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Term
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Description
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MAC
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Media Access Control. Sub-layer of Data Link Control; defined
by the IEEE, as the lower portion of the OSI reference model
data link layer. It is responsible for mapping hardware addresses
to network traffic. The MAC sub layer is concerned with media
access issues, such as whether token passing or contention
will be used.
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Machine Language
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The lowest-level programming language (except for computers
that utilize programmable microcode) Machine languages are
the only languages understood by computers. While easily understood
by computers, machine languages are almost impossible for
humans to use because they consist entirely of numbers. Programmers,
therefore, use either a high-level programming language or
an assembly language. An assembly language contains the same
instructions as a machine language, but the instructions and
variables have names instead of being just numbers.
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Macro
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Pre-defined function that designers can drop into their design,
e.g. a counter or adder
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MAN
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Metropolitan Area Network. Public network service to provide
LAN facilities over a wide area. Similar to a LAN but typically
deployed over a larger area like a city.
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Manual Power Down Mode
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It is the amount of electrical energy consumed by the device
for its operation.
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MAOSCO
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Multi-Application Operating System Company
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Map
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Software process of converting a designer's original design
file into FPGA specific features.
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Master
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The Master or Initiator owns the bus and initiates the data
transfer. Each Initiator must also be a target.
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Master State (Bluetooth)
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Maintains control of a Piconet
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MCNS
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Multimedia Cable Network System
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MCPC
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Multiple Channel Per Carrier.
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MCU
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Microcontroller Unit
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MD, MiniDisc
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MD or MiniDisc is a small-format optical storage medium with
read/write capabilities. This was pioneered by Sony in 1993.
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Media
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Anything which a laser printer can print on, e.g. paper,
card, transparencies and labels.
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Megabyte
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Amount of memory equal to 1,048,576 bytes of information
(Abbreviated MB).
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MEL
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MULTOS Executable Language
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Memory
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Internal storage areas in the computer. The term memory identifies
data storage that comes in the form of chips, and the word
storage is used for memory that exists on tapes or disks.
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Memory Controller
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An ASIC or FPGA which interfaces with a memory and enables
data transfer.
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Memory Corner
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A location on the Xilinx web site that talks specifically
about Xilinx memory solutions. It has links to application
notes and reference designs.
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Messaging System (HAVi)
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One of the Software Elements that comprise the basic mechanisms
in HAVi to achieve interoperability. Each element provides
a certain functionality. The Software Elements that are needed
for interoperability between HAVi devices are the Messaging
System, the Registry, the Event Manager, the Resource Manager,
the Stream Manager and the DCM.
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MFP
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Multifunction Peripheral.Today, this means the class of
devices that scan, copy, print and FAX.
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MHz
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Abbreviation for MegaHertz. One MHz represents one million
cycles per second. The speed of microprocessors, called the
clock speed, is measured in megahertz.
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Microcontroller
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A highly integrated chip that contains all the components
comprising a controller. Typically this includes a CPU, RAM,
some form of ROM, I/O ports, and timers. Unlike a general-purpose
computer, which also includes all of these components, a microcontroller
is designed for a very specific task -- to control a particular
system. As a result, the parts can be simplified and reduced,
which cuts down on production costs.
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Microprocessor
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A silicon chip that contains a CPU. In the world of personal
computers, the terms microprocessor and CPU are used interchangeably.
At the heart of all personal computers and most workstations
sits a microprocessor. Microprocessors also control the logic
of almost all digital devices, from clock radios to fuel-injection
systems for automobiles.
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Microprocessor
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A silicon device that contains a CPU. Microprocessors control
the logic of almost all digital devices, e.g. PCs, workstations,
clock radios, and fuel-injection systems for automobiles.
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Microwave
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Usually referring to all radio frequencies above 2 GHz.
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MII
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Media Independent Interface
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MMDS
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Microwave Multichannel Distribution System is a distribution
service for TV signals using microwave transmissions. Also
called multichannel video distribution system (MVDS). In the
US, it is called "wireless cable".
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Modem
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Modulator/Demodulator. A device for converting digital data
to audio tone and (vice versa) for transmission on an analog
channel.
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Modular Design
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Modular design allows mutilpe designers to simultaneously
develop individual blocks thereby shortening the design cycle.
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Modulate
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To vary the amplitude, frequency or phase of a radio frequency
wave in accordance with the information to be conveyed.
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Modulation
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Any of several techniques for combining user information
with a transmitter's carrier signal.
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Modulation
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QAM, QPSK, OFDM
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MP3
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MP3 (MPEG Layer III Audio Coding) The MPEG Layer 3 audio
compression scheme that was defined as part of the International
Standards Organization (ISO) Moving Picture Experts Group
(MPEG) audio/video coding standard. MPEG-I defined three encoding
schemes, referred to as Layer I, Layer II, and Layer III.
Each of these schemes uses increasing sophisticated encoding
techniques and gives correspondingly better audio quality
at a given bit rate. The three layers are hierarchical, in
that a Layer III decoder can decode Layer I, II, and III bitstreams;
a Layer II decoder Layer II, and I bitstreams; and a Layer
I decoder only Layer I bitstreams. Each of the layers support
decoding audio sampled at 48, 44.1, or 32 kHz. MPEG 2 uses
the same family of codecs but extends it by adding support
for 24, 22.05, or 16 kHz sampling rates as well as more audio
channels for surround sound and multilingual applications.
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MPEG
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Motion Picture Experts Group. Industry organization developing
standards and specifications for the encoding, digitization,
compression and transmission of video information over various
media and network technologies. MPEG-1 is a standard for transmission
of QCIF (1/4 screen) pictures at the primary data rate of
1.54 MHz, resulting in VCR quality video. MPEG-2 is much more
extensive, including a definition of a high-quality video
picture.
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MPEG Audio Layers
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MPEG-1 and MPEG-2 both have a three-layer structure, each
of which represents a family of coding algorithms. These layers
are noted in the standards using Roman figures (Layer I, Layer
II, and Layer III). Note that for Internet audio applications
MPEG-1 Layer III audio has become known as MP3.
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MPEG Stages
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The generations of standards defined by the MPEG working
group are referred to as stages. These stages are normally
noted in Arabic figures (MPEG-1, MPEG-2, and MPEG-4).
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MPEG-2
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MPEG-2 is a video compression standard being developed for
bitrates from 3 - 15 Mbit/s.
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MPEG-2 AAC (Advanced Audio Coding)
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AAC (Advanced Audio Coding) is one of the audio compression
formats defined by the MPEG-2 standard. AAC used to be called
NBC (Non-Backward-Compatible), because it is not compatible
with the MPEG-1 audio formats. MPEG-2 also defined another
audio format called MPEG-2 Multichannel or MPEG-2 BC (Backward
Compatible), which is compatible with MPEG-1. AAC is more
efficient than MP3 (MPEG-1 Layer III) and is the state of
the art in audio compression technology. Formal listening
tests have demonstrate it is able to provide slightly better
audio quality at 96 kb/s than layer-3 at 128 kb/s or layer-2
at 192 kb/s.
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MPEG-4
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Developed by same group supporting MPEG-1 and MPEG-2, this
new A/V codec with better compression capabilities than previous
standards & additional interactive support.
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MultiLINX Cable
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It is used to program (configure) and debug Xilinx FPGAs
and CPLDs.
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Multipath Fading
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A type of fading caused by signals taking different paths
from the transmitter to the receiver and, consequently, interfering
with each other.
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Multipath Interference
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Signal reflections and delayed signal images which are typically
associated with indoor wireless LAN applications, and interfere
with the desired signal.
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Multiple Access
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A method for accommodating more users in the same frequency
band.
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Multiplex
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A stream of all the digital data carrying one or more services
within a single physical channel.
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Multipoint
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A communications circuit interconnecting several nodes (usually
more than two).
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