M

Mac

The abbreviation for Macintosh computer.

MAC

Media Access Control. A protocol for determining which devices have access to a network at any one time, specified by the IEEE. The MAC protocol differs depending on the method used to connect the network (for example Token Ring or Ethernet).

Also see Ethernet IEEE MAC Address Network Protocol Token Ring

MAC Address

Media Access Control address; also called hardware address or physical address. An address associated with a particular network device. NICs and managed devices that connect to a LAN have a MAC address assigned to them as MAC addresses are used to identify devices in a network. MAC addresses are 6 bytes long, are specified by the IEEE and are preassigned to your network equipment.

Also see Byte IEEE LAN MAC Network NIC

Mailserver

The computer (and software running on it) that allows sorting and retrieval of E-mail messages.

Also see E-Mail

MathML (Mathematical Markup Language)

An XML, DTD that describes mathematical data.

Mainframe Computer

A powerful central computer designed for high-level computing tasks. Mainframe computers are often accessed by multiple users via attached workstations.

Mbps

(Megabits Per Second) (not to be confused with megabytes per second -MBps). The measurement of the speed of data transfer in a communications system. A megabit is one million bits. Ten megabits per second (10Mbps) means that 10 million pulses are transmitted per second in a communications system.

Also see Bit MBps

MBps

MegaBytes per second (not to be confused with megabits per second -Mbps). The measurement of the speed of data transfer in a communications system. A megabyte is approximately one million bytes. [1 MB = 1,048,576 bytes.]

Also see Byte Mbps

MDI

Medium Dependent Interface. MDI refers to an Ethernet port connection. The IEEE 802.3 network standard defines MDI as the electrical and mechanical interface between a piece of equipment and a transmission medium.

Within an RJ-45 port there is a transmit line and a receive line. RJ-45 ports can be MDI (the lines are uncrossed) or MDI-X (the lines are crossed). For a connection between two devices to work, the receiver of one device must be connected to the transmitter of the other, therefore, the MDI port of one device must be connected to an MDI-X port of another device using straight-through cable. MDI is also known as Uplink, and MDI-X is known as Normal.

Also see Ethernet IEEE MDI/MDI-X Network Port RJ-45 Straight-through Cable

MDI/MDI-X

Medium Dependent Interface/Medium Dependent Interface crossover. The switch, also known as Uplink/Normal, located on the back of an OfficeConnect switch or hub that is used to alter the operation of a specific port. The 'X' stands for crossing the transmit and receive lines of a port. An MDI port (Uplink, uncrossed) connects to the MDI-X (Normal, crossed) port of another hub.

Also see Hub MDI Port Switch

Megabyte (Mb)

The unit of measurement for a thousand Kilobytes; a million bytes.

Also see Gigabyte Kilobyte

Message (EDI)

metadata

A resource that provides information about another resource.

metalanguage

A language that describes other markup languages. XML is a metalanguage for describing other XML vocabularies.

Mime

(Multipurpose Internet Mail Extensions) a format designed originally to include images, sounds, animations and other types of documents within Internet mail messages.

Mirror site

An FTP site containing exactly the same files as the site it is mirroring. Sites may be mirrored several times, often in different countries around the world. They relieve the load that can be placed on a very popular FTP site, making it easier for users to gain access and download files faster.

Also see Download FTP

mixed content

A content model for a element that combines both element and character data.

Mosaic

Web browser written by a group of people at NCSA. Provides a Graphical User Interface for accessing data on the World Wide Web.

Also see Browser

MPEG

(Motion Picture Experts Group) video compression format used for movie or animation clips on the World Wide Web.

.mpg or .mpeg

Filename extension for MPEG movies

Also see MPEG

Modem

MOdulator-DEModulator. A device that adapts a computer's digital signal into audio frequencies (analog) for transmission down a telephone line, and adapts them back again. Transmission speeds of modems generally range from 2,400bps (2.4Kbps) to 56,000bps (56Kbps).

Also see bps Kbps

Multicast

A message sent simultaneously to a specific group of nodes on a network.

Also see Broadcast Network Node

multidirectional link

An XLink convention that describes a link that joins several documents together in a single link and can be traversed from any one of its resources.

Multilink PPP

Multilink Point-to-Point Protocol. Multilink PPP is a protocol that provides a method for combining multiple PPP connections. Multilink PPP aggregates the two 56 Kbps or 64 Kbps ISDN B channels, creating a virtual single digital connection of 112 Kbps or 128 Kbps.

Also see B channel ISDN Kbps PPP Protocol

Multiplexer

A device used in communication lines for funneling separate data signals simultaneously across a single channel.