Computer and digital glossary: A to Z

A

Accelerated Graphics Port. See AGP.

Access. Ability to connect to the Internet. To store or retrieve data from a storage device such as a disk or a database. Sometimes access is restricted by an authentication scheme, such as a password.

Accessibility. The degree to which hardware or software is designed to allow disabled persons to use a computer. Windowed operating systems have many accessibility features, such as the ability to enlarge fonts, icons, and menus, and to use alternate Human Interface Devices (HIDs).

Acronym. A word formed from the initial letters of a phrase, used as an abbreviation. Examples are ASCII, BIOS and RAM.

Active matrix display. A high-quality, flat panel LCD display in which a separate transistor switch is used for each pixel, allowing viewing from wider angles. See also passive matrix display.

Adapter card. A peripheral, such as a modem, built on a printed circuit board that plugs into an empty expansion slot on the motherboard.

Add-on or add-in. A component that can be attached to a larger device by a simple process such as plugging it into a socket.

Administrator. System administrator, the person responsible for managing security, access authorization, and shared resources in a computer network.

Ad-ware. Software that displays advertising when it is being used. See also shovelware, spyware and trashware.

AGP. Accelerated Graphics Port, an Intel design that, when connected to a compatible graphics adapter, speeds high-resolution images such as those found in "3-D" games. AGP allows main RAM to augment video RAM.

All-in-one. A computer design with all required parts built-in-display, hard drive, optical drive and speakers built-in monitor. Apple's iMac is an example. See also modular laptop, slim-and-light laptop and tower case.

Alphanumeric, alphameric. Containing only the letters of the alphabet and the ten digits 0 to 9.

Alt key. Short for alternate key, a key found on IBM-compatible keyboards that alters the function of a key pressed simultaneously. See also control key, command key.

Analog. A representation of a continuous measurement of some function. A common example is the telephone, where sound is converted to a varying voltage that is transmitted via wires and converted from voltage to sound on the other end. See also digital.

ANSI (an-see). American National Standards Institute, an independent organization that researches and establishes standards in many areas, including computers.

Antivirus program. A program designed to detect, remove, and protect against computer viruses, worms and Trojan Horses. Antivirus programs must be updated regularly to maintain protection against new threats. See also Trojan Horse, virus, and worm.

Apple key. See command key.

Applet. A "miniature" application with a specific purpose, usually adjunct to a larger application or the operating system.

Applications, application software, "app". Programs with a particular function. Typical examples are word processors, spreadsheets, and games. See also OS and system software.

Application suite. A package of programs designed to work together in the operating system environment and share certain common features.

Architecture. Internal structure and design of a CPU or computer system.

Archival storage. Offline storage of information needed for future reference.

ASCII (ask-ee). American Standard Code for Information Interchange. This 7-bit code, originally developed by ANSI, is the standard for text in most computers. Standard ASCII text--a set of 128 common characters--can be used with any word processor. The Extended Set of ASCII--which requires an 8th bit--contains pseudo-graphical symbols for drawing lines and boxes, selected foreign alphabet characters, and a few mathematical symbols.

ASCII file. A file that contains only characters from the Standard ASCII character set. Such files have the advantage of being readable on any computer but contain no formatting or layout information.

Athlon. A family of microprocessors from AMD that competes directly with Intel's Pentium series, and has similar performance. The latest version, called Athlon XP, has clock speeds up to 2.2 GHz, which AMD says is as fast as the more-expensive 3.0 GHz Pentium 4. See also Celeron, Duron, 486, and Pentium.

A to D conversion. The conversion of data or signals from analog to digital format, needed to record, e.g., a wave sound file. See also modem.

Authentication. A method by which a system, such as a computer operating system or a network, prevents access or usage by unauthorized persons or other systems. Personal authentication may involve a user ID and password, or a more sophisticated method such as a "smart card", or biometrics. System authentication may use an encrypted software key, a digital certificate, or a list of globally-unique system identifiers. See also biometric, certificate, encryption, secure system, and smart card.

B    

Backdoor. A secret, or unintended, unsecured entry method into a secure system, such as a network, online service, or BBS. See also hacker.

Background process. A relatively low-priority process that is performed when the CPU is free from other processing duties. On a PC, this is most often printing or file transfers. See also foreground process.

Back up. To copy data or content onto a removable disk, a second hard drive, or other storage medium to prevent loss if the original is damaged.

Backup system. A procedure used to maintain a current copy or prevent the loss of data in case it is damaged or destroyed. See also archival storage.

Backward compatibility. The ability of a new product to properly work with other products that use older technology. See also upgrade path.

Bandwidth. The maximum speed of a data link in bits per second. Ethernet has a bandwidth of 10 to 1000 Mbps, typical consumer-grade DSL has a download bandwidth of 384 to 768 kbps, and a V.90 or V.92 modem connection has a bandwidth of 53.3 kbps or less.

Bar code. A numerical labeling and recognition method that uses a series of parallel bars of varying widths read by an optical scanner.

Basic. A simple, high-level programming language that is usually interpreted, rather than compiled, so Basic programs run slower than programs written in, say, C. Later versions of Basic, such as Visual Basic, can be compiled into efficient machine code.

Bay. A position in a computer case to mount a device, such as a drive.

Beta testing. The test phase of a new product that takes place under actual use conditions and is conducted by a group of representative users. Many bugs are found and removed in beta testing. (Alpha testing takes place under controlled conditions within the company.)

Bidirectional. Capable of transferring information in both directions.

Biometric. Relating to the measurement of one or more properties of the human body. Used for personal authentication in secure systems, a biometric reader may electronically scan the user's fingerprint or ocular iris pattern. It may also measure facial features or voice characteristics. See also authentication and secure system.

BIOS (bye-ose). Basic Input/Output System, the fundamental instructions by which a computer communicates with various peripheral devices. The BIOS usually resides in a firmware chip on the motherboard, allowing the computer to boot. A "flash" BIOS can be updated by overwriting its contents with new data from a file. See also firmware.

Bit. Short for binary digit, it's the smallest piece of data recognized by a computer. Abbreviated as b. See also byte, kilobit, kb, megabit, mb, etc.

Bitmap. A graphics image composed of dots or pixels in a rectangular matrix. A visual object represented in a bitmap cannot be manipulated as an object, only as a group of pixels.

Blue Screen of Death. See BSOD.

Bluetooth. A short-range (35 feet) wireless data protocol to link compatible devices in a secure connection, using the 2.5 GHz radio-frequency band, with transfer speeds of up to 720 kbps. Examples are computer-to-printer, PDA-to-computer, and headset-to-telephone. See also Wi-Fi.

Board. A thin, usually rectangular unit on which various electronic components are mounted. See also card, IC, and motherboard.

Bookmark. An easy way to access frequently visited Websites; the user saves Web-page URLs to a list (called either Bookmarks or Favorites) through a drop-down menu in the browser.

Boolean. Operations used to combine different sets of objects for retrieval in database searching. During a search, for example, the Boolean operator AND retrieves objects that have information in common between data sets, while OR retrieves objects that have the information in at least one of several sets.

Boot. To bring a system into operation. This normally includes loading part or all of the operating system into main memory from a storage device. See also cold boot and warm boot.

Bootable disk. A disk containing the loader program used to boot the system.

Boot device. The storage device (usually a disk) from which the operating system was loaded. See also system disk.

bps. Bits per second, a measure of data transfer rate. Rates are usually expressed with the prefixes k- for kilo-, M- for mega-, or G for giga-. See also bandwidth.

Broadband. As commonly used, a connection to the Internet that has a receiving bandwidth greater than that of dial-up modem or ISDN service, about 128 kbps. (The FCC says "256 kb/s in at least one direction".) Common broadband connections are cable modem, DSL, and satellite. Broadband makes streaming audio and video practical.

BSOD. "Blue Screen of Death", a euphemism for the blue-background explanatory text screen that the Windows OS displays when an unrecoverable system error occurs. Usually, the only remedy for a BSOD is a cold boot.

Buffer. A memory area used to hold data temporarily while it is being transferred from one location or device to another or waiting to be processed. Buffers are essential for the efficient operation of the CPU and are often used in graphics processors, CD-ROM drives, printer drivers, and other input/output devices to compensate for differences in processing speed. See also FIFO.

Bug. An error in a computer program that prevents proper operation. See also debug and beta testing.

Bundle. 1) The software that comes preloaded with many personal computers. This typically includes a word processor, financial program, encyclopedia, productivity suite, and assorted games. See also preloaded. 2) The combination of a PC and peripheral devices such as a monitor, printer, scanner, or accessories, usually as a sales incentive.

Burner. A disk drive that can save data or program content. See CD-writer.

Bus. A pathway that connects devices inside a computer, usually the CPU and memory, or a peripheral such as an adapter card. Common bus designs include PCI and CardBus. See also USB.

Bus speed. The bandwidth, in megahertz (MHz), of the main data pathway through which a microprocessor reads from main memory and communicates with the chipset on the motherboard. Currently, bus speeds up to 800 MHz (800 million 32-bit data words per second, or about 3.2 GB/s) can be achieved with very fast DDR RAM and the fastest Pentium 4 processors.

Byte. The basic storage unit needed to store a single character, nominally 8 bits. Abbreviated as B. See also bit, kilobyte, kB, megabyte, mB, etc.

C    

C. A family of high-level computer languages that compile to produce relatively efficient machine code. Newer versions include C++, Visual C, and C# (C-sharp). See also Java.

Cable modem. A means of providing high-speed Internet service through a TV cable. See also ADSL and ISDN.

Cache. Memory that is dedicated specifically to improve the performance of a computer. This is accomplished by either setting aside part of main memory using a driver or through special high-speed memory. See also disk cache and memory cache.

Card. An electronic circuit board that serves a particular function, such as memory or graphics; in a PC, cards are usually plugged into a bus connector on the motherboard. See also chip and PCMCIA card.

Carpal tunnel syndrome (CTS). A painful, potentially debilitating injury that can arise from very heavy keyboard use. Symptoms may include weakness, numbness, tingling, and burning in the hands and fingers. See also RSI.

Cathode ray tube. See CRT.

CD. Compact disc, a 5-inch, aluminum-coated polycarbonate plastic disc with embedded digital data, read by focusing a laser beam on the data tracks and sensing its reflection. CDs can carry about 650 megabytes (MB) of digital information, which can be entertainment like music and motion video or computer data of many sorts. See also CD-ROM and DVD-ROM.

CD-R. CD-Recordable, a disc that can be recorded, once only, in a CD-writer.

CD-ROM. Compact Disc-Read Only Memory, a 5-inch disc holding data or software; the drive that retrieves digital data from the disc.

CD-R/W. CD-Read/Write, a disk that can be recorded repeatedly, that can be used like a large, floppy disk in a CD-writer.

CD-writer. A drive that lets you create or copy CD-ROM disks. With the right software, you can also create or copy audio and video CDs. CD writers and blank media have dropped in price significantly over the past few years, and are now virtually standard in PCs.

Celeron. A processor series from Intel that is slower and less costly than its Pentium counterpart, used in lower-priced PCs. See also Athlon, Duron, 486, and Pentium.

Certificate (digital). Also called a "digital signature," a block of data appended to a file with an encrypted section uniquely identifying the sender of the document using technology that makes it virtually impossible to "forge." The encrypted section depends on the file content, so changing even one character in the file invalidates the certificate. A certificate assures the recipient that the file indeed comes from its stated sender, and indeed contains what the sender intended.

Character set. The letters and symbols supported by a particular system or software package. The set may consist of only the letters of the alphabet (upper- and lowercase), ten digits (0-9), and special symbols, such as punctuation marks (the Standard ASCII Character Set), or it may include graphics characters as well. Foreign-language character sets, supported in today's operating systems, have special characters for specific languages.

Chat. Internet term for any site or service that allows real-time communication between two or more users, using text, graphics, voice, video or a combination. Participants often refer to the interface as a "chat room." See also instant messaging and IRC.

Check box. A box, next to a selection in a dialog window, that is checked to indicate if that particular selection is activated. See also dialog box and radio buttons.

Chip. An integrated circuit such as those commonly used for a PC's microprocessor and memory systems. Composed of a small, rectangular "chip" of semiconductor material encased in a larger rectangular carrier with electrical connections.

Chipset. The support chips that manage data flow into and between the microprocessor and other parts of a computer.

Client. A single-user terminal or personal computer (workstation) used in a networked environment. See also server.

Client/server. A network architecture in which the client (your computer) issues data processing requests to the server (another designated computer), which returns the information.

Clip art. Prepared graphics images that can be incorporated into a document using a program such as a word processor or desktop publisher.

Clipboard. A reserved block of memory to temporarily hold data (either text or graphics) that has been taken from one application to be placed in another, printed, or saved to a file.

Clock. A circuit in the PC that regulates all processes by synchronizing them to a defined frequency. See also clock speed and bus speed.

Clock/calendar. Part of a computer system that automatically keeps track of the current date and time for reference by application programs.

Clock speed. The rate at which the CPU clock operates, measured in megahertz (MHz) or gigahertz (GHz). In theory, the faster the clock speed, the faster the CPU will perform its operations. Most new PCs now work at clock speeds ranging from 900 MHz to over 3.0 GHz.

CMOS RAM. A small memory chip with battery backup that holds the hardware configuration settings for a personal computer, read by the BIOS at boot time.

Coaxial cable. A type of telecommunications link that carries more data than conventional phone lines. Also used for cable TV. See also optical cable.

Code. A set of instructions, written by a programmer, that tells the computer what to do; to write a program; one or more characters that perform a specific function such as a control code.

Cold boot. To start or restart a computer from the power-off condition, or via a reset button.

COMDEX. Computer Dealers Exposition, refers to an annual trade show in Las Vegas displaying new personal and business computers, components, and software.

Command. An instruction, usually entered directly from the keyboard or pointing device, designed to cause an action to occur.

Command key. A key on many Apple computer keyboards, designated by the symbol of an apple, that functions like a control key.

Compact disk. See CD.

Compiler. A program that interprets high-level (human-readable) source code written by a programmer and converts it into lower-level (machine-readable) instructions that can be directly executed by a microprocessor. See also interpreter.

Compressed file or format. A method of data processing that eliminates all unnecessary and redundant bits, and often encodes the remaining bits to further conserve space, for storage or transmission efficiency. Compression that allows perfect recovery of original data (such as the "zip" format) is called "lossless"; if something, such as the sharpness of a graphic image, is degraded, the compression is "lossy" (such as in the "jpeg" image format).

Computer. A programmable electronic device that can store, retrieve, and process information. All computers consist of the same basic components: the CPU, memory, storage, and input/output devices. See also personal computer.

Configuration. The way various components of a system (such as a computer) are linked. This normally refers not only to the way the hardware is physically connected but also to how the software is set up to govern the system and its parts; the setup and operating parameters of a software program. See also platform.

Context-sensitive. Responsive to a specific item or situation. For example, many software programs and operating systems have context-sensitive help windows, which automatically give the correct help for the process or feature you are using.

Control key. A key found on IBM-compatible and other computer keyboards, usually designated by Ctl or Ctrl, used to enter codes or issue commands.

Controller. A chip or board that governs the transmission of data between a peripheral device, such as a disk drive or graphics display, and the CPU and main memory.

Cpi. Characters per inch, a measure of print pitch.

CPU. Central Processing Unit, the part of the computer that controls and performs all processing activities. It consists of the ALU (arithmetic logic unit), control unit, and main memory. See also microprocessor.

Crash. An uncontrolled shutdown of one task or the entire computer. See also BSOD.

CRT. Cathode Ray Tube, the traditional type of display screen in a computer monitor or TV. See also LCD.

Ctl key or Ctrl key. See control key.

Cursor. A symbol that marks the current position on the screen and moves as the position changes. It is most often a single underline, a vertical line, or a block the size of one character. It may be either steady or blinking. See also mouse pointer.

Cursor control keys. A special group of keys on a keyboard or keypad (designated by arrows pointing up, down, left, and right) that perform cursor movement functions. See also numeric keypad.

Cyber-. Relating to the rapidly growing interactive world between humans and computers.

Cyberspace. First used by William Gibson in the novel Neuromancer to refer to a futuristic computer network into which people plugged their brains and interacted with it. It has come to refer to the interconnection of computers known as the Internet. See also Internet and virtual reality.

Cylinder. On a hard disk, the collection of all the tracks that are in the same location on each disk surface.

D    

Daisy chain. A group of computers or other devices connected by a bus in a string, one to the next.

Data. An item or collection of items of information to be processed, displayed, or stored. Data can be text, numbers, binary code, images, sounds, or any combination.

Database. A collection of data, organized for retrieval, on a specific topic or for a designated purpose.

Data file. A collection of information to be used as input to a program for processing, display, or any other useful purpose. See also program file.

DDR. Double Data Rate, memory that delivers twice as much data on each memory clock cycle as single data rate memory. Rapidly becoming standard.

Debug. To locate and remove the errors (bugs) from a computer program. See also beta testing.

Dedicated line. Telephone line used solely for data or fax services. See also DSL.

Default. A value that is automatically assigned to a setting when no other value is entered. A default password, such as "secret," should be changed to ensure security.

Degradation. Slowing down of a system under the load of processing. This is usually noticeable only on multi-user systems or PCs running multiple tasks. Other qualities of a system that can suffer degradation are stability and security.

Desktop. In a window-based user interface, the bottom-level window you see when no program window is open. The desktop can be set up as a user prefers, with icons allowing easy launching of often-used programs and documents.

Desktop computer. A PC featuring the traditional full-size case, monitor, and keyboard designed to be used in a stationary, "desk-centered" environment. See also laptop computer and portable computer.

Desktop publishing. Using software designed to create and publish professional-looking newsletters, flyers, or books.

Device bay. A plug-and-play standard for easily installing new disk drives or other devices into a PC.

DHCP. Dynamic Host Control Protocol, a network protocol in which one computer assigns internal IP addresses to all the other computers as they request them.

Dialog box. A window that appears onscreen to convey a message (such as a warning or error) or to request input (such as a choice of alternatives or a confirmation of some action). See also check box and radio buttons.

Dial-up line. A communications line that connects through the telephone system, usually by dialing touch-tones. See also DSL, ISDN, and POTS.

Digital. Characterized by the representation of data as numbers. Computers are digital. See also analog.

Digital camera or digicam. A photographic still-image recording device that uses an electronic sensor and memory system instead of film to record and store images as data files. The images can be subsequently transferred to a computer for long-term storage, editing, inclusion in documents, and transfer to others over the Internet. Some digicams can take short, low-resolution motion-video clips as well.

Digital computer. An electronic device designed to process data in digital format. Personal computers (PCs) are general-purpose digital computers, suitable for most applications. See also computer.

Digital rights management. See DRM.

Digital signature. See certificate.

Digitize. To convert an analog signal to digital format.

Digitizer. A device that converts an analog signal (such as video or sound) into a series of digital values.

DIMM. Dual Inline Memory Module, a circuit board that can hold up to 256 MB of RAM and plugs into a DIMM socket on the motherboard.

DirectCD. A method of saving data to a CD-R or CD-RW immediately through drag-and-drop file operations. DirectCD writes data in the "Universal Disk Format" (UDF).

Directory. A listing of the files available on a disk or part of a disk. Typically, files that pertain to a specific application (such as word processing, home finance, database, and games) are grouped together in their own directory, such as C:\Quicken. Windows and Mac OS use the term "folder" to refer to a disk directory. See also pathname and subdirectory.

Disk cache. A portion of memory set aside to keep recently accessed hard drive data for a period of time, shortening access time if the data is needed again. See also memory cache.

Disk cartridge. A removable storage unit of 100 MB or more that offers the capacity of a hard disk and the portability of a diskette. See also Zip drive and Jaz drive.

Diskette. A small, portable, plastic-encased flexible ("floppy") disk used as a magnetic data storage medium. Data is recorded as magnetic signals that are arranged in a series of circular tracks. Most diskettes hold 1.44 megabytes of data, a small capacity by today's standards. See also hard disk and CD-ROM.

Display. Any electronic device that visually conveys information or images, usually graphically. See also CRT and LCD.

Display adapter. See graphics adapter.

DLL. Dynamic Link Library, a Windows file associated with one or more applications containing reusable subroutines that are read into memory as needed by the application.

DMA. Direct Memory Access, refers to the direct transfer of data between a peripheral or other device and main memory without going through the microprocessor.

DNS. Domain-Name Service, the translation of domain names into IP addresses performed by a designated computer on the network or the Internet.

Dock. On Apple's Mac OS X desktop, an icon-filled bar for launching and switching between applications. See also taskbar.

Docking station. A rectangular platform with a connector and a power supply for a laptop or handheld computer to connect it with a CRT monitor, printer, and other peripherals. Essentially, it turns a laptop computer into a desktop computer. See also port expander and dongle.

Document. Any human-readable file containing information entered by the user. Examples are word-processing, spreadsheets, and databases.

Documentation. Material that comes with a software package or a computer system and offers directions for setup and operation, features, capabilities, and troubleshooting advice. More and more, paper documentation is being replaced by "online" help, files installed on the PC's hard disk, a CD-ROM, or the Internet.

Domain. A network or part of a larger network that is managed by a computer called a domain controller, which handles user logins, security, and shared resources.

Domain name. A structured, alphabetic name, such as consumerreports.org, for a location on the Internet. These names are aliases for numeric IP addresses, and are leased from an Internet naming authority by the domain-name owner.

Dongle. Any small peripheral device connected to a computer by a short cord and plug. See also port expander.

DOS. Disk Operating System, a set of programs that activates the computer and allows the user or other programs to perform simple functions; used synonymously with MS- or PC-DOS, early operating systems used in personal computers in the 1970s and 1980s. A simple command-line DOS was built into Windows 95 and 98, and can be invoked in later versions of Windows if needed.

Dot-matrix. An outdated impact printer in which characters are formed by a series of dots. See also impact printer.

Dot pitch. Indicates the spacing of color phosphor-dot triads on a CRT monitor screen; it should be 0.28 mm or less to avoid eyestrain with text. See also triad and pixel.

Double-click. A quick double-press of the left button on a mouse to activate a file or icon.

Download. To transfer a copy of a file from a host (server) computer to a client computer. Term frequently used to describe process of transferring a file or data from the Internet to a computer's hard drive. See also upload.

dpi. Dots per inch, a common measure of the resolution of a printer, scanner, or display. In theory, the higher the dpi, the better the image quality. But the unaided human eye cannot distinguish differences beyond about 200 dpi.

Draft mode. A faster, ink-saving printing mode for ink-jet printers, and a toner-saving mode for laser printers.

Drag and drop. Using a mouse, the way to move objects onscreen, and by reference, among the storage devices, in a GUI-based operating system. Click on an item, representing a folder or file, and drag it while holding the mouse button, then release it wherever you want to place it.

DRAM (dee-ram). Dynamic Random Access Memory, chips designed as a matrix of "memory cells" in rows and columns. Each memory cell is used to store bits of data that can be retrieved by indicating the row and column location (or address) of the data. The data in each cell must be electronically "refreshed" several times a second, hence the term dynamic. See also DDR, RDRAM, SDRAM, and SRAM.

Drive. A unit that writes data to or reads it from a storage medium such as a tape or disk.

Driver. A program that controls some component of the system such as a monitor, disk drive, or printer.

DRM. Digital rights management, any scheme used to prevent the unauthorized use or dissemination of copyrighted, file-based content, such as music, video or software. DRM often makes use of data encryption in combination with a software or hardware decoder that performs user authentication at the point of content use. Hackers are often able to "crack" DRM schemes and provide programs over the Internet to allow other users to circumvent DRM.

DSL. Digital Subscriber Line, provides high-speed Internet access through existing phone lines without affecting normal phone operation. See also cable modem, dial-up line and ISDN.

D to A conversion. The change of data or signals from digital to analog format. See also A to D conversion and modem.

Duplex. The ability to transfer data in two directions. If the signals can go both ways at the same time, it is called full duplex; if simultaneous transmission is not permitted, it is known as half-duplex. See also simplex.

Duron. A processor family from AMD that is generally slower and less-costly than its Athlon counterpart and used in lower-priced PCs. See also Athlon, Celeron, and Pentium.

DVD. Digital Versatile Disk or Digital Video Disk an optical digital storage medium the same size as a CD, but with at least 4 times the capacity. DVDs were originally used for consumer distribution of movies, and were adopted for computer use. There are now drives with write-once (DVD-R) and re-write (DVD-RW, DVD+RW and DVD-RAM) capabilities.

DVI. Digital Visual Interface, a display-device connection standard for digital displays. A DVI-D port is for digital monitors only, while a DVI-I port can also connect to analog monitors.

E

e-anything. Refers to an electronic or online version of anything traditionally done non-electronically, such as e-mail or e-commerce. See also i-anything.

Easter egg. An undocumented animation, usually featuring the programmers' names, hidden in a program and activated by a "secret" sequence of actions.

ECP. Enhanced Capabilities Port, a type of parallel port on a computer, providing higher speed and bidirectional communication with multiple devices. The parallel port is being supplanted by the USB port on personal computers.

Edit. To make changes in a document, data, or other file.

Editor. A program that permits you to create or make changes in a document. A word processor is an advanced type of editor, with special features such as word wrap, headers and footers, and print attributes (boldface, underline, italics).

EFT. Electronic funds transfer, a system commonly used by banks and other money handlers that involves secure, computer-controlled money transfers between accounts.

EIDE. Enhanced IDE, an advanced version of the IDE disk drive interface standard that runs faster and supports larger drives. See also Ultra DMA.

Electronic commerce.Shopping through electronic catalogs and making purchases using the Internet.

e-mail or email. Electronic mail lets you send and receive personal messages, including those with attached files such as text or graphics, through the Internet, an online service, a BBS, a network, or other system.

Emoticons. Short for "emotional icons," the use of strings of ASCII characters to represent the user's emotions. Examples are :-) for "that's funny", ;-) for "just kidding", and :-( for "I'm unhappy". Some users call these "smilies" or "smileys".

Encryption. A process applied to a data file to render its contents unreadable to a non-authorized user or computer system. Reading an encrypted file requires a software "key" that is available only to an authenticated user. Encryption is a mathematical science whose goal is to create algorithms whose resulting encryption is impossible to "crack" with currently-available computing power and hacker tools. See also authentication, certificate, and secure system.

End user. The final person or business to make use of a product or service. This is generally you, the consumer. See also EULA.

Energy Star. A label that designates compliance with energy efficiency goals developed by the United States Environmental Protection Agency. In order to qualify for the Energy Star standard, a typical computer or monitor must power down to no more than about 10% of normal power consumption after a period of inactivity.

Ergonomic. Designed with the needs and comfort of the human user in mind.

ESD. Electrostatic discharge, the great destroyer of digital electronics. Static build-up on your body in the winter can produce enough ESD to damage a keyboard, mouse, or laptop PC. ESD can be reduced by humidifying the air.

Ethernet The most common type of local area network (see LAN) used to connect personal computers to each other, or to a router or other devices on a network.

EULA. End-User License Agreement. A legal instrument accompanying most software that states the terms under which the company is allowing its use by the consumer. An EULA is typically written in virtually-incomprehensible legal jargon, but must often be agreed with by clicking an on-screen "I Agree" button before one can use the software.

Expansion board or card. A unit with electronic components, plugged into a computer's expansion slot. This may be a new feature such as a TV tuner or an interface to an external device. See also PC-card.

Expansion slot. A position in a computer for adding an expansion board or card. Desktop PCs usually have at least two free PCI expansion slots. Laptops use PC-cards for expansion.

Expert system. An AI (Artificial Intelligence) system that employs a database and set of rules for solving some specific problem. Expert systems are commonly used in applications such as medical diagnostics, trip routing, financial forecasting, and behavioral analysis.

Export. To transfer from the file format currently in use to another one. See also import.

External bay. A front-mounted drive bay in a desktop computer that allows physical access. Floppy disks, tapes, and CD-ROMs are normally housed in external bays. See also internal bay, modular bay and device bay.

External drive. A storage device that is physically separate from the computer. Such drives often have their own power supply and attach to the computer through a FireWire port, SCSI port, or a PC-card on a laptop. See also internal drive.

F    

FAQ. A list of Frequently Asked Questions and answers, meant to help users of a product or service understand its features and operation, and perform simple troubleshooting.

Fatal error. The cause of premature termination of processing, often as a crash. Fatal errors can occur as a result of read/write errors, program bugs, system conflicts, and hardware defects. Some errors crash only one application, others require the PC to be restarted.

F connector. A type of coaxial connector, most frequently used to connect cable or satellite television signals to components such as TVs, VCRs, and PC tuner cards.

Fiber optics. See optical cable.

FIFO. First-in, first-out. Describes the most common type of data buffer, in which the first data to come in is the first to go out. See also buffer.

Field. An individual item in a database record. See also record.

File. A collection of related records. Computer data and documents are normally stored as files. See also data file and program file.

File extension.An identifier of the type or purpose of a file, usually written as one to three letters following the filename and separated from it by a period. For example, the file My Letter.doc might be a text document while Numbers.dat could be a data file. File extensions are used by Windows to determine what program to use to open a file, and are hidden by default if Windows has registered a program for the extension.

Filename. The unique identification given to a program or data file for storage. Filenames were once limited to eight characters (plus a three-character extension) in older operating systems like DOS. Newer operating systems such as Windows and Mac OS allow much longer filenames. See also filespec and pathname.

File server. A high-speed computer in a network that provides common storage and retrieval of program and data files shared by the users. See also server.

File-sharing. One of the common uses for a network. Files can be designated as shared by their owners on one PC, and accessed by other authorized users in the same network workgroup, or over the Internet through peer-to-peer protocols. See also file-swapping.

File specification or filespec. The complete description of a file, giving the path, filename, extension, and drive indicator, if needed. For example, the file d:\games\bigdice.exe might be an executable program file named Bigdice located in a folder called Games on drive D.

File-swapping. An Internet activity popularized by free, peer-to-peer services such as Kazaa and Gnutella, with which users can search for files they are interested in and download them from designated shared folders on a network of thousands of other users' PCs. File-swapping has been criticized because users often trade files containing copyrighted material. See also DRM.

Firewall. A network gateway (software or hardware) that "filters" data requests, rejecting those that lack the necessary security clearance; originally used to protect corporate, government, or institutional networks from unauthorized access, but now in use by individuals to keep their computers safe from intruders on the Internet. See also Intranet and proxy server.

FireWire. A common name for the high-speed wired interface standardized by IEEE-1394, which provides synchronous multimedia data exchange between devices such as a digital camcorder and a PC. Also called iLink.

Firmware. Programs permanently stored on a ROM chip, or on an EPROM chip, to allow for occasional updates. Firmware programs usually control the basic processes within a hardware device, such as a modem. See also BIOS and flash memory.

Fixed disk. An IBM term for hard disk.

Flash animation. A programming platform commonly used for embedding animation in Web pages. Flash "movies" are relatively small, allowing them to download quickly on slow dialup connections. Playing a Flash movie requires a plug-in for the browser.

Flash memory. A low-cost, high-density, erasable RAM memory chip that holds its data without power. Used in computers and peripheral devices to hold settings and allow easy BIOS updating, and packaged in plug-in cards to act as data storage in small portable devices like digital cameras.

Flat-panel display. A thin display screen employing one of several technologies, usually LCD or plasma. Flat panel displays are commonly used on portable devices to reduce size and weight, and are increasing in popularity as desktop monitor replacements. Also used in costly, but lightweight televisions. See active matrix display, dual-scan LCD, and LCD.

Flat-screen. Refers to a monitor or a TV with a screen nearly or completely free of curvature. Flat screens allow square corners and reduce glare and image distortion.

Floppy disk. See diskette.

FLOPS. Floating-point instructions per second, a measure of computer processor performance doing math instructions. See also MIPS.

Folder. The Windows 95/98 and Mac OS name for a disk directory.

Font. A typeface enhancement such as bold or script. Although it is not precisely correct, the term is often used to refer to a typeface style such as Arial, Times Roman, or Courier.

Footer. A special message or identification placed at the bottom of a document page. See also header and tagline.

Footprint. The space on a floor or table occupied by a piece of hardware.

Foreground process. A high-priority process that is performed while any others that are running are assigned to wait until CPU resources are available. See also background process.

Format. To initialize a data-storage medium; to lay out in a specific pattern, such as a screen or report format; the layout or pattern itself.

Forum. An information exchange, usually found on the internet confined to a single topic or area of interest.

486. Also known as the 80486 or i486, an older Intel's micro-processor. Some consumers may still own computers with 486 processors, but new Windows-based PCs usually use Intel's Pentium or AMD's Athlon. See also Athlon, Celeron, Duron, Pentium, and PowerPC.

Frame rate. Expressed in FPS (frames-per-second), the rate at which a display of moving graphical images is updated. Motion picture film runs at 24 FPS, the minimum considered to be essentially jitter-free. Computer-generated graphics, such as from games, can run at much higher rates, limited by the graphics processor. Avid gamers look for rates of 50 FPS or higher, producing more-realistic motion. See also refresh rate.

Freeware. Software that is distributed, mostly via the Internet, essentially without charge to all interested users. See also public domain software and shareware.

FPS. See frame rate.

FTP. File Transfer Protocol, an Internet protocol that allows you to transfer files between your computer and an FTP site. "Anonymous" FTP allows a user to retrieve files without having to establish a user ID and password.

Full-stroke key. The type found on most keyboards, characterized by a marked give or depression when pressed, often with an associated key click. See also limited-stroke key.

Function key. A key that can be programmed to perform a specific operation. This may be a permanent programming by the operating system, or temporary programming by the user or the application software in use.

G    

G4. The newest family of PowerPC microprocessors from Motorola, available in Apple Macintosh computers ranging in speed from 800 MHz to 1420 MHz.

Game controller. Originally limited to knobs and joysticks, now includes driving simulators, cockpit simulators, movement sensors, and the entire class of human interface devices (HIDs).

Game port. A 15-pin serial port used for attaching joysticks or other game controllers as well as MIDI music devices. Game ports can handle a pair of controllers and may come as part of the original system or be supplied on sound boards. They are becoming less common on new PCs, supplanted by newer interfaces like USB.

GB. See Gigabyte.

GIF (jiff). Graphics Interchange Format, a lossless, compressed file format for image bitmaps invented by the CompuServe online service to reduce download time.

Gigabyte. 1,024 megabytes, which is 1,073,741,824 bytes. Sometimes manufacturers will "inflate" hard drive sizes by defining a GB as a "billion bytes," but that is not strictly accurate.

GIGO (gig-go). Garbage-In, Garbage-Out, a colorful way of saying that the output cannot be reliable if the input is not.

Glitch. A nonreproducible problem in a system. Glitches often result from voltage fluctuations, static discharges, and data transmission errors. See also soft error.

Graphical user interface. See GUI.

Graphics. Special characters or drawings such as graphs, charts, and picture-like rendering of various objects or entire scenes. See also bitmap.

Graphics processor or GPU. A set of chips on a graphics adapter that has built-in firmware, processing capabilities, and adequate memory (usually 32 to 128 MB) to relieve the CPU of much of the burden of processing graphics.

Graphics board or adapter. An expansion card in a computer (or circuitry built into the motherboard) that provides the memory and graphics coprocessor necessary to produce text and graphics displays; along with the monitor, determines the resolution and colors that can be displayed.

GUI (gooey). Graphical User Interface, a graphics-based user interface that allows you to operate by pointing and clicking with a mouse rather than entering typed text commands. The two main GUIs are Windows and the Macintosh OS.

H    

H. At the end of a number (such as 384H), it indicates the hexadecimal format has been used in expressing that number. See also hexadecimal number system.

Hacker. A nonprofessional computer whiz; usually, one who tries to gain unlawful access to a computer system, or alters programs to allow unlicensed usage.

Handheld. Short for any device that is operated while held in the hand. See also PDA.

Handshake. Control signals exchanged between computers or between a computer and its peripherals to govern the transfer of data. See also protocol.

Hard copy. Printed text.

Hard disk or hard drive. A magnetic data storage system using one or more rigid platters sealed in a dustproof housing, and spun at several thousand RPM. Data is recorded as magnetic signals arranged in a pattern of concentric circles on the surfaces. Typical storage capacities range from about 20 to 200 gigabytes. See also diskette.

Hard error. A permanent problem that is not removed by rereading the data or any other action. This usually means that there is a flaw, such as a bad memory chip or spot on a disk, that must be avoided in the future. See also glitch and soft error.

Hardware. The electronic equipment that makes up a system. In a computer system, hardware includes the CPU, monitor, printer, circuit boards, drives, cables, etc. It does not include data or computer programs, which are software.

Hardware interface. A direct connection between two hardware components, such as a computer processor and graphics adapter or modem, usually established by means of a data bus or a cable. See also interface and user interface.

Hard-wired. Connected to the PC with a cable; permanently wired.

Head. The part of a disk or tape drive that writes data to the storage medium (disk or tape) or reads data from it.

Header. A special message or identification that is placed at the top of a document page; the information, sometimes hidden, at the top of an email message listing each computer the message passed through from sender to recipient, along with the date and time. See also footer.

Hertz or Hz. A measure of frequency being the number of cycles per second.

Hexadecimal number system. A number system that is based on the number 16 and uses the sixteen characters 0-9 and A-F. Since a group of four binary digits can be expressed as one hexadecimal digit, this system is often used to express binary values in a more compact format.

Hibernation. A shutdown mode in many PCs and most laptops that saves the current state of the machine and all its running processes on the hard drive for quick restoration on demand. Also called suspend-to-disk. See also standby.

High-level language. A programming language such as BASIC or C that is structured primarily from the logic of the problem rather than the machine design. A high-level program must be compiled or interpreted into machine code to run on a computer.

High-resolution. Showing great detail; the higher the resolution of a television, computer monitor or printer, the greater the detail of a drawing or image it is able to reproduce.

Home page. The page in a Web site usually visited first, that contains links to other pages in the site or other sites. The home page is automatically selected when you type a Web address ending in ".com," ".org," or another common domain suffix.

Host computer. A computer that serves as a source for data and information retrieval for client computers, usually networked PCs. See also network.

Hotkey. A key or combination of keys that when pressed take priority in causing some action to take place. Typical uses for hotkeys include initiating menu options or interrupting an ongoing process.

HTML. HyperText Markup Language, the standard language for creating pages on the World Wide Web. Even if you do not understand HTML, you can create it with Web-page authoring programs, popular word-processors, or basic step-by-step instructions at certain Web sites to build pages. See also hypertext and XML.

HTTP. HyperText Transfer Protocol, a protocol developed for exchange of hypertext documents across the Internet. All Web addresses begin with http://, which a browser will automatically insert for you. See also hypertext.

Hub. A multi-port device that connects several computers together into a wired network, without performing any data management functions. A "switched" hub adds the ability to prevent data "collisions," increasing overall speed. See also router.

Human Interface Device (HID). Refers to any type of hardware device that accepts input from a user to control a computer program. Includes keyboards, mice, trackballs, biometric sensors, joysticks, and various game controllers.

Hyperlink. A clickable object within a hypertext document that retrieves another location within the document or anywhere else on the Web. These can be either graphics or text; text links are usually blue and underlined.

Hypertext. A method of linking information within and between text or other files. The linked data may be almost anything from text to graphics to programs. The Internet's World-Wide Web is an ad-hoc collection of linked hypertext documents.
I

i-anything. Refers to anything done using the Internet that was or is also done in non-Internet ways. See also e-anything.

IBM-compatible. Generally, hardware or software that is designed for PCs based on the Intel x86 microprocessor architecture, first popularized by IBM. Most IBM-compatible PCs now run Microsoft Windows.

IC. Integrated Circuit, an assembly of electrical components etched from and interconnected on an encapsulated silicon wafer.

Icon. A small graphical image that appears on a graphical user interface (GUI) such as a computer's desktop in a Windows or Mac system. These normally represent a specific file or program or cause a desired action to occur when clicked with a mouse.

IDE. Integrated Drive Electronics, a hard disk interface technology. See also EIDE, SCSI and Ultra DMA.

IEEE. A standards organization that publishes computer-industry-defined standards for hardware, software, and data communications. IEEE 1394 is the standard for the FireWire interface, and IEEE 802.11b is the standard for Wi-Fi wireless networking.

iMac. A value-line Macintosh computer from Apple, a compact, Internet-ready desktop series with an all-in-one case.

Import. To transfer data from another file into the one currently in use. See also export.

Incompatible. Unable to work with, usually referring to a program that can't be run under a different operating system than it was created for, or a device not supported by a computer's hardware or BIOS. See also standard.

Initialize. To set up, prepare, or start from the beginning. Initializing a disk deletes any data on it and makes it ready for use by a system. See also boot and format.

Ink-jet printer. A printer that uses tiny jets or droplets of charged ink particles, projected from a set of nozzles, to create images, usually of high quality. Ink-jet printers are currently the most popular printers for home use and are the most economical means of producing high-quality, full-color printouts.

Instant messaging. An online system, usually proprietary, that lets you hold a private, real-time, text-based conversation between two users. Messaging among more than two users is usually referred to as chat, though it may use the same system. See also chat and IRC.

Instruction. In the computer world, a command to the CPU to carry out an operation.

Integrated circuit. See IC.

Integrated software. A software package that offers two or more types of applications, such as a word processor, spreadsheet, and database manager. See also application suite.

Intelligent system. An automated system designed to process information and make decisions using written rules that mimic the way a human would work. Intelligent systems can be used to monitor physical processes in real time and make critical decisions in the absence of human interaction. They are also used to help humans decide on a course of action based on a number of existing conditions, such as in medical diagnoses. Some systems are programmed to learn from errors.

Interactive. Able to respond to a user's wishes. Interactive software usually refers to a multimedia presentation that the user controls, moving at a speed and in a direction the user wishes.

Interface. The connection between two components such as the PC and a printer; to connect two components together. See also hardware interface and user interface.

Interlaced. Video display in which odd and even scan lines are displayed on alternate cycles. Interlaced signals require less processing and tend to be faster but can produce flicker. Standard-definition televisions use an interlaced display. See also noninterlaced.

Internal bay. A drive bay inside a computer that can hold a hard drive, not requiring physical access to the outside. See also external bay.

Internal drive. A drive housed within the computer's case. Such drives normally derive power from the computer's power supply. See also external drive.

Internet. A "super" network consisting of a collection of many commercial, academic, and governmental networks throughout the world. Public access to the Internet, now used by millions of people, is obtained through a contract with an Internet Service Provider (ISP). See also FTP and World Wide Web.

Internet gateway. A device or computer that provides the connection and protocols to link a single computer or a network to the Internet.

Interpreter. A program that translates source code written in a high-level language to object code in machine language, executing each line as it is converted. BASIC is an interpreted programming language.

Interrupt. A pause in the normal execution of a computer program during which the operating system transfers control to another process. See also IRQ.

Intranet. An "Internet-like," hyperlinked information-exchange system established within an organization or institution for its own purposes, protected from unauthorized public access. See also firewall and proxy server.

I/O. Input/output, referring to transfer of digital data or analog signals.

IP or IP address. Internet Protocol address, a means of referring to locations on the Internet. Composed of four numbers from 0 through 255, separated by decimal points. All machines on the Internet have one, often assigned by the ISP at connection time.

IP Telephony. Use of IP protocols to establish two-way voice communications between users.

IRC. Internet Relay Chat, Internet communication where anyone can carry on real-time conversation by typing back and forth. See also instant messaging and chat.

IRQ. Interrupt Request, one of several control lines into a computer's CPU to provide a means for hardware components such as disk controllers, printers, and modems to gain the attention of the CPU. See also interrupt.

ISA (eye-sa). Industry Standard Architecture, a bus standard developed for IBM-PC expansion cards. Originally it was 8-bit and eventually expanded to 16-bit architecture. Now supplanted by 32-bit interfaces. See also PCI and AGP.

ISDN. Integrated Services Digital Network, a high-speed telephone line that is a faster but expensive alternative to traditional dial-up modems, and available farther from the telephone office than DSL. See also DSL and POTS.

J    

Java or Javascript. A programming language that brings animation and interactivity to Web pages by embedding program code that gets run on the client PC.

Joystick. A device used with games and other interactive programs to manually control the cursor, an object, or the action by moving a stick back and forth, right and left, or by the push of a "fire" button.

JPEG. Joint Photographic Experts Group, an image file format allowing several levels of file compression from lossless (high quality, large file) to quite lossy (lower quality, small file) to suit different needs. Commonly used on Web pages or digital camera files. See also compressed file.

Jumper. A small, plastic-covered metal clip used to close a connection (circuit) between two pins such as for configuring settings on a board.

Justification. The alignment of text or images in a document, usually to the left and/or right margins, or centered.

K    

K or KB. Kilobyte, which is exactly 1,024 bytes but is usually thought of as 1,000 bytes. Sometimes incorrectly represented by a small k, which is just the prefix kilo.

kb. Kilobit.

Kernel. The most rudimentary part of a program, most typically of an operating system, that remains in memory at all times. Making the kernel "crash-proof" is a primary goal of operating-system designers. See also interface.

Key. The button on a keyboard. In a database, an item, usually a field within a record, used to identify the record uniquely.

Keyboard. The typewriter-like panel used to enter and manipulate text or data and enter instructions to direct the computer's operations. See also multifunction keyboard.

Keypad. A set of keys grouped together and performing a particular function. The most common keypads on a computer are the numeric and cursor control.

Kilo-. A prefix meaning 1,000. Because of the binary nature of computers, kilo is also used to refer to 1,024. See also K.

Kilobit. 1,024 bits (2 to the 8th power), usually thought of as 1,000 bits.

Kilobyte. 1,024 bytes (2 to the 8th power), usually thought of as 1,000 bytes.

L    

LAN. Local Area Network, a system of two or more computers within an area (typically a building) that share some of the same facilities, such as disks, printers, and software. See also Ethernet and Wi-Fi.

Landscape. The page or screen orientation in which information is printed across the longer dimension. See also portrait.

Language. In programming, a command syntax comprising the lexicon a programmer uses when writing source code. Languages include Basic, C, Pascal, Cobol, Lisp, Java, HTML, XML, Forth and Perl, among many others.

Laptop computer. A portable, battery-equipped computer with a flat-panel display screen, small enough to be used on the lap or small table. Also called notebook computers. Some are complete systems offering advanced features nearly the equal of desktop PCs, along with wireless networking capability. See also portable computer and tablet PC.

Laser printer. A fast, economical page printer that produces very high-quality print and graphics. Only black-and-white laser printers have been affordable for consumers, though color ones are dropping in price.

Launch. Load and run a program.

LCD. Liquid Crystal Display, a technology allowing thin, flat, high-resolution color displays, used for laptop computers and some desktop monitors. See also active matrix display and passive matrix display.

LED. Light-emitting diode, a small electrical component that produces light when a current is passed through it. LED's and are very efficient and can now produce virtually any color of light.

Limited-stroke key. The type of key found on some keyboards and laptop computers that depresses only slightly when pressed. See also full-stroke key.

Link. See hyperlink.

Linux. A freely-downloadable, user-supported, open-source OS, based on UNIX. Linux is touted as an alternative to Windows, but is more suited to certain business applications such as Web-servers. See also open source and UNIX.

List. An ordered sequence of information. See also queue.

Load. To read a program or data into a PC's memory. See also launch, retrieve, and save.

Local area network. See LAN.

Logical drive. A section of a physical drive that has been designated as an independent storage device. For example, a single hard drive could contain logical drives C: and D:. See also partition.

Lost cluster. Units of disk storage that have lost the information that links them to the proper file name. Lost clusters can occur if a computer is shut down with files left open, such as when power is suddenly lost or the system is turned off with applications still running. Running a utility, such as Windows' ScanDisk, can locate and repair lost clusters and other defects.
M

MAC address. Media Access Control address, a globally-unique hexadecimal string, such as 00-10-3C-B6-45-DG, embedded into every hardware device that can connect to a network. MAC addresses are used by routers to direct Internet packets to the right user.

Mac. Short for Apple's Macintosh computer.

Mac OS. The windowed operating system of the Apple Macintosh computer family. Mac OS X (version ten) departed radically from earlier versions in being UNIX-based, and having its user-interface modernized with an equivalent to the Windows taskbar called the "dock."

Machine language or code. Programming instructions in binary format, the basic coding of a particular microprocessor family.

Machine-specific. Software or hardware that can be used on only one type or model of computer.

Macintosh. A computer from Apple that was the first to use a mouse and icon-based operating system to make it user friendly.

Macro. A series of commands that can be initiated easily, often by a solitary keystroke or simple combination of keys; a sequence of instructions embedded in a spreadsheet or other document that can be easily executed at will.

Magnetic tape. See tape.

Mailing list. A list of subscribers to a topical information exchange that operates through e-mail. Most mailing list users refer to their group as "the list." The list-server is the host software, residing on a server computer that manages the traffic for the list. A directory of over 50,000 public lists is at www.lsoft.com/catalist.html.

Mainframe. A large, expensive, multi-processor computer system capable of handling many users and running many programs simultaneously. Such systems are extremely fast and support a wide range of peripherals. They are normally found in large businesses, universities, and government agencies. See supercomputer.

Main memory. The data storage locations inside a computer and directly accessible by the CPU; memory can range from as little as 1 MB to more than 8 GB.

Matrix. An array or an ordered arrangement. For example, 63 dots might be arranged into a rectangular matrix or array of nine rows and seven columns.

Mb. Megabit.

MB. Megabyte.

Media. The physical object, usually a disk or tape, upon which digital data is stored.

Media player. Generically, a program that decodes file- or Internet-based multimedia material into an audible and/or visual presentation. Examples are Windows Media Player, RealOne Player, and MusicMatch Jukebox.

Meg. Short for megabyte or megahertz.

Mega-. A prefix usually meaning one million, but because of the binary nature of computers, used to refer to 1,048,576 (or 2 to the twentieth power).

Megabit. 1,024 kilobits, yielding 1,048,576 bits, usually considered a million.

Megabyte. 1,024 kilobytes, yielding 1,048,576 bytes, usually considered a million.

Megahertz. 1 million hertz.

Memory. See main memory, RAM, and VRAM.

Memory cache. A high-speed block of memory that acts between the main memory and processor to speed the execution of instructions and processing of data. See also disk cache.

Memory-resident. See resident.

Menu. A list of available options, often in a "drop-down" or "pull-down" list hidden until activated via a mouse-click.

Menu bar. A bar across the top of the screen that presents the first level of options for a drop-down menu system.

Menu-driven. A program or system that uses a series of menus to make it easier to use. The user selects the desired option by clicking on an entry with the mouse, typing the corresponding letter or number, or moving the cursor to the proper selection and hitting the Enter key, and the program will then perform the chosen function. See also drop-down menu.

MHz. Megahertz.

Microcomputer. See personal computer.

Micron. One-millionth of a meter or one-thousandth of a millimeter.

Microprocessor. The CPU of a personal computer, such as the Pentium 4 or Athlon XP. Microprocessors have an arithmetic logic unit to perform calculations and a control unit with limited memory to hold instructions. The main memory is added externally, and communicates with the microprocessor via a data bus. Microprocessors have an associated chipset to manage data flow among all the hardware components of the computer. See also motherboard and chipset.

Microsecond. One-millionth of a second.

MIDI. Musical Instrument Digital Interface, standard for the exchange of information between various musical devices, including instruments, synthesizers, and computers that are MIDI-capable. See also sound board.

Minicomputer. A medium-size computer capable of handling several users and multiple tasks, and acting as a database host. Normally found in small businesses and schools.

Minitower case and microtower case. Smaller versions of the tower case.

MIPS. Million Instructions Per Second, a very rough measure of the performance of a processor in terms of the number of instructions carried out in one second. 1 MIPS = 1,000,000 instructions per second. But MIPS values alone are not good indicators of relative system performance. See also FLOPS.

MM. See multimedia.

Mode. A condition or set of conditions for operation. A printer may have modes for different print qualities, or a serial port for different transmission speeds or protocols.

Modem. Modulator/Demodulator, used to connect a digital device (computer) to a data communications channel (telephone line, cable, or radio link). Modems perform the necessary D-to-A (modulation) and A-to-D (demodulation) conversions. A modem is used to send a fax, to access e-mail, and to get online to the Internet. A modem intended to work with normal dial-up telephone lines (see POTS) has a top speed of nominally 56 kilobits per second (kbps). A connection between 34k and 53k (the U.S. limit) can be established only if both the local telephone line and the ISP (Internet Service Provider) are properly equipped. See also V.90.

Modular bay. A device bay in a modular laptop computer that accepts a device such as an optical disk drive, a diskette drive, a second battery, a back-up hard drive, or a memory-card reader.

Modular laptop. A laptop PC that contains one or more modular bays allowing various drives or a battery to be inserted as desired, or removed to save travel weight. See also all-in-one and slim-and-light.

Monitor. The "face" of the computer, most often a CRT screen. Monitors are similar to TVs but usually do not have a tuner and so cannot directly receive television broadcast signals. See also CRT and LCD.

Monochrome. One color, usually referring to a monitor or printer.

Motherboard. The main board inside a PC into which the memory, microprocessor, and other components are plugged.

Mouse. A palm-size device that controls the cursor, an object on the screen, or other screen action by moving it around on a flat surface. A small ball or optical sensor on the bottom of the mouse senses direction of the motion, transferring this action to the screen. One or more buttons are also used for additional control, such as clicking and dragging. See also trackball.

Mouse pad. A thin, resilient pad used as a surface to support a computer mouse, providing a better "grip" for the ball than some desk surfaces, as well as a cushion for the wrist.

Mouse pointer. A type of cursor used by a mouse or other pointing device to indicate a specific screen location. The pointer may be any number of different shapes, but the most common types are the arrow and crosshair.

MPEG. Motion Picture Experts Group, modern standard format for compression and storage of video files. MPEG-1 allows a full-length movie to be stored on a standard CD-ROM disc with a moderate amount of visual artifacts; MPEG-2 allows a full-length movie to be stored on a DVD-ROM with few visual artifacts.

MP3. Nickname for "MPEG-1 Layer-3," an encoding format for compressed digital music files that offers high quality with less than one-tenth the data rate of an uncompressed CD-music bitstream. The small files required for typical songs allow for fairly fast transfer over consumer-grade Internet connections, and have spawned a hobby of sharing music over the Internet, both legally as well as in violation of copyright laws. See also DRM.

MS-DOS. Microsoft DOS, the version of the IBM PC-DOS disk operating system used by IBM-compatible computers. It has been replaced by Windows.

MSN TV. Formerly called WebTV, a Microsoft-owned service that uses a TV setup box to access the Internet.

Multifrequency. See multiscan.

Multifunction keyboard. A computer keyboard that has additional keys to launch email, the Internet, and selected applications, and control computer functions like the CD or DVD drive, sound volume, and sleep mode.

Multifunction printer. An ink-jet, laser, or thermal printer that, in addition to printing, may serve as a phone, fax machine, scanner, copier, or other device.

Multimedia. Generally, any system or application that incorporates two or more of graphics, text, audio, and video into an integrated presentation.

Multimedia PC. A PC equipped for multimedia use. Common multimedia systems for home use are equipped with high-resolution graphics, CD-ROM drives, and sound boards in addition to the traditional disk drives.

Multiscan. A type of monitor that accepts various combinations of screen resolution and refresh rate.

Multiprocessor. A computer that has more than one processor, which can improve performance when combined with an OS that supports multiprocessing.

Multitasking. The ability to run more than one program or process at the same time. For example, printing a document while surfing the Web. The increasing power of 32-bit and 64-bit processors has made multitasking more efficient and popular.

Multiuser. Designed to support more than one user at a time. Most personal computers are single-user PCs. Also refers to the ability of some operating systems to keep track of custom settings and permissions for more than one user.

N    

Nagware. Software, normally shareware, that displays messages to remind (nag) the user to register and, usually, to pay a fee.

Network. Any system of two or more connected computers, along with their peripherals, organized to share files and resources. See also bus and LAN.

Newsgroup. One of the informal information-sharing message boards on the part of the Internet known as Usenet. Accessed through a newsreader, such as Outlook Express.

NIC. Network Interface Card, an expansion card used to connect a computer to a LAN.

Node. A computer (client or server) or peripheral device in a network.

Noise. Unwanted electrical or communication signals; interference.

Noise filter. An electric device designed to reduce electrical noise on a data line or AC line.

Noninterlaced. Video display mode used in computer monitors and HDTV in which every scan line is displayed progressively. Noninterlaced images are more stable to view, but place more demands on the monitor. See also interlaced.

Nonvolatile. A memory design in which the stored data is not lost when the power is removed from the system. See also flash memory and volatile.

Notebook computer. Another name for a laptop computer.

Numeric. Containing only numbers, which may include only the ten digits 0-9, a plus or minus sign, and a decimal point.

Numeric keypad. A group of keys set aside for the entry of numeric data and performing simple arithmetic operations. See also cursor control keys.

O    

OCR. Optical Character Recognition, a text-recognition program that can convert scanned paper documents into a word-processing file format for storage, editing, and incorporation into other documents. See also scanner.

OEM. Original Equipment Manufacturer; technically, the original maker of a piece of equipment who usually markets to a reseller, but may also market direct to the end-user.

Office suite. An application suite of office-oriented programs. Examples are Microsoft Office, Corel WordPerfect Office, Lotus SmartSuite, and Sun StarOffice.

Offline. Not currently accessible by the PC; a PC that is not networked.

Offline storage. See archival storage.

Online. Connected to the Internet or to another computer via modem, cable, or satellite. Going online refers to using the Internet.

Online help. A feature of many programs that provides assistance with how to operate the program. It is normally accessed by hitting a key such as F1 or selecting a menu option. Online help is often all that is needed to become proficient in using an application. See also context-sensitive.

Online service. A collection of information databases and other offerings that can be accessed via a modem or the Internet. The various features range from reference material (encyclopedias and atlases) to current updates (weather and stocks) to interactive features with other users (bulletin boards and games). Popular services include America Online, CompuServe, and Microsoft Network.

Open source. Describing a program or system whose code is freely available and publicly supported. Anyone can modify open-source programs for their own needs, and make those modifications available to other users through Websites established for the purpose.

Operating system. See OS.

Optical cable. Cable that contains very thin, flexible glass or plastic fibers through which information is carried using a modulated light beam. Used in cable TV systems and in high-speed data communication links.

Optical disk. Generally refers to any disk read or written to by a laser or other light-emitting/sensing device.