Identifying information and the amount are recorded in magneti-
zable ink at the bottom of the check; a computer input device
called a magnetic ink character reader magnetizes the ink, recog-
nizes the numbers, and transmits the data to the memory of the
bank’s computer to permit the check to be processed.
Magnetic tape unit A computer file device that stores (writes)
data on magnetic tape and retrieves (reads) data from tape back
into memory; the usual device on which sequential access files
are stored. See alsoSequential access file.
Mainframe The type of computer system that is used as the main,
central computing system of most major corporations and govern-
ment agencies, ranging in cost from $500,000 to $20,000,000 or
more and in power from 2,500 to 1,000,000 MFLOPS; used for large
business general processing, as the server in client/server applica-
tions, as a large Web server, and for a wide range of other
applications.
Maintenance The process of making changes to a system after
it has been placed in operation, including changes required to
correct errors, to adapt the system to changes in the environment,
and to enhance the system’s functionality. Vendors of a purchased
system may be contracted to carry out maintenance as part of the
purchase contract.
Make-or-buy decision Within the context of systems develop-
ment, the choice between customized application development
and purchasing a software package.
Manufacturing Automation Protocol (MAP) A communica-
tions protocol (a set of rules) for communicating between auto-
mated equipment on a factory floor. MAP, which was pioneered
by General Motors and has now been accepted by most major
manufacturers and IT vendors, ensures an open manufacturing
system in which communication between equipment from
various vendors is possible.
Manufacturing resources planning (MRP II) A computer-
based manufacturing administration system that usually
incorporates three major components—the master production
schedule, which sets the overall production goals; material
requirements planning, which develops the detailed production
schedule; and shop floor control, which releases orders to the
shop floor based on the detailed schedule and actual production
to date.
MAP SeeManufacturing Automation Protocol.
Massively parallel processor (MPP) A parallel processor
computer with some large number of parallel CPUs; in general,
32 or more parallel CPUs is considered an MPP if the different
CPUs are capable of performing different instructions at the same
time, or 1,000 or more parallel CPUs is considered an MPP if the
different CPUs must all carry out the same instruction at the same
time.See alsoParallel processor.
Master data management The disciplines, technologies, and
methods to ensure the currency, meaning, and quality of
reference data within and across various subject areas.
Material requirements planning (MRP) A computer-based
system that accepts the master production schedule for a factory
as input and then develops a detailed production schedule, using
parts explosion, production capacity, inventory, and lead time
data; usually a component of a manufacturing resources planning
(MRP II) system.
MegaFLOPS (MFLOPS) Shorthand for millions of floating
point operations per second, a commonly used speed rating for
computers. MegaFLOPS ratings are derived by running a parti-
cular set of programs in a particular language on the machines
being investigated.
Memory The primary area for storage of data in a computer
system; also referred to as main memory or primary memory. In a
computer system all data flows to and from memory. Memory is
divided into cells, and a fixed amount of data can be stored in
each cell.
Mesh topology A network topology in which most devices are
connected to two, three, or more other devices in a seemingly
irregular pattern that resembles a woven net, or a mesh. Examples
of a mesh topology include the public telephone network and the
network of networks that makes up the Internet.
Metadata Data about data, or documentation about the busi-
ness and technical characteristics of data, such as the description
and maximum length of customer name.
Metadata repository SeeData dictionary/directory (DD/D).
Metcalfe’s Law A theory in which the value of a network
to each of its members is a nonlinear increasing function of
the number of users; more formally, the value is proportional to
(n^2 – n)/2, where “n” is the number of nodes on the network.
MFLOPS SeeMegaFLOPS.
MICR SeeMagnetic ink character recognition.
Microcomputer The category of computers with the least cost
($200 to $4,000) and the least power (500 to 5,000 MFLOPS), gen-
erally used for personal computing and small business processing
and as a Web client and a client in client/server applications; also
called micros or personal computers (PCs).
Microwave Considered as a transmission medium, although
strictly speaking it is line-of-sight broadcast technology in which
radio signals are sent out into the air. With transmission speeds of
256 thousand bits per second (bps) to 1 billion bps, microwave
transmission is widely used for long-distance telephone commu-
nication and for corporate voice and data networks.
Middleware A term that covers all of the software needed to
support interactions between clients and servers in client/server
systems. Middleware usually includes three categories of soft-
ware: server operating systems to create a “single-system image”
for all services on the network; transport software to allow
communications employing a standard protocol to be sent across
the network; and service-specific software to carry out specific
services such as electronic mail.
Midrange system This broadest category of computer
systems, which stretches all the way from microcomputers to the
much larger mainframes and supercomputers, has evolved from
two earlier categories of computers—workstations and mini-
computers. Prices vary from $4,000 to $1,000,000, with power
ranging from 2,500 to 250,000 MFLOPS; applications include680 Glossary