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Glossary
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m. Standard abbreviation for megabyte; 1,024 kilobytes; or 1,084,576 bytes.
MAC. Media access control (MAC). This is a sublayer of networking protocols that allows the computers on a network to take turns sending data on the physical network medium. This layer is also responsible for ensuring that the data reaches the other computer without any errors
Mac OS. Mac OS is often referred to as Macintosh Operating System.
MacBinary II. Because of its forked file structure, transferring Mac OS files to non-Macintosh computers is problematic. MacBinary was developed as a means of preserving this structure without sacrificing portability. It combines the data and resource forks and Finder information of a file into a single document, which is then suitable for transport via FTP, the World Wide Web and electronic mail or for storage on computers that run different operating systems, such as Unix or Windows. It is similar to BinHex, but MacBinary produces binary files as opposed to ASCII text. Thus, MacBinary files take up less disk space than BinHex files, but older applications and servers are more likely to corrupt them.
machine language. A "low-level" computer language that communicates directly with the computer hardware. Programs are written in secret code (binary); each instruction corresponds to a single computer operation. Often, an assembly language is used to make the machine language codes more understandable by computer programmers.
Macintosh alias. An alias icon is a feature of the Mac OS introduced with version 7.0. An alias's name always appears in italics, and they are therefore easily spotted. Aliases act as pointer files -- double clicking an alias makes the operating system find the file the alias is pointing to, and then open it. This is a useful feature for making the files you use most often easier to find and open quickly. Once an alias is created, it will always open the original, even if the original has been moved or renamed. This link between an alias and an original holds true until the original is deleted (or minor hard disk errors cause it to forget where its original can be found). At this point, the alias is broken, and should be deleted (and then re-created, if desired).
Mac PPP. MacPPP was the first major freeware PPP client for Mac OS. The Merit Network, Inc. first released it for the University of Michigan in 1993. The university ceased development after version 2.0.1, but made the source code publicly available. Many organizations and individuals have modified it and released their own versions since. Apple Computer, for example, distributed several updates of its MacPPP variant with the Internet Connection Kit. FreePPP was also originally based on MacPPP.
macro. A "high-level" programming tool used to automate tasks or procedures within a program. Unlike standard programming languages, macro works only within Microsoft Excel to automate complex, repetitious tasks.
macro assembler. A program that lets you construct assembly language macros. An assembly language macro is an instruction that represents several other machine language instructions at once.
macro virus. A macro is a piece of code that can be embedded in a data file. Some word processors (e.g., Microsoft Word) and spreadsheet programs (e.g., Microsoft Excel) allow you to attach macros to the documents they create. In this way documents can control and customize the behavior of the programs that created them or even extend the capabilities of the program. For example, a macro attached to a Microsoft Word document might be executed every time the document is saved and cause the text of the document to be run through an external spell checking program. A macro virus is a virus that exists as a macro that is attached to a data file. In most respects macro viruses are like all other viruses. The main difference is that they are attached to data files rather than executable programs. By some estimates 75% of all computer viruses now in existence are macro viruses.
MacTCP. The MacTCP control panel is used, in older versions of Mac OS, to establish connections with TCP/IP networks. Along with a physical network connection (e.g., via PPP or Ethernet), MacTCP is required for distributed applications like BetterTelnet, Fetch, and Netscape Navigator. MacTCP is compatible with Mac OS 6 through 7.5.5, and with the Network control panel, forms Apple's Classic Networking. MacTCP is not compatible with Mac OS 7.6 or later, nor will it function on PCI-bus Mac OS computers (all shipping models and all but the oldest Power Macintoshes). For these newer technologies, Open Transport has replaced MacTCP.
mail merge. A mail merge is a method of taking data from a database and inserting it into a document such as a letter, mailing labels, and name tags. It usually requires two files. One stores the data to be used, while the other contains information on how to format the data.
mailbox. An e-mail account or "address" to which you can send message to people on networked or remote computers.
mainframe. A powerful computer to which "dumb" terminals are often connected. A mainframe is identified by its storage and computing capacity; its capacity to create multiple, virtual computer; and its variety of input/output options. A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy that starts with a simple microprocessor at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe. The distinction between small mainframes and minicomputers is vague, depending really on how the manufacturer wants to market its machines. Unisys and IBM are the largest manufacturers of mainframes.
map. The process of designating a disk drive letter to refer to a directory on a file server.
math coprocessor. A math coprocessor in the traditional sense is a chip or part of a chip that specializes in doing math, extending the capabilities of a CPU in a transparent manner. It is a piece of hardware that attaches to the motherboard or is part of the CPU.
MB. A megabyte is 1,048,576 (1,024 x 1,024) bytes, not one million bytes as might be expected. This odd number is due to computers using binary (base two) math, instead of a decimal (base ten) system. 1 byte is the space necessary to store one ASCII character, 8 bits. Computer storage and memory is typically measured in megabytes (MB). A medium sized novel contains about 1MB of information.
Melissa macro virus. Melissa is a Microsoft Word macro virus (or worm) that is transmitted via e-mail attachments. The subject line of the suspect message reads: Important Message From Username where Username is the name of the person whose computer is sending the messages.
memory. Commonly refers to the chips inside a computer in which information is stored. Two types of internal memory exist: read-only memory, (ROM) permanently holds information vital to the computer's operation, such as the BIOS. Random-access memory (RAM) holds information that you are currently using. Where as the information in ROM is permanent, the information in RAM goes away when you turn off the computer.
menu. A list of commands or options available within a program. When several options are available at a particular time, programs often present those options in menus. The menu shows each available option and, using the mouse or keyboard, you can choose a command from the menu.
menu bar. An area, usually located at the top of the screen, that contains several menus listed across in a single line. It's from the menu bar that you can choose commands.
menu item. An individual command or option that appears on a menu.
message box. A box or small window that appears on the screen and presents a message from the program you are using. Message boxes can appear as the result of your choosing a command or option. The often inform you of mistakes or provide warnings about your actions.
method. Similar to properties in an object-oriented world; however, instead of merely setting the characteristics of an object, methods invoke an action for that object. For instance, a Web browser object may have a method you invoke for connecting to and displaying a Web site.
microcomputer. Actually intended as a disparaging term for the new personal computers that started appearing in the mid-1970s. The term micro came from the micro-processor, the chip that provided the brains for these new computers. The term fell into disuse when PCs became popular in the mid-1980s.
microprocessor. The central processing chip in a microcomputer. Common microprocessors include the Motorola 68000, 68030, and 68040 used in Macintoshes, and the Intel 286, 386, 486 and Pentium chips used in DOS machines. The microprocessor controls most of the core functions of the computer but can be enhanced with coprocessor chips.
MIME (Multipurpose Internet Mail Extension). A set of schemes for transmitting various file formats (usually multimedia) across the Internet. In Internet standard that defines the method in which files are attached to SMTP messages.
MMDS. Multipoint Microwave Distribution System, also known as Multi-channel multi-point Distribution System and wireless cable, is another wireless broadband technology for Internet Access. MMDS channels come in 6 MHz chunks and runs on licensed and unlicensed channels. Each channel can reach transfer rates as high as 27 Mbps (over unlicensed channels: 99 MHz, 2.4 GHz, and 5.7 to 5.8 GHz) or 1 Gbps (over licensed channels). MMDS is a line-of-sight service (see Fresnel Zone definition), so it won't work well around mountains, but it will work in rural area, where copper lines are not available.
modem. A communications device that allows two computers to communicate over a telephone line by converting the digital signals from the computers into analog signals to travel over the phone line.
modulation. Modulation is the addition of information (or the signal) to an electronic or optical signal carrier. Modulation can be applied to direct current (mainly by turning it on and off), to alternating current, and to optical signals. One can think of blanket waving as a form of modulation used in smoke signal transmission (the carrier being a steady stream of smoke). Morse code, invented for telegraphy and still used in amateur radio, uses abinary (two-state) digital code similar to the code used by modern computers. For most of radio and telecommunication today, the carrier is alternating current (AC) in a given range of frequencies. Common modulation methods include:
These are sometimes known as continuous wave modulation methods
to distinguish them from pulse code modulation (PCM), which is used to
encode both digital and analog information in a binary way. Radio and
television broadcast stations typically use AM or FM. Most two-way radios
use FM, although some employ a mode known as single sideband (SSB).
More complex forms of modulation are Phase Shift Keying (PSK) and Quadrature
Amplitude Modulation (QAM). Optical signals are modulated by applying
an electromagnetic current to vary the intensity of a laserbeam.
morphing. A graphical trick where one image is smoothly blended into another. The word "morph" may also be used. It's from the Greek metamorphosis, which means "to transform."
motherboard. The main circuit board of a computer, to which most devices connect. The motherboard is the real estate upon which the computer's CPU, ROM chips, and often the RAM chips sit and work.
mount. A term used to describe that something, usually a disk drive, is being used. In a networking context, mounting a volume means to connect to a remote disk drive, making is accessible from your computer. This comes from the olden computer days when they physically had to mount a reel of computer tape on the machine before anyone could access it. Nowadays, the mounting takes place through software commands that make the connections over various wires and hoses.
mouse. A mouse is a small device that a computer user
pushes across a desk surface in order to point to a place on a display
screen and to select one or more actions to take from that position. The
mouse first became a widely-used computer tool when Apple Computer made
it a standard part of the Apple Macintosh. Today, the mouse is an integral
part of the graphical user interface (GUI) of any personal computer. The
mouse apparently got its name by being about the same size and color as
a toy mouse.
A mouse consists of a metal or plastic housing
or casing, a ball that sticks out of the bottom of the casing and is rolled
on a flat surface, one or more buttons on the top of the casing, and a
cable that connects the mouse to the computer. As the ball is moved over
the surface in any direction, a sensor sends impulses to the computer
that causes a mouse-responsive program to reposition a visible indicator
(called a cursor) on the display screen. The positioning is relative to
some variable starting place. Viewing the cursor's present position, the
user readjusts the position by moving the mouse.
The most conventional kind of mouse has two buttons
on top: the left one is used most frequently. In the Windows operating
systems, it lets the user click once to send a "Select" indication
that provides the user with feedback that a particular position has been
selected for further action. The next click on a selected position or
two quick clicks on it causes a particular action to take place on the
selected object. For example, in Windows operating systems, it causes
a program associated with that object to be started. The second button,
on the right, usually provides some less-frequently needed capability.
For example, when viewing a Web page, you can click on an image to get
a popup menu that, among other things, lets you save the image on your
hard disk. Some mouses have a third button for additional capabilities.
Some mouse manufacturers also provide a version for left-handed people.
Windows 95 and other operating systems let the
user adjust the sensitivity of the mouse, including how fast it moves
across the screen, and the amount of time that must elapse within a "double
click.". In some systems, the user can also choose among several
different cursor appearances. Some people use amousepad to improve traction
for the mouse ball.
Although the mouse has become a familiar part
of the personal computer, its design continues to evolve and there continue
to be other approaches to pointing or positioning on a display. Notebook
computers include built-in mouse devices that let you control the cursor
by rolling your finger over a built-in trackball. IBM's ScrollPoint mouse
adds a small "stick" between two mouse buttons that lets you
scroll a Web page or other content up or down and right or left. Users
of graphic design and CAD applications can use a stylus and a specially-sensitive
pad to draw as well as move the cursor. Other display screen-positioning
ideas include a video camera that tracks the user's eye movement and places
the cursor accordingly.
mouse, cordless. A cordless mouse frees you from cord problems. It connects to your computer with a radio (rather than an infrared) signal, powered by two AAA batteries. One manufacturer, Logitech, offers two versions of a three-button mouse; one includes a button positioned for the thumb (for right-handed users). The buttons can be assigned different uses during system setup.
mouse pad. A flat surface, usually padded, used to roll your mouse around. The ball on the mouse operates best on a clean, flat surface.
MS-DOS. An acronym for Microsoft Disk Operating System. The most widely used operating system for personal computers. Also simply called DOS. To organize disks and data, it uses a tree-like directory structure wherein files can be stored inside directories and subdirectories.
multimedia. Relating to video, audio, and graphics. Multimedia software combines two or more media for presentation or analysis purposes. Large multimedia applications are often stored on CD-ROM devices because of the incrediblesize and memory requirements.
multitasking. The capability for one machine to run two or more programs at the same time without knowing how to use any of them. Multitasking is commonly used for background operations, such as printing, fax and data communications, and complex calculations.
multiuser. Relating to multiple users. A program or operating system that supports more than one user at the same time. A multiuser database, for example, allows numerous computers to access the data at the same time. Multiuser software uses a network to connect users to the data.
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