Accelerated Graphics Port (AGP)

An Intel-design expansion port found on Pentium II and later computers that allows a separate data path for display adapters.

access speed

The time required to complete read or write instructions as required by the memory controller chip. Usually measured in nanoseconds (ns) for memory chips and milliseconds (ms) for disk drives. Most manufacturers rate average access time on a hard disk as the time required for a seek across one-third of the total number of cylinders plus one half of the time for a single revolution of the disk platters.

address bus

A group of parallel conductors (circuit traces) found on the motherboard that are used by the CPU to “address” memory locations. Determines what information or code is sent to or received from the data bus.


A measurement of electrical current strength.

ASCII file

Commonly used term to refer to a text file that contains only data as set forth by the American Standard Code for Information Interchange to conform to their standard.


Not synchronized—the computer is free to transmit any number of characters at any time. The bits constituting a single character are transmitted at a fixed rate, but the pauses between transmission can be of any duration.


A file attached to e-mail; most e-maiI clients allow the user to append files (for instance, graphics files like GIFs or JPEGs) to e-mail as a handy way of sending information to other people.


backslash (\)

Symbol used lo separate each directory level, for instance C:\Windows\utilities. For this reason, it is a reserved character and cannot be used as part of a filename.


Used in several ways to denote the amount of data or load capacity of medium. 1) The range of frequencies that an electronic system can transmit. High bandwidth allows fast transmission or the ability to transmit many signals at once. 2) On a monitor screen, a higher bandwidth that provides a sharper image. 3) The rate at which data can be send over a modern or other telecommunication device.





BBS (bulletin board system)




binary file


binary system

The language used by computers– it is based on something being either on or off. There are only two digits used in binary language; 1 equals on and 0 equals off.

BIOS (basic input/output system)

Software that includes hundred of little programs stored on ROM chip, used during the startup routine to check out the system and prepare to run the hardware.



boot partition


boot up

To start a computer; drawn from the phrase “pulling oneself up by one’s own bootstraps.”

bps (bits per second)

The speed at which a modem transmits data. Typical rates are 14,400, 28,800, 33,600 and 56,600 bps. This represents the actual number of data bits ‘that can be trans- mitted per second.




A network with high bandwidth (greater than 256 bps).


Software used to navigate the World Wide Web, such as Microsoft’s Internet Explorer and Netscape Navigator.

bulletin board system See BBS



bus mastering


bus network







A place where data is stored so that it does not need to be read from a slower device. Copies of frequently used disk sectors are stored in RAM so they can be accessed without accessing the hard disk.

case sensitivity

The ability of the operating system to distinguish between uppercase and lowercase letters. MS-DOS commands are not case-sensitive; UNIX commands are.

cathode-ray tube See CRT

CD-ROM (compact disc read-only memory)

A disc similar to an audio compact disc, but it contains computer data.

central processing unit Sec CPU

CGA (Color Graphics Adapter)

An early color graphics adapter standard with resolutions of 320 pixels by 200 pixels or 640 x 200. CGA supported no more than four colors.


The ultimate integrated circuit; contains the complete arithmetic and logic unit of a computer. See microprocessor

chip set

A group of computer chips or ICs (integrated circuits) that, when working in harmony, manage and control the computer system. This set includes the CPU and other chips that control the flow of data throughout the system. Typical chip sets consist of a bus controller, a memory controller, data and address buffer, and a peripheral controller.

CISC (complex instruction set computing)

A computer with many different machine-language instructions.


A computer that connects to a network and uses the available resources provided by the server.



clock speed

Measured in megahertz (MHz) — millions of cycles per second — it is the speed at which a clock can cycle, or how fast a CPU can execute a command.


A term that derives from the early days of personal computing used to denote a computer compatible with, but not manufactured by IBM.


A unit of storage on a mass-storage device such as a hard disk drive or CD-ROM disc. On a hard drive a cluster usually consists of two to eight sectors. The actual amount of data a cluster can hold is dependent on the operating system and controller type.

CMOS (complementary metal-oxide semiconductor)

A chip that gets its name from the way it is manufactured and not the information it holds. Unlike other ROM chips, CMOS chips store data that is read by the BIOS to complete the programs needed to talk to changeable hardware.

CMOS battery


coaxial cable

Made of two conductors that share the same axis. The center is a relatively stiff copper wire encased in insulating plastic. A wire-mesh tube around the insulation serves as shielding. The outside is a tough insulating plastic tube.


A way of representing information on a machine or in some physical form so that the information can be placed on the external data bus to be read by all devices. Also, statements (source code) written in a programming language, which are compiled into executable instructions (object code).

cold boot

The process of restarting a computer after it has been powered down.


The names assigned to the first two serial ports on a PC.

command mode

The character mode used in an operating system such as Microsoft Windows, MS-DOS, or UNIX that has a prompt and in which actions take place while the user enters text strings to execute commands.


“Squeezing” a file down in size by getting rid of all the bits it doesn’t really need. Many files (especially those with graphics) are very large and require a long time to travel over the Internet, so they are best compressed before sent.


Different areas of conversation in an e-mail system that are topic-specific rather than individualized.

conventional memory

The memory area between 0 and 640 KB that is designated for running MS-DOS and MS-DOS applications.


A separate circuit inside a computer that adds additional functions to the CPU or handles extra work while the CPU is busy.

CPU (central processing unit)

The part of a computer in which arithmetic and logical operations are performed and instructions are decoded and executed. It controls the operation of the computer.

CRT (cathode ray tube)

The main component of a monitor. One end of the tube is a very slender cylinder containing an electron gun(s). The fatter end is the display screen.


When entering data, whether in an application or in an MS-DOS command, the cursor (often a small flashing line) indicates the place at which the characters will be inserted.



data bus

A group of parallel conductors (circuit traces) found on the motherboard that is used by the CPU to send and receive data from all the devices in the computer. Also called the external data bus.

Data Communications Equipment (DCE)

The receiver in a telecommunications connection.

default drive

The active drive on the computer. Each drive has its own letter designation. Unless otherwise specified, any commands are performed upon the default drive.


Running a program to organize the files on a hard disk so that the various clusters of data for each file are once again contiguous, This helps to speed up the hard disk.

device driver

A program that extends the operating system to support specific devices.

direct memory access (DMA)

Allows a peripheral device to access the memory of a computer directly, without going through the CPU. This speeds up the transfer of data to or from external devices.


A location where files are grouped together on the disk. In the Microsoft Windows environment and Apple Macintosh operating systems, these are known as folders.

DLC (Data Link Control)

A protocol developed by IBM to connect token-ring-based workstations to IBM mainframe computers. Printer manufacturers have adopted the protocol to connect remote printers to network print servers.

DMA See direct memory access

DOS (disk operating system)

The system used by most early PCs as the operating system software to manage hardware, data, and applications.

DOS prompt

Displays the active drive letter (for instance, C:) and directory. This indicates that the operating system is ready to accept the next command.

DOS Protected Mode Interface (DPMI)

Specification that allows multiple applications to access extended memory at the same time. It has been endorsed by most memory manager producers and application developers. Microsoft Windows uses the DPMI specification.


The ability to transfer a file from a remote computer.

dpi (dots per inch)

Units used to measure the resolution of images on many printers and scanners. Keep in mind that dpi is an exact measurement in laser printers, but often used as an approximation in ink jet printers.

DRAM (dynamic random access memory)

Memory that requires a refresh signal to he sent to it periodically.

Dynamic Data Exchange (DDE)

A data exchange protocol that allow for the automatic updating of a file or open application when the source is modified.



ECC (error-correction coding)

The use of a code to verify or disprove that a data string received is the same as the data sent.

ECP (Extended Capabilities Port)

Developed by Hewlett-Packard and Microsoft. It features 2 MB per second data transfer and bidirectional 8-bit operation. ECP specifies whether transmitted information consists of data or commands for the peripheral.

EGA (Enhanced Graphics Adapter)

An improvement on the older CGA standard. Supports a resolution of up to 640 pixels by 350 Pixels at 16 colors in text-only mode or 640 x 200 at 2 colors in graphics mode. The EGA standard was not fully backward-compatible with CGA and MDA.

e-mail (electronic mail)

The transmission of messages by computer from one person to another, often via the Internet.

Enhanced IDE (EIDE)

A standard developed in order to increase the size of available disk drives and the speed of data transfer between the host and the disk drive. See also Integrated Drive Electronics (IDE)

EPP (Enhanced Parallel Port)

Features 2 MB per second data transfer rates, bidirectional 8-bit operation, and addressing to support multiple (daisy-chained) peripherals on a single computer.

error messages

Brief technical messages that are displayed when an error occurs.


A type of local area network in which communication takes place by means of radio frequency signals carried by a UTP and coaxial cable.

Expanded Memory (EMS)

A technique, developed by Lotus/Intel/Microsoft (LIM), that adds addressable memory to a computer system, overcoming the original MS-DOS upper memory limit. The LIM expanded memory specification uses a 64-KB section of memory (usually in upper memory) to provide a “window” into which data can he written. Once in this area, the data can be transferred to the expanded memory. The memory chips are located on an expansion card installed inside the computer.

expansion buses

Provide the connection between expansion cards (drive controllers, video cards, modems and so forth) and the system bus.

expansion slots

Specialized sockets that allow additional devices (circuit boards/adapter cards) to be attached to the motherboard (by means of the expansion bus). These are used to expand or customize a computer. They are an extension of the computer’s bus system.

extended memory (XMS)

RAM above the 1-MB address. Extended memory is accessed through an extended memory manager (HIMEM.SYS for DOS).



Fiber-optic cable

A cable that is made out of light-conducting glass or plastic fibers. Multiple fiber cores can be bundled in the center of ifs protective tubing.

Filename (also filespec)

Ways to designate files. A filename is made up three parts – a name of up to eight characters, a period, and extension of up to three characters. The name can include any number, character, or the following symbols: _()~’!%$&#. For example: “myfile.doc.” Spaces cannot be used in MS-DOS filenames.

File Transfer Protocol (FTP)

1) An application used for transferring files to and from another computer, usually over the Internet. 2) The protocol by means of which these transfers take place.

floppy disk drive

Low-capacity magnetic removable storage drive.

form factor

The standard physical configuration of a typical device such as a motherboard or a 3.5-inch hard disk drive.


Scattering of data in files throughout a disk drive caused by the continual addition and deletion of files. Although not harmful to the computer, fragmentation will slow down a hard drive because it causes the computer to access two or more places to retrieve a file.




A link between different computer networks. It is usually a computer that acts as a translator between two completely dissimilar systems. Because it is both a translator and a router, it is usually slower than a bridge or router alone.


A system of information retrieval that “digs” down through layers of menus to reach what you want. A Gopher system is generally text-based and is best for finding documents buried in archives such as university libraries. Some Web sites offer access to Gopher, but Gopher has been largely replaced by information archives on Web sites.

GPF (General Protection Fault)

An error that occurs in Microsoft Windows when a program tries to access a memory location that is not allocated to it.

greater than (>)

This symbol is used to indicate that a command can be redirected to an output device. For example, to redirect the directory command to a printer, type dir > lpt1.

GUI (graphical user interface)

Microsoft Windows is a GUI-based operating system. A GUI allows users to choose commands and functions by pointing to a graphical icon using either a keyboard or pointing device such as a mouse




A term used to describe the sequence of data and related tones used to align and synchronize two modems before working data is sent between the devices.

hard disk drive

High-capacity magnetic disk for data storage and program files. Also called a fixed disk.


The physical elements of the computer system.

high memory area (HMA)

An irregularity found in the Intel chip architecture that allowed MS-DOS to address the first 64 KB of extended memory on machines with a 80286 or higher processors. This special area is called the high memory area.

High Sierra format

An industry-wide formal specification for the logical structure, file structure, and record structures on a CD. The specification is named after a meeting on CD-ROM held near Lake Tahoe in November 1985. It served as the basis for the international standard ISO 9660.


A computer that you connect to in order to access information. For instance, a computer at an ISP that lets you access the Internet is a host.

HRR (horizontal retreah rate)

The speed at which the electron beam in a CRT completes one horizontal trace.

HTML (Hypertext Markup Language)

An application of SGML ( Standardized Genera! Markup Language) used to create Web pages.

HTTP (Hypertext Transter Protocol)

The protocol used to transmit data in the HTML format.



I/O address

A unique name assigned to each device that allows the CPU to recognize the device with which it is communicating.


A small picture on a computer screen that represents a group of files, an object, or operations. A user accesses the item he or she wants by clicking on the picture with the mouse.

Industry Standard Architecture (ISA)

One of several common expansion slot and card designs.

integrated circuit (IC)

An electronic device con- sisting of many miniature transistors and other circuit elements (resistors and capacitors and so forth).

Integrated Drive Electronics (IDE)

The most common standard for interfacing hard disk and CD-ROM drives in the PC environment. Much of the actual work of controlling the hard disk drive is handled by the system BIOS. This reduces hardware cost, but introduces an overall system performance penalty during I/O operations. See also Enhanced IDE (ElDE)

internal cache

High-speed memory built into the processor to store frequently used data. This avoids accessing slower devices such as RAM or hard drives.

International Organization for Standardization (ISO)

Groups of experts drawn from the industry that set standards for various technologies. The work of these teams has led to development of SCSI, SMAL and the Internet, and the ASCII character set.


A system that links computer networks all over the world.

IP (Internet Protocol)

The protocols used to define how data is transmitted over the Internet.

IP address (Internet Protocol address)

A unique address that identifies every network and host on the Internet. (A host is defined as the TCP/IP network interface within the computer, not the computer itself– a computer with two network cards will have two IP addresses).

IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange)

NetWare core protocol developed by Novell in the early 1980s.

IRQ (interrupt request)

A wire used by the CPU to control the flow of data. It prevents devices from trying to communicate with the CPU at the same time by “interrupting” and temporarily stopping the CPU to deal with a particular request.


A telecommunication standard that allows a channel to carry voice and data in digital form over a single line.

ISP (Internet Service Provider)

A host computer that users can dial into over a modem to connect to the Internet.





A socket for plugging in an audio source. Usually mounted in a motherboard and can be seen at the back and front panel of a computer system. Audio jacks are found on many types of audio equipment and musical instruments that accept external sound sources.










A primary input device for a computer, used for entering text and shortcuts for command functions.

kilobyte (KB)

A unit of memory equal to 1,024 characters or bytes (1 KB = one kilobyte).



LAN (local area network)

A network that covers a limited distance (such as a single building or facility) to allow computers to share information and resources.


Means, also known as a hyperlink, by which reader is moved to a different location on the Internet when the link is activated. When text is used for a hyperlink, it is often colored differently from the body text of the page so it stands out.

local bus

A separate bus in the computer designed to provide extra-fast access to the CPU for certain devices, such as video cards.

logging on

Means by which–when connecting to a remote computer–the host computer (the one that is called) gives permission to connect. The process of sending the appropriate information to sign on is called logging on. Often a user name and password are required.


The names assigned to the parallel printer ports on a PC.



mailing list

A list of subscribers to a particular discussion group. This database can be used to distribute eZines (electronic magazines).

Mainboard Seemotherboard

MDA (Monochrome Display Adapter)

Displays text only at a resolution of 720 pixels by 350 pixels. An MDA is perfect for use with MS-DOS-based word-processing and spreadsheet programs. The MDA uses a 9-pin male connector.

megabyte (MB)

An amount of computer memory equal to 220. 1.048.576 bytes = 1024 kilobytes. One megabyte can store more than one million characters.

megahertz (MHz)

One million hertz (one million cycles per second). A measurement of clock speed.


The area within a computer where information is stored while being worked on. It stores information (in the form of data bits) that the CPU and software need to keep running.

Micro Channel Architecture (MCA)

A short-lived 32-bit expansion bus that was a proprietary design of IBM used on the IBM PS/2 computer. By abandoning the open design of the existing PC market, IBM limited the willingness of developers and buyers alike to use MCA.


Just like the microphone on a tape recorder. Allows input of voice or music to be recorded and saved to a computer file.


An integrated circuit containing the entire CPU of a computer, all on one chip, so that only the memory and input/output devices need to be added

mini connector

A type of power supply connector primarily used on 3.5-inch floppy disk drive.

modem (MOdulator/DEModulator)

Converts computer data to information that can be transmitted via wires (telephone, ISDN, fiber optics, as well as wireless communication). Allows communication between computers over long and short distances.

Molex connector

Type of power supply connector primarily used for devices that need both 12-volt and 5-volt power (floppy disk drives). The most common type of connector.


The primary output device that resembles a television set–it visually displays text and graphics.


Also known as a PWB or printed wiring board. The large circuit board found inside the computer. For all practical purposes, it is the computer. It contains the following items: chip set, data bus, address bus, expansion slots, clock, battery, and memory.


Device used with graphical environments to point and select objects on the system’s monitor. They come in a variety of shapes and sizes.

MTBF (mean time between failures)

A standard means by which vendors estimate the expected lifespan of a given product line.


The operation of more than one application at what appears to be the same time on the same PC. The CPU quickly switches between the various programs, making it possible to work in more than one program at once.



nanosecond (ns)

One-billionth of one second. The time increment used to measure access speed of the memory chip.

NetBIOS/NetBEUI (networked basic input/output system/NetBios Enhanced User Interface)



A group of computers connected together in order to share data and resources.

network card

An expansion card that connects a computer to a group of computers so they can access information and programs. Also known as a network interface card. NIC and network adapter card.




Networked computers that are not actively connected so that transmission of data is not possible.

offline reader

A program to display e-mail messages that have been downloaded to a computer.


A unit of electrical resistance.


The state in which two or more computers are connected to each other, making possible data transmission.

operating system

The program that controls a PC and makes it possible for users to run their own applications. The operating system provides the built-in routines that allow the computer to recognize commands, manage files, connect devices, and perform input/output operations.




A group of consecutive characters transmitted from one computer to another over a network.


The transmission of several bits at the same time over separate wires.

parity bit

A very basic method of error-correcting code that uses the value of an extra bit sent at the end of a data string. The bit must have a set value based on an algorithm to verify that the data at the receiving end is correct.


The address to a file. The path consists of the drive name, the location of the file in the directory structure, and the filename. Example: C:\Mystuff\Myfile.doc.

peer-to-peer network

A network in which each connected computer acts as either a server or a client depending on the users’ needs. Each user or workstation establishes its own security and determines which resources are available to other users. These networks are limited in size, usually 15 to 20 workstation.


An external device connected to a computer such as a printer, scanner, modem, or joystick.


The amount of time a pixel stays visible on a monitor screen, which is a factor of the decay of activity in the phosphor coating.

PGA (Professional Graphics Adapter)

An adapter that was originally marketed to the engineering and scientific communities. It was expensive and required three ISA slots when fully configured. This system offered 3-D rotation and 60 frames per second animation. It used a 15-pin, three-row, female DB-type connector. It gained limited use in CAD environments, but was quickly replaced by better mass-market solutions.


Short for “picture element.” One of the dots that make up a graphical image.


Similar to a printer, but uses pen(s) to draw an image. Used most often with graphics and drawing programs.


Specific channel used by a network service. For example, Gopher often uses port 70, while some Web sites use port 80.


The strength or force actually put forth by electricity. Electrical power is measured in watts, which is measured by multiplying voltage by current.

power supply

Takes alternating current ( AC ) power from a local source (a wall outlet) and converts it to direct current (DC ) for on-board electronics use.


A peripheral device that transfers computer output to paper or other form of hard copy.


The command prompt—a user interface provided by COMMAND.COM to signal to the user that the computer is ready to receive input (for example, c:\> or A:\>).

protected mode

A mode introduced with 80286 processors that used an operating system like OS/2 or Windows to allow creation of “virtual machine.” These provided the functionality of a standard computer in real mode but allowed multiple tasks to take place at the same time. The term refers to the fact that processor, memory, and other hardware are “protected” from the software applications by the operating system, which allocates the memory and processor time.


A set of rules that govern the transfer of information. The format used to upload or download files to allow two different computers to communicate in a standard format.





Quick and Dirty Operating System (OS, PC, MS-DOS, predecessor)

Quad Core

A multi-core processor system composed of four independent cores. It can be described as an integrated circuit to which two or more individual processors, allowing computers to handle multiple tasks faster.

quick launch

Is a customizable toolbar that lets you display the Windows Desktop or start a program, such as Internet Explorer or the Windows Media Player, with a single click. You can also add additional buttons to launch your favorite programs from the Quick Launch location on the taskbar.


QuickTime is Apple’s multiplatform, multimedia technology for handling video, sound, animation, graphics, text, interactivity, and music. As a cross-platform technology, QuickTime can deliver content on Mac OS and Windows computers. Many applications, including Final Cut Pro, use the powerful architecture of QuickTime to view, create, import, and export media.



RAID (redundant array of independent disks)

The combining of several drives using either hardware or software controls to make them seem to be one drive.

RAM (random access memory)

The main memory where a computer temporarily stores data.

read-only memory See ROM

real mode

An MS-DOS mode in which a computer can perform only one operation at a time and an application expects full control of the system. Real mode operates within the MS-DOS 1 MB limitation.


Temporary memory storage areas located inside the CPU. Used to hold the intermediate results of calculations or other operations.


A file or set of files in Windows 95 and later that stores information about a computer`s hardware and software configuration.


A device that works like an amplifier; it increases or boosts a signal to allow transmissions over longer distances.


A measurement of the detail of images produced by a monitor or printer. Normally measured by a horizontal and vertical number of pixels for monitors or dots per inch for laser printers. The higher the number, the better the quality and more memory required by the system.

ring network

A type of network in which all the servers and clients are connected in a closed loop.

RISC (Reduced Instruction Set Computing)

Uses a smaller and simpler set of instructions to control the processor thereby greatly enhancing the processing speed.

ROM (read-only memory)

Computer memory that contains instructions that do not need to be changed, such as operating system startup instructions. The computer can access data from ROM but cannot put new data into it.


A device that works like a bridge but is able to select the best route from network to network based on traffic load. A router can also connect dissimilar networks.




A peripheral that converts information from the written page (or a printed graphic) to digital information that can be used by the computer. Works similarly to the scanning process in a photocopy machine.


A process that converts a photograph, graphic, or even text image found on paper into an electronic computer file.

SCSI (Small Computer System Interface)

A standard way of interfacing a computer to disk drives and other devices that require high-speed data transfer. Up to 16 SCSI devices, including the host adapter, can he connected in a daisy chain fashion. These devices can be hard disk drives, CD-ROMs, scanners, or printers. SCSI is the only common computer interface that allows adding both internal and external devices on the same chain. (Pronounced “scuzzy.”)

search engine

A program that searches indexes of Internet addresses using keywords. There are hundreds of search engines located on servers throughout the Internet. Some popular search engines are Google, AltaVista, Yahoo, HotBot, and Excite.


Transmission of 1 bit at a time over a single wire.


The computer that runs the network operating system, manages security, and administers access to resources. Strictly speaking, any computer that stores information and allows outside users to get copies of that information.

server network

This type of network requires a central server (dedicated computer) to manage access to all shared files and peripherals.

shadow RAM

Many high-speed motherboard use shadow RAM to improve the performance of a computer. Shadow RAM rewrites (or shadows) the contents of the ROM BIOS and/or video BIOS into extended RAM (between the 640-KB boundary and 1 MB). This allows systems to operate faster when application software calls BIOS routines. In some cases, system speed can be increased up to 400 percent.


Any program (set of instructions) that causes a computer to carry out a task or function.


Holds computer output before sending it to a printer. This enables the main program to run more quickly because output is handled by the print spooler, which then distributes it to the printer at the proper speed

star network

A type of network configuration in which all computers are connected to a central point called a hub. The hub collects and distributes the flow data within the network. In large networks, several hubs may be connected. This is the easiest form of network topology to troubleshoot because all information goes through a hub, making it easier to isolate problems.


Technology found in Pentium processors allowing the Pentium to have two instruction pipelines, thereby increasing the speed of processing.

surge suppresser

Used to prevent large power spikes (such as from lightning) from damaging a computer.

SVGA (Super Video Graphics Array)

A video standard. The minimum requirement for SVGA compatibility is 640 pixels by 480 pixels at 256 colors. At the low end, typical SVGA systems are operated at 800 x 600 at any color depth. Today, most SVGAs run at 1024 x 768 at 256 with 64K colors or better.

switch box

Allows the user to manually (or automatically) switch cable connections so that one computer can use several different printers or devices with one parallel port.


Form of computer communication in which data is transmitted in packets containing more than one character. This is faster than asynchronous transmission because there is no start/stop bit between each individual character.


Specific rules that prescribe how the symbols of a programming language can be written in order to form meaningful statements that will be understood by the PC.

sysop (system operator)

The system operator of a small BBS. (Pronounced “SIS-op.”)

system bus

Supports the CPU, RAM, and other motherboard components that provide the controlling element to the computer. It is responsible for coordinating the operation of the individual system components and central to the communications system of a computer. Also called the control bus.

system crystal

Determines the speed at which a CPU is operated (sets the clock speed); it is usually a quartz oscillator.


tape drive

A high-capacity removable magnetic data storage device. Ideal for backups and retrieval of large amounts of data. Works like a tape recorder and saves information is a linear format.

TCP/IP (Transfer Control Protocol/ Internet Protocol)

The name given to a collection of protocols that were designed in the 1970s for use on the large-scale mixed-platform that became the Internet.

telecom software

An application that allows two computers to communicate. Both computers must use compatible software for communication to take place.




A terminal emulation program that allows you to log into another computer system over the Internet. You can then run programs on that machine as though you dialed in directly.


The layout scheme that describes the way in which network nodes are wired in relation to each other.


An electronic device that allows a small current in one place to control a larger current in another place; commonly used as amplifiers in radio and audio circuits.

TSR (terminate-and-stay-resident program)

A computer program, also known as a memory after being run so that it can be called up later. These extend the capabilities of the operating system or provide “pop-up” functions (such as a calendar or calculator) that can be brought up in the middle of another program without disturbing the program. These programs were popular in the days of MS-DOS, but lead to lots of problems due to memory usage conflicts.

twisted-pair cable

Consists of two insulated wires twisted around each other to form a pair. One or more twisted pairs are used in a twisted-pair cable.



universal serial bus (USB)


mass storage devices such as ZIP drives, modems, and printer.



upper memory area (UMA)




VGA (Video Graphics Array)


Virtual Control Program Interface (VCPI)

A memory management specification that accesses extended memory for MS-DOS-based applications. It allows only one application to control extended memory and does not support multi-tasking. Windows is not compatible with the VCPI specification.

virtual memory




VRR (vertical refresh rate)

The speed at which a monitor completes all vertical traces.



WAN (wide area network)

A network that spans a large geographical area. The network is connected

by means of telephone lines, ISDN (Integrated Services Digital Network) lines, radio waves, or satellite links.

warm boot

The process of restarting a computer that is already running by holding down the CTRL, ALT, and DELETE keys simultaneously. It can also refer to choosing a “Shut-down and Restart” option under Windows 9x or Windows NT.


A keyboard character that represents one or more characters in a string, usually for specifying more than one file by name. The question mark (?) matches any character in a specified position, and the asterisk (*) matches any number of characters up to the end of the filename or extension.


The largest amount of data that can be handled by the microprocessor in one operation and also, as a rule, the width of the main data bus.