Computer Science

MAC
Media Access Control - a sublayer of the Data Link Layer. The MAC address is the address that is hard-wired onto the NIC by the manufacturer, it's "hardware address."

Mail Server
Server used for E-mail.

Maillist
A Mailing List - Allows users to send e-mail to one address and then their message is copied and sent to all recipients in the mail list.

MAN
Metropolitan Area Network

Management Software
The primary software package used by the administrator.

MAU/MSAU
Multistation Access Unit in a Token Ring network, a device to attach multiple network stations in a star topology, internally wired to connect the stations into a logical ring.

MB
Megabyte

MCA
Micro-Channel Architecture

MCA Bus
Micro Channel Architecture, a 32-bit bus, introduced by IBM for its PS/2 computer line, totally incompatible with the original PC bus.

Media
A method of data transmission.

Megabyte
An amount of computer memory equal to 220 = 1,048,576 bytes = 1024 kilobytes. One megabyte can store more than one million characters.

Megahertz
MHz - Million hertz or million cycles per second. A measurement of clock speed.

Memory
The space within a computer where information is stored while being worked on. It temporarily stores information (in the form of data bits) that the CPU and software needs to keep running.

Mesh Topology
Every device is connected to every other device by separate cables and has redundant paths.

MFM
Modified Frequency Modulation

MHS
Message Handling System - A standard defined by ITU-T as X.400 and by ISO as Message-Oriented Text Interchange Standard (MOTIS). MHS provides the functions for global E-mail transfer among local mail systems, and is used by CompuServe, among others.

MHz
Megahertz

Microphone
Just like the microphone on a tape recorder. Allows input of voice or music to be recorded and saved to a computer file.

Microprocessor
An integrated circuit containing the entire CPU of a computer, all on one chip, so that only the memory and input/output devices need to be added.

Microwave Transmissions
A wireless network standard that uses microwave signals for data transmission.

MIME
Multipurpose Internet Mail Extensions - The standard for attaching non-text files to standard Internet mail messages. Non-text files include graphics, spreadsheets, formatted word-processor documents, sound files, etc.

Mini Connector
Type of Power Supply connector. Primarily used on 3.5 inch floppy drives.

Mirror
To create and maintain an exact copy of something. Many Internet site maintain "mirror sites" that are used to provide faster or more wide-spread access to a site. Also refers to the process of copying all data to more that one hard disk simultaneously, to provide fault tolerance in the event of a disk failure.

Modem
Modulator/DEModulator - Converts computer data to information that can be transmitted via telephone wires. Allows communication between computers over long and short distances.

Molex Connector
Type of Power Supply connector. Primarily used for devices that need both 12v and 5v power (floppy drives). Most common type of connector.

Monitor
The primary output device, it visually displays text and graphics.

MOO
Mud, Object Oriented - One of several kinds of multi-user role-playing environments, they are text-based.

MOS
Metal Oxide Semiconductor

Mosaic
The first WWW browser that was available for the Macintosh, Windows, and UNIX all with the same interface. Mosaic really started the popularity of the Web. The source-code to Mosaic has been licensed by several companies and there are several other pieces of software as good or better than Mosaic, most notably, Netscape.

Motherboard
Also known as a PWB or printed wiring board. The large circuit board found inside the computer. For all practical purposes, it is the computer. It contains the following items: Chip Set, Data Bus, Address Bus, Expansion Slots, Clock, Battery, Memory.

Mouse
Pointing device used with graphical environments to point and select objects on the system's monitor. Comes in a variety of shapes and sizes.

MSD
Microsoft Diagnostics

MTBF
Mean Time Between Failures

MUD
(Multi-User Dungeon or Dimension) -- A (usually text-based) multi-user simulation environment. Some are purely for fun and flirting, others are used for serious software development, or education purposes and all that lies in between. A significant feature of most MUDs is that users can create things that stay after they leave and which other users can interact with in their absence, thus allowing a world to be built gradually and collectively.

Multimeter
One of the most basic tools for electronic troubleshooting.

Multistation Access Unit
A type of hub. The actual ring in a Token Ring network is in the hub.

Multitasking
The operation of more than one application at apparently the same time on the same PC. The CPU quickly switches between the various programs making it possible to work in more than one program at once.

MUSE
Multi-User Simulated Environment - A kind of MUD - usually "G" rated.