Mainframe
A computer created for large corporations' one-way computing processes. Mainframes are not interactive and are associated with centralized rather than distributed computing.
Megabytes
A measure of one million bytes, or 1,024 kilobytes.
Megahertz (MHz)
A measure of frequency equal to one million Hertz.
Microprocessor (aka Central Processing Unit or CPU)
Computer on a digital semiconductor chip. It performs math and logic operations and executes instructions from memory.
Microwave
Line-of sight, point-to-point transmission of signals at high frequency. Microwaves are used in data, voice and indeed all types of information transmission. The growth of fiber optic networks has tended to curtail the growth and use of microwave relays.
MIME (Multipurpose Internet Mail Extensions)
A widely used method for attaching non-text files to e-mails.
Modem
This device allows a computer to be connected to a phone line, which in turn enables the computer to receive and exchange data with other machines.
Modulator
A device that modulates a carrier. Modulators are found in broadcasting transmitters and satellite transponders. The devices are also used by CATV companies to place a baseband video television signal onto a desired VHF or UHF channel. Home video tape recorders also have built-in modulators that enable the recorded video information to be played back using a television receiver tuned to VHF channel 3 or 4.
MPEG-1
This name refers to the ISO Motion Pictures Experts Group standard for the compression of motion or still video for transmission or storage.
MPEG-2
The new International video compression standard.
MP3 (MP3)
An audio compression format that lets users download sound files, such as music, onto their computers in a short time without taking up all the room on the hard drive.
Multicasting
The practice of sending a message from one point on a network to many selected points at the same time instead of sending it to one user or to every user on the network.
Multipoint Distribution System (MDS)
A common carrier licensed by the FCC to operate a broadcast-like omnidirectional microwave transmission facility within a given city. MDS carriers often pick up satellite pay-TV programming and distribute it, via their local MDS transmitter, to specially installed antennas and receivers.
