sound, graphics and animation or video.
Modem	Contraction for Modulator/Demodulator. Modems convert analog data into digital data and vice-versa so that computers can communicate over phone lines.
Monitor	The most commonly used output device for displaying text and graphics from a computer. CRTs (Cathode Ray Tubes) are the most common. LCDs (Liquid Crystal Displays) are used on laptops and are available for desktop systems.
Motherboard	The printed circuit board in a computer that contains the CPU, Chipset, expansion slots, memory and device controllers. Sometimes called the System Board, Main Board, Planar Board or Logic Board.
Mouse	An input device that translates movements on a horizontal surface (the mousepad) into movements of a pointer or cursor on the monitor screen.
MPEG	Moving Pictures Experts Group. A standard that has been developed for compression of motion video. It keeps track of the movement from frame to frame and only replaces or stores the data that has changed.
MSDOS.SYS	One of the system files in the MS-DOS Operating System. A hidden file in the root directory, sometimes called the kernal for DOS. When an application needs to access a device or peripheral, this file translates the request into actions that IO.SYS can perform.
Multimedia	Computer presentations that can make use of video, animation, sound and pictures.
Multimedia Extensions	See MMX.
Multimeter	A Voltmeter or Ammeter that has a switch setting allowing it to measure voltage (ac or dc), resistance in ohms or continuity of a circuit.
Multiplier	The factor by which the bus speed is multiplied to get the CPU clock speed.