Mobile IP, Mobile Internet Protocol Mobile data networking through the Internet is coming into de-mand as the number of laptops and the availability ofwireless modem services increases..
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telecommunications service providers, MIDP is a set
of Sun JavaAPIs that is part ofthe J2ME application
runtime environment for mobile information devices,
along with the Connected Limited Device
Configu-ration (CLDC) MillP was developed through the
Java Community Process It specifies aspects of
stor-age, application life cycle, networking, and user
in-teraction
MIDP for PalmOS is an implementation of CLDC
and MIDP optimized for PalmOS handheld platforms
Mobile IP, Mobile Internet Protocol Mobile data
networking through the Internet is coming into
de-mand as the number of laptops and the availability
ofwireless modem services increases Since the
prob-lems of maintaining contact with a network and
net-work security are concerns on mobile systems, a set
of extensions to Internet Protocol (IP) is being
de-veloped to handle the special needs of mobile users
Mobile IP uses a dual addressing scheme so that the
communications node and the mobile unit can be
tracked and administered In simple terms, the
loca-tion of the mobile system becomes a forwarding
ad-dress to which packets are retransmitted Security is
incorporated to prevent an unauthorized person from
intercepting the transmission See Foreign Agent
Mobile Management ForumMMF A forum of the
Open Group, announced in May 2000, as a means to
pursue the objectives ofthe Open Group Wireless and
Mobile Program The MMF supports and promotes
the deployment ofinteroperable wireless applications
and devices into enterprise environments
http://www.opengroup.orglmobile/
Mobile Maritime CommitteeMMC.Aninformal
committee of the U.S Coast Guard that has existed
for some time to express and address local maritime
issues and problems In February 2000, a more
for-mal organization was established to promote actions
to improve the safety, security, mobility, and
environ-mental protection of the Mobile, Alabama, port
Members consist of port and waterway users and
regulatory agencies See Marine Safety Office
Mobile Meteorological EquipmentMME Through
the work of the Ad Hoc Group for Mobile
Meteoro-logical Equipment (AHGIMME), the Federal
Direc-tory of Mobile Meteorological Equipment and
Ca-pabilities was prepared to assist agencies in individual
responsibilities and planning activities in response to
requirements and emergencies The Directory
cata-logs mobile meteorological equipment, software, and
capabilities ofU.S federal departments and agencies
to facilitate interagency cooperation The Department
of Defense (DoD) has been particularly active in the
development and deployment of mobile systems
Mobile Multimedia Communication projectMMC
project A multidisciplinary research project
coordi-nated within Delft University of Technology in the
Netherlands The MMC project was established to
research solutions to wired and wireless Internet-style
applications and bandwidth applications as they can
be adapted to mobile networks such as cellular
sys-tems The project ran from April 1996 to September
2000 Some of the work in the project has been
trans-ferred to the UbiCom (Ubiquitous Communication) program
Mobile Network Location Protocol MNLP In CDPD mobile communications, the MNLP provides
a means to track the Mobile End System (M-ES), that
is, the laptop modem, cellular phone, or other device that allows the user to link into the network, and to interlink the Home Mobile Data Intermediate System (MD-IS) and the Serving MD-IS This works in con-junction with a Mobile Network Registration Proto-col (MNRP) to verify the user's Network Entity Iden-tifier (NEI), a security ill used to monitor and con-fine service to authorized users
Mobile Network Registration ProtocolMNRP See Mobile Network Location Protocol
mobile phoneAnaudio broadcast system designed
to provide mobile communications through hardware interfaces resembling traditional phone handsets The earliest mobile phone systems were bulky, limited contrivances developed after the tum of the century and first demonstrated in 1919, but they were ac-knowledged as having an important place in future communications
Historically similar to broadcast TV, a powerful trans-mitter was located to provide maximum range, up to perhaps 30 miles, for traveling subscribers To in-crease the limited range and channel distribution of the single tower design, cellular networks were de-veloped, which increased available bandwidth by pro-viding many lower power transmitters, closely lo-cated to one another, over a wide geographic region There are now a number of types of mobile phones, from short-range FM cordless phones with a range
of a few hundred feet, to digital PCS and cellular sys-tems with roaming capabilities that range from hun-dreds to thousands of miles See cellular phone
Mobile Solutions Partner Program MSPP A Microsoft program initiated in August 2000 to pro-mote development of mobile communications solu-tions based on Net Mobile Web technology MSPP supports vendors who are developing for the Micro-soft Pocket PC operating system The program was initiated in part as a competitive response to Palm's business lead in the mobile communications industry
Mobile Subscriber UnitMSU A main component
of a mobile phone system consisting of a portable or transportable control unit and cellular radio trans-ceiver Convenience, size, transceiver power, and battery life are traded off in the various systems Larger, more powerful units may be mounted to car batteries, and often split the telephone and the hand-set into separate units Smaller handhelds frequently have less range and shorter battery life See cellular phone, mobile phone
Mobile Telephone Switching OfficeMTSO Amain component of a mobile phone service, which per-forms wireless relaying, switching, and administra-tion tasks similar to those carried out by a wired tele-phone switching office, except that it must handle the specific technical needs ofusers who are moving and roaming (changing from one transceiving area to another) with signal monitoring and processing,
Trang 2between the mobile services and connections to
wire-line services, as many mobile services are actually
hybrid technologies, often taking calls from mobile
users and connecting them with a wireline
destina-tion, and vice versa
Mobilization Against Terrorism ActMATA See
Anti-Terrorism Act of2001
Mockapetris, PaulThe developer of the JEEVES
DNS Resolver, the first implementation of the
Do-main Name System, now incorporated into the
Inter-net Mockapetris is responsible for a number of
sig-nificant Request for Comments documents related to
the development of the Internet His DNS Resolver
spawned several subsequent implementations, the
most significant being the Berkeley Internet Name
Domain (BIND) In June 2001, Mockapetris was
an-nounced as Chairman of the Board for Nominum,
Inc., a naming and address management solutions
provider See JEEVES DNS Resolver
modalIn applications programming, a type of user
window, dialog, or other input or information display
operation which does not suspend access to other
pro-cesses For example, suppose the user has selected a
Quit function, and the software displays a dialog box
that says,- "Do you really want to quit? If so, the
pro-gram will end without saving." Options to Quit or to
Cancel will be presented Ifthe dialog allows the user
to go back to the application without responding to
the Quit/Cancel query, the operation is modal If the
user must reply before continuing with using the
soft-ware, thenitis not While modal (multitasked)
op-erations are preferred in many situations, in others, a
response should be solicited before continuing,
es-pecially if it involves the possible loss of data
modeIn some older operating systems, a distinction
was made between text mode and graphics mode, but
most systems now work in graphics mode with text
represented graphically This system is more flexible
modemmodulator/demodulator 1 A device which
modulates and demodulates a signal Digital data are
typically modulated to be carried over analog
trans-mission systems, and broadcast waves are modulated
to add infonnation to the carrier band These are then
demodulated again at the receiving end 2 A
com-puter hardware peripheral specifically designed to
convert the digital signals generated by the computer
into analog systems that can be carried across an
ana-log transmissions medium such as twisted-pair
cop-per wire, and demodulate them back into digital data
at the receiving end Many standards exist for the
transmission ofthis type ofdata, and the sending and
receiving modems must be able to negotiate a
com-mon format in order for the signals to be
meaning-fully received Current modems commonly transmit
at rates of 19,200 bps, 38,400 bps, and higher; most
include facsimile transmission capabilities, and some
include voice mail capabilities as well They
incor-porate a number of error control, data compression,
and modulation protocols in order to maximize speed
of transmission over lines that people once claimed
could never transmit data faster than 600 bps See
modulation protocol, serial port
modem poolA set of modems usually servicing a network through which several users can dial out of the system, or through which a number of users can dial in, as to a BBS or Internet Services Provider (ISP) Most higher educational institutions have mo-dem pools for users to access the system from home
or classrooms, or through which they can dial out to community services or extra service providers Of-ten the modems in a pool will have different charac-teristics For example, only a few lines may be high speed lines, due to higher cost, and the remainder may
be a variety of slower, less expensive modems Some modem pools are extremely large For example, one of the largest commercial Internet providers has over 100,000 modems in its pool
A pool is a flexible way to maximize resources A dozen modems can service a hundred workstations, provided the users do not need constant access to dialup resources.Itis also easier for system admin-istrators to carry out hardware maintenance and to maintain security when the modems are grouped and placed in a secure environment
Modems
Two different computer modems: the Global Village
on the left has a built-in 9-pin DIN connector, and operates at 33,600 bps; the SuperModern on the right has a standard 25-pin connection supporting V:34 standards Each can be connected (daisy-chained) with a regular telephone set.
modem serverAnetworked workstation application which manages the administrative and access tasks associated with a modem pool, or an intelligent mo-dem hub which manages incoming and outgoing data from more than one user.Inlarge modem pools, a system may be dedicated to assigning user requests for modems, for sending messages to the user (e.g.,
"All systems are currently busy, please make your request again in 15 minutes."), for evaluating which modems to allocate first (there may be different mo-dems with different capabilities, such as access speed), and for assigning priorities and connect times, when appropriate
modem standardsThis is one ofthe areas where de
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factovendor standards and industry standards (e.g.,
lTD-TV Series Recommendations) have continually
leapfrogged one another, and engaged in an uneasy
competitive race The constant consumer demand for
faster modems and the vendor desire to be the first
to market with the next generation modem, have
caused many vendors to develop their own standards
ahead ofthe global cooperative standards process For
this reason, many modems are dual-standard
mo-dems, in order to support both the vendor and
gener-ally accepted industry standards Some modems
sup-port either vendor or industry standards, which are
often not compatible, and it is important to find out
their status before purchasing
Inmany cases, the early versions ofmodems
support-ing the faster speeds are the ones most likely to go
out of date quickly In the early days, many vendors
followed Bell and Hayes standards, whereas in
re-cent years, vendors have tended to go with the
indus-try standards once the specifications are finalized and
made available The Hayes command set remains,
although most vendors implement a superset of the
original Hayes commands, which were quite simple
and limited
The Microcom Network Protocol standards for error
control and data compression are widely supported
modem standards See Microcom Networking
Pro-tocol, V Series Recommendations
modifed chemical vapor deposition MCVD See
vapor deposition
Modified Final Judgment, Modification of Final
Judgment MFJ The name given to a historic 7-year
antitrust lawsuit between the U.S Justice Department
and AT&T, which resulted in the breakup of AT&T
It is associated with Judge Harold Greene's decision
regarding the 1983 to 1984 (clarification and revision)
divestiture ofAT&T Under this judgment, AT&Twas
permitted to retain ownership of Bell Laboratories
and AT&T Technologies (Western Electric), but the
Regional Bell Operating Companies (RBOCs) were
banned from manufacturing, and Local Access
Trans-port Areas (LATAs) were created rather than
retain-ing the existretain-ing local exchange boundaries
Prior to the MFJ, charges were handled through
Di-vision of Revenues, but this was changed to an
ac-cess charge tariffsystem See AT&T; Greene, Harold;
Kingsbury Commitment; Local Exchange Carrier;
Willis Graham Act of 1921
Modified Huffman MH Huffman is a
variable-length, tree-oriented data encoding scheme that
op-timizes on the basis of more frequently occurring
characters in order to achieve compression in fewer
bits Modified Huffman is widely used in facsimile
transmissions See Huffman encoding
modular Composed ofseparately organized entities,
loosely or tightly coordinated or connected to create
a larger whole Modular programming is
program-ming in which the larger application is composed of
smaller associated elements such as blocks, objects,
primitives, self-contained functions, etc
Object-oriented programming is a type ofmodular
program-ming Amodular office is one in which the individual
components of the facilities can be changed around fairly easily; that is, desks, screens, phones, cables, etc can be rearranged without undue effort Amodu-lar phone system is one in which handsets or phone sets can be unplugged and moved or rearranged within a building or department Modular software
is software in which a number of separate or related utilities, tools, and functions can be used together in
a number ofways For example, there may be a vari-ety of functions that do file conversions, image pro-cessing, filtering, special effects, etc which can be used separately or in conjunction with a variety of programs Some of the more flexible, stand-alone
"plugins" exhibit these properties of modularity For example, there may be a watercolor plugin which can
be used independently to alter the contents ofa graph-ics file, or may work as a plugin in the context of sev-eral programs such as an image processing program, a drawing program, etc
modular multi-satellite preprocessor MMSP A frame synchronizer designed to provide an interface between a host computer and synchronized mapper telemetry data The MMSP takes the raw telemetry data, frame aligns and samples it, and transmits the information to the host computer, where it is further processed and the image information extracted from the data
modulate To change gradually from one state to an-other To tune or adjust To vary the amplitude, fre-quency, or phase, typically to add information to a carrier wave To change the velocity of electrons in
an electron beam, as in a cathode-ray tube
modulation Akey element in the transmission of in-formation By changing or modulating an electrical pulse through a wire or other conducting medium, or
an airborne electromagnetic wave, it is possible to convey information Similarly, by manipulating its
in-tensity and duration, light can be modulated to send information Some of the simplest forms ofmodula-tion include turning a signal on or off, or varying it between high and low states
For computer users, one of the most familiar modu-lating devices is the dialup modem, which takes a digital signal from the computer and modulates it to
be carried over analog phone lines At the receiving end, a modem then demodulates the signal, turning
it back into digital signals that are transferred to the receiving computer
There are many modulation techniques used through-out the telecommunications industry, some very simple, and some so sophisticated only computers can control them The most common types ofmodulation are amplitude modulation (AM), frequency modula-tion (FM), and phase modulamodula-tion (PM) Sometimes different modulation schemes are combined Each scheme has its own unique characteristics
Early detractors said frequency modulation was math-ematically impossible, but Edwin Armstrong demon-strated, after 10 years of hard research applied to the problem, not only that it could be done, but also that
it was a great thing.Ithas since been used in thousands
of applications from radio programming to cordless
Trang 4tant contribution to modulation was the work ofJohn
R Carson, who demonstrated how a portion of a
modulated signal could be transmitted, instead ofthe
whole thing, and the original signal rebuilt at the
re-ceiving end, thus reducing bandwidth without loss of
information See amplitude modulation; Annstrong,
Edwin; frequency modulation; phase shift keying;
quadrature amplitude modulation; sigma-delta
modu-lation; single sideband
modulation protocol Adata encoding technique used
to convert digital data into analog signals This
de-termines the raw (uncompressed) speed at which the
modem can transfer data Current modems
incorpo-rate more than one protocol See modem
modulation, light A means of conveying
informa-tion by manipulating a beam of light The light can
be directly influenced, by turning it on or off, or
vary-ing its intensity; it can be indirectly influenced by
interposing shutters, gels, or other objects between
the sender and the receiver Light modulation is used
in fiber optic transmissions, with lasers and
light-emitting diodes used as common light sources
moire 1 In raster-oriented imagery, moire is a visual
artifact that appears as an undesirable, distracting
secondary pattern which disturbs the intended
appear-ance ofthe image 2 In traditional printing on a press,
especially process color printing, small dots are
of-ten interleaved to simulate the appearance of more
colors Ifthe angles and patterns ofthese dots are not
carefully controlled, a moire pattern, resembling light
through silk, may emerge Better desktop publishing
programs provide print settings to set the angle and
type of halftone to match the technology on which
the job is printed 3 In video images, mixing high
frequency moire
moisture barrier A cover, sheet, bag, or other bar-rier, usually plastic, intended to retard or prevent moisture from coming in contact with building struc-tures, wires, or electrical components Moisture bar-riers are used to prevent rot, condensation, and elec-trical short circuits
MOKE magneto-optic Kerr effect See Kerr effect molding raceway A channel system incorporated into wood, plastic, or metal moldings to hold, pro-tect, and direct interior wiring circuits Molding race-ways are of modular construction with a variety of fittings, so individual sections can be interconnected and holes can be punched where needed Molding raceways are commonly used on baseboards and wainscots, where they blend naturally with the de-cor See raceway
Monolithic Microwave Integrated Circuit MMIC Analog circuits incorporating a number ofintegrated functions operating at microwave frequencies Many types ofMMICs can be purchased for $5 or less per chip MMICs provide support for wireless commu-nications technologies, making it possible to design low-cost, high-bandwidth data transmissions links MMICs can be used to convert between baseband and modulated microwave signals and, as such, can be used in conjunction with traditional integrated circuits (lCs) handling the baseband signals
MMIC arrays developed by the NASA/Lewis Re-search Center and the Air Force Rome Laboratory were demonstrated in the mid-l 990s in conjunction with NASAAdvanced Communications Technology Satellite (ACTS) technology These proof-of-concept MMIC arrays were in the KIKa-band frequencies,
Radio Frequency Transmission Schemes
transmits at any time, and continues to transmit
if there is an acknowledgment It is not a high-efficiency method, but there are circumstances where it is practical
Code Division Multiple Access CDMA A hybrid scheme which incorporates time/
frequency multiplexingtoprovide spread spectrum modulation Thus, central channels can be handled without timing
synchronization
Frequency Division Multiple Access FDMA A traditional method of channel allocation in
which bandwidth is subdivided into frequency bands, with guard bands providing a buffer between channels
Packet Reservation Multiple Access PRMA A type of enhanced TDMA which incorporates
aspects of S-ALOHA Suitable for mobile transmissions
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indicating that high-density MMIC integration at 20
and 30 GHz was feasible
Once MMICs became commercially available, they
began to be of interest for many types of commercial
and scientific applications The Search for
Extrater-restrial Intelligence (SETI) League, for example,
con-siders the technology useful for constructing research
devices for space communications and the possible
interception of communications emanating from
other regions of the Universe
The Wireless Systems Innovation lab of NTT has
developed uniplanar and multi planar MMICs more
compact and less expensive than earlier technologies
that are suitable for radio, wireless area networks
(WANs), and satellite transponders With MMICs
incorporated into beam-forming networks, it is
en-visaged that Earth station satellite terminals can be
designed to be as small as cellular telephones
monopole Aslender self-supporting tower for
attach-ing wireless antennas/aerials
Moonbounce, Earth-Moon-Earth bounce EME A
means of using the Moon as a passive reflector for
communications signals Due to the great distances
involved, very large antennas and strong signals are
required, but given these in conjunction with the right
weather conditions, Moonbounce transmissions have
been demonstrated
The first Moonbounced signal was recorded in
Janu-ary 1946 in New Jersey, where army engineers used
a recently invented FM transmitter and receiver
de-veloped by E.H Armstrong to send pulses to the
Moon, which returned as a slight hum This was a
sig-nificant achievement as it not only showed the
po-tential ofFM broadcasts, but also demonstrated that
radio waves could pass through the ionosphere and
beyond
Gordon E Moore -Intel Founder
Gordon E Moore, cofounder ofIII tel Corporation
not only cofounded and headed up one of the most
successful computer chip companies in the world, but
is also well rememberedfor his predictions about
semi-conductor evolution now encapsulated as "Moore's
law " [Photo copyright Intel Corporation; used
ac-cording to Illtel Press Room conditions.}
Moore, Gordon E (1929- )AnAmerican chemist and business executive, Moore cofounded Fairchild Semiconductor, then Intel Corporation, in 1968, along with Robert Noyce, one of the inventors ofintegrated circuit technology (1959) In 1975, Moore became President and CEO until elected chairman and CEO
in 1979 He retained the position of CEO until 1987 and became chairman emeritus in 1997 In May 2001, Moore retired from the board, having reached the age
at which he had set mandatory retirement from the corporation
Moore is a fellow ofthe IEEE Society and Chairman
of the Board ofTrustees of the California Institute of Technology He was awarded the National Medal of Technology in 1990 See Intel Corporation; Moore's law; Noyce, Robert
Moore's law Semiconductor chip technology will
roughly double in capacity (and circuit density) about every year or so (later revised to every 2 years) This prediction, charted by Gordon E Moore at a speech
in 1965, turned out to be memorably prescient and has since been the basis for many industry planning decisions and forecasts See Gilder's law; Moore, Gordon
monochromator A device used in spectroscopic
scanning devices For slit to fiber transmissions, cou-plers/adapters may be incorporated into the device For fiber to fiber transmissions, off-axis paraboloi-dal mirrors may be used to eliminate aberrations and
to provide a point image from a collimated beam to support high-resolution applications The device may include multiple gratingstopermit selection of the desired spectral range Monochromators are designed
to support different optical wavelengths and more than one device may be needed, depending upon the wavelength selections desired See off-axis parabo-loidal
Morse code A system of character encoding using
dots and dashes, or long and short sounds or lights, that can be readily sent over distance over many types
of transmission media due to its simplicity Interna-tional Morse code (continental Morse code) and American Morse code (railroad code) have been de-rived from this
Morse code is flexible in that it can be sent with tones, clicks, dots and dashes, and lights, in a variety of media In 1862, two Philadelphia inventors patented
a signal light system using a shuttered oil lamp for sending Morse code which was intended to be mounted on the masthead of ships
International Morse code developed from Austro-Germanic code, a variation on Morse code used in radio transmissions partly because American Morse code, while suitable for telegraph communications, was more difficult to interpret over radio waves In
1851 it became the code of choice for transatlantic cable communications Basic skill in Morse code has been a requirement of receiving amateur radio li-censes for many decades The code was apparently developed by Morse's collaborator, Alfred Vail, and
is named for the inventor of the printing telegraph, Samuel F.B Morse See Morse code history
Trang 6ing telegraph designed by Samuel Morse employed
a system ofnumbers which were then correlated with
words, according to a lookup reference The lookup
reference developed by Morse was very large and the
system itself somewhat slow and cumbersome; it
re-quired the maintenance of a reference and the
some-what arbitrary assignment of nonmnemonic code
number sequences to every word Asimpler, more
di-rect system was needed
Alfred Vail was from a family offabricators and acted
for years as assistant to and collaborator with Samuel
Morse Mechanically adept, he built many of the
mechanical components designed by Morse In the
process of creating the mechanisms for the Morse
printing telegraph key, Vail changed the orientation
ofthe keying mechanism from horizontal to vertical,
thus providing a more comfortable hand position The
change also resulted in a stylus which would lift up
from the paper, leaving dots and dashes, rather than
zigzag-shaped dips on the tape record that Morse's
original mechanism produced
Vail's assistant, Baxter, reported to Franklin Pope that
Vail set to work simplifying Morse's unwieldy lookup
code system Vail apparently visited local printers to
analyze typesetting cases to determine the
frequen-cies of letter usage Pope subsequently reported the
story in 1888 in The Century: Illustrated Monthly
Magazine The code Vail developed evolved into
American Morse code, and International Morse Code
became a further streamlined variation As Morse's
assistant, Vail had agreed to tum over his inventions
to the elder inventor [Thanks to Karen Weiss and B
Neal McEwen for unearthing and reporting Vail's
possible unacknowledged contribution to history.]
Morse sounderA type of early telegraph sounding
instrument, which used audible clicks to broadcast
the incoming message rather than a paper tape
print-out, which was slow The sounder incorporated an
electromagnet as a pole piece, mounted on a
pivot-ing soundpivot-ing lever with two stop positions
Releas-ing the magnet as it was energized produced the
click-ing sound The duration of the clicks represented the
coded dots and dashes ofthe Morse code system and
were interpreted aurally by the receiving operator
Typically the sounder was connected to the sending
instrument with only one wire The viability of the
single wire circuit was observed by Steinheil in 1837
in Germany, and independently the following year by
Morse in America Both discovered that a second wire
was not needed to complete the circuit if the two
in-struments were connected through the ground, using
it as the return path for the circuit This worked even
over distance
Morse, Samuel Finly Breese (1791-1872) An
American artist and inventor in the 1800s chiefly
known for the code that bears his name He was a
re-spected artist and one of the founders ofthe National
Academy of the Arts of Design In the 1820s he
be-came increasingly interested in science and invented
electromechanical telegraph devices, some ofthe first
inventions to use electricity for communication
Morse was able to construct a basic working design for the telegraph by 1837
Samuel Morse demonstrated his invention to the presidential administration in 1838 and in 1843 won funding support from the u.S Congress to construct
a telegraph line between Baltimore and Washington, D.C He sent his first public message over this line
in May 1844, an event that launched a revolution in communications
Morse became friends with the Vail family, who were talented fabricators and were able to assist him in constructing practical working models of his ideas Many ofMorse's inventions were built by Alfred Vail, Morse's assistant and collaborator See Gale, Leonard D.; International Telegraph Union; telegraph; tele-graph history; Vail, Alfred
Mosaic, NCSA MosaicNCSA Mosaic is one of the most significant landmark applications in the history
of the Internet as it spurred the evolution of point-and-click visual interface that nontechnical computer users, even children, could understand and quickly learn to use The simplified Internet access and sup-port of images provided by Mosaic and its succes-sors dramatically fueled the growth ofthe World Wide Web
The first version ofx-mosaic was programmed at The National Center for Supercomputing Applications (NCSA) by Marc Andreessen in 1992 with Mosaic 1.0 released in November 1993 Mosaic was subse-quently enhanced and ported to support the X dow System, Apple Macintosh, and Microsoft Win-dows platforms
In 1994, Andreessen and other NCSA personnel left
to form Mosaic Communications Corporation based
on the Mosaic concept However, due to trademark ownership by the University ofIllinois, the company and the software product were renamed Netscape Communications Corporation and Netscape Naviga-tor, respectively, with the Board of Trustees of the University of Illinois retaining copyright ownership ofNCSA Mosaic The University of Illinois entered into an agreement for Spyglass, Inc to negotiate com-mercial NCSA Mosaic licenses in 1994
Other commercial Web browsers were in develop-ment in the mid-1990s, including OmniWeb by Light-house Design, Ltd., which was released in March
1995 In spite of the commercialization ofbrowsers, the Software Development Group at NCSA contin-ued development on the Mosaic project until Mosaic 3.0 was released in January 1997 See Gopher, Inter-net Explorer, Netscape Navigator, OmniWeb
MOST1 See Multidisciplinary Optical Switching Technology Center 2 See multiplexed optical scan-ner technology
motion picturesAny images which, when sequen-tially displayed, convey the appearance of motion, whether in real time or by presentation of a fast se-quential series ofstill pictures, especially videos, film reels, and animated computer images Traditional motion film pictures consist of a series of still im-ages on a transparent medium played through a
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projector, usually from 20 to 30 frames per second,
with 24 or 30 being common, as these are the speeds
at which human perception merges successive still
frames into a cohesive impression of connected
mo-tion
The development of motion picture photography
owes some of its roots to a bet over a dispute as to
whether a running horse lifted all four hoofs off the
ground Thomas Edison was one of the first to
ex-periment with displaying a series of still frames in
rapid succession in 1889 The first commercial
mo-tion picture, backed by the Canadian Pacific Railway,
is attributed to Clifford Sutton in the early 1900s See
animation, celluloid, MPEG
Motorola A significant computer chip designer and
manufacturer and electronic appliances manufacturer
since the 1960s It is descended from the Galvin
Manufacturing Company from the early 1930s In
1974 it released the MC6800, the first in a long
fam-ily of chips still being developed a quarter of a
cen-tury later One ofthe first microcomputers developed
with the Motorola family of microprocessors was the
Altair 680, released late in the fall of 1975 Since that
time whole families of computers have been based
on the subsequent MC68000 family of chipsets,
in-cluding Macintosh, Atari, Amiga, Sun, Apollo, SGI,
NeXT, and others Motorola is also well known for
products in the mobile data communications
indus-try The Motorola CPU Sample chart shows a brief
summary of some of Motorola's best-known
desk-top computer microprocessors, prior to the
collabo-ration with IBM to produce the PowerPC chips
In1998, Motorola teamed up with the McCaw/Gates
Teledesic project to provide Celestri technology to
the orbiting satellite network See Altair 680 See Sampling of Evolution of Popular Motorola CPUs chart
Mott insulatorAninteresting material discovered in the 1930s that appears to have the band structure of
a conductor but acts, instead, as an insulator because
of its energy gap characteristics However, ifthe ma-terial is doped, it can be encouraged to behave as a high-temperature superconductors Mott insulators have spurred closer scrutiny into band and energy gap structures to improve our understanding of their in-teractions and importance When they are better un-derstood, it will be easier to predict and harness the capabilities of poorly understood materials The Mott insulator is named after Nobel laureate N Mott Mountain Bell The familiar name for the Mountain States Telephone and Telegraph Company
Mountain States Telephone and Telegraph Com-panyAnearly telephone company, better known as Mountain Bell, which was formed in 1911 from the merger of the Tri-State and Colorado telephone com-panies, and the purchase ofthe Rocky Mountain tele-phone company
mouse A hardware human interface device that re-ceives hand and finger movements and transmits them to a computing device They are then interpreted into actions by the operating system and applications software The mouse is named for its basic shape, which typically consists of a palm-sized, rounded or squarish object, with one or more buttons under the fingers and a "tail," a cord that electrically connects the mouse with the computer Mice come in various shapes and sizes: friction mice have a ball on the side that makes contact with a hard surface; optical mice
Sampling of Evolution of Popular Motorola Central Processing Units (CPUs)
Processor Introd Proc Data Bus Addr Bus Notes
MC68000 1979 32 16 23 16 32-bit registers Supervisor and user mode
CISC architecture
MC68020 1982 32 16/32 32 256-byte cache Dynamic bus sizing
MC68030 1987 32 16/32 32 Paged MMU on processor 16-byte burst
MC68060 1994 32 32 32 Superscalar pipelined Power-saving
The PowerPC family was created in collaboration with IBM and Apple Computer This was a RISC-based line from the PPC 401 to 750 (G3), with speeds ranging from 20 to 500 MHz
MPC7400 (G4) 1999 64 64 32 Double-precision FPU, AltiVec instruction set
External L2 cache interface 350 to 450 MHz
Trang 8clude finger pads and rollerballs, which are not
strictly mice, but which employ the same basic
move-ment and input concepts
mouse history The invention ofthe computer mouse
is attributed to Doug Engelbart and is variously
re-ported as having been invented around 1959 to 1963
By the late 1960s, Engelbart was testing a
three-but:-ton mouse in conjunction with a keyset that was used
in the other hand During the early 1980s, when the
Apple Lisa was being developed (the first of the
Macintosh line), there were discussions at Apple as
to whether to use a two- or three-button mouse The
testing and rationale supplied by Larry Tesler
indi-cated a one-button mouse was completely
appropri-ate, and the Macintosh line still works very well with
this device 15 years later The majority ofcompeting
desktop computers use two-button mice
MPSee Multilink Protocol
MP3Apopular abbreviation for MPEG-l Layer 3 or
MPEG-2 Layer 3 See MPEG
MPEGMotion Pictures Experts Group A series of
international standards developed by ajoint
commit-tee under the aegis of the International Organization
for Standardization (ISO) and the International
Electrotechnical Commission (lEe) to facilitate the
development of digital video and audio formats and
decoding schemes Leonardo Chairiglione and
Hiroshi Yasuda originated the MPEG development
efforts in 1988 MPEG has received widespread
ac-ceptance for the playback of digital animations
The development of media formats is somewhat
de-pendent upon how the final compressed product will
be used In the case of MPEG series standards,
con-sumer entertainment products (e.g., optical media)
were taken into consideration, and thus the
percep-tual characteristics of the humans who would
even-tually be viewing or listening to the decoded MPEGs
were factored into its development
Video and audio technologies typically require a lot
of bandwidth and file space, so a large part of the
MPEG effort has concentrated on decompression
schemes and fast playback algorithms The
compres-sion itself is left up to the discretion of individual
vendors
MPEG is a family of standards numbered from 1 to
4, but the numbers do not necessarily indicate a
pro-gression Some changes and development for specific
needs occurred on the road from l to
MPEG-4 What the different variants have in common is that
they support the compression and playback of
digi-tal audio and video data (see chart)
MPEG is an asymmetric technology, based upon the
use of MPEG encoders (to compress and store or
transmit data) and MPEG decoders (to decompress
and display data).Itis asymmetric in the sense that
the speed and processing power required for
encod-ing is not necessarily the same as that needed to
de-code the MPEG data stream
MPEG decoders are used to decompress and play
back MPEG-based sound and videos either separately
or together The digital technology offers many
MPEG video is combined with MPEG sound or with Dolby Digital sound One ofthe reasons for the quick acceptance of digital videodiscs is their versatility
For example, on a DVD disc, there may be a video track, several sound tracks, and even data tracks for the display oftextual commentary or subtitles Thus,
a favorite movie could be viewed several times, in its original form, in other languages, or in its origi-nal form with subtitles or other textual information
Many commercial entertainment DVDs include au-dio commentaries with the verbal thoughts and im-pressions of the directors and actors superimposed over the original movie (with the original soundtrack
at a lower sound level in the background) This value-added means ofpackaging entertainment titles is one ofthe forces behind the quick acceptance ofMPEG-based commercial products
To be practical for the delivery of cinema-style edu-cation and entertainment programs, the playback dis-play ofMPEG data needs to be fast, so the technol-ogy is optimized with playback in mind
Individual contributors hold a number of patents to various technologies which have been incorporated
There have been several enhancements to MPEG since its introduction as shown in the MPEG Versions chart See animation, B-frame, I-frame, JPEG, MPEG decoder, MPEG encoder, P-frame
MPEGdecoder A mechanism for ''unraveling'' the data on an MPEG-encoded medium to make it ac-cessible for playback MPEG decoders are built into DVD players, Web browser plugin applications, and
a number of other consumer products The decoder sometimes has to handle more than just the fast de-compression and display of frames Many MPEG-encoded products come with several playback op-tions, necessitating that the decoder be coupled with human interface algorithms to enable the user to se-lect the MPEG options desired On commercial DVDs, these algorithms are usually presented in much the same manner as application menus and but-tons as are used on desktop computers When the user selects an option, the information is used to config-ure and control the way in which the information is decoded for playback See MPEG, MPEG encoder
MPEGencoder A mechanism for creating MPEG-format compressed data styles for storage or trans-mission While the format for MPEG compression has been standardized, the algorithms and hardware systems for creating MPEG-format data have been left up to the discretion ofdevelopers Thus, MPEG-format files can be created in a number ofways on a variety ofmedia and developers can create the MPEG files in a way that is appropriate for their application
MPEG decoders can even be incorporated into dedi-cated chips, for optimal portability or optimization for the task of encoding MPEG-format files
In general, MPEG encoding seeks to minimize file sizes without significantly compromising picture
Trang 9Fiber Optics Illustrated Dictionary
quality This enables faster delivery of MPEG data
over computer networks and makes it possible to fit
more content on storage media.Toaccomplish these
goals, a number ofclever schemes for exploiting
pic-ture redundancy (where a frame is similar to a
pre-ceding frame) have been developed, such as
differ-ential encoding.
Differential encoding is when you analyze a series
of image frames and make some assessments about their similarities and differences and then use this infonnation to remove redundancies (and thus reduce file size) Since video sequences commonly include many frames in a row with almost the same picture information (e.g., a kite fluttering against a blue sky),
MPEG Versions
MPEG-1 A relatively low-quality video standard initially developed for progressive video Later
adaptations also supported interlaced video but, in general, MPEG-1 has been
superseded by other fonnats for applications that require higher quality video
Coding of Moving Pictures and Associated Audio for Digital Storage Media at up to about 1.5 Mbps ISO/IEC 11172, standardized between 1993 and 1995
Anoptimized 1.5 Mbps bit stream for compressed video and audio, for compatibility with existing CD and DAT data rates Non-interlaced color video is typically implemented at 352 x 240 (288 in Europe), which is relatively low resolution, as it derives from a CCIR-601 digital television standard Replay speed is 30 frames per second (25 in Europe), fast enough for natural-looking motion Sample precision is 8 bits
MPEG-2 A higher quality fonnat than MPEG-l and supports both progressive and interlaced
video and both two-channel and multichannel (surround) sound It is a popular format that gained fast consumer acceptance and is suitable for a variety of digital videodisc (DVD), high definition television (HDTV), and other video applications In consumer products, MPEG-2 sound compression technologies are not always used for the audio portion of an MPEG-2 disc; sometimes Dolby Digital is substituted (or included with the others) MPEG-2 supports a variety of bit-rates and picture resolution levels
Multiple audio and video streams can be multiplexed together for recording or transmission over a network
Generic Coding of Moving Pictures and Associated Audio ISOIIEC 13818, presented
in draft form in 1993 ITU-T recommendation H.262
Similar in structure to MPEG-1, the documentation includes four parts in addition to the categories discussed in MPEG-1 MPEG-2 can address very low bit-rate applications with limited bandwidth needs, and support for surround sound multichannel applications Video resolution is typically implemented at 720 to
550 x 480, somewhat similar to computer monitors, and a frame may be either interlaced or progressive formats
MPEG':l+ MPEG-l presented at MPEG-2 resolution Frames are de-interlaced and compressed MPEG-3 Originally slated to support HDTV, but it was found that the MPEG-2 standards could
be devised to support both DVD and HDTV and MPEG-3 was never developed MP3
is sometimes mistaken for MPEG-3 but MP3 actually refers to either MPEG-l or MPEG-2 Layer 3 formats
Merged into MPEG-2 when it was decided that MPEG-2 syntax could be scaled to support HDTV applications Often confused with MPEG-I/2 Layer3 (MP3).
MPEG-4 Developed to support the world of data communications over networks which are
frequently shared or limited in their transmission rates Thus, it is optimized for the world of computer networks, uses different compression techniques than the other MPEG formats, and is more appropriate for applications such as videoconferencing, whiteboarding, and streaming video rather than for high-quality optical media-based consumer entertainment applications
Very Low Bitrate Audio-Visual Coding Launched in 1992 to develop new algorithms for providing support for a wider range of applications, and to improve efficiency New applications include low-bitrate speech coding and interactive mobile communications
Trang 10mission space by encoding only those portions ofthe
image that change from one frame or field to the next
As with many optimization schemes, differential
cod-ing comprises a tradeoff If a series of frames must
be reconstructed "on the fly," based upon a reference
frame, with only the differences encoded, you
can-not randomly jump to any frame in the sequence in
the playback process and see the full picture without
some fancy footwork and fast processing in the
back-ground The other disadvantage to differential
cod-ing is that the playback algorithm must handle the
reconstruction process and the error-checking
accu-rately, or errors in decoding the reference frame, from
which the others are derived, would be propagated
through any frames that subsequently depend upon it
To help mitigate propagation errors that could occur
from frame to frame in the playback of differentially
encoded MPEGs, a scheme to insert the occasional
full-frame picture has been developed An intra-coded
picture (I-picture) is a complete image that is inserted
every few frames to stop any reference image errors
from continuing for a large number of frames How
often these frames should be inserted is a matter of
balancing file size and potential error levels Since
differential encoding is intended to reduce file sizes,
inserting I-pictures too frequently would negate this
advantage
Sometimes images are constructed based upon the
previous frames, but image processing can work the
other way as well A prediction-error picture
(P-pic-ture) is an image constructed from information taken
from previous1-or P-pictures, while a
bidirection-ally encoded picture (B-picture) is one that uses later
images to construct a previous image Confused?
Think of it this way: imagine watching a video of a
car driving past a house Most of the image stays the
same from one frame to the next since the house isn't
moving (assume a stationary camera photographing
the scene) As the car moves past the house, however,
some of the image changes File space can be saved
by encoding only the portions that change and
con-structing the successive frames from the information
that is known rather than displaying every frame
Now here comes the tricky part Suppose this scene
opened with the car parked in front of the house
be-fore pulling out and driving by There's no way to
construct the portion ofthe house obscured by the car
from previous frames because the information isn't
there With bidirectional predicted/interpolated
en-coding, the processor can look forward, to the frames
ofthe house that show the portions that were obscured
before the car drove off-camera, and insert that
in-formation into previous frames in the encoding
pro-cess Thus, differential encoding may be used to
con-struct the scene based upon previous and later frames
Sound complicated? It can be, which is why MPEG
is an asymmetric technology Depending upon how
it's done, a significant amount of processing may be
required to encode a movie to fit onto a DVD, for
ex-ample, and the equipment to accomplish the task may
cost hundreds ofthousands ofdollars, compared to a
MPEG, MPEG decoder
MP lambda switching MPIS (note MPLS in all up-percase is used as an abbreviation for multiprotocol label switching) multiprotocollambda switching See lambda switching
MPLS See Multiprotocol Label Switching
MPOA MultiProtocol Over ATM A client/server protocol integration effort specified by a working group of the ATM Forum to provide direct connec-tivity across an ATM network between ATM hosts, legacy devices, and future network-layer protocols from different logical networks This will enable the production of lower-latency, scalable ATM intemet-works through a standardized virtual network with fewer router hops See Anchorage Accord, LANE, 1Pv4, Next Hop Resolution Protocol
MPOA ClientAnATM term A device which imple-ments the client side of one or more of the MPOA client/server protocols, (Le., a SCP clientpran RDP client) An MPOA Client is either an Edge Device Functional Group (EDFG) or a Host Behavior Func-tional Group (HBFG)
MPOA over ATM sub-working group Agroup that seeks to solve some ofthe implementation problems associated with asynchronous transfer mode (ATM)
Itis integrating LAN Emulation (LANE), Next Hop Resolution Protocol (NHRP), ClassicalIF, multipro-tocol encapsulation, and multicast address resolution
in order to provide end-to-end intemetworking ATM connectivity MPOA is a packet-oriented protocol similar to LANE The group provides courses, sup-port, research, documents, and systems testing ser-vices
MPOA Reference Model MultiProtocol Over ATM Reference Model A specification approved by the ATM Forum in June 1997 for routing/switching over ATM networks There are Internet MPOA resources (links, white papers, specifications, etc.) at the ATM Forum's site
http://www.atmfonnncorn/atmfomm/specsiapproved.html MPP See Multichannel Point-to-Point Protocol MRI See magnetic resonance imaging
MRU maximum receive unit
MS Mobile Station
MS-CDEX A set of Microsoft DOS extensions for CD-ROM which allow MS-DOS to recognize the presence of a CD-ROM drive and access it accord-ingly
MS-DOS Microsoft disk operating system MS-DOS originated from a commercial text-oriented operat-ing system developed from Tim Paterson's QDOS (which was based upon a CP/M manual according to Paterson), first released by Microsoft in 1981 to ac-company ffiM's Intel-based microcomputer system This was a somewhat different move for ffiM, as the company had often created its products in-house But IBM was under pressure to release a successful mi-crocomputer in order to avoid being locked out ofthe growing market; Radio Shack at one point had almost 80% market share with its TRS-80 line ffiM's move
to look outside its own research and development