30001b03 glossary final02€¦ · hard drive that boots the os. windows nt/2000/ xp calls the...

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Glossary This glossary defines the key terms listed at the end of each chapter and other terms related to managing and maintaining a personal computer. 100BaseT — An Ethernet standard that operates at 100 Mbps and uses STP cabling. Also called Fast Ethernet. Variations of 100BaseT are 100BaseTX and 100BaseFX. 10Base2 — An Ethernet standard that operates at 10 Mbps and uses small coaxial cable up to 200 meters long. Also called ThinNet. 10Base5 — An Ethernet standard that operates at 10 Mbps and uses thick coaxial cable up to 500 meters long. Also called ThickNet. 32-bit flat memory mode — A protected processing mode used by Windows NT/2000/XP to process programs written in 32-bit code early in the boot process. 3-D RAM — Special video RAM designed to improve 3-D graphics simulation. 80 conductor IDE cable — An IDE cable that has 40 pins but uses 80 wires, 40 of which are ground wires designed to reduce crosstalk on the cable. The cable is used by ATA/66, ATA/100, and ATA/133 IDE drives. 802.11b See IEEE 802.11b. access point (AP) — A device connected to a LAN that provides wireless communication so that computers, printers, and other wireless devices can communicate with devices on the LAN. ACPI (Advanced Configuration and Power Inter- face) — Specification developed by Intel, Com- paq, Phoenix, Microsoft, and Toshiba to control power on notebooks and other devices. Windows 98 and Windows 2000/XP support ACPI. active backplane — A type of backplane system in which there is some circuitry, including bus con- nectors, buffers, and driver circuits, on the backplane. Active Directory — A Windows 2000 and Windows 2003 directory database and service that allows for a single point of administration for all shared resources on a network, including files, peripheral devices, databases, Web sites, users, and services. active matrix — A type of video display that ampli- fies the signal at every intersection in the grid of electrodes, which enhances the pixel quality over that of a dual-scan passive matrix display. active partition — The primary partition on the hard drive that boots the OS. Windows NT/2000/ XP calls the active partition the system partition. active terminator — A type of terminator for single- ended SCSI cables that includes voltage regulators in addition to the simple resistors used with pas- sive termination. adapter address See MAC address. adapter card — A small circuit board inserted in an expansion slot and used to communicate between the system bus and a peripheral device. Also called an interface card. administrator account — In Windows NT/ 2000/ XP, an account that grants to the administrator(s) rights and permissions to all hardware and soft- ware resources, such as the right to add, delete, and change accounts and to change hardware configurations. 1167

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Page 1: 30001b03 Glossary Final02€¦ · hard drive that boots the OS. Windows NT/2000/ XP calls the active partition the system partition. active terminator — A type of terminator for

Glossary

This glossary defines the key terms listed at the endof each chapter and other terms related to managingand maintaining a personal computer.

100BaseT — An Ethernet standard that operates at100 Mbps and uses STP cabling. Also called FastEthernet. Variations of 100BaseT are 100BaseTXand 100BaseFX.

10Base2 — An Ethernet standard that operates at 10Mbps and uses small coaxial cable up to 200meters long. Also called ThinNet.

10Base5 — An Ethernet standard that operates at 10Mbps and uses thick coaxial cable up to 500meters long. Also called ThickNet.

32-bit flat memory mode — A protected processingmode used by Windows NT/2000/XP to processprograms written in 32-bit code early in the bootprocess.

3-D RAM — Special video RAM designed to improve3-D graphics simulation.

80 conductor IDE cable — An IDE cable that has 40pins but uses 80 wires, 40 of which are groundwires designed to reduce crosstalk on the cable.The cable is used by ATA/66, ATA/100, andATA/133 IDE drives.

802.11b — See IEEE 802.11b.

access point (AP) — A device connected to a LANthat provides wireless communication so thatcomputers, printers, and other wireless devicescan communicate with devices on the LAN.

ACPI (Advanced Configuration and Power Inter-face) — Specification developed by Intel, Com-

paq, Phoenix, Microsoft, and Toshiba to controlpower on notebooks and other devices. Windows98 and Windows 2000/XP support ACPI.

active backplane — A type of backplane system inwhich there is some circuitry, including bus con-nectors, buffers, and driver circuits, on thebackplane.

Active Directory — A Windows 2000 and Windows2003 directory database and service that allowsfor a single point of administration for all sharedresources on a network, including files, peripheraldevices, databases, Web sites, users, and services.

active matrix — A type of video display that ampli-fies the signal at every intersection in the grid ofelectrodes, which enhances the pixel quality overthat of a dual-scan passive matrix display.

active partition — The primary partition on thehard drive that boots the OS. Windows NT/2000/XP calls the active partition the system partition.

active terminator — A type of terminator for single-ended SCSI cables that includes voltage regulatorsin addition to the simple resistors used with pas-sive termination.

adapter address — See MAC address.

adapter card — A small circuit board inserted in anexpansion slot and used to communicate betweenthe system bus and a peripheral device. Alsocalled an interface card.

administrator account — In Windows NT/ 2000/XP, an account that grants to the administrator(s)rights and permissions to all hardware and soft-ware resources, such as the right to add, delete,and change accounts and to change hardwareconfigurations.

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Advanced Options menu — A Windows 2000/XPmenu that appears when you press F8 when Win-dows starts. The menu can be used to trou-bleshoot problems when loading Windows2000/XP.

Advanced SCSI Programming Interface (ASPI) — Apopular device driver that enables operating sys-tems to communicate with a SCSI host adapter.(The “A” originally stood for Adaptec.)

Advanced Transfer Cache (ATC) — A type of L2cache contained within the Pentium processorhousing that is embedded on the same core proces-sor die as the CPU itself.

AirPort — The term Apple computers use to describethe IEEE 802.11b standard.

alternating current (AC) — Current that cycles backand forth rather than traveling in only one direc-tion. In the United States, the AC voltage from astandard wall outlet is normally between 110 and115 V. In Europe, the standard AC voltage from awall outlet is 220 V.

ammeter — A meter that measures electrical currentin amps.

ampere or amp (A) — A unit of measurement forelectrical current. One volt across a resistance ofone ohm will produce a flow of one amp.

amplifier repeater — A repeater that does not distin-guish between noise and signal; it amplifies both.

ANSI (American National Standards Institute) — Anonprofit organization dedicated to creating tradeand communications standards.

answer file — A text file that contains informationthat Windows NT/2000/XP requires in order todo an unattended installation.

antivirus (AV) software — Utility programs thatprevent infection or scan a system to detect andremove viruses. McAfee Associates’ VirusScanand Norton AntiVirus are two popular AVpackages.

application program interface (API) call — Arequest from software to the OS to access hard-ware or other software using a previously definedprocedure that both the software and the OSunderstand.

ARP (Address Resolution Protocol) — A protocolthat TCP/IP uses to translate IP addresses intophysical network addresses (MAC addresses).

ASCII (American Standard Code for InformationInterchange) — A popular standard for writingletters and other characters in binary code. Origi-nally, ASCII characters were seven bits, so therewere 127 possible values. ASCII has beenexpanded to an 8-bit version, allowing 128 addi-tional values.

asynchronous SRAM — Static RAM that does notwork in step with the CPU clock and is, therefore,slower than synchronous SRAM.

AT — A form factor, generally no longer produced,in which the motherboard requires a full-size case.Because of their dimensions and configuration,AT systems are difficult to install, service, andupgrade. Also called full AT.

AT command set — A set of commands that a PCuses to control a modem and that a user can enterto troubleshoot the modem.

ATAPI (Advanced Technology Attachment PacketInterface) — An interface standard, part of theIDE/ATA standards, that allows tape drives, CD-ROM drives, and other drives to be treated likean IDE hard drive by the system.

attenuation — Signal degeneration over distance.Attenuation is solved on a network by addingrepeaters to the network.

ATX — The most common form factor for PC sys-tems presently in use, originally introduced byIntel in 1995. ATX motherboards and cases makebetter use of space and resources than did the ATform factor.

audio/modem riser (AMR) — A specification for asmall slot on a motherboard to accommodate anaudio or modem riser card. A controller on themotherboard contains some of the logic for theaudio or modem functionality.

autodetection — A feature on newer system BIOSand hard drives that automatically identifies andconfigures a new drive in the CMOS setup.

Autoexec.bat — A startup text file once used byDOS and used by Windows to provide backward-compatibility. It executes commands automati-

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cally during the boot process and is used to createa16-bit environment.

Automated System Recovery (ASR) — The Win-dows XP process that allows you to restore anentire hard drive volume or logical drive to itsstate at the time the backup of the volume wasmade.

Automatic Private IP Address (APIPA) — An IPaddress in the address range 169.254.x.x, used bya computer when it cannot successfully lease an IPaddress from a DHCP server.

autorange meter — A multimeter that senses thequantity of input and sets the range accordingly.

Baby AT — An improved and more flexible versionof the AT form factor. Baby AT was the industrystandard from approximately 1993 to 1997 andcan fit into some ATX cases.

back side bus — The bus between the CPU and theL2 cache inside the CPU housing.

backplane system — A form factor in which there isno true motherboard. Instead, motherboard com-ponents are included on an adapter card pluggedinto a slot on a board called the backplane.

backup — An extra copy of a file, used in the eventthat the original becomes damaged or destroyed.

backup domain controller (BDC) — In WindowsNT, a computer on a network that holds a read-only copy of the SAM (security accounts man-ager) database.

Backup Operator — A Windows 2000/XP useraccount that can back up and restore any files onthe system regardless of its having access to thesefiles.

bandwidth — In relation to analog communication,the range of frequencies that a communicationschannel or cable can carry. In general use, theterm refers to the volume of data that can travelon a bus or over a cable stated in bits per second(bps), kilobits per second (Kbps), or megabits persecond (Mbps). Also called data throughput orline speed.

bank — An area on the motherboard that containsslots for memory modules (typically labeled bank0, 1, 2, and 3).

baseline — The level of performance expected froma system, which can be compared to current mea-surements to determine what needs upgrading ortuning.

basic disk — A way to partition a hard drive, usedby DOS and all versions of Windows, that storesinformation about the drive in a partition table atthe beginning of the drive. Compare to dynamicdisk.

batch file — A text file containing a series of OScommands. Autoexec.bat is a batch file.

baud rate — A measure of line speed between twodevices such as a computer and a printer or amodem. This speed is measured in the number oftimes a signal changes in one second. See also bitsper second (bps).

beam detect mirror — Detects the initial presence ofa laser printer’s laser beam by reflecting the beamto an optical fiber.

best-effort protocol — See connectionless protocol.

binary number system — The number system usedby computers; it has only two numbers, 0 and 1,called binary digits, or bits.

binding — The process by which a protocol is associ-ated with a network card or a modem card.

BIOS (basic input/output system) — Firmware thatcan control much of a computer’s input/ outputfunctions, such as communication with the floppydrive and the monitor. Also called ROM BIOS.

bit (binary digit) — A0or1used by the binary num-ber system.

bits per second (bps) — A measure of data transmis-sion speed. For example, a common modem speedis 56,000 bps, or 56 Kbps.

block mode — A method of data transfer betweenhard drive and memory that allows multiple datatransfers on a single software interrupt.

blue screen — A Windows NT/2000/XP error thatdisplays against a blue screen and causes the sys-tem to halt. Also called a stop error.

Bluetooth — A standard for wireless communicationand data synchronization between devices, devel-oped by a group of electronics manufacturers andoverseen by the Bluetooth Special Interest Group.

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Bluetooth uses the same frequency range as802.11b, but does not have as wide a range.

BNC connector — A connector used with thin coax-ial cable. Some BNC connectors are T-shaped andcalled T-connectors. One end of the T connects tothe NIC, and the two other ends can connect tocables or end a bus formation with a terminator.

boot loader menu — A startup menu that gives theuser the choice of which operating system to loadsuch as Windows 98 or Windows XP which areboth installed on the same system, creating a dualboot.

boot partition — The hard drive partition where theWindows NT/2000/XP OS is stored. The systempartition and the boot partition may be differentpartitions.

boot record — The first sector of a floppy disk orlogical drive in a partition; it contains informationabout the disk or logical drive. On a hard drive, ifthe boot record is in the active partition, then it isused to boot the OS. Also called boot sector.

boot sector — See boot record.

boot sector virus — An infectious program that canreplace the boot program with a modified,infected version of the boot command utilities,often causing boot and data retrieval problems.

Boot.ini — A Windows NT/2000/XP hidden text filethat contains information needed to build theboot loader menu.

bootable disk — For DOS and Windows, a floppydisk that can upload the OS files necessary forcomputer startup. For DOS or Windows 9x, itmust contain the files Io.sys, Msdos.sys, andCommand.com.

bootstrap loader — A small program at the end ofthe boot record that can be used to boot an OSfrom the disk or logical drive.

bridge — A device used to connect two or more net-work segments. It can make decisions about allow-ing a packet to pass based on the packet’s destina-tion MAC address.

bridging protocol — See line protocol.

Briefcase — A system folder in Windows 9x that isused to synchronize files between two computers.

broadband — A transmission technique that carriesmore than one type of transmission on the samemedium, such as cable modem or DSL.

broadcast — Process by which a message is sent froma single host to all hosts on the network, withoutregard to the kind of data being sent or the desti-nation of the data.

brouter — A device that functions as both a bridgeand a router. A brouter acts as a router when han-dling packets using routable protocols such asTCP/IP and IPX/SPX. It acts as a bridge whenhandling packets using nonroutable protocolssuch as NetBEUI.

brownouts — Temporary reductions in voltage,which can sometimes cause data loss.

buffer — A temporary memory area where data iskept before being written to a hard drive or sentto a printer, thus reducing the number of writes tothe devices.

built-in user account — An administrator accountand a guest account that are set up when Win-dows NT/2000/XP is first installed.

burst EDO (BEDO) — A refined version of EDOmemory that significantly improved access timeover EDO. BEDO was not widely used becauseIntel chose not to support it. BEDO memory isstored on 168-pin DIMM modules.

burst SRAM — Memory that is more expensive andslightly faster than pipelined burst SRAM. Data issent in a two-step process; the data address issent, and then the data itself is sent withoutinterruption.

bus — The paths, or lines, on the motherboard onwhich data, instructions, and electrical powermove from component to component.

bus mouse — A mouse that plugs into a bus adaptercard and has a round, 9-pin mini-DIN connector.

bus riser — See riser card.

bus speed — The speed, or frequency, at which thedata on the motherboard is moving.

bus topology — A LAN architecture in which all thedevices are connected to a bus, or one communica-tion line. Bus topology does not have a centralconnection point.

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byte — A collection of eight bits that is equivalent toa single character. When referring to system mem-ory, an additional error-checking bit might beadded, making the total nine bits.

cabinet file — A file with a .cab extension that con-tains one or more compressed files and is oftenused to distribute software on disk. The Extractcommand is used to extract files from the cabinetfile.

cable modem — A technology that uses cable TVlines for data transmission requiring a modem ateach end. From the modem, a network cable con-nects to a NIC in the user’s PC.

CAM (Common Access Method) — A standardadapter driver used by SCSI.

capacitor — An electronic device that can maintainan electrical charge for a period of time and isused to smooth out the flow of electrical current.Capacitors are often found in computer powersupplies.

CardBus — The latest PCMCIA specification. Itimproves I/O speed, increases the bus width to 32bits, and supports lower-voltage PC Cards, whilemaintaining backward compatibility with earlierstandards.

cards — Adapter boards or interface cards placedinto expansion slots to expand the functions of acomputer, allowing it to communicate with exter-nal devices such as monitors or speakers.

carrier — A signal used to activate a phone line toconfirm a continuous frequency; used to indicatethat two computers are ready to receive or trans-mit data via modems.

CAS Latency (CL) — A feature of memory thatreflects the number of clock cycles that pass whiledata is written to memory.

CAU (Controlled-Access Unit) — See MAU.

CCITT (Comité Consultatif InternationalTélégraphique et Téléphonique) — An interna-tional organization that was responsible for devel-oping standards for international communica-tions. This organization has been incorporatedinto the ITU. See also ITU.

CD (change directory) command — A commandgiven at the command prompt that changes thedefault directory, for example CD \Windows.

CDFS (Compact Disc File System) — The 32-bit filesystem for CD discs and some CD-R and CD-RWdiscs that replaced the older 16-bit mscdex filesystem used by DOS. See also Universal Disk For-mat (UDF).

CD-R (CD-recordable) — A CD drive that can recordor write data to a CD. The drive may or may notbe multisession, but the data cannot be erasedonce it is written.

CD-RW (CD-rewritable) — A CD drive that canrecord or write data to a CD. The data can beerased and overwritten. The drive may or may notbe multisession.

central processing unit (CPU) — Also called amicroprocessor or processor. The heart and brainof the computer, which receives data input, pro-cesses information, and executes instructions.

chain — A group of clusters used to hold a single file.

checksum — A method of error checking transmitteddata, whereby the digits are added and their sumcompared to an expected sum.

child directory — See subdirectory.

child, parent, grandparent backup method — Aplan for backing up and reusing tapes or remov-able disks by rotating them each day (child), week(parent), and month (grandparent).

chip creep — A condition in which chips loosenbecause of thermal changes.

chip set — A group of chips on the motherboardthat controls the timing and flow of data andinstructions to and from the CPU.

CHS (cylinder, head, sector) mode — The tradi-tional method by which BIOS reads from andwrites to hard drives by addressing the correctcylinder, head, and sector. Also called normalmode.

circuit board — A computer component, such as themain motherboard or an adapter board, that haselectronic circuits and chips.

CISC (complex instruction set computing) — EarlierCPU type of instruction set.

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clamping voltage — The maximum voltage allowedthrough a surge suppressor, such as 175 or 330volts.

clean install — Installing an OS on a new hard driveor on a hard drive that has a previous OSinstalled, but without carrying forward any set-tings kept by the old OS, including informationabout hardware, software, or user preferences. Afresh installation.

client/server — A computer concept whereby onecomputer (the client) requests information fromanother computer (the server).

client/server application — An application that hastwo components. The client software requestsdata from the server software on the same oranother computer.

clock speed — The speed, or frequency, expressed inMHz, that controls activity on the motherboardand is generated by a crystal or oscillator locatedsomewhere on the motherboard.

clone — A computer that is a no-name Intel- andMicrosoft-compatible PC.

cluster — One or more sectors that constitute thesmallest unit of space on a disk for storing data(also referred to as a file allocation unit). Files arewritten to a disk as groups of whole clusters.

CMOS (complementary metal-oxide semiconductor)— The technology used to manufacturemicrochips. CMOS chips require less electricity,hold data longer after the electricity is turned off,are slower, and produce less heat than earliertechnologies. The configuration, or setup, chip isa CMOS chip.

CMOS configuration chip — A chip on the mother-board that contains a very small amount of mem-ory, or RAM — enough to hold configuration, orsetup, information about the computer The chipis powered by a battery when the PC is turned off.Also called CMOS setup chip or CMOS RAMchip.

CMOS setup — (1) The CMOS configuration chip.(2) The program in system BIOS that can changethe values in the CMOS RAM.

CMOS setup chip — See CMOS configuration chip.

COAST (cache on a stick) — Memory modules thathold memory used as a memory cache. See mem-ory cache.

coaxial cable — Networking cable used with10-Mbps Ethernet ThinNet or ThickNet.

cold boot — See hard boot.

combo card — An Ethernet card that contains morethan one transceiver, each with a different port onthe back of the card, in order to accommodatedifferent cabling media.

Command.com — Along with Msdos.sys and Io.sys,one of the three files that are the core componentsof the real-mode portion of Windows 9x. Com-mand.com provides a command prompt andinterprets commands.

comment — A line or part of a line in a programthat is intended as a remark or comment and isignored when the program runs. A semicolon oran REM is often used to mark a line as a comment.

communication and networking riser (CNR) — Aspecification for a small expansion slot on a moth-erboard that accommodates a small audio,modem, or network riser card.

compact case — A type of case used in low-end desk-top systems. Compact cases, also called low-profile or slimline cases, follow either the NLX,LPX, or Mini LPX form factor. They are likely tohave fewer drive bays, but they generally still pro-vide for some expansion.

Compatibility Mode utility — A Windows XP utilitythat provides an application with the olderMicrosoft OS environment it was designed tooperate in.

compressed drive — A drive whose format has beenreorganized in order to store more data. A com-pressed drive is really not a drive at all; it’s actu-ally a type of file, typically with a host drivecalled H.

computer name — Character-based host name orNetBIOS name assigned to a computer.

Config.sys — A text file used by DOS and supportedby Windows 9x that lists device drivers to beloaded at startup. It can also set system variablesto be used by DOS and Windows.

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Configuration Manager — A component of Win-dows Plug and Play that controls the configura-tion process of all devices and communicatesthese configurations to the devices.

connectionless protocol — A protocol such as UDPthat does not require a connection before sendinga packet and does not guarantee delivery. Anexample of a UDP transmission is streaming videoover the Web. Also called a best-effort protocol.

connection-oriented protocol — In networking, aprotocol that confirms that a good connection hasbeen made before transmitting data to the otherend. An example of a connection-oriented proto-col is TCP.

console — A centralized location from which to exe-cute commonly used tools.

constant angular velocity (CAV) — A technologyused by hard drives and newer CD-ROM driveswhereby the disk rotates at a constant speed.

constant linear velocity (CLV) — A CD-ROM for-mat in which the spacing of data is consistent onthe CD, but the speed of the disc varies dependingon whether the data being read near the center orthe edge of the disc.

continuity — A continuous, unbroken path for theflow of electricity. A continuity test can determinewhether or not internal wiring is still intact, orwhether a fuse is good or bad.

control blade — A laser printer component that pre-vents too much toner from sticking to the cylindersurface.

conventional memory — Memory addressesbetween 0 and 640K. Also called base memory.

cooler — A combination cooling fan and heat sinkmounted on the top or side of a processor to keepit cool.

CRC (cyclical redundancy check) — A process inwhich calculations are performed on bytes of databefore and after they are transmitted to check forcorruption during transmission.

credit card memory — A type of memory used onolder notebooks that could upgrade existing mem-ory by way of a specialized memory slot.

C-RIMM (Continuity RIMM) — A placeholder RIMMmodule that provides continuity so that everyRIMM slot is filled.

cross-linked clusters — Errors caused when morethan one file points to a cluster, and the filesappear to share the same disk space, according tothe file allocation table.

crossover cable — A cable used to connect two PCsinto the simplest network possible. Also used toconnect two hubs.

CVF (compressed volume file) — The file on thehost drive of a compressed drive that holds allcompressed data.

data bus — The lines on the system bus that the CPUuses to send and receive data.

data cartridge — A type of tape medium typicallyused for backups. Full-sized data cartridges are4 × 6 2� inches in size. A minicartridge is only3¼ × 2½ 2� inches in size.

data line protector — A surge protector designed towork with the telephone line to a modem.

data path size — The number of lines on a bus thatcan hold data, for example, 8, 16, 32, and 64lines, which can accommodate 8, 16, 32, and 64bits at a time.

data throughput — See bandwidth.

datagram — See packet.

DC controller — A card inside a notebook that con-verts voltage to CPU voltage. Some notebookmanufacturers consider the card to be an FRU.

DCE (Data Communications Equipment) — Thehardware, usually a dial-up modem, that providesthe connection between a data terminal and acommunications line. See also DTE.

default gateway — The gateway a computer on anetwork will use to access another network unlessit knows to specifically use another gateway forquicker access to that network.

default printer — The printer Windows prints tounless another printer is selected.

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defragment — To “optimize” or rewrite a file to adisk in one contiguous chain of clusters, thusspeeding up data retrieval.

demodulation — The process by which digital datathat has been converted to analog data is con-verted back to digital data. See modulation.

desktop — The initial screen that is displayed whenan OS has a GUI interface loaded.

device driver — A program stored on the hard drivethat tells the computer how to communicate withan input/output device such as a printer or modem.

DHCP (Dynamic Host Configuration Protocol) server— A service that assigns dynamic IP addresses tocomputers on a network when they first accessthe network.

diagnostic cards — Adapter cards designed to dis-cover and report computer errors and conflicts atPOST time (before the computer boots up), oftenby displaying a number on the card.

diagnostic software — Utility programs that helptroubleshoot computer systems. Some Windowsdiagnostic utilities are CHKDSK and SCANDISK.PC-Technician is an example of a third-partydiagnostic program.

dial-up networking — A Windows 9x and WindowsNT/2000/XP utility that uses a modem and tele-phone line to connect to a network.

differential backup — Backup method that backs uponly files that have changed or have been createdsince the last full backup. When recovering data,only two backups are needed: the full backup andthe last differential backup.

differential cable — A SCSI cable in which a signalis carried on two wires, each carrying voltage, andthe signal is the difference between the two. Dif-ferential signaling provides for error checking andgreater data integrity. Compare to single-endedcable.

digital certificate — A code used to authenticate thesource of a file or document or to identify andauthenticate a person or organization sendingdata over the Internet. The code is assigned by acertificate authority such as VeriSign and includesa public key for encryption. Also called digital IDor digital signature.

digital ID — See digital certificate.

digital signature — See digital certificate.

DIMM (dual inline memory module) — A miniaturecircuit board used in newer computers to holdmemory. DIMMs can hold up to 2 GB of RAMon a single module.

diode — An electronic device that allows electricityto flow in only one direction. Used in a rectifiercircuit.

DIP (dual inline package) switch — A switch on acircuit board or other device that can be set on oroff to hold configuration or setup information.

direct current (DC) — Current that travels in onlyone direction (the type of electricity provided bybatteries). Computer power supplies transformAC to low DC.

Direct Rambus DRAM — A memory technology byRambus and Intel that uses a narrow, very fastnetwork-type system bus. Memory is stored on aRIMM module. Also called RDRAM or DirectRDRAM.

Direct RDRAM — See Direct Rambus DRAM.

directory table — An OS table that contains fileinformation such as the name, size, time and dateof last modification, and cluster number of thefile’s beginning location.

discrete L2 cache — A type of L2 cache containedwithin the Pentium processor housing, but on adifferent die, with a cache bus between the proces-sor and the cache.

disk cache — A method whereby recently retrieveddata and adjacent data are read into memory inadvance, anticipating the next CPU request.

disk cloning — See drive imaging.

disk compression — Compressing data on a harddrive to allow more data to be written to the drive.

disk imaging — See drive imaging.

Disk Management — A Windows 2000/XP utilityused to display, create, and format partitions onbasic disks and volumes on dynamic disks.

disk quota — A limit placed on the amount of diskspace that is available to users. Requires a Win-dows 2000/XP NTFS volume.

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disk thrashing — A condition that results when thehard drive is excessively used for virtual memorybecause RAM is full. It dramatically slows downprocessing and can cause premature hard drivefailure.

Display Power Management Signaling (DPMS) —Energy Star standard specifications that allow forthe video card and monitor to go into sleep modesimultaneously. See also Energy Star.

distribution server — A file server holding Windowssetup files used to install Windows on computersnetworked to the server.

DMA (direct memory access) channel — A numberidentifying a channel whereby a device can passdata to memory without involving the CPU.Think of a DMA channel as a shortcut for datamoving to/from the device and memory.

DMA transfer mode — A transfer mode used bydevices, including the hard drive, to transfer datato memory without involving the CPU.

DNS (domain name service or domain name sys-tem) — A distributed pool of information (calledthe name space) that keeps track of assigneddomain names and their corresponding IPaddresses, and the system that allows a host tolocate information in the pool. Compare to WINS.

DNS server — A computer that can find an IPaddress for another computer when only thedomain name is known.

docking station — A device that receives a notebookcomputer and provides additional secondary stor-age and easy connection to peripheral devices.

domain — In Windows NT/2000/XP, a logical groupof networked computers, such as those on a col-lege campus, that share a centralized directorydatabase of user account information and securityfor the entire domain.

domain controller — A Windows NT/2000 com-puter which holds and controls a database of (1)user accounts, (2) group accounts, and (3) com-puter accounts used to manage access to thenetwork.

domain name — A unique, text-based name thatidentifies a network.

DOS box — A command window.

Dosstart.bat — A type of Autoexec.bat file that isexecuted by Windows 9x in two situations: whenyou select Restart the computer in MS-DOS modefrom the shutdown menu or you run a program inMS-DOS mode.

dot pitch — The distance between the dots that theelectronic beam hits on a monitor screen.

Double Data Rate SDRAM (DDR SDRAM) — A type ofmemory technology used on DIMMs that runs attwice the speed of the system clock.

doze time — The time before an Energy Star or“Green” system will reduce 80 percent of itsactivity.

Dr. Watson — A Windows utility that can recorddetailed information about the system, errors thatoccur, and the programs that caused them in a logfile. Windows 9x names the log file \Windows\Drwatson\WatsonXX.wlg, where XX is an incre-menting number. Windows 2000 names the file\Documents and Settings\user\Documents\ DrWat-son\Drwtsn32.log. Windows XP calls the fileDrwatson.log.

drive imaging — Making an exact image of a harddrive, including partition information, boot sec-tors, operating system installation, and applica-tion software to replicate the hard drive onanother system or recover from a hard drivecrash. Also called disk cloning and disk imaging.

DriveSpace — A Windows 9x utility that compressesfiles so that they take up less space on a diskdrive, creating a single large file on the disk tohold all the compressed files.

drop height — The height from which a manufac-turer states that its drive can be dropped withoutmaking the drive unusable.

DSL (Digital Subscriber Line) — A telephone linethat carries digital data from end to end, and canbe leased from the telephone company for individ-ual use. DSL lines are rated at 5 Mbps, about 50times faster than regular telephone lines.

DTE (Data Terminal Equipment) — Both the com-puter and a remote terminal or other computer towhich it is attached. See also DCE.

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dual boot — The ability to boot using either of twodifferent OSs, such as Windows 98 and WindowsXP.

dual-scan passive matrix — A type of video displaythat is less expensive than an active-matrix dis-play and does not provide as high-quality animage. With dual-scan display, two columns ofelectrodes are activated at the same time.

dual-voltage CPU — A CPU that requires two differ-ent voltages, one for internal processing and theother for I/O processing.

dump file — A file that contains information cap-tured from memory at the time a stop erroroccurred.

DVD (digital video disc or digital versatile disk) —A faster, larger CD format that can read olderCDs, store over 8 GB of data, and hold full-lengthmotion picture videos.

dye-sublimation printer — A type of printer withphoto-lab-quality results that uses transparentdyed film. The film is heated, which causes thedye to vaporize onto glossy paper.

dynamic disk — A way to partition one or morehard drives, introduced with Windows 2000, inwhich information about the drive is stored in adatabase at the end of the drive. Compare to basicdisk.

dynamic IP address — An assigned IP address that isused for the current session only. When the ses-sion is terminated, the IP address is returned tothe list of available addresses.

dynamic RAM (DRAM) — The most common type ofsystem memory, it requires refreshing every fewmilliseconds.

dynamic volume — A volume type used withdynamic disks for which you can change the sizeof the volume after you have created it.

dynamic VxD — A VxD that is loaded and unloadedfrom memory as needed.

ECC (error-correcting code) — A chip set feature ona motherboard that checks the integrity of datastored on DIMMs or RIMMs and can correct sin-gle-bit errors in a byte. More advanced ECC

schemas can detect, but not correct, double-biterrors in a byte.

ECHS (extended CHS) mode — See large mode.

ECP (Extended Capabilities Port) — A bidirectionalparallel port mode that uses a DMA channel tospeed up data flow.

EDO (extended data out) — A type of RAM thatmay be 10–20 percent faster than conventionalRAM because it eliminates the delay before itissues the next memory address.

EEPROM (electrically erasable programmable ROM)— A type of chip in which higher voltage may beapplied to one of the pins to erase its previousmemory before a new instruction set is electroni-cally written.

EIDE (Enhanced IDE) — A standard for managingthe interface between secondary storage devicesand a computer system. A system can support upto six serial ATA and parallel ATA IDE devices orup to four parallel ATA IDE devices such as harddrives, CD-ROM drives, and Zip drives.

electromagnetic interference (EMI) — A magneticfield produced as a side effect from the flow ofelectricity. EMI can cause corrupted data in datalines that are not properly shielded.

electrostatic discharge (ESD) — Another name forstatic electricity, which can damage chips anddestroy motherboards, even though it might notbe felt or seen with the naked eye.

Emergency Repair Disk (ERD) — A Windows NTrecord of critical information about your systemthat can be used to fix a problem with the OS.The ERD enables restoration of the Windows NTregistry on your hard drive.

Emergency Repair Process — A Windows 2000 pro-cess that restores the OS to its state at the comple-tion of a successful installation.

emergency startup disk (ESD) — See rescue disk.

Emm386.exe — A DOS and Windows 9x utility thatprovides access to upper memory for 16-bit devicedrivers and other software.

Encrypted File System (EFS) — A way to use a keyto encode a file or folder on an NTFS volume toprotect sensitive data. Because it is an integrated

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system service, EFS is transparent to users andapplications and is difficult to attack.

encrypting virus — A type of virus that transformsitself into a nonreplicating program in order toavoid detection. It transforms itself back into areplicating program in order to spread.

encryption — The process of putting readable datainto an encoded form that can only be decoded(or decrypted) through use of a key.

Energy Star — “Green” systems that satisfy the EPArequirements to decrease the overall consumptionof electricity. See also Green Standards.

enhanced BIOS — A system BIOS that has been writ-ten to accommodate large-capacity drives (over504 MB, usually in the gigabyte range).

EPIC (explicitly parallel instruction computing) —The CPU architecture used by the Intel Itaniumchip that bundles programming instructions withinstructions on how to use multiprocessing abili-ties to do two instructions in parallel.

EPP (Enhanced Parallel Port) — A parallel port thatallows data to flow in both directions (bidirec-tional port) and is faster than original parallelports on PCs that allowed communication only inone direction.

EPROM (erasable programmable ROM) — A type ofchip with a special window that allows the cur-rent memory contents to be erased with specialultraviolet light so that the chip can be repro-grammed. Many BIOS chips are EPROMs.

error correction — The ability of a modem to iden-tify transmission errors and then automaticallyrequest another transmission.

Ethernet — The most popular LAN architecture thatcan run at 10 Mbps (ThinNet or ThickNet), 100Mbps (Fast Ethernet), or 1 Gbps(Gigabit Ethernet).

Execution Trace Cache — A type of Level 1 cacheused by some CPUs to hold decoded operationswaiting to be executed.

executive services — In Windows NT/2000/XP, agroup of components running in kernel mode thatinterfaces between the subsystems in user modeand the HAL.

expansion bus — A bus that does not run in syncwith the system clock.

expansion card — A circuit board inserted into aslot on the motherboard to enhance the capabilityof the computer.

expansion slot — A narrow slot on the motherboardwhere an expansion card can be inserted. Expan-sion slots connect to a bus on the motherboard.

extended memory — Memory above 1024K used ina DOS or Windows 9x system.

extended partition — The only partition on a harddrive that can contain more than one logical drive.

external cache — Static cache memory, stored onthe motherboard or inside the CPU housing, thatis not part of the CPU (also called L2 or L3 cache).

external command — Commands that have theirown program files.

faceplate — A metal plate that comes with the moth-erboard and fits over the ports to create a well-fitted enclosure around them.

Fast Ethernet — See 100BaseT.

FAT (file allocation table) — A table on a hard driveor floppy disk that tracks the clusters used to con-tain a file.

FAT12 — The 12-bit wide, one-column file allocationtable for a floppy disk, containing informationabout how each cluster or file allocation unit onthe disk is currently used.

fault tolerance — The degree to which a system cantolerate failures. Adding redundant components,such as disk mirroring or disk duplexing, is a wayto build in fault tolerance.

Fiber Distributed Data Interface (FDDI) — A ring-based network that does not require a centralizedhub and can transfer data at a rate of 100 Mbps.

field replaceable unit (FRU) — A component in acomputer or device that can be replaced with anew component without sending the computer ordevice back to the manufacturer. Examples:power supply, DIMM, motherboard, floppy diskdrive.

file allocation unit — See cluster.

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file extension — A three-character portion of thename of a file that is used to identify the file type.In command lines, the file extension follows thefilename and is separated from it by a period. Forexample, Msd.exe, where exe is the file extension.

file system — The overall structure that an OS usesto name, store, and organize files on a disk.Examples of file systems are FAT32 and NTFS.

file virus — A virus that inserts virus code into anexecutable program file and can spread wheneverthat program is executed.

filename — The first part of the name assigned to afile. In DOS, the filename can be no more thaneight characters long and is followed by the fileextension. In Windows, a filename can be up to255 characters.

firewall — Hardware or software that protects acomputer or network from unauthorized access.

FireWire — See IEEE 1394.

firmware — Software that is permanently stored in achip. The BIOS on a motherboard is an exampleof firmware.

flash ROM — ROM that can be reprogrammed orchanged without replacing chips.

flat panel monitor — A desktop monitor that usesan LCD panel.

FlexATX — A version of the ATX form factor thatallows for maximum flexibility in the size andshape of cases and motherboards. FlexATX isideal for custom systems.

flow control — When using modems, a method ofcontrolling the flow of data to adjust for prob-lems with data transmission. Xon/Xoff is anexample of a flow control protocol.

folder — See subdirectory.

folder redirection — A Windows XP feature thatallows a user to point to a folder that can be onthe local PC or somewhere on the network, andits location can be transparent to the user.

forced perfect terminator (FPT) — A type of SCSIactive terminator that includes a mechanism toforce signal termination to the correct voltage,eliminating most signal echoes and interference.

forgotten password floppy disk — A Windows XPdisk created to be used in the event the user for-gets the user account password to the system.

form factor — A set of specifications on the size,shape, and configuration of a computer hardwarecomponent such as a case, power supply, ormotherboard.

formatting — Preparing a hard drive volume orfloppy disk for use by placing tracks and sectorson its surface to store information (for example,FORMAT A:).

FPM (fast page mode) — A memory mode usedbefore the introduction of EDO memory. FPMimproved on earlier memory types by sending therow address just once for many accesses to mem-ory near that row.

fragmentation — The distribution of data files on ahard drive or floppy disk such that they are storedin noncontiguous clusters.

fragmented file — A file that has been written todifferent portions of the disk so that it is not incontiguous clusters.

frame — The header and trailer information addedto data to form a data packet to be sent over anetwork.

front-side bus — See system bus.

FTP (File Transfer Protocol) — The protocol used totransfer files over a TCP/IP network such that thefile does not need to be converted to ASCII for-mat before transferring it.

full AT — See AT.

full backup — A complete backup, whereby all ofthe files on the hard drive are backed up eachtime the backup procedure is performed. It is thesafest backup method, but it takes the most time.

full-duplex — Communication that happens in twodirections at the same time.

fully qualified domain name (FQDN) — A hostname and a domain name such asjsmith.amazon.com. Sometimes loosely referred toas a domain name.

gateway — A computer or other device that connectsnetworks.

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GDI (Graphics Device Interface) — A Windows 9xcomponent that controls screens, graphics, andprinting.

General Protection Fault (GPF) — A Windows errorthat occurs when a program attempts to access amemory address that is not available or is nolonger assigned to it.

Gigabit Ethernet — The newest version of Ethernet.Gigabit Ethernet supports rates of data transferup to 1 gigabit per second but is not yet widelyused.

gigahertz (GHz) — One thousand MHz, or one bil-lion cycles per second.

global user account — Sometimes called a domainuser account, the account is used at the domainlevel, created by an administrator, and stored inthe SAM (security accounts manager) database ona Windows 2000 or Windows 2003 domaincontroller.

graphics accelerator — A type of video card that hasan on-board processor that can substantiallyincrease speed and boost graphical and videoperformance.

Green Standards — A computer or device that con-forms to these standards can go into sleep or dozemode when not in use, thus saving energy andhelping the environment. Devices that carry theGreen Star or Energy Star comply with thesestandards.

ground bracelet — A strap you wear around yourwrist that is attached to the computer case,ground mat, or another ground so that ESD isdischarged from your body before you touch sensi-tive components inside a computer. Also calledstatic strap, ground strap, ESD bracelet.

group profile — A group of user profiles. All profilesin the group can be changed by changing thegroup profile.

guard tone — A tone that an answering modemsends when it first answers the phone, to tell thecalling modem that a modem is on the other endof the line.

Guest user — A user who has limited permissions ona system and cannot make changes to it. Guest

user accounts are intended for one-time or infre-quent users of a workstation.

HAL (hardware abstraction layer) — The low-levelpart of Windows NT/2000/XP, written specifi-cally for each CPU technology, so that only theHAL must change when platform componentschange.

half life — The time it takes for a medium storingdata to weaken to half of its strength. Magneticmedia, including traditional hard drives andfloppy disks, have a half-life of five to seven years.

half-duplex — Communication between two deviceswhereby transmission takes place in only onedirection at a time.

handshaking — When two modems begin to com-municate, the initial agreement made as to how tosend and receive data.

hard boot — Restart the computer by turning off thepower or by pressing the Reset button. Also calleda cold boot.

hard copy — Output from a printer to paper.

hard drive — The main secondary storage device ofa PC, a small case that contains magnetic coatedplatters that rotate at high speed.

hard drive controller — The firmware that controlsaccess to a hard drive contained on a circuitboard mounted on or inside the hard drive hous-ing. Older hard drives used firmware on a con-troller card that connected to the drive by way oftwo cables, one for data and one for control.

hard drive standby time — The amount of timebefore a hard drive will shut down to conserveenergy.

hard-disk loading — The illegal practice of installingunauthorized software on computers for sale.Hard-disk loading can typically be identified bythe absence of original software disks in the origi-nal system’s shipment.

hardware — The physical components that consti-tute the computer system, such as the monitor,the keyboard, the motherboard, and the printer.

hardware address — See MAC address.

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hardware cache — A disk cache that is contained inRAM chips built right on the disk controller. Alsocalled a buffer.

hardware interrupt — An event caused by a hard-ware device signaling the CPU that it requiresservice.

hardware profile — A set of hardware configurationinformation that Windows keeps in the registry.Windows can maintain more than one hardwareprofile for the same PC.

HCL (hardware compatibility list) — The list of allcomputers and peripheral devices that have beentested and are officially supported by WindowsNT/2000/XP (see www.microsoft.com/whdc/hcl/default.mspx).

HD-DVD (high-density or high-definition DVD) —A new DVD standard that supports high-definition video encoding using blue or violetlasers. HD-DVD discs cannot be read by regularDVD drives.

head — The top or bottom surface of one platter ona hard drive. Each platter has two heads.

heat sink — A piece of metal, with cooling fins, thatcan be attached to or mounted on an integratedchip (such as the CPU) to dissipate heat.

hertz (Hz) — Unit of measurement for frequency,calculated in terms of vibrations, or cycles per sec-ond. For example, for 16-bit stereo sound, a fre-quency of 44,000 Hz is used. See also megahertz.

hexadecimal notation (hex) — A numbering systemthat uses 16 digits, the numerals 0–9, and the let-ters A–F. Hexadecimal notation is often used todisplay memory addresses.

hibernation — A notebook OS feature that con-serves power by using a small trickle of electricity.Before the notebook begins to hibernate, every-thing currently stored in memory is saved to thehard drive. When the notebook is brought out ofhibernation, open applications and their data arereturned to the state before hibernation.

hidden file — A file that is not displayed in a direc-tory list. Whether to hide or display a file is oneof the file’s attributes kept by the OS.

high memory area (HMA) — The first 64K ofextended memory.

High Voltage Differential (HVD) — A type of SCSIdifferential signaling requiring more expensivehardware to handle the higher voltage. HVDbecame obsolete with the introduction of SCSI-3.

high-level formatting — Formatting performed bymeans of the DOS or Windows Format program(for example, FORMAT C:/S creates the bootrecord, FAT, and root directory on drive C andmakes the drive bootable). Also called OSformatting.

Himem.sys — The DOS and Windows 9x memorymanager extension that allowed access to memoryaddresses above 1 MB.

hive — Physical segment of the Windows NT/ 2000/XP registry that is stored in a file.

hop count — See time to live (TTL).

host — Any computer or other device on a networkthat has been assigned an IP address.Also called node.

host adapter — The circuit board that controls aSCSI bus supporting as many as seven or fifteenseparate devices. The host adapter controls com-munication between the SCSI bus and the PC.

host bus — See memory bus or system bus.

host drive — Typically drive H on a compresseddrive. See compressed drive.

host name — A name that identifies a computer,printer, or other device on a network.

hot-pluggable — See hot-swappable.

hot-swappable — A device that can be plugged intoa computer while it is turned on and the computerwill sense the device and configure it withoutrebooting, or the device can be removed withoutan OS error. Also called hot-pluggable.

HTML (HyperText Markup Language) — A markuplanguage used for hypertext documents on theWorld Wide Web. This language uses tags to for-mat the document, create hyperlinks, and marklocations for graphics.

HTTP (HyperText Transfer Protocol) — The proto-col used by the World Wide Web.

HTTPS (HTTP secure) — A version of the HTTP pro-tocol that includes data encryption for security.

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hub — A network device or box that provides a cen-tral location to connect cables.

hypertext — Text that contains links to remotepoints in the document or to other files, docu-ments, or graphics. Hypertext is created usingHTML and is commonly distributed from Websites.

i.Link — See IEEE 1394.

IBM Data Connector – See IDC.

IDC (IBM Data Connector) — A connector used withSTP cable on a Token Ring network. Also called aUDC (Universal Data Connector).

I/O addresses — Numbers that are used by devicesand the CPU to manage communication betweenthem. Also called ports or port addresses.

I/O controller card — An older card that can containserial, parallel, and game ports and floppy driveand IDE connectors.

IBM-compatible PC — A computer that uses an Intel(or compatible) processor and can run DOS andWindows.

ICMP (Internet Control Message Protocol) — Part ofthe IP layer that is used to transmit error messagesand other control messages to hosts and routers.

IDE (Integrated Drive Electronics or IntegratedDevice Electronics) — A hard drive whose diskcontroller is integrated into the drive, eliminatingthe need for a controller cable and thus increasingspeed, as well as reducing price. See also EIDE.

IEEE 1284 — A standard for parallel ports andcables developed by the Institute for Electrical andElectronics Engineers and supported by manyhardware manufacturers.

IEEE 1394 — Standards for an expansion bus thatcan also be configured to work as a local bus. It isexpected to replace the SCSI bus, providing aneasy method to install and configure fast I/Odevices. Also called FireWire and i.Link.

IEEE 1394.3 — A standard, developed by the 1394Trade Association, that is designed for peer-to-peer data transmission and allows imaging devicesto send images and photos directly to printerswithout involving a computer.

IEEE 802.11b — An IEEE specification for wirelesscommunication and data synchronization thatcompetes with Bluetooth. Also known as Wi-Fi.Apple Computer’s version of 802.11b is calledAirPort.

IMAP4 (Internet Message Access Protocol version 4) — Version 4 of the IMAP protocol, which isan e-mail protocol that has more functionalitythan its predecessor, POP. IMAP can archive mes-sages in folders on the e-mail server and can allowthe user to choose not to download attachmentsto messages.

incremental backup — A time-saving backupmethod that only backs up files changed or newlycreated since the last full or incremental backup.Multiple incremental backups might be requiredwhen recovering lost data.

infestation — Any unwanted program that is trans-mitted to a computer without the user’s knowl-edge and that is designed to do varying degrees ofdamage to data and software. There are a numberof different types of infestations, includingviruses, Trojan horses, worms, and logic bombs.

information (.inf) file — Text file with an .inf fileextension, such as Msbatch.inf, that containsinformation about a hardware or softwareinstallation.

infrared transceiver — A wireless transceiver thatuses infrared technology to support some wirelessdevices such as keyboards, mice, and printers. Amotherboard might have an embedded infraredtransceiver, or the transceiver might plug into aUSB or serial port. The technology is defined bythe Infrared Data Association (IrDA). Also calledan IrDA transceiver or infrared port.

initialization files — Configuration informationfiles for Windows. System.ini is one of the mostimportant Windows 9x initialization files.

inkjet printer — A type of ink dispersion printerthat uses cartridges of ink. The ink is heated to aboiling point and then ejected onto the paperthrough tiny nozzles.

Institute of Electrical and Electronics Engineers(IEEE) — A nonprofit organization that developsstandards for the computer and electronicsindustries.

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instruction set — The set of instructions, on theCPU chip, that the computer can perform directly(such as ADD and MOVE).

intelligent UPS — A UPS connected to a computerby way of a USB or serial cable so that softwareon the computer can monitor and control theUPS. Also called smart UPS.

interlaced — A type of display in which the elec-tronic beam of a monitor draws every other linewith each pass, which lessens the overall effect ofa lower refresh rate.

internal bus — The bus inside the CPU that is usedfor communication between the CPU’s internalcomponents.

internal cache — Memory cache that is faster thanexternal cache, and is contained inside CPU chips(also referred to as primary, Level 1, or L1 cache).

internal command — Commands that are embeddedin the Command.com file.

Internet Connection Firewall (ICF) — Windows XPsoftware designed to protect a PC from unautho-rized access from the Internet.

Internet Connection Sharing (ICS) — A Windows98 and Windows XP utility that uses NAT andacts as a proxy server to manage two or morecomputers connected to the Internet.

Internet service provider (ISP) — A commercialgroup that provides Internet access for a monthlyfee. AOL, Earthlink, and CompuServe are largeISPs.

intranet — A private network that uses the TCP/IPprotocols.

Io.sys — Along with Msdos.sys and Command.com,one of the three files that are the core componentsof the real mode portion of Windows 9x. It is thefirst program file of the OS.

IP (Internet Protocol) — The rules of communica-tion in the TCP/IP stack that control segmentingdata into packets, routing those packets acrossnetworks, and then reassembling the packets oncethey reach their destination.

IP address — A 32-bit address consisting of fournumbers separated by periods, used to uniquelyidentify a device on a network that uses TCP/IPprotocols. The first numbers identify the network;

the last numbers identify a host. An example ofan IP address is 206.96.103.114.

IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) — A networkingprotocol suite first used by Novell NetWare, andwhich corresponds to the TCP/IP protocols.

IrDA transceiver — See infrared transceiver.

IRQ (interrupt request) line — A line on a bus thatis assigned to a device and is used to signal theCPU for servicing. These lines are assigned a refer-ence number (for example, the normal IRQ for aprinter is IRQ 7).

ISA (Industry Standard Architecture) slot — Anolder slot on the motherboard used for slower I/Odevices, which can support an 8-bit or a 16-bitdata path. ISA slots are mostly replaced by PCIslots.

ISDN (Integrated Services Digital Network) — Adigital telephone line that can carry data at aboutfive times the speed of regular telephone lines.Two channels (telephone numbers) share a singlepair of wires.

isochronous data transfer — A method used byIEEE 1394 to transfer data continuously withoutbreaks.

ITU (International Telecommunications Union) —The international organization responsible fordeveloping international standards of communica-tion. Formerly CCITT.

JPEG (Joint Photographic Experts Group) — Agraphical compression scheme that allows theuser to control the amount of data that is aver-aged and sacrificed as file size is reduced. It is acommon Internet file format. Most JPEG fileshave a .jpg extension.

jumper — Two wires that stick up side by side onthe motherboard and are used to hold configura-tion information. The jumper is considered closedif a cover is over the wires, and open if the coveris missing.

kernel — The portion of an OS that is responsiblefor interacting with the hardware.

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kernel mode — A Windows NT/2000/XP “privi-leged” processing mode that has access to hard-ware components.

key — (1) In encryption, a secret number or codeused to encode and decode data. (2) In Windows,a section name of the Windows registry.

keyboard — A common input device through whichdata and instructions may be typed into computermemory.

LAN (local area network) — A computer networkthat covers only a small area, usually within onebuilding.

lands — Microscopic flat areas on the surface of aCD or DVD that separate pits. Lands and pits areused to represent data on the disk.

laptop computer — See notebook.

large mode — A mode of addressing information onhard drives that range from 504 MB to 8.4 GB,addressing information on a hard drive by trans-lating cylinder, head, and sector information inorder to break the 528-MB hard drive barrier.Also called ECHS mode.

large-capacity drive — A hard drive larger than 504MB.

laser printer — A type of printer that uses a laserbeam to control how toner is placed on the pageand then uses heat to fuse the toner to the page.

Last Known Good configuration — In WindowsNT/2000/XP, registry settings and device driversthat were in effect when the computer last bootedsuccessfully. These settings can be restored duringthe startup process to recover from errors duringthe last boot.

LBA (logical block addressing) mode — A mode ofaddressing information on hard drives in whichthe BIOS and operating system view the drive asone long linear list of LBAs or addressable sec-tors, permitting drives to be larger than 8.4 GB(LBA 0 is cylinder 0, head 0, and sector 1).

Level 1 (L1) cache — See internal cache.

Level 2 (L2) cache — See external cache.

Level 3 (L3) cache — See external cache.

Limited user — Windows XP user accounts knownas Users in Windows NT/2000, which have read-write access only on their own folders, read-onlyaccess to most system folders, and no access toother users’ data.

line conditioner — A device that regulates, or condi-tions, power, providing continuous voltage duringbrownouts and spikes.

line protocol — A protocol used to send data pack-ets destined for a network over telephone lines.PPP and SLIP are examples of line protocols.

line speed — See bandwidth.

line-interactive UPS — A variation of a standby UPSthat shortens switching time by always keepingthe inverter that converts AC to DC working, sothat there is no charge-up time for the inverter.

LMHosts — A text file located in the Windows folderthat contains NetBIOS names and their associatedIP addresses. This file is used for name resolutionfor a NetBEUI network.

local bus — A bus that operates at a speed synchro-nized with the CPU frequency. The system bus isa local bus.

local I/O bus — A local bus that provides I/O deviceswith fast access to the CPU. The PCI bus is a localI/O bus.

local printer — A printer connected to a computerby way of a port on the computer. Compare tonetwork printer.

local profile — User profile that is stored on a localcomputer and cannot be accessed from anothercomputer on the network.

local user account — A user account that appliesonly to a local computer and cannot be used toaccess resources from other computers on thenetwork.

logic bomb — Dormant code added to software thatis triggered by a predetermined time or event.

logical drive — A portion or all of a hard drive parti-tion that is treated by the operating system asthough it were a physical drive. Each logical driveis assigned a drive letter, such as drive C, and con-tains a file system. Also called a volume.

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logical geometry — The number of heads, tracks,and sectors that the BIOS on the hard drive con-troller presents to the system BIOS and the OS.The logical geometry does not consist of the samevalues as the physical geometry, although calcula-tions of drive capacity yield the same results.

Logical Unit Number (LUN) — A number assignedto a logical device (such as a tray in a CDchanger) that is part of a physical SCSI device,which is assigned a SCSI ID.

lost allocation units — See lost clusters.

lost clusters — File fragments that, according to thefile allocation table, contain data that does notbelong to any file. The command CHKDSK/F canfree these fragments. Also called lost allocationunits.

low insertion force (LIF) socket — A socket thatrequires the installer to manually apply an evenforce over the microchip when inserting the chipinto the socket.

Low Voltage Differential (LVD) — A type of differen-tial signaling that uses lower voltage than doesHVD, is less expensive, and can be compatiblewith single-ended signaling on the same SCSI bus.

low-level formatting — A process (usually per-formed at the factory) that electronically createsthe hard drive tracks and sectors and tests for badspots on the disk surface.

low-profile case — See compact case.

LPX — A form factor in which expansion cards aremounted on a riser card that plugs into a mother-board. The expansion cards in LPX systems aremounted parallel to the motherboard, rather thanperpendicular to it as in AT and ATX systems.

MAC (Media Access Control) address — A 6-bytehexadecimal hardware address unique to eachNIC card and assigned by the manufacturer. Theaddress is often printed on the adapter. An exam-ple is 00 00 0C 08 2F 35. Also called a physicaladdress, an adapter address, or a hardwareaddress.

macro — A small sequence of commands, containedwithin a document, that can be automatically exe-

cuted when the document is loaded, or executedlater by using a predetermined keystroke.

macro virus — A virus that can hide in the macros ofa document file.

main board — See motherboard.

mandatory user profile — A roaming user profilethat applies to all users in a user group, and indi-vidual users cannot change that profile.

Master Boot Record (MBR) — The first sector on ahard drive, which contains the partition table anda program the BIOS uses to boot an OS from thedrive.

master file table (MFT) — The database used by theNTFS file system to track the contents of a logicaldrive.

material safety data sheet (MSDS) — A documentthat explains how to properly handle substancessuch as chemical solvents; it includes informationsuch as physical data, toxicity, health effects, firstaid, storage, disposal, and spill procedures.

megahertz (MHz) — One million Hz, or one millioncycles per second. See hertz (Hz).

memory — Physical microchips that can hold dataand programming, located on the motherboard orexpansion cards.

memory address — A number assigned to each bytein memory. The CPU can use memory addressesto track where information is stored in RAM.Memory addresses are usually displayed as hex-adecimal numbers in segment/offset form.

memory bus — See system bus.

memory cache — A small amount of faster RAMthat stores recently retrieved data, in anticipationof what the CPU will request next, thus speedingup access. See also system bus.

memory dump — The contents of memory saved toa file at the time an event halted the system. Sup-port technicians can analyze the dump file to helpunderstand the source of the problem.

memory extender — For DOS and Windows 9x, adevice driver named Himem.sys that managesRAM, giving access to memory addresses above 1MB.

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memory paging — In Windows, swapping blocks ofRAM memory to an area of the hard drive toserve as virtual memory when RAM is low.

memory-resident virus — A virus that can stay lurk-ing in memory even after its host program isterminated.

microATX — A recent version of the ATX form fac-tor. MicroATX addresses some new technologiesthat have been developed since the original intro-duction of ATX.

MicroDIMM — A type of memory module used onsub-notebooks that has 144 pins and uses a 64-bitdata path.

microprocessor — See central processing unit (CPU).

Microsoft Management Console (MMC) — A utilityto build customized consoles. These consoles canbe saved to a file with an .msc file extension.

Mini PCI — The PCI industry standard for desktopcomputer expansion cards, applied to a muchsmaller form factor for notebook expansion cards.

Mini-ATX — A smaller ATX board that can be usedwith regular ATX cases and power supplies.

minicartridge — A tape drive cartridge that is only3¼ × 2½ × �inches. It is small enough to allowtwo drives to fit into a standard 5½ -inch drivebay of a PC case.

minifile system — In Windows NT/2000/XP, a sim-plified file system that is started so that Ntldr (NTLoader) can read files from any file system the OSsupports.

Mini-LPX — A smaller version of the LPXmotherboard.

mixed mode — A Windows 2000 mode for domaincontrollers used when there is at least one Win-dows NT domain controller on the network.

MMX (Multimedia Extensions) — Multimediainstructions built into Intel processors to add func-tionality such as better processing of multimedia,SIMD support, and increased cache.

modem — From MOdulate/DEModulate. A devicethat modulates digital data from a computer to ananalog format that can be sent over telephonelines, then demodulates it back into digital form.

modem eliminator — See null modem cable.

modem riser card — A small modem card that usesan AMR or CNR slot. Part of the modem logic iscontained in a controller on the motherboard.

modem speed — The speed at which a modem cantransmit data along a phone line, measured in bitsper second (bps). Also called line speed.

modulation — Converting binary or digital data intoan analog signal that can be sent over standardtelephone lines.

monitor — The most commonly used output devicefor displaying text and graphics on a computer.

motherboard — The main board in the computer,also called the system board. The CPU, ROMchips, SIMMs, DIMMs, RIMMs, and interfacecards are plugged into the motherboard.

motherboard bus — See system bus.

motherboard mouse — See PS/2-compatible mouse.

mouse — A pointing and input device that allows theuser to move a cursor around a screen and selectprograms with the click of a button.

MP3 — A method to compress audio files that usesMPEG level 1. It can reduce sound files as low asa 1:24 ratio without losing much sound quality.

MPEG (Moving Pictures Experts Group) — A process-ing-intensive standard for data compression formotion pictures that tracks movement from oneframe to the next and only stores the data thathas changed.

Msdos.sys — In Windows 9x, a text file that containssettings used by Io.sys during booting. In DOS,the Msdos.sys file was a program file that con-tained part of the DOS core.

multicasting — A process in which a message is sentby one host to multiple hosts, such as when avideo conference is broadcast to several hosts onthe Internet.

multimeter — A device used to measure the variouscomponents of an electrical circuit. The mostcommon measurements are voltage, current, andresistance.

multipartite virus — A combination of a boot sectorvirus and a file virus. It can hide in either type ofprogram.

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multiplier — The factor by which the bus speed orfrequency is multiplied to get the CPU clock speed.

multiscan monitor — A monitor that can workwithin a range of frequencies and thus can workwith different standards and video cards. It offersa variety of refresh rates.

multisession — A feature that allows data to be readfrom or written to a CD during more than onesession. This is important if the disk was only par-tially filled during the first write.

Multistation Access Unit (MSAU or MAU) — A cen-tralized hub used in Token Ring networks to con-nect stations. Also called CAU.

multitasking — Doing more than one thing at atime. A true multitasking system requires two ormore CPUs, each processing a different thread atthe same time. Compare to cooperative multitask-ing and preemptive multitasking.

multithreading — The ability to pass more than onefunction (thread) to the OS kernel at the sametime, such as when one thread is performing aprint job while another reads a file.

name resolution — The process of associating aNetBIOS name or host name to an IP address.

narrow SCSI — One of the two main SCSI specifica-tions. Narrow SCSI has an 8-bit data bus. Theword “narrow” is not usually included in thenames of narrow SCSI devices.

NAT (Network Address Translation) — A processthat converts private IP addresses on a LAN tothe proxy server’s IP address before a data packetis sent over the Internet.

native mode — A Windows 2000 mode used bydomain controllers when there are no WindowsNT domain controllers present on the network.

NetBEUI (NetBIOS Extended User Interface) — Afast, proprietary Microsoft networking protocolused only by Windows-based systems, and limitedto LANs because it does not support routing.

NetBIOS (Network Basic Input/Output System) —An API protocol used by some applications tocommunicate over a NetBEUI network. NetBIOShas largely been replaced by Windows Socketsover a TCP/IP network.

network adapter — See network interface card.

network drive map — Mounting a drive to a com-puter, such as drive E, that is actually hard drivespace on another host computer on the network.

network interface card (NIC) — An expansion cardthat plugs into a computer’s motherboard andprovides a port on the back of the card to connecta PC to a network. Also called a network adapter.

network operating system (NOS) — An operatingsystem that resides on the controlling computer inthe network. The NOS controls what software,data, and devices a user on the network canaccess. Examples of an NOS are Novell Netwareand Windows 2000 Server.

network printer — A printer that any user on thenetwork can access, through its own networkcard and connection to the network, through aconnection to a standalone print server, orthrough a connection to a computer as a localprinter, which is shared on the network.

NLX — A low-end form factor that is similar to LPXbut provides greater support for current andemerging processor technologies. NLX wasdesigned for flexibility and efficiency of space.

NNTP (Network News Transfer Protocol) — The pro-tocol used by newsgroup server and clientsoftware.

node — See host.

noise — An extraneous, unwanted signal, often overan analog phone line, that can cause communica-tion interference or transmission errors. Possiblesources are fluorescent lighting, radios, TVs, light-ning, or bad wiring.

noninterlaced — A type of display in which the elec-tronic beam of a monitor draws every line on thescreen with each pass.

non-memory-resident virus — A virus that is termi-nated when the host program is closed. Compareto memory-resident virus.

nonparity memory — Eight-bit memory withouterror checking. A SIMM part number with a 32in it (4 × 8 bits) is nonparity.

nonvolatile — Refers to a kind of RAM that is stableand can hold data as long as electricity is power-ing the memory.

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normal mode — See CHS mode.

North Bridge — That portion of the chip set hubthat connects faster I/O buses (for example, AGPbus) to the system bus. Compare to South Bridge.

notebook — A portable computer that is designedfor travel and mobility. Notebooks use the sametechnology as desktop PCs, with modifications forconserving voltage, taking up less space, and oper-ating while on the move. Also called a laptopcomputer.

NTFS (NT file system) — The file system for theWindows NT/2000/XP operating systems. NTFScannot be accessed by other operating systemssuch as DOS. It provides increased reliability andsecurity in comparison to other methods of orga-nizing and accessing files. There are several ver-sions of NTFS that might or might not becompatible.

Ntldr (NT Loader) — In Windows NT/2000/XP, theOS loader used on Intel systems.

NTVDM (NT virtual DOS machine) — An emulatedenvironment in which a 16-bit DOS applicationresides within Windows NT/2000/XP with itsown memory space or WOW (Win16 on Win32).

null modem cable — A cable that allows two dataterminal equipment (DTE) devices to communi-cate in which the transmit and receive wires arecross-connected and no modems are necessary.

octet — Term for each of the four 8-bit numbers thatmake up an IP address. For example, the IPaddress 206.96.103.114 has four octets.

ohm (����) — The standard unit of measurement forelectrical resistance. Resistors are rated in ohms.

on-board ports — Ports that are directly on themotherboard, such as a built-in keyboard port oron-board serial port.

operating system (OS) — Software that controls acomputer. An OS controls how system resourcesare used and provides a user interface, a way ofmanaging hardware and software, and ways towork with files.

operating system formatting — See high-levelformatting.

P1 connector — Power connection on an ATXmotherboard.

P8 connector — One of two power connectors on anAT motherboard.

P9 connector — One of two power connectors on anAT motherboard.

packet — Segment of network data that alsoincludes header, destination address, and trailerinformation that is sent as a unit. Also called datapacket or datagram.

page fault — An OS interrupt that occurs when theOS is forced to access the hard drive to satisfy thedemands for virtual memory.

page file — See swap file.

Pagefile.sys — The Windows NT/2000/XP swap file.

page-in — The process in which the memory man-ager goes to the hard drive to return the datafrom a swap file to RAM.

page-out — The process in which, when RAM isfull, the memory manager takes a page and movesit to the swap file.

pages — 4K segments in which Windows NT/ 2000/XP allocates memory.

parallel ATA (PATA) — An older IDE cablingmethod that uses a 40-pin flat data cable or an 80-conductor cable and a 40-pin IDE connector. Seealso serial ATA.

parallel port — A female 25-pin port on a computerthat can transmit data in parallel, 8 bits at a time,and is usually used with a printer. The names forparallel ports are LPT1 and LPT2.

parity — An error-checking scheme in which a ninth,or “parity,” bit is added. The value of the paritybit is set to either 0 or 1 to provide an even num-ber of ones for even parity and an odd number ofones for odd parity.

parity error — An error that occurs when the num-ber of 1s in the byte is not in agreement with theexpected number.

parity memory — Nine-bit memory in which theninth bit is used for error checking. A SIMM part

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number with a 36 in it (4 × 9 bits) is parity. OlderPCs almost always use parity chips.

partition — A division of a hard drive that can beused to hold logical drives.

partition table — A table at the beginning of thehard drive that contains information about eachpartition on the drive. The partition table is con-tained in the Master Boot Record.

passive backplane — A type of backplane system inwhich the backplane contains no circuitry at all.Passive backplanes locate all circuitry on a moth-ercard plugged into a backplane.

passive terminator — A type of terminator for sin-gle-ended SCSI cables. Simple resistors are used toprovide termination of a signal. Passive termina-tion is not reliable over long distances and shouldonly be used with narrow SCSI.

patch — An update to software that corrects anerror, adds a feature, or addresses security issues.Also called an update or service pack.

patch cable — A network cable that is used to con-nect a PC to a hub.

path — (1) A drive and list of directories pointing toa file such as C:\Windows\command. (2) The OScommand to provide a list of paths to the systemfor finding program files to execute.

PC Card — A credit-card-sized adapter card that canbe slid into a slot in the side of many notebookcomputers and is used for connecting to modems,networks, and CD-ROM drives. Also calledPCMCIA Card.

PC Card slot — An expansion slot on a notebookcomputer, into which a PC Card is inserted. Alsocalled a PCMCIA Card slot.

PCI (Peripheral Component Interconnect) bus — Abus common on Pentium computers that runs atspeeds of up to 33 MHz or 66 MHz, with a 32-bit-wide or 64-bit-wide data path. PCI-X, releasedin September 1999, enables PCI to run at 133MHz. For some chip sets, it serves as the middlelayer between the memory bus and expansionbuses.

PCMCIA (Personal Computer Memory Card Interna-tional Association) Card — See PC Card.

PCMCIA Card slot — See PC Card slot.

PDA (Personal Digital Assistant) — A small, hand-held computer that has its own operating systemand applications.

peer-to-peer network — A network of computersthat are all equals, or peers. Each computer hasthe same amount of authority, and each can act asa server to the other computers.

peripheral devices — Devices that communicatewith the CPU but are not located directly on themotherboard, such as the monitor, floppy drive,printer, and mouse.

physical address — See MAC address.

physical geometry — The actual layout of heads,tracks, and sectors on a hard drive. Refer also tological geometry.

PIF (program information file) — A file used byWindows to describe the environment for a DOSprogram to use.

pin grid array (PGA) — A feature of a CPU socketwhereby the pins are aligned in uniform rowsaround the socket.

Ping (Packet Internet Groper) — A Windows andUnix command used to troubleshoot networkconnections. It verifies that the host can communi-cate with another host on the network.

pinout — A description of how each pin on a bus,connection, plug, slot, or socket is used.

PIO (Programmed I/O) transfer mode — A transfermode that uses the CPU to transfer data from thehard drive to memory. PIO mode is slower thanDMA mode.

pipelined burst SRAM — A less expensive SRAMthat uses more clock cycles per transfer than non-pipelined burst but does not significantly slowdown the process.

pits — Recessed areas on the surface of a CD orDVD, separating lands, or flat areas. Lands andpits are used to represent data on a disc.

pixel — A small spot on a fine horizontal scan line.Pixels are illuminated to create an image on themonitor.

Plug and Play (PnP) — A standard designed to makethe installation of new hardware devices easier byautomatically configuring devices to eliminate sys-

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tem resource conflicts (such as IRQ or I/O addressconflicts). PnP is supported by Windows 9x, Win-dows 2000, and Windows XP.

polling — A process by which the CPU checks thestatus of connected devices to determine if theyare ready to send or receive data.

polymorphic virus — A type of virus that changes itsdistinguishing characteristics as it replicates itself.Mutating in this way makes it more difficult forAV software to recognize the presence of the virus.

POP (Post Office Protocol) — The protocol that an e-mail server and client use when the client requeststhe downloading of e-mail messages. The mostrecent version is POP3. POP is being replaced byIMAP.

port — (1) As applied to services running on a com-puter, a number assigned to a process on a com-puter so that the process can be found by TCP/IP.Also called a port address or port number. (2)Another name for an I/O address. See also I/Oaddress. (3) A physical connector, usually at theback of a computer, that allows a cable from aperipheral device, such as a printer, mouse, ormodem, to be attached.

port address — See I/O address.

port number — See port.

port replicator — A device designed to connect to anotebook computer in order to make it easy toconnect the notebook to peripheral devices.

port settings — The configuration parameters ofcommunications devices such as COM1, COM2,or COM3, including IRQ settings.

port speed — The communication speed between aDTE (computer) and a DCE (modem). As a gen-eral rule, the port speed should be at least fourtimes as fast as the modem speed.

POST (power-on self test) — A self-diagnostic pro-gram used to perform a simple test of the CPU,RAM, and various I/O devices. The POST is per-formed by startup BIOS when the computer isfirst turned on, and is stored in ROM-BIOS.

power conditioner — A line conditioner that regu-lates, or conditions, power, providing continuousvoltage during brownouts.

power scheme — A feature of Windows XP supportfor notebooks that allows the user to creategroups of power settings for specific sets ofconditions.

power supply — A box inside the computer case thatsupplies power to the motherboard and otherinstalled devices. Power supplies provide 3.3, 5,and 12 volts DC.

power-on password — A password that a computeruses to control access during the boot process.

PPP (Point-to-Point Protocol) — A protocol thatgoverns the methods for communicating viamodems and dial-up telephone lines. The Win-dows Dial-up Networking utility uses PPP.

PPPoE (Point-to-Point Protocol over Ethernet) —The protocol that describes how a PC is to inter-act with a broadband converter box, such as cablemodem, when the two are connected by an Ether-net cable, connected to a NIC in a PC.

preemptive multitasking — A type of pseudo-multitasking whereby the CPU allows an applica-tion a specified period of time and then preemptsthe processing to give time to another application.

primary cache — See internal cache.

primary domain controller (PDC) — In a WindowsNT network, the computer that controls the direc-tory database of user accounts, group accounts,and computer accounts on a domain. See also backup domain controller.

primary partition — A hard disk partition that cancontain only one logical drive.

primary storage — Temporary storage on the moth-erboard used by the CPU to process data andinstructions. Memory is considered primarystorage.

printer — A peripheral output device that producesprinted output to paper. Different types includedot matrix, ink-jet, and laser printers.

printer maintenance kit — A kit purchased from aprinter manufacturer that contains the parts,tools, and instructions needed to perform routineprinter maintenance.

private IP address — An IP address that is used on aprivate TCP/IP network that is isolated from theInternet.

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process — An executing instance of a programtogether with the program resources. There canbe more than one process running for a programat the same time. One process for a program hap-pens each time the program is loaded into mem-ory or executed.

processor — See central processing unit (CPU).

processor speed — The speed, or frequency, atwhich the CPU operates. Usually expressed inGHz.

product activation — The process that Microsoftuses to prevent software piracy. For example,once Windows XP is activated for a particularcomputer, it cannot be installed on anothercomputer.

program — A set of step-by-step instructions to acomputer. Some are burned directly into chips,while others are stored as program files. Programsare written in languages such as BASIC and C++.

program file — A file that contains instructionsdesigned to be executed by the CPU.

protected mode — An operating mode that supportspreemptive multitasking, the OS manages mem-ory and other hardware devices, and programscan use a 32-bit data path. Also called 32-bitmode.

protocol — A set of rules and standards that two enti-ties use for communication.

Protocol.ini — A Windows initialization file that con-tains network configuration information.

proxy server — A server that acts as an intermediarybetween another computer and the Internet. Theproxy server substitutes its own IP address for theIP address of the computer on the network mak-ing a request, so that all traffic over the Internetappears to be coming from only the IP address ofthe proxy server.

PS/2-compatible mouse — A mouse that plugs intoa round mouse PS/2 port on the motherboard.Sometimes called a motherboard mouse.

public IP address — An IP address available to theInternet.

QIC (Quarter-Inch Committee or quarter-inch car-tridge) — A name of a standardized method usedto write data to tape. These backup files havea .qic extension.

RAID (redundant array of inexpensive disks orredundant array of independent disks) — Sev-eral methods of configuring multiple hard drivesto store data to increase logical volume size andimprove performance, or to ensure that if onehard drive fails, the data is still available fromanother hard drive.

RAM (random access memory) — Memory moduleson the motherboard containing microchips usedto temporarily hold data and programs while theCPU processes both. Information in RAM is lostwhen the PC is turned off.

RAM drive — An area of memory that is treated asthough it were a hard drive, but works muchfaster than a hard drive. The Windows 9x startupdisk uses a RAM drive. Compare to virtualmemory.

RARP (Reverse Address Resolution Protocol) — Aprotocol used to translate the unique hardwareNIC addresses (MAC addresses) into IP addresses(the reverse of ARP).

RDRAM — See Direct Rambus DRAM.

read/write head — A sealed, magnetic coil devicethat moves across the surface of a disk either read-ing data from or writing data to the disk.

real mode — A single-tasking operating modewhereby a program has 1024K of memoryaddresses, has direct access to RAM, and uses a16-bit data path. Using a memory extender(Himem.sys) a program in real mode can accessmemory above 1024K. Also called 16-bit mode.

Recovery Console — A Windows 2000/XP commandinterface utility and OS that can be used to solveproblems when Windows cannot load from thehard drive.

rectifier — An electrical device that converts AC toDC. A PC power supply contains a rectifier.

refresh — The process of periodically rewriting data,such as on dynamic RAM.

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refresh rate — As applied to monitors, the numberof times in one second an electronic beam can fillthe screen with lines from top to bottom. Alsocalled vertical scan rate.

registry — A database that Windows uses to storehardware and software configuration informa-tion, user preferences, and setup information.

re-marked chips — Chips that have been used andreturned to the factory, marked again, and resold.The surface of the chips may be dull or scratched.

Remote Assistance — A Windows XP feature thatallows a support technician at a remote locationto have full access to the Windows XP desktop.

repeater — A device that amplifies signals on a net-work so they can be transmitted further down theline.

rescue disk — A floppy disk that can be used to startup a computer when the hard drive fails to boot.Also called emergency startup disk (ESD) orstartup disk.

resistance — The degree to which a device opposesor resists the flow of electricity. As the electricalresistance increases, the current decreases. Seeohm and resistor.

resistor — An electronic device that resists oropposes the flow of electricity. A resistor can beused to reduce the amount of electricity being sup-plied to an electronic component.

resolution — The number of pixels on a monitorscreen that are addressable by software (example:1024 × 768 pixels).

restore point — A snapshot of the Windows Me/XPsystem state, usually made before installation ofnew hardware or applications.

REt (Resolution Enhancement technology) — Theterm used by Hewlett-Packard to describe the waya laser printer varies the size of the dots used tocreate an image. This technology partly accountsfor the sharp, clear image created by a laser printer.

RIMM — A type of memory module developed byRambus, Inc.

ring topology — A network topology in which thenodes in a network form a ring. Each node is con-nected only to two other nodes, and a centralizedhub is not required.

RISC (Reduced Instruction Set Computing) chips —Chips that incorporate only the most frequentlyused instructions, so that the computer operatesfaster (for example, the PowerPC uses RISC chips).

riser card — A card that plugs into a motherboardand allows for expansion cards to be mountedparallel to the motherboard. Expansion cards areplugged into slots on the riser card.

RJ-11 — A phone line connection found on modems,telephones, and house phone outlets.

RJ-45 connector — A connector used with twisted-pair cable that connects the cable to the NIC.

roaming user profile — A user profile for a roaminguser. Roaming user profiles are stored on a serverso that the user can access the profile from any-where on the network.

ROM (read-only memory) — Chips that contain pro-gramming code and cannot be erased.

ROM BIOS — See BIOS.

root directory — The main directory created when ahard drive or disk is first formatted. In Linux, it’sindicated by a forward slash. In DOS and Win-dows, it’s indicated by a backward slash.

routable protocol — A protocol that can be routedto interconnected networks on the basis of a net-work address. TCP/IP is a routable protocol, butNetBEUI is not.

router — A device that connects networks andmakes decisions as to the best routes to use whenforwarding packets.

sampling rate — The rate of samples taken of ananalog signal over a period of time, usuallyexpressed as samples per second, or hertz.

SBAC (SCSI bus adapter chip) — The SCSI chipwithin a device housing that controls data transferover the SCSI bus.

SCAM (SCSI Configuration AutoMatically) — Amethod of configuring SCSI device settings thatfollows the Plug and Play standard. SCAM makesinstallation of SCSI devices much easier, providedthat the devices are SCAM-compliant.

scanning mirror — A component of a laser printerconsisting of an octagonal mirror that can be

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directed in a sweeping motion to cover the entirelength of a laser printer drum.

SCSI (Small Computer System Interface) — A fastinterface between a host adapter and the CPUthat can daisy chain as many as 7 or 15 deviceson a single bus.

SCSI ID — A number from 0 to 15 assigned to eachSCSI device attached to the daisy chain.

SDRAM II — See Double Data Rate SDRAM (DDRSDRAM).

secondary storage — Storage that is remote to theCPU and permanently holds data, even when thePC is turned off, such as a hard drive.

sector — On a disk surface one segment of a track,which almost always contains 512 bytes of data.

security accounts manager (SAM) — A portion ofthe Windows NT/2000/XP registry that managesthe account database that contains accounts, poli-cies, and other pertinent information about localaccounts.

sequential access — A method of data access usedby tape drives, whereby data is written or readsequentially from the beginning to the end of thetape or until the desired data is found.

serial ATA (SATA) — An ATAPI cabling method thatuses a narrower and more reliable cable than the80-conductor cable. See also parallel ATA.

serial ATA cable — An IDE cable that is narrowerand has fewer pins than the parallel IDE 80-conductor cable.

serial mouse — A mouse that uses a serial port andhas a female 9-pin DB-9 connector.

serial port — A male 9-pin or 25-pin port on a com-puter system used by slower I/O devices such as amouse or modem. Data travels serially, one bit ata time, through the port. Serial ports are some-times configured as COM1, COM2, COM3, orCOM4.

service pack — See patch.

session — An established communication linkbetween two software programs. On the Internet,a session is created by TCP.

SFC (System File Checker) — A Windows tool thatchecks to make sure Windows is using the correctversions of system files.

SGRAM (synchronous graphics RAM) — Memorydesigned especially for video card processing thatcan synchronize itself with the CPU bus clock.

shadow RAM or shadowing ROM — ROM program-ming code copied into RAM to speed up the sys-tem operation, because of the faster access speedof RAM.

shell — The portion of an OS that relates to the userand to applications.

shielded twisted-pair (STP) cable — A cable that ismade of one or more twisted pairs of wires and issurrounded by a metal shield.

shortcut — An icon on the desktop that points to aprogram that can be executed or to a file or folder.

signal-regenerating repeater — A repeater that isable to distinguish between noise and signal. Itreads the signal and retransmits it without theaccompanying noise.

Sigverif.exe — A Windows 2000/XP utility thatallows you to search for digital signatures.

SIMD (single instruction, multiple data) — A pro-cess that allows the CPU to execute a singleinstruction simultaneously on multiple pieces ofdata, rather than by repetitive looping.

SIMM (single inline memory module) — A minia-ture circuit board used in older computers to holdRAM. SIMMs hold 8, 16, 32, or 64 MB on a sin-gle module.

simple volume — A type of dynamic volume used ona single hard drive that corresponds to a primarypartition on a basic disk.

single-ended (SE) cable — A type of SCSI cable inwhich two wires are used to carry a signal, one ofwhich carries the signal itself; the other is aground for the signal.

single-voltage CPU — A CPU that requires one volt-age for both internal and I/O operations.

slack — Wasted space on a hard drive caused by notusing all available space at the end of clusters.

sleep mode — A mode used in many “Green” sys-tems that allows them to be configured through

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CMOS to suspend the monitor or even the drive,if the keyboard and/or CPU have been inactive fora set number of minutes. See also Green Standards.

slimline case — See compact case.

SLIP (Serial Line Internet Protocol) — A line proto-col used by regular telephone lines that has largelybeen replaced by PPP.

Smart Multistation Access Unit (SMAU) — See MAU.

smart UPS – See intelligent UPS.

SMARTDrive — A hard drive cache program thatcame with Windows 3.x and DOS and can be exe-cuted as a TSR from the Autoexec.bat file (forexample, Device=Smartdrv.sys 2048).

SMTP (Simple Mail Transfer Protocol) — The proto-col used by e-mail clients and servers to send e-mail messages over the Internet. See POP andIMAP.

snap-ins — Components added to a console usingthe Microsoft Management Console.

SNMP (Simple Network Management Protocol) — Aprotocol used to monitor and manage networktraffic on a workstation. SNMP works with TCP/IP and IPX/SPX networks.

socket — See session.

SO-DIMM (small outline DIMM) — A type of mem-ory module used in notebook computers that usesDIMM technology and can have either 72 pins or144 pins.

soft boot — To restart a PC without turning off thepower, for example, in Windows XP, by clickingStart, Turn Off Computer, and Restart. Alsocalled warm boot.

soft power — See soft switch.

soft switch — A feature on an ATX system thatallows an OS to power down the system andallows for activity such as a keystroke or networkactivity to power up the system. Also called softpower.

software — Computer programs, or instructions toperform a specific task. Software may be BIOS,OSs, or applications software such as a word-processing or spreadsheet program.

software cache — Cache controlled by softwarewhereby the cache is stored in RAM.

solid ink printer — A type of printer that uses sticksor blocks of solid ink. The ink is melted and thenjetted onto the paper as the paper passes by on adrum.

SO-RIMM (small outline RIMM) — A 160-pin mem-ory module used in notebooks that uses Rambustechnology.

South Bridge — That portion of the chip set hubthat connects slower I/O buses (for example, anISA bus) to the system bus. Compare to NorthBridge.

spacers — See standoffs.

spanned volume — A type of dynamic volume usedon two or more hard drives that fills up the spaceallotted on one physical disk before moving to thenext.

SPI (SCSI Parallel Interface) — The part of theSCSI-3 standard that specifies how SCSI devicesare connected.

spikes — Temporary surges in voltage, which candamage electrical components.

spooling — Placing print jobs in a print queue sothat an application can be released from the print-ing process before printing is completed. Spoolingis an acronym for simultaneous peripheral opera-tions online.

SSE (Streaming SIMD Extension) — A technologyused by the Intel Pentium III and later CPUs anddesigned to improve performance of multimediasoftware.

SSL (secure socket layer) — A secure protocoldeveloped by Netscape that uses a digital certifi-cate including a public key to encrypt and decryptdata.

staggered pin grid array (SPGA) — A feature of aCPU socket whereby the pins are staggered overthe socket in order to squeeze more pins into asmall space.

standby time — The time before a “Green” systemwill reduce 92 percent of its activity. See alsoGreen Standards.

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standoffs — Round plastic or metal pegs that sepa-rate the motherboard from the case, so that com-ponents on the back of the motherboard do nottouch the case.

star bus topology — A LAN that uses a logical busdesign, but with all devices connected to a centralhub, making a physical star.

star ring topology — A topology that is physicallyarranged in a star formation but is logically a ringbecause of the way information travels on it.Token Ring is the primary example.

star topology — A LAN in which all the devices areconnected to a central hub.

start bits — Bits that are used to signal the approachof data.

startup BIOS — Part of system BIOS that is responsi-ble for controlling the PC when it is first turnedon. Startup BIOS gives control over to the OSonce it is loaded.

startup disk — See rescue disk.

startup password — See power-on password.

stateless — Term for a device or process that man-ages data or some activity without regard to allthe details of the data or activity.

static electricity — See ESD.

static IP address — An IP address permanentlyassigned to a workstation.

static RAM (SRAM) — RAM chips that retain infor-mation without the need for refreshing, as long asthe computer’s power is on. They are more expen-sive than traditional DRAM.

static VxD — A VxD that is loaded into memory atstartup and remains there for the entire OS session.

stealth virus — A virus that actively conceals itselfby temporarily removing itself from an infectedfile that is about to be examined, and then hidinga copy of itself elsewhere on the drive.

stop error — An error severe enough to cause theoperating system to stop all processes.

streaming audio — Downloading audio data fromthe Internet in a continuous stream of data with-out first downloading an entire audio file.

striped volume — A type of dynamic volume usedfor two or more hard drives that writes to thedisks evenly rather than filling up allotted spaceon one and then moving on to the next. Compareto spanned volume.

subdirectory — A directory or folder contained inanother directory or folder. Also called a childdirectory or folder.

subnet mask — A subnet mask is a group of fournumbers (dotted decimal numbers) that tell TCP/IP if a remote computer is on the same or a differ-ent network.

subsystems — The different modules into which theWindows NT/2000/XP user mode is divided.

surge suppressor or surge protector — A device orpower strip designed to protect electronic equip-ment from power surges and spikes.

suspend time — The time before a “Green” systemwill reduce 99 percent of its activity. After thistime, the system needs a warm-up time so that theCPU, monitor, and hard drive can reach fullactivity.

swap file — A file on the hard drive that is used bythe OS for virtual memory. Also called a page file.

switch — A device used to segment a network. It candecide which network segment is to receive apacket, on the basis of the packet’s destinationMAC address.

synchronization — The process by which files andprograms are transferred between PDAs and PCs.

synchronous DRAM (SDRAM) — A type of memorystored on DIMMs that runs in sync with the sys-tem clock, running at the same speed as themotherboard.

synchronous SRAM — SRAM that is faster and moreexpensive than asynchronous SRAM. It requires aclock signal to validate its control signals,enabling the cache to run in step with the CPU.

SyncLink DRAM (SLDRAM) — A type of DRAMdeveloped by a consortium of 12 DRAM manufac-turers. It improved on regular SDRAM but is nowobsolete.

Sysedit — The Windows System Configuration Edi-tor, a text editor generally used to edit system files.

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system BIOS — BIOS located on the motherboard.

system board — See motherboard.

system bus — The bus between the CPU and mem-ory on the motherboard. The bus frequency indocumentation is called the system speed, such as400 MHz. Also called the memory bus, front-sidebus, local bus, or host bus.

system clock — A line on a bus that is dedicated totiming the activities of components connected toit. The system clock provides a continuous pulsethat other devices use to time themselves.

system disk — Windows terminology for a bootabledisk.

system partition — The active partition of the harddrive containing the boot record and the specificfiles required to load Windows NT/2000/XP.

system resource — A channel, line, or address onthe motherboard that can be used by the CPU ora device for communication. The four systemresources are IRQ, I/O address, DMA channel,and memory address.

System Restore — A Windows Me/XP utility, simi-lar to the ScanReg tool in earlier versions of Win-dows, that is used to restore the system to arestore point. Unlike ScanReg, System Restorecannot be executed from a command prompt.

system state data — In Windows 2000/XP, files thatare necessary for a successful load of the operat-ing system.

System Tray — An area to the right of the taskbarthat holds the icons of small applets launched atstartup.

System.ini — A text configuration file used by Win-dows 3.x and supported by Windows 9x forbackward-compatibility.

TAPI (Telephony Application Programming Inter-face) — A standard developed by Intel andMicrosoft that can be used by 32-bit Windowscommunications programs for communicatingover phone lines.

TCP (Transmission Control Protocol) — Part of theTCP/IP protocol suite. TCP guarantees delivery of

data for application protocols and establishes asession before it begins transmitting data.

TCP/IP (Transmission Control Protocol/ InternetProtocol) — The suite of protocols that supportscommunication on the Internet. TCP is responsi-ble for error checking, and IP is responsible forrouting.

telephony — A term describing the technology ofconverting sound to signals that can travel overtelephone lines.

terminating resistor — The resistor added at theend of a SCSI chain to dampen the voltage at theend of the chain.

termination — A process necessary to prevent anecho effect of power at the end of a SCSI chain,resulting in interference with the data transmission.

thermal printer — A type of line printer that useswax-based ink, which is heated by heat pins thatmelt the ink onto paper.

ThickNet — See 10Base5 Ethernet.

ThinNet — See 10Base2 Ethernet.

thread — Each process that the CPU is aware of; asingle task that is part of a longer task or program.

TIFF (Tagged Image File Format) — A bitmappedfile format used to hold photographs, graphics,and screen captures. TIFF files can be rather large,and have a .tif file extension.

time to live (TTL) — Number of routers a networkpacket can pass through on its way to its destina-tion before it is dropped. Also called hop count.

TLS (Transport Layer Security) — A protocol usedto secure data sent over the Internet. It is animproved version of SSL.

token ring — An older LAN technology developedby IBM that transmits data at 4 Mbps or 16 Mbps.

top-level domain — The highest level of domainnames, indicated by a suffix that tells somethingabout the host. For example, .com is for commer-cial use and .edu is for educational institutions.

touch screen — An input device that uses a monitoror LCD panel as a backdrop for user options.Touch screens can be embedded in a monitor orLCD panel or installed as an add-on device.

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tower case — The largest type of personal computercase. Tower cases stand vertically and can be ashigh as two feet tall. They have more drive baysand are a good choice for computer users whoanticipate making significant upgrades.

trace — A wire on a circuit board that connects twocomponents or devices.

track — One of many concentric circles on the sur-face of a hard drive or floppy disk.

training — See handshaking.

transceiver — The component on a NIC that isresponsible for signal conversion. Combines thewords transmitter and receiver.

transformer — A device that changes the ratio ofcurrent to voltage. A computer power supply isbasically a transformer and a rectifier.

transistor — An electronic device that can regulateelectricity and act as a logical gate or switch foran electrical signal.

translation — A technique used by system BIOS andhard drive controller BIOS to break the 504-MBhard drive barrier, whereby a different set of driveparameters are communicated to the OS andother software than that used by the hard drivecontroller BIOS.

Travan standards — A popular and improved groupof standards for tape drives based on the QICstandards and developed by 3M.

Trojan horse — A type of infestation that hides ordisguises itself as a useful program, yet is designedto cause damage at a later time.

TSR (terminate-and-stay-resident) — A programthat is loaded into memory and remains dormantuntil called on, such as a screen saver or a mem-ory-resident antivirus program.

UART (universal asynchronous receiver-transmitter) chip — A chip that controls serialports. It sets protocol and converts parallel databits received from the system bus into serial bits.

UDC (Universal Data Connector) — See IDC (IBMData Connector).

UDP (User Datagram Protocol) — A connectionlessprotocol that does not require a connection to

send a packet and does not guarantee that thepacket arrives at its destination. UDP is fasterthan TCP because TCP takes the time to make aconnection and guarantee delivery.

unattended installation — A Windows NT/ 2000/XP installation that is done by storing the answersto installation questions in a text file or script thatWindows NT/2000/XP calls an answer file so thatthe answers do not have to be typed in during theinstallation.

Universal Disk Format (UDF) file system — A filesystem for optical media used by all DVD discsand some CD-R and CD-RW discs.

unshielded twisted-pair (UTP) cable — A cable thatis made of one or more twisted pairs of wires andis not surrounded by a metal shield.

upgrade install — The installation of an OS on ahard drive that already has an OS installed insuch a way that settings kept by the old OS arecarried forward into the upgrade, including infor-mation about hardware, software, and userpreferences.

upper memory — In DOS and Windows 9x, thememory addresses from 640K up to 1024K, origi-nally reserved for BIOS, device drivers, and TSRs.

upper memory block (UMB) — In DOS and Win-dows 9x, a group of consecutive memoryaddresses in RAM from 640K to 1MB that can beused by 16-bit device drivers and TSRs.

UPS (uninterruptible power supply) — A devicedesigned to provide a backup power supply dur-ing a power failure. Basically, a UPS is a batterybackup system with an ultrafast sensing device.

URL (Uniform Resource Locator) — An address fora resource on the Internet. A URL can contain theprotocol used by the resource, the name of thecomputer and its network, and the path and nameof a file on the computer.

USB (universal serial bus) port — A type of portdesigned to make installation and configurationof I/O devices easy, providing room for as manyas 127 devices daisy-chained together.

USB host controller — Manages the USB bus. If themotherboard contains on-board USB ports, theUSB host controller is part of the chipset. The

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USB uses only a single set of resources for alldevices on the bus.

user account — The information, stored in the SAMdatabase, that defines a Windows NT/ 2000/XPuser, including username, password, member-ships, and rights.

user component — A Windows 9x component thatcontrols the mouse, keyboard, ports, and desktop.

user mode — In Windows NT/2000/XP, a mode thatprovides an interface between an application andthe OS, and only has access to hardware resourcesthrough the code running in kernel mode.

user profile — A personal profile about a user thatenables the user’s desktop settings and other oper-ating parameters to be retained from one sessionto another.

User State Migration Tool (USMT) — A WindowsXP utility that helps you migrate user files andpreferences from one computer to another inorder to help a user makes a smooth transitionfrom one computer to another.

V.92 — The latest standard for data transmissionover phone lines that can attain a speed of 56Kbps.

value data — In Windows, the name and value of asetting in the registry.

VCACHE — A built-in Windows 9x 32-bit softwarecache that doesn’t take up conventional memoryspace or upper memory space as SMARTDrive did.

VESA (Video Electronics Standards Association) VLbus — An outdated local bus used on 80486 com-puters for connecting 32-bit adapters directly tothe local processor bus.

VFAT (virtual file allocation table) — A variation ofthe original DOS 16-bit FAT that allows for longfilenames and 32-bit disk access.

video card — An interface card installed in the com-puter to control visual output on a monitor. Alsocalled display adapter.

virtual device driver (VxD or VDD) — A Windowsdevice driver that may or may not have directaccess to a device. It might depend on a Windowscomponent to communicate with the device itself.

virtual machine — One or more logical machinescreated within one physical machine by Windows,allowing applications to make serious errorswithin one logical machine without disturbingother programs and parts of the system.

virtual memory — A method whereby the OS usesthe hard drive as though it were RAM. Compareto RAM drive.

virtual real mode — An operating mode that workssimilarly to real mode provided by a 32-bit OS fora 16-bit program to work.

virus — A program that often has an incubationperiod, is infectious, and is intended to cause dam-age. A virus program might destroy data and pro-grams or damage a disk drive’s boot sector.

virus signature — A set of distinguishing characteris-tics of a virus used by antivirus software to iden-tify the virus.

VMM (Virtual Machine Manager) — A Windows 9xprogram that controls virtual machines and theresources they use including memory. The VMMmanages the page table used to access memory.

volatile — Refers to a kind of RAM that is tempo-rary, cannot hold data very long, and must be fre-quently refreshed.

volt (V) — A measure of potential difference in anelectrical circuit. A computer ATX power supplyusually provides five separate voltages: +12V, –12V, +5V, –5V, and +3.3V.

voltage — Electrical differential that causes currentto flow, measured in volts. See volt.

voltage regulator module (VRM) — A device embed-ded or installed on the motherboard that regulatesvoltage to the processor.

voltmeter — A device for measuring electrical AC orDC voltage.

volume — See logical drive.

VRAM (video RAM) — RAM on video cards thatholds the data that is being passed from the com-puter to the monitor and can be accessed by twodevices simultaneously. Higher resolutions oftenrequire more video memory.

VxD — See virtual device driver.

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wait state — A clock tick in which nothing happens,used to ensure that the microprocessor isn’t get-ting ahead of slower components. A 0-wait stateis preferable to a 1-wait state. Too many waitstates can slow down a system.

WAN (wide area network) — A network or group ofnetworks that span a large geographical area.

warm boot — See soft boot.

watt (W) — The unit used to measure power. A typi-cal computer may use a power supply that pro-vides 200W.

wattage — Electrical power measured in watts.

WDM (Win32 Driver Model) — The only Windows9x Plug and Play component that is found in Win-dows 98 but not Windows 95. WDM is the com-ponent responsible for managing device driversthat work under a driver model new to Windows98.

WFP (Windows File Protection) — A Windows 2000/XP tool that protects system files frommodification.

wide SCSI — One of the two main SCSI specifica-tions. Wide SCSI has a 16-bit data bus. See alsonarrow SCSI.

Wi-Fi — See IEEE 802.11b.

wildcard — A*or ? character used in a command linethat represents a character or group of charactersin a filename or extension.

Win.ini — The Windows initialization file that con-tains program configuration information neededfor running the Windows operating environment.Its functions were replaced by the registry begin-ning with Windows 9x, which still supports it forbackward compatibility with Windows 3.x.

Win16 on Win32 (WOW) — A group of programsprovided by Windows NT/2000/XP to create a

virtual DOS environment that emulates a 16-bitWindows environment, protecting the rest of theOS from 16-bit applications.

Win386.swp — The name of the Windows 9x swapfile. Its default location is C:\Windows.

WINS (Windows Internet Naming Service) — AMicrosoft resolution service with a distributeddatabase that tracks relationships between Net-BIOS names and IP addresses. Compare to DNS.

WinSock (Windows Sockets) — A part of the TCP/IP utility software that manages API calls fromapplications to other computers on a TCP/IPnetwork.

wireless LAN (WLAN) — A type of LAN that doesnot use wires or cables to create connections, butinstead transmits data over radio or infraredwaves.

workgroup — In Windows, a logical group of com-puters and users in which administration,resources, and security are distributed throughoutthe network, without centralized management orsecurity.

worm — An infestation designed to copy itselfrepeatedly to memory, on drive space or on a net-work, until little memory or disk space remains.

WRAM (window RAM) — Dual-ported video RAMthat is faster and less expensive than VRAM. Ithas its own internal bus on the chip, with a datapath that is 256 bits wide.

zero insertion force (ZIF) socket — A socket thatuses a small lever to apply even force when youinstall the microchip into the socket.

zone bit recording — A method of storing data on ahard drive whereby the drive can have more sec-tors per track near the outside of the platter.

1198 GLOSSARY Glossary