Glossary A+ 200-701 702.txt

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Glossary A+ 200-701 702.txt
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  1. 802.11a
    A wireless standard that operates at 5GHz and provides wireless speeds up to 54Mbps.
  2. 802.11b
    A wireless standard that operates at 2.4GHz and provides wireless speeds up to 11Mbps.
  3. 802.11g
    A wireless standard that operates at 2.4GHz, is backward compatible with 802.11b, and provides data transmission of up to 54Mbps.
  4. 802.3
    An IEEE standard that defines a physical bus topology network that uses a 50-ohm coaxial baseband cable and carries transmissions at a minimum of 10Mbps. (The current standard supports speeds up to 10Gbps.) This standard group's data bits into frames and uses the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) cable access method to put data on the cable. Ethernet is a common implementation of IEEE 802.3.
  5. 802.5
    An IEEE standard that specifies a physical star, logical ring topology that uses a token-passing technology to put the data on a network cable. IBM's Token Ring is the most common implementation of IEEE 802.5.
  6. 100BaseT
    An Ethernet standard that operates at 100 Mbps and uses STP cabling. Also called Fast Ethernet. Variations of 100BaseT are 100BaseTX and 100BaseFX.
  7. 10Base2
    An Ethernet standard that operates at 10 Mbps and uses small coaxial cable up to 200 meters long. Also called ThinNet.
  8. 10Base5
    An Ethernet standard that operates at 10 Mbps and uses thick coaxial cable up to 500 meters long. Also called ThickNet.
  9. 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.
  10. 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.
  11. 5-4-3 Rule
    The 5-4-3 represents the creation of a single collision domain, and the numbers are maximums: (5-) no more than five segments between any two nodes that communicate with each other, (-4-) no more than four repeaters in those five segments, and (-3) no more than three of the five segments can have active devices (clients or servers).
  12. Access control list (ACL)
    The set of rules that determines which traffic gets through a firewall and which traffic is blocked.
  13. 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.
  14. Advanced Configuration and Power Interface (ACPI)
    Specification developed by Intel, Compaq, Phoenix, Microsoft, and Toshiba to control power on notebooks and other devices. Windows 98 and Windows 2000/XP support ACPI.
  15. Active Backplane
    A type of backplane system in which there is some circuitry, including bus connectors, buffers, and driver circuits, on the backplane.
  16. Active Directory
    A Windows 2000 and Windows .NET directory database 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.
  17. Active hub
    A type of hub that uses electronics to amplify and clean up the signal before it is retransmitted to the other ports.
  18. Active Matrix
    A type of video display that amplifies the signal at every intersection in the grid of electrodes, which enhances the pixel quality over that of a dual-scan passive matrix display.
  19. Active Partition
    The primary partition on the hard drive that boots the OS. Windows NT/2000/XP calls the active partition the system partition.
  20. Active Terminator
    A type of terminator for single-ended SCSI cables that includes voltage regulators in addition to the simple resistors used with passive termination.
  21. 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.
  22. Advanced SCSI Programming Interface (ASPI)
    A popular device driver that enables operating systems to communicate with a SCSI host adapter. (The "A" originally stood for Adaptec.)
  23. Advanced Transfer Cache (ATC)
    A type of L2 cache contained within the Pentium processor housing that is embedded on the same core processor die as the CPU itself.
  24. Active sniffing
    Involves an attacker gaining access to a host in the network by injecting traffic onto the network in order to obtain data that would otherwise be unavailable.
  25. Address Resolution Protocol (ARP)
    A TCP/IP protocol used to resolve IP addresses to MAC addresses.
  26. Alternating Current (AC)
    Current that cycles back and forth rather than traveling in only one direction. In the United States, the AC voltage from a standard wall outlet is normally between 110 and 115 V. In Europe, the standard AC voltage from a wall outlet is 220 V.
  27. Ampere or Amp (A)
    A unit of measurement for electrical current. One volt across a resistance of one ohm will produce a flow of one amp.
  28. Amplifier repeater
    A Repeater That Does Not Distinguish Between Noise And Signal; It Amplifies Both.
  29. American National Standards Institute (ANSI)
    A nonprofit organization dedicated to creating trade and communications standards.
  30. Answer File
    A text file that contains information that Windows NT/2000/XP requires in order to do an unattended installation.
  31. Application Program Interface (API) Call
    A request from software to the OS to access hardware or other software using a previously defined procedure that both the software and the OS understand.
  32. Address Resolution Protocol (ARP)
    A protocol that TCP/IP uses to translate IP addresses into physical network addresses (MAC addresses).
  33. ASCII (American Standard Code for Information Interchange)
    A popular standard for writing letters and other characters in binary code. Originally, ASCII characters were seven bits, so there were 127 possible values. ASCII has been expanded to an 8-bit version, allowing 128 additional values.
  34. Asynchronous SRAM
    Static RAM that does not work in step with the CPU clock and is, therefore, slower than synchronous SRAM.
  35. 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, and upgrade. Also called full AT.
  36. Advanced Technology Attachment Packet Interface (ATAPI)
    An interface standard, part of the IDE/ATA standards, that allows tape drives, CD-ROM drives, and other drives to be treated like an IDE hard drive by the system.
  37. Attenuation
    Signal degeneration over distance. Attenuation is solved on a network by adding repeaters to the network.
  38. Archive
    Any collection of data that is removed from the system because it's no longer needed on a regular basis.
  39. Archive bit
    An attribute of the file that is cleared during backup. Windows Backup works by looking at the archive bit.
  40. AT system connector
    The 12-pin power connector found on older motherboards that receives the P8/P9 pair of 6-conductor connectors from the power supply.
  41. Attended installation
    An installation where a user is required to provide answers to options during the installation process.
  42. ATX
    The most common form factor for PC systems presently in use, originally introduced by Intel in 1995. ATX motherboards and cases make better use of space and resources than did the AT form factor.
  43. ATX system connector
    The 20-pin power connector found on ATX motherboards to which ATX power supplies connect. These connectors have been replaced by the 24-pin ATX12V connector.
  44. Auto-detection
    A feature on newer system BIOS and hard drives that automatically identifies and configures a new drive in the CMOS setup.
  45. Autoexec.bat
    A startup text file once used by DOS and used by Windows to provide backward-compatibility. It executes commands automatically during the boot process and is used to create a16-bit environment.
  46. Automated System Recovery (ASR)
    The Windows XP process that allows you to restore an entire hard drive volume or logical drive to its state at the time the backup of the volume was made.
  47. Audit files
    Files that hold information about a resource's access by users.
  48. Authentication
    A process that proves that a user or system is actually who they say they are.
  49. Automatic Private IP Addressing (APIPA)
    A TCP/IP standard used to automatically configure IP-based hosts that are unable to reach a DHCP server.
  50. Baby AT
    An improved and more flexible version of the AT form factor. Baby AT was the industry standard from approximately 1993 to 1997 and can fit into some ATX cases.
  51. Back Side Bus (BSB)
    The bus between the CPU and the L2 cache inside the CPU housing. When present the bus between the Northbridge and the cache controller. Often implemented in SECCs and multicavity modules (MCMs), where the CPU and L2 cache are collocated.
  52. Backplane System
    A form factor in which there is no true motherboard. Instead, motherboard components are included on an adapter card plugged into a slot on a board called the backplane.
  53. B Channel
    The ISDN channel that carries 64Kbps of data; also known as a bearer channel.
  54. Back Door (backdoor)
    An opening left in a program application (usually by the developer) that allows additional access to data. Typically, these are created for debugging purposes and aren't documented. Before the product ships, the back doors are closed; when they aren't closed, security loopholes exist.
  55. Backlight
    A small fluorescent lamp placed behind or below an LCD display to provide light.
  56. Basic Rate Interface (BRI)
    An ISDN line with two B channels. Each channel can be used separately for voice and/or data transmissions.
  57. Bandwidth
    In relation to analog communication, the range of frequencies that a communications channel or cable can carry. In general use, the term refers to the volume of data that can travel on a bus or over a cable stated in bits per second (bps), kilobits per second (Kbps), or megabits per second (Mbps). Also called data throughput or line speed. In communications, the difference between the highest and the lowest frequencies available for transmission in any given range. In networking, the transmission capacity of a computer or a communications channel stated in megabits or megabytes per second; the higher the number, the faster the data transmission takes place.
  58. Bank
    An area on the motherboard that contains slots for memory modules (typically labeled bank 0, 1, 2, and 3).
  59. Baseline
    The level of performance expected from a system, which can be compared to current measurements to determine what needs upgrading or tuning.
  60. Basic Disk
    A way to partition a hard drive, used by DOS and all versions of Windows, that stores information about the drive in a partition table at the beginning of the drive. Compare to dynamic disk.
  61. Batch File
    A text file containing a series of OS commands. Autoexec.bat is a batch file.
  62. Baud Rate
    A measure of line speed between two devices such as a computer and a printer or a modem. This speed is measured in the number of times a signal changes in one second. See also bits per second (bps).
  63. Beam Detect Mirror
    Detects the initial presence of a laser printer's laser beam by reflecting the beam to an optical fiber.
  64. Beep Code
    A series of beeps from the computer's speaker that indicate a problem. The number, duration, and pattern of the beeps can sometimes tell you what component is causing the problem.
  65. Binding
    The process by which a protocol is associated with a network card or a modem card.
  66. BIOS (Basic Input/Output System)
    Firmware that can control much of a computer's input/ output functions, such as communication with the floppy drive and the monitor. Also called ROM BIOS. The firmware embedded in a ROM chip that is responsible for running POST, booting the system, and presenting an interface for its own configuration.
  67. Blanks
    Pieces of metal or plastic that come with the case and cover the expansion slot openings to help keep dust and other matter from the inside of the computer.
  68. Bits per Second (Bps)
    A measure of data transmission speed. For example, a common modem speed is 56,000 bps, or 56 Kbps.
  69. Biometrics
    The science of identifying a person by using one or more of their features. The feature can be a thumbprint, a retina scan, or any other biological trait.
  70. Block Mode
    A method of data transfer between hard drive and memory that allows multiple data transfers on a single software interrupt.
  71. Blue Screen of Death (BSOD)
    A condition that occurs when Windows encounters a critical error from which it cannot recover and is followed by a dump of physical memory. The name comes from the fact that the error screen is blue and you have no choice but to attempt to reboot the computer.
  72. Bluetooth
    A standard for wireless communication and data synchronization between devices, developed by a group of electronics manufacturers and overseen by the Bluetooth Special Interest Group. Bluetooth uses the same frequency range as 802.11b, but does not have as wide a range. A popular standard for wireless communication that operates in the 2.4GHz range. The current Bluetooth standard is Version 2.1, which can support data transmissions of up to 3Mbps. The most common type of Bluetooth device (Class 2) has a transmission range of 10 meters (30 feet) and consumes 2.5 mW of power.
  73. BNC Connector
    A connector used with thin coaxial cable. Some BNC connectors are T-shaped and called T-connectors. One end of the T connects to the NIC, and the two other ends can connect to cables or end a bus formation with a terminator.
  74. Boot Loader Menu
    A startup menu that gives the user the choice of which operating system to load such as Windows 98 or Windows 2000 which are both installed on the same system, creating a dual boot.
  75. Boot Partition
    The hard drive partition where the Windows NT/2000/XP OS is stored. The system partition and the boot partition may be different partitions.
  76. Boot Record
    The first sector of a floppy disk or logical drive in a partition; it contains information about the disk or logical drive. On a hard drive, if the boot record is in the active partition, then it is used to boot the OS. Also called boot sector.
  77. Boot Sector Virus
    An infectious program that can replace the boot program with a modified, infected version of the boot command utilities, often causing boot and data retrieval problems.
  78. Boot.ini
    A Windows NT/2000/XP hidden text file that contains information needed to build the boot loader menu.
  79. Bonding
    Combining two bearer channels into one 128Kbps data or voice connection to maximize throughput.
  80. Boot Logging
    Logs all boot information to a file called ntbtlog.txt. You can then check the log for assistance in diagnosing system startup problems.
  81. Bootable Disk
    For DOS and Windows, a floppy disk that can upload the OS files necessary for computer startup. For DOS or Windows 9x, it must contain the files Io.sys, Msdos.sys, and Command.com.
  82. Bootstrap Loader
    A small program at the end of the boot record that can be used to boot an OS from the disk or logical drive.
  83. Bridge
    A device used to connect two or more network segments. It can make decisions about allowing a packet to pass based on the packet's destination MAC address. A type of connectivity device that operates in the Data Link layer of the OSI model. Similar to a switch.
  84. Broadband
    A transmission technique that carries more than one type of transmission on the same medium, such as cable modem or DSL. The general designation for higher-speed Internet connections.
  85. Broadcast
    Process by which a message is sent from a single host to all hosts on the network, without regard to the kind of data being sent or the destination of the data. To send a signal to all entities that can listen to it. In networking, it refers to sending a signal to all entities connected to that network.
  86. Brouter
    A device that functions as both a bridge and a router. A brouter acts as a router when handling packets using routable protocols such as TCP/IP and IPX/SPX. It acts as a bridge when handling packets using non-routable protocols such as NetBEUI.
  87. Brownouts
    Temporary reductions in voltage, which can sometimes cause data loss.
  88. Brute-Force Attack
    A type of attack that relies purely on trial and error.
  89. Buffer
    A temporary memory area where data is kept before being written to a hard drive or sent to a printer, thus reducing the number of writes to the devices.
  90. Bubble-Jet Printer
    A type of sprayed-ink printer. It uses an electric signal that energizes a heating or vibrating element, causing ink to vaporize and be pushed out of the pinhole and onto the paper. Also see inkjet printer.
  91. Burst EDO (BEDO)
    A refined version of EDO memory that significantly improved access time over EDO. BEDO was not widely used because Intel chose not to support it. BEDO memory is stored on 168-pin DIMM modules.
  92. Burst SRAM
    Memory that is more expensive and slightly faster than pipelined burst SRAM. Data is sent in a two-step process; the data address is sent, and then the data itself is sent without interruption.
  93. Bus
    The paths, or lines, on the motherboard on which data, instructions, and electrical power move from component to component. A parallel set of communications lines that act as a cohesive unit and optionally have multiple arbitrary insertion points.
  94. Bus Speed
    The speed, or frequency, at which the data on the motherboard is moving.
  95. Bus Topology
    A LAN architecture in which all the devices are connected to a bus, or one communication line. Bus topology does not have a central connection point.
  96. Cabinet File
    A file with a .cab extension that contains one or more compressed files and is often used to distribute software on disk. The Extract command is used to extract files from the cabinet file.
  97. Cable Internet
    Internet access across a common cable television service.
  98. Cable Modem
    A device used to obtain broadband Internet access through a cable television provider. A technology that uses cable TV lines for data transmission requiring a modem at each end. From the modem, a network cable connects to a NIC in the user's PC.
  99. Cache Memory
    One of two or three levels of fast silicon memory of limited size most often forged from static RAM and positioned between the CPU and RAM.
  100. Calibration
    The process by which a device such as a printer (or a scanner) is brought within functional specifications.
  101. Caliper
    The thickness measurement of a given sheet of paper, which can affect a printer's feed mechanism.
  102. Carriage Belt
    The printer belt placed around two small wheels or pulleys and attached to the print head carriage. The carriage belt is driven by the carriage motor and moves the print head back and forth across the page during printing.
  103. Carriage Motor
    A stepper motor used to move the print head back and forth on a dot-matrix printer.
  104. Carriage Stepper Motor
    The printer motor that makes the print head carriage move.
  105. Capacitor
    An electronic device that can maintain an electrical charge for a period of time and is used to smooth out the flow of electrical current. Capacitors are often found in computer power supplies.
  106. CardBus
    The latest PCMCIA specification. It improves I/O speed, increases the bus width to 32 bits, and supports lower-voltage PC Cards, while maintaining backward compatibility with earlier standards.
  107. Cards
    Adapter boards or interface cards placed into expansion slots to expand the functions of a computer, allowing it to communicate with external devices such as monitors or speakers.
  108. Carrier
    A signal used to activate a phone line to confirm a continuous frequency; used to indicate that two computers are ready to receive or transmit data via modems.
  109. CAS Latency (CL)
    A feature of memory that reflects the number of clock cycles that pass while data is written to memory.
  110. CD (Change Directory) Command
    A command given at the command prompt that changes the default directory, for example CD \Windows.
  111. Chain
    A group of clusters used to hold a single file.
  112. Checksum
    A method of error checking transmitted data, whereby the digits are added and their sum compared to an expected sum.
  113. Child, Parent, Grandparent Backup Method
    A plan for backing up and reusing tapes or removable disks by rotating them each day (child), week (parent), and month (grandparent).
  114. Certificates
    A common form of authentication.
  115. Challenge Handshake Authentication Protocol (CHAP)
    An authentication protocol that challenges a system to verify identity.
  116. Characters Per Second (CPS)
    A rating of how fast dot-matrix printers can produce output.
  117. Charging Corona
    The wire or roller that is used to put a uniform charge on the EP drum inside a toner cartridge.
  118. Charging Step
    The second step in EP printing, at which a special wire or roller in the toner cartridge gets a high voltage from the high voltage power supply (HVPS). It uses this high voltage to apply a strong, uniform negative charge (around 600VDC) to the surface of the photosensitive drum.
  119. Chip Creep
    Movement of components, such as Integrated Circuits, RAM chips, and expansion cards, out of their sockets. A condition in which chips loosen because of thermal changes.
  120. Chip Set
    A group of chips on the motherboard that controls the timing and flow of data and instructions to and from the CPU. Commonly one or two integrated circuits comprising Northbridge and South-bridge functionality, allowing the CPU to communicate with I/O components of various speeds and capabilities.
  121. Centralized Processing
    A network processing scheme in which all intelligence is found in one computer and all other computers send requests to the central computer to be processed. Mainframe networks use centralized processing.
  122. Clark-Wilson Model
    An integrity model for creating a secure architecture.
  123. CHS (Cylinder, Head, Sector) Mode
    The traditional method by which BIOS reads from and writes to hard drives by addressing the correct cylinder, head, and sector. Also called normal mode.
  124. Circuit Board
    A computer component, such as the main motherboard or an adapter board that has electronic circuits and chips.
  125. Complex Instruction Set Computing (CISC)
    Earlier CPU type of instruction set.
  126. Clamping Voltage
    The maximum voltage allowed through a surge suppressor, such as 175 or 330 volts.
  127. Client/Server
    A computer concept whereby one computer (the client) requests information from another computer (the server).
  128. Client/Server Application
    An application that has two components. The client software requests data from the server software on the same or another computer.
  129. Clock Speed
    The speed, or frequency, expressed in MHz, that controls activity on the motherboard and is generated by a crystal or oscillator located somewhere on the motherboard.
  130. Clone
    A computer that is a no-name Intel- and Microsoft-compatible PC.
  131. Clark-Wilson model
    An integrity model for creating a secure architecture.
  132. Cleaning Cycle
    A set of steps the bubble-jet or inkjet printer goes through in order to purge the print heads of any dried ink.
  133. Cleaning Step
    The first step in the EP print process, at which excess toner is scraped from the EP drum with a rubber blade.
  134. Client Computers
    A computer that requests resources from a network, often referred to as a workstation.
  135. Client Software
    Software that allows a device to request resources from a network.
  136. Cluster
    Also known as allocation unit, the collection of sectors that is treated as a single unit by the operating system. Only one file can occupy a cluster at a time. One or more sectors that constitute the smallest unit of space on a disk for storing data (also referred to as a file allocation unit). Files are written to a disk as groups of whole clusters.
  137. CMOS (Complementary Metal-Oxide Semiconductor)
    One of two types of technologies used to manufacture microchips (the other type is TTL or transistor-transistor logic chips). CMOS chips require less electricity; hold data longer after the electricity is turned off, are slower, and produce less heat than TTL chips. The configuration, or setup, chip is a CMOS chip.
  138. CMOS Configuration Chip
    A chip on the motherboard that contains a very small amount of memory, or RAM enough to hold configuration, or setup, information about the computer. Also called CMOS setup chip or CMOS RAM chip.
  139. CMOS Setup
    (1) The chip on the motherboard that holds configuration information about the system, such as date and time, and which CPU, hard drives, or floppy drives are installed. Also called CMOS or CMOS RAM. The chip is powered by a battery when the PC is turned off. (2) The program in system BIOS that can change the values in CMOS RAM.
  140. CMOS Memory
    The extremely small storage space that holds user settings and dynamically discovered parameters for the BIOS.
  141. CMYK (Cyan, Magenta, Yellow, and Black)
    The four standard colors used in printers. Some printers will have all colors on the same cartridge. Others will have separate black and CMY cartridges, while higher-end (mostly laser) printers will have separate cartridges for each color.
  142. COAST (Cache on a Stick)
    Memory modules that hold memory used as a memory cache.
  143. Coaxial Cable
    Networking cable used with10-Mbps Ethernet ThinNet or ThickNet. A medium for connecting computer components that contains a center conductor, made of copper, surrounded by a plastic jacket, with a braided shield over the jacket.
  144. Combo Card
    An Ethernet card that contains more than one transceiver, each with a different port on the back of the card, in order to accommodate different cabling media.
  145. Command.com
    Along with Msdos.sys and Io.sys, one of the three files that are the core components of the real-mode portion of Windows9x. Command.com provides a command prompt and interprets commands.
  146. Collision
    When two or more stations transmit onto a shared medium simultaneously, invalidating the data sent from each station.
  147. Compression
    A feature that gives you the option of compressing existing files in a particular folder. If the feature is turned on, Windows automatically compresses the subfolders and files. If not, only new files created in the directory are compressed.
  148. Comment
    A line or part of a line in a program that is intended as a remark or comment and is ignored when the program runs. A semicolon or an REM is often used to mark a line as a comment.
  149. Communication and Networking Riser (CNR)
    A specification for a small expansion slot on a motherboard that accommodates a small audio, modem, or network riser card.
  150. Compatibility Mode Utility
    A Windows XP utility that provides an application with the older Microsoft OS environment it was designed to operate in.
  151. Compressed Drive
    A drive whose format has been reorganized in order to store more data. A compressed drive is really not a drive at all; it's actually a type of file, typically with a host drive called H.
  152. Config.sys
    A text file used by DOS and supported by Windows 9x that lists device drivers to be loaded at startup. It can also set system variables to be used by DOS and Windows.
  153. Configuration Manager
    A component of Windows Plug and Play that controls the configuration process of all devices and communicates these configurations to the devices.
  154. Connectionless Protocol
    A protocol such as UDP that does not require a connection before sending a packet and does not guarantee delivery. An example of a UDP transmission is streaming video over the Web. Also called a best-effort protocol.
  155. Connection-Oriented Protocol
    In networking, a protocol that confirms that a good connection has been made before transmitting data to the other end. An example of a connection-oriented protocol is TCP.
  156. Constant Angular Velocity (CAV)
    A technology used by hard drives and newer CD-ROM drives whereby the disk rotates at a constant speed.
  157. Constant Linear Velocity (CLV)
    A CD-ROM format in which the spacing of data is consistent on the CD, but the speed of the disc varies depending on whether the data being read near the center or the edge of the disc.
  158. Continuity
    A continuous, unbroken path for the flow of electricity. A continuity test can determine whether or not internal wiring is still intact, or whether a fuse is good or bad.
  159. Control Blade
    A laser printer component that prevents too much toner from sticking to the cylinder surface.
  160. Conventional Memory
    Memory addresses between 0 and 640K. Also called base memory.
  161. Cyclical Redundancy Check (CRC)
    A process in which calculations are performed on bytes of data before and after they are transmitted to check for corruption during transmission.
  162. C-Rimm (Continuity Rimm)
    A placeholder RIMM module that provides continuity so that every RIMM slot is filled.
  163. Cross-Linked Clusters
    Errors caused when more than one file points to a cluster and the files appear to share the same disk space, according to the file allocation table.
  164. Connectivity Device
    Any device that facilitates connections between network devices. Some examples include hubs, routers, switches, and bridges.
  165. Code Division Multiple Access (CDMA)
    A cellular standard of Qualcomm. It allows for multiple transmissions to occur at the same time without interference.
  166. Cold Cathode Fluorescent Lamp (CCFL)
    A common type of backlight used in laptop computers.
  167. Contention
    Competition between two or more network devices for the same bandwidth.
  168. Corona Roller
    A type of transfer corona assembly that uses a charged roller to apply charge to the paper.
  169. Corona Wire
    A type of transfer corona assembly. Also, the wire in that assembly that is charged by the high-voltage power supply. It is narrow in diameter and located in a special notch under the EP print cartridge.
  170. Crossover Cable
    A cable used to connect two PCs into the simplest network possible. Also used to connect two hubs.
  171. Compressed Volume File (CVF)
    The file on the host drive of a compressed drive that holds all compressed data.
  172. Cylinder
    The collection of similarly numbered tracks across all writable surfaces of a hard disk assembly.
  173. Data Bus
    The lines on the system bus that the CPU uses to send and receive data.
  174. Data Line Protector
    A surge protector designed to work with the telephone line to a modem.
  175. Data Path Size
    The number of lines on a bus that can hold data, for example, 8, 16, 32, and 64 lines, which can accommodate 8, 16, 32, and 64 bits at a time.
  176. DC Controller
    A card inside a notebook that converts voltage to CPU voltage. Some notebook manufacturers consider the card to be an FRU.
  177. Data Communications Equipment (DCE)
    The hardware, usually a dial-up modem that provides the connection between a data terminal and a communications line. See also DTE.
  178. Default Gateway
    The gateway a computer on a network will use to access another network unless it knows to specifically use another gateway for quicker access to that network.
  179. Default Printer
    The printer Windows prints to unless another printer is selected.
  180. Defragment
    To optimize or rewrite a file to a disk in one contiguous chain of clusters, thus speeding up data retrieval.
  181. Demodulation
    The process by which digital data that has been converted to analog data is converted back to digital data. See modulation.
  182. Device Driver
    A program stored on the hard drive that tells the computer how to communicate with an input/output device such as a printer or modem.
  183. Daisy-Wheel Printer
    An impact printer that uses a plastic or metal print mechanism with a different character on the end of each spoke of the wheel. As the print mechanism rotates to the correct letter, a small hammer strikes the character against the ribbon, transferring the image onto the paper.
  184. Data Over Cable Service Internet Specification (DOCSIS)
    The standard used by most cable systems for transmitting Internet traffic to a subscriber via television cable.
  185. D Channel
    The signaling channel of an ISDN circuit; also referred to as the Delta channel.
  186. DDR
    A type of SDRAM that doubles the data rate of standard SDRAM by transmitting a single bit on both edges of each FSB clock cycle.
  187. DDR2
    A type of SDRAM that uses both edges of each cycle, transferring two bits per edge.
  188. DDR2-667
    A form of DDR2 memory that populates a PC2-5300 module and is made for a 667MHz FSB.
  189. DDR3
    A type of SDRAM that uses both edges of each FSB clock cycle, transferring four bits per edge.
  190. DDR3-1600
    A form of DDR3 memory that populates a PC3-12800 module and is made for a 1600MHz FSB.
  191. Dedicated Server
    The server that is assigned to perform a specific application or service.
  192. DHCP (Dynamic Host Configuration Protocol) Server
    A service that assigns dynamic IP addresses to computers on a network when they first access the network.
  193. Diagnostic Cards
    Adapter cards designed to discover and report computer errors and conflicts at POST time (before the computer boots up), often by displaying a number on the card.
  194. Diagnostic Software
    Utility programs that help troubleshoot computer systems. Some DOS diagnostic utilities are CHKDSK and SCANDISK. PC-Technician is an example of a third-party diagnostic program.
  195. Differential Backup
    Backup method that backs up only files that have changed or have been created since the last full backup. When recovering data, only two backups are needed: the full backup and the last differential backup.
  196. Differential Cable
    A SCSI cable in which a signal is carried on two wires, each carrying voltage, and the signal is the difference between the two. Differential signaling provides for error checking and greater data integrity. Compare to single-ended cable.
  197. Digital Signature
    Digital codes used to identify and authenticate the source of a file or document.
  198. DIMM (Dual Inline Memory Module)
    A miniature circuit board used in newer computers to hold memory. DIMMs can hold up to 2 GB of RAM on a single module.
  199. Denial-Of-Service (Dos) Attacks
    Attacks that prevent access to resources by users authorized to use those resources.
  200. Department Of Defense (DOD) Model
    A four-layer networking model loosely corresponding to the OSI model, upon which the basis for the TCP/IP protocol suite was developed.
  201. Developing Roller
    The roller inside a toner cartridge that presents a uniform line of toner to help apply the toner to the image written on the EP drum.
  202. Developing Step
    The fourth step in the EP print process, at which the image written on the EP drum by the laser is developed that is, it has toner stuck to it.
  203. Device Driver
    A software file that allows an operating system to communicate with a hardware device. Also called a driver.
  204. Dictionary Attack
    The act of attempting to crack passwords by testing them against a list of dictionary words. With today's powerful computers, an attacker can combine one of many available automated password cracking utilities with several large dictionaries or wordlists and crack huge numbers of passwords in a matter of minutes. Any password based on any dictionary word is vulnerable to such an attack.
  205. Diode
    An electronic device that allows electricity to flow in only one direction. Used in a rectifier circuit.
  206. DIP (Dual Inline Package) Switch
    A switch on a circuit board or other device that can be set on or off to hold configuration or setup information.
  207. Direct Current (DC)
    Current that travels in only one direction (the type of electricity provided by batteries). Computer power supplies transform AC to low DC.
  208. DIMM
    A memory module packaging style that features a circuit board with independent pins on both sides of the module's card edge.
  209. Distributed Denial Of Service (Ddos) Attack
    A derivative of a DoS attack in which multiple hosts in multiple locations all focus on one target to reduce its availability to the public. See denial of service (DoS) attack.
  210. Distributed Processing
    A computer system in which processing is performed by several separate computers linked by a communications network. The term often refers to any computer system supported by a network, but more properly refers to a system in which each computer is chosen to handle a specific workload and the network supports the system as a whole.
  211. Domain Name System (DNS)
    A system which resolves computer hostnames to IP addresses.
  212. Domains
    Also referred to as a client-server networking model, a domain is a network where security is managed by a centralized server, often known as a domain controller.
  213. Dot-Matrix Printer
    An impact printer that has a print head containing a row of pins (short, sturdy stalks of hard wire) that are used to strike the ink ribbon to create an image.
  214. Double-Sided Memory
    A memory module that comprises two modules in one.
  215. DRAM
    A pervasive type of volatile memory that requires a periodic refresh signal to keep its contents.
  216. DRDRAM
    A type of SDRAM from Rambus implemented on RIMMs.
  217. Drive Interface
    An interface and related circuitry designed to connect one of a few possible drive types to a motherboard or adapter card; often manifests as a header on the motherboard.
  218. Driver
    A software file that allows an operating system to communicate with a hardware device. Also called a device driver.
  219. DSL Endpoint
    The device used to access DSL, commonly referred to mistakenly as a DSL modem.
  220. D-Subminiature
    Also known as D-sub, a trapezoidal connector and port pairing that features an interface that is broader on one edge than the other with angled sides connecting the edges; commonly found on classic I/O ports, such as RS-232 serial and parallel.
  221. Dual-Channel Memory
    A RAM implementation scheme in which the memory controller requires two paired standard memory modules to read from or write to simultaneously. RIMM offers a single module that alone satisfies both channels on compatible motherboards.
  222. Dye-Sublimation Printer
    A printer that uses heat to diffuse solid dyes onto the printing surface as a gas that resolidifies without ever going through a liquid state.
  223. Dynamic Host Configuration Protocol (DHCP)
    A protocol (and service) in the TCP/IP protocol suite that automatically configures network clients with IP configuration information when they join the network.
  224. Direct Rambus Dram
    A memory technology by Rambus and Intel that uses a narrow, very fast network-type system bus. Memory is stored on a RIMM module. Also called RDRAM or Direct RDRAM.
  225. Directory Table
    An OS table that contains file information such as the name, size, time and date of last modification, and cluster number of the file's beginning location.
  226. Discrete L2 Cache
    A type of L2 cache contained within the Pentium processor housing, but on a different die, with a cache bus between the processor and the cache.
  227. Disk Cache
    A method whereby recently retrieved data and adjacent data are read into memory in advance, anticipating the next CPU request.
  228. Disk Cloning
    Making an exact image of a hard drive, including partition information, boot sectors, operating system installation, and application software to replicate the hard drive on another system or recover from a hard drive crash. Also called disk imaging.
  229. Disk Compression
    Compressing data on a hard drive to allow more data to be written to the drive.
  230. Disk Management
    A Windows 2000/XP utility used to display and create and format partitions on basic disks and volumes on dynamic disks.
  231. Disk Quota
    A limit placed on the amount of disk space that is available to users. Requires a Windows 2000/XP NTFS volume.
  232. Disk Thrashing
    A condition that results when the hard drive is excessively used for virtual memory because RAM is full. It dramatically slows down processing and can cause premature hard drive failure.
  233. Display Power Management Signaling (DPMS)
    Energy Star standard specifications that allow for the video card and monitor to go into sleep mode simultaneously. See also Energy Star.
  234. DMA (Direct Memory Access) Channel
    A number identifying a channel whereby the device can pass data to memory without involving the CPU. Think of a DMA channel as a shortcut for data moving to/from the device and memory.
  235. DNS (Domain Name Service or Domain Name System)
    A distributed pool of information (called the name space) that keeps track of assigned domain names and their corresponding IP addresses, and the system that allows a host to locate information in the pool. Compare to WINS.
  236. DNS Server
    A computer that can find an IP address for another computer when only the domain name is known.
  237. Docking Station
    A device that receives a notebook computer and provides additional secondary storage and easy connection to peripheral devices.
  238. Domain
    In Windows NT/2000/XP, a logical group of networked computers, such as those on a college campus, that share a centralized directory database of user account information and security for the entire domain.
  239. Domain Controller
    A Windows NT/2000 computer which holds and controls a database of (1) user accounts, (2) group accounts, and (3) computer accounts used to manage access to the network.
  240. Domain Name
    A unique, text-based name that identifies a network.
  241. Dosstart.bat
    A type of Autoexec.bat file that is executed by Windows 9x in two situations: when you select Restart the computer in MS-DOS mode from the shutdown menu or you run a program in MS-DOS mode.
  242. Dot Pitch
    The distance between the dots that the electronic beam hits on a monitor screen.
  243. Double Data Rate SDRAM (DDR SDRAM)
    A type of memory technology used on DIMMs that runs at twice the speed of the system clock.
  244. Dr. Watson
    A Windows utility that can record detailed information about the system, errors that occur, and the programs that caused them in a log file. Windows 9x names the log file \Windows\ Drwatson\WatsonXX.wlg, where XX is an incrementing number. Windows 2000 names the file \Documents and Settings\user\Documents\ DrWatson\Drwtsn32.log. Windows XP calls the file Drwatson.log.
  245. DriveSpace
    A Windows 9x utility that compresses files so that they take up less space on a disk drive, creating a single large file on the disk to hold all the compressed files.
  246. DSL (Digital Subscriber Line)
    A telephone line that carries digital data from end to end, and can be leased from the telephone company for individual use. DSL lines are rated at 5 Mbps, about 50 times faster than regular telephone lines. A broadband Internet access technology that uses the existing phone line from your home to the phone company to carry digital signals at higher speeds.
  247. Data Terminal Equipment (DTE)
    Both the computer and a remote terminal or other computer to which it is attached. See also DCE.
  248. Dual Boot
    The ability to boot using either of two different OSs, such as Windows 98 and Windows 2000.
  249. Dual-Scan Passive Matrix
    A type of video display that is less expensive than an active-matrix display and does not provide as high-quality an image. With dual-scan display, two columns of electrodes are activated at the same time.
  250. Dual-Voltage CPU
    A CPU that requires two different voltages, one for internal processing and the other for I/O processing.
  251. Dump File
    A file that contains information captured from memory at the time a stop error occurred.
  252. Dynamic Disk
    A way to partition one or more hard drives, introduced with Windows 2000, in which information about the drive is stored in a database at the end of the drive. Compare to basic disk.
  253. Dynamic IP Address
    An assigned IP address that is used for the current session only. When the session is terminated, the IP address is returned to the list of available addresses.
  254. Dynamic RAM (DRAM)
    The most common type of system memory, it requires refreshing every few milliseconds.
  255. Dynamic Volume
    A volume type used with dynamic disks for which you can change the size of the volume after you have created it.
  256. Electronic Stepper Motor
    A special electric motor in a printer that can accurately move in very small increments. It powers all of the paper transport rollers as well as the fuser rollers.
  257. Electrostatic Discharge (ESD)
    Occurs when two objects of dissimilar electrical charge come in contact with each other; the charge can damage electronic components.
  258. Emergency Repair Disk (ERD)
    A disk that contains backup copies of portions of your Registry. It can be used to recover the system in the event of an operating system failure.
  259. Environment Variable
    A variable used by the operating system that holds a value defining the computing environment.
  260. EP Print Process
    The process by which an EP laser printer forms images on paper.
  261. eSATA
    An external interface for the attachment of SATA devices that requires a shielded cable and different connector from the one used with internal SATA attachment.
  262. Ethernet
    A network technology based on the IEEE 802.3 CSMA/CD standard. The original Ethernet implementation specified 10MBps, baseband signaling, coaxial cable, and CSMA/CD media access. Ethernet standards now support data transmissions of up to 10Gbps.
  263. Expansion Card
    A daughter card that is inserted into a bus slot in the motherboard to expand the native capabilities of a computer system.
  264. Expansion Slot
    One of the arbitrary insertion points in an expansion bus, based on a specific technology PCI, for example.
  265. ECC (Error-Correcting Code)
    A chip set feature on a system board that checks the integrity of data stored on DIMMs or RIMMs and can correct single-bit errors in a byte. More advanced ECC schemas can detect, but not correct, double-bit errors in a byte. An error-checking scheme that is able to discover one or two bits in a byte that contain errors, and correct single-bit errors.
  266. Extended Capabilities Port (ECP)
    A bidirectional parallel port mode that uses a DMA channel to speed up data flow.
  267. EDO (Extended Data Out)
    A type of RAM that may be 10 20 percent faster than conventional RAM because it eliminates the delay before it issues the next memory address.
  268. EEPROM (Electrically Erasable Programmable ROM)
    A type of chip in which higher voltage may be applied to one of the pins to erase its previous memory before a new instruction set is electronically written.
  269. EIDE (Enhanced IDE)
    A standard for managing the interface between secondary storage devices and a computer system. A system can support up to four IDE devices such as hard drives, CD-ROM drives, and Zip drives.
  270. Electromagnetic Interference (EMI)
    A magnetic field produced as a side effect from the flow of electricity. EMI can cause corrupted data in data lines that are not properly shielded.
  271. Emergency Repair Disk (ERD)
    A WindowsNT record of critical information about your system that can be used to fix a problem with the OS. The ERD enables restoration of the Windows NT registry on your hard drive.
  272. Emm386.exe
    A DOS and Windows 9x utility that provides access to upper memory for 16-bit device drivers and other software.
  273. Encrypted File System (EFS)
    A way to use a key to encode a file or folder to protect sensitive data. Because it is an integrated system service, EFS is transparent to users and applications and is difficult to attack.
  274. Encrypting Virus
    A type of virus that transforms itself into a nonreplicating program in order to avoid detection. It transforms itself back into a replicating program in order to spread.
  275. Encryption
    The process of putting readable data into an encoded form that can only be decoded (or decrypted) through use of a key.
  276. Enhanced BIOS
    A system BIOS that has been written to accommodate large-capacity drives (over 504 MB, usually in the gigabyte range).
  277. EPIC (Explicitly Parallel Instruction Computing)
    The CPU architecture used by the Intel Itanium chip that bundles programming instructions with instructions on how to use multiprocessing abilities to do two instructions in parallel.
  278. Enhanced Parallel Port (EPP)
    A parallel port that allows data to flow in both directions (bidirectional port) and is faster than original parallel ports on PCs that allowed communication only in one direction.
  279. EPROM (Erasable Programmable ROM)
    A type of chip with a special window that allows the current memory contents to be erased with special ultraviolet light so that the chip can be reprogrammed. Many BIOS chips are EPROMs.
  280. Error Correction
    The ability of a modem to identify transmission errors and then automatically request another transmission.
  281. Ethernet
    A LAN architecture that uses a bus or star topology, uses CSMA/CD when two computers are trying to gain access to the network at the same time, and is the most popular network architecture in use today.
  282. Execution Trace Cache
    A type of Level 1 cache used by some CPUs to hold decoded operations waiting to be executed.
  283. Executive Services
    In Windows NT/2000/XP, a group of components running in kernel mode that interfaces between the subsystems in user mode and the HAL.
  284. Expansion Bus
    A bus that does not run in sync with the system clock.
  285. Expansion Card
    A circuit board inserted into a slot on the motherboard to enhance the capability of the computer.
  286. Expansion Slot
    A narrow slot on the motherboard where an expansion card can be inserted. Expansion slots connect to a bus on the motherboard.
  287. Extended Memory
    Memory above 1024K used in a DOS or Windows 9 x systems.
  288. Extended Partition
    The only partition on a hard drive that can contain more than one logical drive.
  289. External Cache
    Static cache memory, stored on the motherboard or inside the CPU housing that is not part of the CPU (also called L2 or L3 cache).
  290. External Command
    Commands that have their own program files.
  291. Faceplate
    A metal plate that comes with the motherboard and fits over the ports to create a well-fitted enclosure around them.
  292. Feeder
    A device that feeds paper or other media into a printer.
  293. Feed Roller
    The rubber roller in a laser printer that feeds the paper into the printer.
  294. Field-Replaceable Units (FRUS)
    Parts that are designed to be able to be replaced by a technician working in the field.
  295. File Permissions
    These serve the purpose of controlling who has access and what type of access to what files or objects they have.
  296. File Servers
    Servers on a network designed to hold and store files for clients.
  297. File Transfer Protocol (FTP)
    A protocol in the TCP/IP protocol suite that is optimized for file transfers. It uses ports 20 and 21.
  298. Finisher
    A device on a printer that performs such final functions as folding, stapling, hole punching, sorting, or collating the documents being printed.
  299. Firewall
    Software or hardware used to limit traffic based on a set of rules, usually an access control list.
  300. FireWire
    Apple's original implementation of IEEE 1394b, a high-speed serial I/O interface, ideal for video applications between a computer and an external video source or destination. FireWire is a competing standard of USB.
  301. Firmware
    Systems programming software embedded in a hardware device, such as a ROM chip; often used to control the low-level functionality of the system in which it is installed.
  302. Flash Memory
    A nonvolatile form of solid-state memory similar in makeup to primary RAM but used for semipermanent storage, similar to writable disks.
  303. Format
    To prepare a volume (such as a hard drive) to receive files and folders by defining the file structure.
  304. Formatting
    The process of preparing the partition on a storage device such as a hard drive or flash memory to store data in a particular fashion.
  305. Frame
    The Data Link layer product that includes a portion of the original user data, upper-layer headers, and the Data Link header and trailer.
  306. Frontside Bus
    The high-speed bus controlled by the Northbridge on which RAM, cache (in the absence of the backside bus [BSB]), PCIe slots, AGP slots, and other local-bus components are interconnected with the CPU and, in some cases, each other.
  307. Full-Duplex Communication
    Communications where both entities can send and receive simultaneously.
  308. Function Key
    Key marked with the letters Fn that produces particular functions when pressed and held while pressing one of the function keys.
  309. Fuser
    A device on an EP printer that uses two rollers to heat the toner particles and melt them to the paper. The fuser is made up of a halogen heating lamp, a Teflon-coated aluminum fusing roller, and a rubberized pressure roller. The lamp heats the aluminum roller. As the paper passes between the two rollers, the rubber roller presses the paper against the heated roller. This causes the toner to melt and become a permanent image on the paper.
  310. Fusing Step
    The sixth and final step in the EP printing process, when the toner image on the paper is fused to the paper using heat and pressure. The heat melts the toner, and the pressure helps fuse the image permanently to the paper.
  311. FAT (File Allocation Table)
    A table on a hard drive or floppy disk that tracks the clusters used to contain a file.
  312. FAT12
    The 12-bit wide, one-column file allocation table for a floppy disk, containing information about how each cluster or file allocation unit on the disk is currently used.
  313. Fault Tolerance
    The degree to which a system can tolerate failures. Adding redundant components, such as disk mirroring or disk duplexing, is a way to build in fault tolerance.
  314. Fiber Distributed Data Interface (FDDI)
    A ring-based network that does not require a centralized hub and can transfer data at a rate of 100 Mbps.
  315. Field Replaceable Unit (FRU)
    A component in a computer or device that can be replaced with a new component without sending the computer or device back to the manufacturer. Examples: power supply, DIMM, motherboard, floppy disk drive.
  316. File Extension
    A three-character portion of the name of a file that is used to identify the file type. In command lines, the file extension follows the filename and is separated from it by a period. For example, Msd.exe, where exe is the file extension.
  317. File System
    The overall structure that an OS uses to name, store, and organize files on a disk. Examples of file systems are FAT32 and NTFS.
  318. Filename
    The first part of the name assigned to a file. In DOS, the filename can be no more than eight characters long and is followed by the file extension. In Windows, a filename can be up to 255 characters.
  319. Firewall
    Hardware or software that protects a computer or network from unauthorized access.
  320. Firmware
    Software that is permanently stored in a chip. The BIOS on a motherboard is an example of firmware.
  321. Flash ROM
    ROM That Can Be Reprogrammed Or Changed Without Replacing Chips.
  322. FlexATX
    A version of the ATX form factor that allows for maximum flexibility in the size and shape of cases and motherboards. FlexATX is ideal for custom systems.
  323. Flow Control
    When using modems, a method ofcontrolling the flow of data to adjust for problems with data transmission. Xon/Xoff is an example of a flow control protocol.
  324. Folder Redirection
    A Windows XP feature that allows a user to point to a folder that can be on the local PC or somewhere on the network and its location can be transparent to the user.
  325. Forced Perfect Terminator (FPT)
    A type of SCSI active terminator that includes a mechanism to force signal termination to the correct voltage, eliminating most signal echoes and interference.
  326. Form Factor
    A set of specifications on the size, shape, and configuration of a computer hardware component such as a case, power supply, or motherboard.
  327. Formatting
    Preparing a new floppy disk for use by placing tracks and sectors on its surface to store information (for example, FORMAT A:). Old disks can be reformatted, but all data on them will be lost.
  328. Fast Page Mode (FPM)
    A memory mode used before the introduction of EDO memory. FPM improved on earlier memory types by sending the row address just once for many accesses to memory near that row.
  329. Fragmentation
    The distribution of data files on a hard drive or floppy disk such that they are stored in noncontiguous clusters.
  330. Fragmented File
    A file that has been written to different portions of the disk so that it is not in contiguous clusters.
  331. Frame
    The header and trailer information added to data to form a data packet to be sent over a network.
  332. Full Backup
    A complete backup, whereby all of the files on the hard drive are backed up each time the backup procedure is performed. It is the safest backup method, but it takes the most time.
  333. Full-Duplex
    Communication that happens in two directions at the same time.
  334. Fully Qualified Domain Name (FQDN)
    A host name and a domain name such as jsmith.amazon.com. Sometimes loosely referred to as a domain name.
  335. General Protection Fault (GPF)
    A general protection fault (GPF) happens in Windows when a program accesses memory that another program is using or when a program accesses a memory address that doesn't exist.
  336. Global System for Mobile Communications (GSM)
    The most popular cellular standard. It uses a variety of bands to transmit. The most popular are 900MHz and 1800MHz, but 400, 450, and 850MHz are also used.
  337. Gateway
    A computer or other device that connects networks.
  338. Gigabit Ethernet
    The newest version of Ethernet. Gigabit Ethernet supports rates of data transfer up to 1 gigabit per second but is not yet widely used.
  339. Gigahertz (GHz)
    One thousand MHz, or one billion cycles per second.
  340. Global User Account
    Sometimes called a domain user account, the account is used at the domain level, created by an administrator, and stored in the SAM (security accounts manager) database on a Windows 2000 or Windows .NET domain controller.
  341. Graphics Accelerator
    A type of video card that has an on-board processor that can substantially increase speed and boost graphical and video performance.
  342. Half-Duplex Communication
    Communications that occur when only one entity can transmit or receive at any one instant.
  343. Hard Disk Drive
    A disk drive that contains magnetically coated platters in a sealed case and is often used as the main secondary-storage medium.
  344. Hardening
    The process of reducing or eliminating weaknesses, securing services, and attempting to make your environment immune to attacks.
  345. Header
    In hardware, a technology-specific connector on a circuit board for cabling an internal peripheral device to the board. In software, protocol-specific control information added to the original data or to the protocol data unit from the next-higher protocol in the stack. Information attached to the beginning of a network data frame.
  346. Heat Sink
    A block of aluminum or other metal, with veins throughout or fins, that sits on top of a heat-producing component, drawing its heat away.
  347. heat spreader
    A flat heat sink of sorts that adds surface area to a heat-producing component, allowing better heat transfer to the surrounding air; often coupled with a fan for devices that run at a higher temperature.
  348. Hermaphroditic Data Connector
    A connector that is both male and female.
  349. High-Voltage Probe
    A tool with a very large needle, a gauge that indicates volts, and a wire with an alligator clip used to discharge electricity from electronic devices.
  350. Hop
    In networking, an intermediate device and cabling between two other devices.
  351. Host
    Any computer or device on a TCP/IP network that has an IP address.
  352. Host-Based Firewall
    A firewall implemented on a single machine. It is usually a software implementation. Contrast with network-based firewall.
  353. Hot Fix/Hotfix
    Another word for a patch. When Microsoft rolls a bunch of hot fixes together, they become known as a service pack.
  354. Hub
    A basic connectivity device used to link several computers together into a physical star topology. A hub repeats any signal that comes in on one port and copies it to the other ports.
  355. Hypertext Transfer Protocol (HTTP)
    A protocol in the TCP/IP protocol suite that is the backbone for Internet (web) traffic. It uses port 80.
  356. Hypertext Transfer Protocol Secure (HTTPS)
    Secure protocol for most Internet traffic; it uses port 443 by default.
  357. Hardware Abstraction Layer (HAL)
    The low-level part of Windows NT/2000/XP, written specifically for each CPU technology, so that only the HAL must change when platform components change.
  358. Half Life
    The time it takes for a medium storing data to weaken to half of its strength. Magnetic media, including traditional hard drives and floppy disks, have a half-life of five to seven years.
  359. Half-Duplex
    Communication between two devices whereby transmission takes place in only one direction at a time.
  360. Handshaking
    When two modems begin to communicate, the initial agreement made as to how to send and receive data.
  361. Hard Boot
    Restart the computer by turning off the power or by pressing the Reset button. Also called a cold boot.
  362. Hard Copy
    Output from a printer to paper.
  363. Hard Drive
    The main secondary storage device of a PC, a small case that contains magnetic coated platters that rotate at high speed.
  364. Hard Drive Controller
    The firmware that controls access to a hard drive contained on a circuit board mounted on or inside the hard drive housing. Older hard drives used firmware on a controller card that connected to the drive by way of two cables, one for data and one for control.
  365. Hard Drive Standby Time
    The amount of time before a hard drive will shut down to conserve energy.
  366. Hard-Disk Loading
    The illegal practice of installing unauthorized software on computers for sale. Hard-disk loading can typically be identified by the absence of original software disks in the original system's shipment.
  367. Hardware
    The physical components that constitute the computer system, such as the monitor, the keyboard, the motherboard, and the printer.
  368. Hardware Cache
    A disk cache that is contained in RAM chips built right on the disk controller.
  369. Hardware Interrupt
    An event caused by a hardware device signaling the CPU that it requires service.
  370. Hardware Profile
    A set of hardware configuration information that Windows keeps in the registry. Windows can maintain more than one hardware profile for the same PC.
  371. Hardware Compatibility List (HCL)
    The list of all computers and peripheral devices that have been tested and are officially supported by Windows NT/2000/XP.
  372. Head
    The top or bottom surface of one platter on a hard drive. Each platter has two heads.
  373. Heat Sink
    A piece of metal, with cooling fins, that can be attached to or mounted on an integrated chip (such as the CPU) to dissipate heat.
  374. Hertz (Hz)
    Unit of measurement for frequency, calculated in terms of vibrations, or cycles per second. For example, for 16-bit stereo sound, a frequency of 44,000 Hz is used. See also megahertz.
  375. Hexadecimal Notation (Hex)
    A numbering system that uses 16 digits, the numerals 0-9, and the letters A-F. Hexadecimal notation is often used to display memory addresses.
  376. Hidden File
    A file that is not displayed in a directory list. Whether to hide or display a file is one of the file's attributes kept by the OS.
  377. High Memory Area (HMA)
    The first 64K of extended memory.
  378. High Voltage Differential (HVD)
    A type of SCSI differential signaling requiring more expensive hardware to handle the higher voltage. HVD became obsolete with the introduction of SCSI-3.
  379. High-Level Formatting
    Formatting performed by means of the DOS or Windows Format program (for example, FORMAT C:/S creates the boot record, FAT, and root directory on drive C and makes the drive bootable). Also called OS formatting.
  380. Himem.sys
    The DOS and Windows 9x memory manager extension that allowed access to memory addresses above 1 MB.
  381. Hive
    Physical segment of the Windows NT/ 2000/XP registry that is stored in a file.
  382. Host
    Any computer or other device on a network that has been assigned an IP address.
  383. Host Adapter
    The circuit board that controls a SCSI bus supporting as many as seven or fifteen separate devices. The host adapter controls communication between the SCSI bus and the PC.
  384. Host Drive
    Typically drive H on a compressed drive. See compressed drive.
  385. Host Name
    A name that identifies a computer, printer, or other device on a network.
  386. Hot-Swappable
    A device that can be plugged into a computer while it is turned on and the computer will sense the device and configure it without rebooting, or the device can be removed without an OS error. Also called hot-pluggable.
  387. HTML (HyperText Markup Language)
    A markup language used for hypertext documents on the World Wide Web. This language uses tags to format the document, create hyperlinks, and mark locations for graphics.
  388. HTTP (HyperText Transfer Protocol)
    protocol used by the World Wide Web.
  389. HTTPS (HTTP Secure)
    A version of the HTTP protocol that includes data encryption for security.
  390. Hub
    A network device or box that provides a central location to connect cables.
  391. Hypertext
    Text that contains links to remote points in the document or to other files, documents, or graphics. Hypertext is created using HTML and is commonly distributed from Web sites.
  392. IBM Data Connector (IDC)
    A unique, hermaphroditic connector commonly used with IBM's Token Ring technology and Type 1 or 2 STP cable.
  393. ICMP Attack
    An attack that occurs by triggering a response from the Internet Control Message Protocol (ICMP) when it responds to a seemingly legitimate maintenance request.
  394. Illegal Operation Error
    An illegal operation error usually means that a program was forced to quit because it did something Windows didn't like.
  395. Impact Printers
    Any printer that forms an image on paper by forcing a character image against an inked ribbon. Dot-matrix, daisy-wheel, and line printers are all impact printers, whereas laser printers are not.
  396. Incident
    An attempt to violate a security policy, a successful penetration, a compromise of a system, or unauthorized access to information.
  397. Infrared
    A type of wireless transmission between devices that use radiation in the infrared range of the electromagnetic spectrum.
  398. Infrared Data Association (IrDA)
    The association that creates and maintains infrared standards.
  399. Infrared Transmissions
    Wireless transmission between devices that use radiation in the infrared range of the electromagnetic spectrum.
  400. Ink Cartridge
    A reservoir of ink and a print head, in a removable package.
  401. Inkjet Printers
    A type of sprayed-ink printer. Often called a bubble-jet.
  402. Inoculating
    Making the computer resistant to computer viruses.
  403. Integrated Services Digital Network (ISDN)
    A worldwide digital communications network emerging from existing telephone services, intended to replace all analog systems with a completely digital transmission system.
  404. Integrated System Board
    A motherboard that has I/O interfaces and their circuitry built in.
  405. Interface
    The point of connectivity between a port in the system unit and a cable with an opposite-gender compatible connector. The port or connection through which a device attaches to an external component, such as a printer's parallel or USB port for connection to a computer, as well as the software that enables the port to communicate with the external component, such as a Windows XP driver for an HP LaserJet.
  406. Interface Software
    The operating system-specific driver that enables communication between the computer and a peripheral.
  407. Internet Control Message Protocol (ICMP)
    A message and management protocol for TCP/IP that transmits error messages and network statistics. The ping utility uses ICMP.
  408. Internet Message Access Protocol (IMAP)
    A protocol commonly used to retrieve e-mail from e-mail servers.
  409. Internet Protocol (IP)
    The underlying communications protocol on which the Internet is based. IP provides addressing on a TCP/IP network and allows a data packet to travel across many networks before reaching its final destination.
  410. Internet Service Provider (ISP)
    A company that provides Internet access and e-mail addresses for users.
  411. Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX)
    The default communication protocol for versions of the Novell NetWare operating system before NetWare 5. IPX and SPX correspond loosely to IP and TCP, respectively, in the TCP/IP protocol suite.
  412. Inverter
    A small circuit board installed behind the LCD panel that takes AC power and converts (inverts) it for the backlight.
  413. IP Spoofing
    An attack during which a hacker tries to gain access to a network by pretending their interface has the same network address as the internal network.
  414. ISDN Terminal Adapter
    The device that connects a computer to an ISDN line.
  415. I/O Addresses
    Numbers that are used by devices and the CPU to manage communication between them. Also called ports or port addresses.
  416. I/O Controller Card
    An older card that can contain serial, parallel, and game ports and floppy drive and IDE connectors.
  417. IBM-Compatible PC
    A computer that uses an Intel (or compatible) processor and can run DOS and Windows.
  418. Internet Control Message Protocol (ICMP)
    Part of the IP layer that is used to transmit error messages and other control messages to hosts and routers.
  419. IDE (Integrated Drive Electronics)
    A standard governing hard drive technology and how secondary storage devices, such as hard drives, CD-ROM drives, and Zip drives, related to a system.
  420. IEEE 1284
    A standard for parallel ports and cables developed by the Institute for Electrical and Electronics Engineers and supported by many hardware manufacturers.
  421. IEEE 1394
    Standards for an expansion bus that can also be configured to work as a local bus. It is expected to replace the SCSI bus, providing an easy method to install and configure fast I/O devices. Also called FireWire and i.Link.
  422. IEEE 1394.3
    A standard, developed by the 1394 Trade Association, that is designed for peer-to-peer data transmission and allows imaging devices to send images and photos directly to printers without involving a computer.
  423. IEEE 802.11b
    An IEEE specification for wireless communication and data synchronization that competes with Bluetooth. Also known as Wi-Fi. Apple Computer's version of 802.11b is called AirPort.
  424. IMAP4 (Internet Message Access Protocol version 4)
    Version 4 of the IMAP protocol, which is an e-mail protocol that has more functionality than its predecessor, POP. IMAP can archive messages in folders on the e-mail server and can allow the user to choose not to download attachments to messages.
  425. Incremental Backup
    A time-saving backup method that only backs up files changed or newly created since the last full or incremental backup. Multiple incremental backups might be required when recovering lost data.
  426. Infestation
    Any unwanted program that is transmitted to a computer without the user's knowledge and that is designed to do varying degrees of damage to data and software. There are a number of different types of infestations, including viruses, Trojan horses, worms, and logic bombs.
  427. Information (.inf) File
    Text file with an .inf file extension, such as Msbatch.inf, that contains information about a hardware or software installation.
  428. Initialization Files
    Configuration information files for Windows. System.ini is one of the most important Windows 9x initialization files.
  429. Installable File System (Ifs)
    A Windows 9x Plug and Play component that is responsible for all disk access.
  430. Institute of Electrical and Electronics Engineers (IEEE)
    A nonprofit organization that develops standards for the computer and electronics industries.
  431. Instruction Set
    The set of instructions, on the CPU chip, that the computer can perform directly (such as ADD and MOVE).
  432. Integrated Device Electronics or Integrated Drive Electronics (IDE)
    A hard drive whose disk controller is integrated into the drive, eliminating the need for a controller cable and thus increasing speed, as well as reducing price.
  433. Intelligent UPS
    A UPS connected to a computer by way of a serial cable so that software on the computer can monitor and control the UPS.
  434. Interlaced
    A type of display in which the electronic beam of a monitor draws every other line with each pass, which lessens the overall effect of a lower refresh rate.
  435. Internal Bus
    The bus inside the CPU that is used for communication between the CPU's internal components.
  436. Internal Cache
    Memory cache that is faster than external cache, and is contained inside 80486 and Pentium chips (also referred to as primary, Level 1, or L1 cache).
  437. Internal Command
    Commands that are embedded in the Command.com file.
  438. Internet Connection Firewall (ICF)
    Windows XP software designed to protect a PC from unauthorized access from the Internet.
  439. Internet Connection Sharing (ICS)
    A Windows 98 and Windows XP utility that uses NAT and acts as a proxy server to manage two or more computers connected to the Internet.
  440. Internet Service Provider (ISP)
    A commercial group that provides Internet access for a monthly fee. AOL, Earthlink, and CompuServe are large ISPs.
  441. intranet
    A private network that uses the TCP/IP protocols.
  442. Io.sys
    Along with Msdos.sys and Command.com, one of the three files that are the core components of the real mode portion of Windows 9x. It is the first program file of the OS.
  443. IP (Internet Protocol)
    The rules of communication in the TCP/IP stack that control segmenting data into packets, routing those packets across networks, and then reassembling the packets once they reach their destination.
  444. IP address
    A 32-bit address consisting of four numbers separated by periods, used to uniquely identify a device on a network that uses TCP/IP protocols. The first numbers identify the network; the last numbers identify a host. An example of an IP address is 206.96.103.114.
  445. IRQ (Interrupt Request) Line
    A line on a bus that is assigned to a device and is used to signal the CPU for servicing. These lines are assigned a reference number (for example, the normal IRQ for a printer is IRQ 7).
  446. ISA (Industry Standard Architecture) slot
    An older slot on the motherboard used for slower I/O devices, which can support an 8-bit or a 16-bit data path. ISA slots are mostly replaced by PCI slots.
  447. Isochronous Data Transfer
    A method used by IEEE 1394 to transfer data continuously without breaks.
  448. ITU (International Telecommunications Union)
    The international organization responsible for developing international standards of communication. Formerly CCITT.
  449. JPEG (Joint Photographic Experts Group)
    A graphical compression scheme that allows the user to control the amount of data that is averaged and sacrificed as file size is reduced. It is a common Internet file format. Most JPEG files have a .jpg extension.
  450. Jumper
    Two wires that stick up side by side on the motherboard and are used to hold configuration information. The jumper is considered closed if a cover is over the wires, and open if the cover is missing.
  451. Kerberos
    An authentication scheme that uses tickets (unique keys) embedded within messages. Named after the three-headed guard dog that stood at the gates of Hades in Greek mythology.
  452. KVM Switch
    A device that switches a single keyboard/video/mouse set among multiple computer systems
  453. Kernel
    The portion of an OS that is responsible for interacting with the hardware.
  454. Kernel Mode
    A Windows NT/2000/XP privileged processing mode that has access to hardware components.
  455. Key
    (1) In encryption, a secret number or code used to encode and decode data. (2) In Windows, a section name of the Windows registry.
  456. L1 Cache
    Cache memory that is built into the processor die (the CPU's silicon wafer).
  457. L2 Cache
    Cache memory that can be collocated with the CPU in the same packaging or placed on the motherboard, external to the CPU packaging. L2 cache is not built into the processor die.
  458. L3 Cache
    Cache memory on the motherboard that is named as such only when L2 cache is in the CPU packaging. L3 cache is the new name, in such a situation, for what used to be termed L2 cache.
  459. Lane
    In PCIe, a switched point-to-point signal path between any two PCIe components. The designation x16, for example, in PCIe represents a component's ability to communicate over 16 lanes simultaneously.
  460. Laser Printer
    A generic name for a printer that uses the electro photographic (EP) print process.
  461. Last Known Good Configuration
    An advanced boot option that lets you restore the system to a prior, functional state, which will allow you to log in again.
  462. Latency
    The amount of delay between sending a network data request and receiving a response.
  463. LCD Cutoff Switch
    Switch for changing the display state on a laptop accessed by pressing the function key and another key, often F8 or F4.
  464. Link
    In PCIe, the single lane or combined collection of lanes that the PCIe switch interconnects between devices. Two PCIe devices can only request links as wide as the narrowest lane rating between the two, such as four lanes between an x4 component and an x16 component.
  465. Liquid Cooling
    A cooling method used to keep CPUs and other hot-running components from overheating by pumping a liquid from outside the system through tubing that leads to blocks that mount to the components like heat sinks.
  466. Local Area Network (LAN)
    A group of computers and associated peripherals connected by a communications channel, capable of sharing files and other resources among several users.
  467. Logical Topologies
    The topology that defines how the data flows in a network.
  468. Loopback Address
    Used to test basic TCP/IP functionality for your network card. The IP address 127.0.0.1 is reserved as the loopback address.
  469. Lands
    Microscopic flat areas on the surface of a CD or DVD that separate pits. Lands and pits are used to represent data on the disk.
  470. Large Mode
    A mode of addressing information on hard drives that range from 504 MB to 8.4 GB, addressing information on a hard drive by translating cylinder, head, and sector information in order to break the 528-MB hard drive barrier. Another name for large mode. Also called ECHS mode.
  471. Large-Capacity Drive
    A hard drive larger than 504 MB.
  472. LBA (Logical Block Addressing) Mode
    A mode of addressing information on hard drives in which the BIOS and operating system view the drive as one long linear list of LBAs or addressable sectors, permitting drives to be larger than 8.4 GB (LBA 0 is cylinder 0, head 0, and sector 1).
  473. Line Conditioner
    A device that regulates, or conditions, power, providing continuous voltage during brownouts and spikes.
  474. Line Protocol
    A protocol used to send data packets destined for a network over telephone lines. PPP and SLIP are examples of line protocols.
  475. Line-Interactive UPS
    A variation of a standby UPS that shortens switching time by always keeping the inverter that converts AC to DC working, so that there is no charge-up time for the inverter.
  476. LMHosts
    A text file located in the Windows folder that contains NetBIOS names and their associated IP addresses. This file is used for name resolution for a NetBEUI network.
  477. Local Bus
    A bus that operates at a speed synchronized with the CPU frequency. The system bus is a local bus.
  478. Local I/O Bus
    A local bus that provides I/O devices with fast access to the CPU.
  479. Local Printer
    A printer connected to a computer by way of a port on the computer. Compare to network printer.
  480. Local Profile
    User profile that is stored on a local computer and cannot be accessed from another computer on the network.
  481. Local User Account
    A user account that applies only to a local computer and cannot be used to access resources from other computers on the network.
  482. Logic Bomb
    Dormant code added to software that is triggered by a predetermined time or event.
  483. Logical Drive
    A portion or all of a hard drive partition that is treated by the operating system as though it were a physical drive. Each logical drive is assigned a drive letter, such as drive C, and contains a file system. Also called a volume.
  484. Logical Geometry
    The number of heads, tracks, and sectors that the BIOS on the hard drive controller presents to the system BIOS and the OS. The logical geometry does not consist of the same values as the physical geometry, although calculations of drive capacity yield the same results.
  485. Logical Unit Number (LUN)
    A number assigned to a logical device (such as a tray in a CD changer) that is part of a physical SCSI device, which is assigned a SCSI ID.
  486. Lost Clusters
    File fragments that, according to the file allocation table, contain data that does not belong to any file. The command CHKDSK/F can free these fragments. Also called lost allocation units.
  487. Low Insertion Force (LIF) Socket
    A socket that requires the installer to manually apply an even force over the microchip when inserting the chip into the socket.
  488. Low Voltage Differential (LVD)
    A type of differential signaling that uses lower voltage than does HVD, is less expensive, and can be compatible with single-ended signaling on the same SCSI bus.
  489. Low-Level Formatting
    A process (usually performed at the factory) that electronically creates the hard drive tracks and sectors and tests for bad spots on the disk surface.
  490. LPX
    A form factor in which expansion cards are mounted on a riser card that plugs into a motherboard. The expansion cards in LPX systems are mounted parallel to the motherboard, rather than perpendicular to it as in AT and ATX systems.
  491. Macro Virus
    A software exploitation virus that works by using the macro feature included in many applications.
  492. Main Motor
    A printer stepper motor that is used to advance the paper.
  493. Maintenance Station
    Provides a zero position for an ink- or bubble-jet print head and keeps the print nozzles clear between print jobs.
  494. Man-In-The-Middle Attack
    An attack that occurs when someone/-thing that is trusted intercepts packets and retransmits them to another party. Man-in-the-middle attacks have also been called TCP/IP hijacking in the past.
  495. Material Safety Data Sheet (MSDS)
    A document that contains safety information about a given product. Information provided includes safe handling procedures, what to do in case of an accident, and disposal information.
  496. Media Access Control (MAC)
    The unique physical address for each NIC. One of two layers of the Data Link layer in the OSI model. A 6-byte hexadecimal hardware address unique to each NIC card and assigned by the manufacturer. The address is often printed on the adapter. An example is 00 00 0C 08 2F 35. Also called a physical address, an adapter address, or a hardware address.
  497. Memory Bank
    A requirement of a CPU and memory controller, based on system-bus width and single/dual-channel support, that reflects on the minimum number of memory chips or modules required to satisfy a single read or write cycle. Leads to physical constraints that must be observed during initial installation or upgrading of the system's RAM, such as the ability to install single modules or a minimum of a pair, quad, and so forth.
  498. Mesh Topology
    A type of logical topology in which each device on a network is connected to every other device on the network. This topology uses routers to search multiple paths and determine the best path.
  499. microSD
    A solid-state, or flash, memory card format related to SD cards.
  500. miniSD
    A solid-state, or flash, memory card format related to SD cards.
  501. Modem
    A contraction of the term modulator/demodulator. Modems connect digital devices over analog connections. The term has been adapted for any device that connects personal computers and personal networks to a service provider's network, such as DSL modems and cable modems, for instance.
  502. Molex Connector
    The larger power connector that most often provides power to hard disk drives and other devices that require more current to power their motors than offered by a Berg connector.
  503. Mopiers
    A laser printer that includes copier-like functions (coalition, stapling, and so on), so each copy is essentially an original.
  504. Multicore
    The CPU technology that places multiple processor dies in the same packaging, or the equivalent thereof.
  505. Multifactor
    The term employed anytime more than one factor must be considered.
  506. Multifunction Printers
    A peripheral that is essentially a printer, copier, scanner, and fax machine all in one.
  507. MultiMediaCard (MMC)
    A solid-state, or flash, memory card format.
  508. Multipartite Virus
    A virus that attacks a system in more than one way.
  509. Multipurpose Server
    A server that has more than one use. For example, a multipurpose server can be both a file server and a print server.
  510. Musical Instrument Digital Interface (MIDI)
    A technology that daisy-chains components to one another with a 5-pin standard DIN connector and uses special packets to communicate with other MIDI devices and the computer's audio subsystem.
  511. Macro
    A small sequence of commands, contained within a document that can be automatically executed when the document is loaded, or executed later by using a predetermined keystroke.
  512. Macro Virus
    A virus that can hide in the macros of a document file. Typically, viruses do not reside in data or document files.
  513. Mandatory User Profile
    A roaming user profile that applies to all users in a user group, and individual users cannot change that profile.
  514. Master Boot Record (MBR)
    The first sector on a hard drive, which contains the partition table and a program the BIOS uses to boot an OS from the drive.
  515. Master File Table (MFT)
    The database used by the NTFS file system to track the contents of a logical drive.
  516. Material Safety Data Sheet (MSDS)
    A document that explains how to properly handle substances such as chemical solvents; it includes information such as physical data, toxicity, health effects, first aid, storage, disposal, and spill procedures.
  517. Megahertz (MHz)
    One million Hz, or one million cycles per second. See hertz (Hz).
  518. Memory
    Physical microchips that can hold data and programming, located on the motherboard or expansion cards.
  519. Memory Address
    A number assigned to each byte in memory. The CPU can use memory addresses to track where information is stored in RAM. Memory addresses are usually displayed as hexadecimal numbers in segment/offset form.
  520. Memory Cache
    A small amount of faster RAM that stores recently retrieved data, in anticipation of what the CPU will request next, thus speeding up access. See also system bus.
  521. Memory Dump
    The contents of memory saved to a file at the time an event halted the system. Support technicians can analyze the dump file to help understand the source of the problem.
  522. Memory Extender
    For DOS and Windows 9x, a device driver named Himem.sys that manages RAM, giving access to memory addresses above 1 MB.
  523. Memory Paging
    In Windows, swapping blocks of RAM memory to an area of the hard drive to serve as virtual memory when RAM is low.
  524. Memory-Resident Virus
    A virus that can stay lurking in memory even after its host program is terminated.
  525. microATX
    A recent version of the ATX form factor. MicroATX addresses some new technologies that have been developed since the original introduction of ATX.
  526. Microsoft Management Console (MMC)
    A utility to build customized consoles. These consoles can be saved to a file with an .msc file extension.
  527. Mini-ATX
    A smaller ATX board that can be used with regular ATX cases and power supplies.
  528. Minicartridge
    A tape drive cartridge that is only 31?4 2 21?2 2 3?5 inches. It is small enough to allow two drives to fit into a standard 51?2-inch drive bay of a PC case.
  529. Minifile System
    In Windows NT/2000/XP, a simplified file system that is started so that Ntldr (NT Loader) can read files from any file system the OS supports.
  530. Mini-LPX
    A smaller version of the LPX motherboard.
  531. Mixed Mode
    A Windows 2000 mode for domain controllers used when there is at least one Windows NT domain controller on the network.
  532. MMX (Multimedia Extensions)
    Multimedia instructions built into Intel processors to add functionality such as better processing of multimedia, SIMD support, and increased cache.
  533. Modem Riser Card
    A small modem card that uses an AMR or CNR slot. Part of the modem logic is contained in a controller on the motherboard.
  534. Modem Speed
    The speed at which a modem can transmit data along a phone line, measured in bits per second (bps). Also called line speed.
  535. Modulation
    Converting binary or digital data into an analog signal that can be sent over standard telephone lines.
  536. Monitor
    The most commonly used output device for displaying text and graphics on a computer.
  537. Motherboard
    The main board in the computer, also called the system board. The CPU, ROM chips, SIMMs, DIMMs, RIMMs, and interface cards are plugged into the motherboard.
  538. MP3
    A method to compress audio files that uses MPEG level 3. It can reduce sound files as low as a 1:24 ratio without losing much sound quality.
  539. MPEG (Moving Pictures Experts Group)
    A processing-intensive standard for data compression for motion pictures that tracks movement from one frame to the next and only stores the data that has changed.
  540. Msdos.sys
    In Windows 9x, a text file that contains settings used by Io.sys during booting. In DOS, the Msdos.sys file was a program file that contained part of the DOS core.
  541. Multicasting
    A process in which a message is sent by one host to multiple hosts, such as when a video conference is broadcast to several hosts on the Internet.
  542. Multimeter
    A device used to measure the various components of an electrical circuit. The most common measurements are voltage, current, and resistance.
  543. Multipartite Virus
    A combination of a boot sector virus and a file virus. It can hide in either type of program.
  544. Multiplier
    The factor by which the bus speed or frequency is multiplied to get the CPU clock speed.
  545. Multiscan Monitor
    A monitor that can work within a range of frequencies and thus can work with different standards and video cards. It offers a variety of refresh rates.
  546. Multisession
    A feature that allows data to be read from or written to a CD during more than one session. This is important if the disk was only partially filled during the first write.
  547. Multistation Access Unit (MSAU or MAU)
    A centralized hub used in token ring networks to connect stations. Also called CAU. The central device in a Token Ring network that provides both the physical and logical connections to the stations.
  548. Multitasking
    Doing more than one thing at a time. A true multitasking system requires two or more CPUs, each processing a different thread at the same time. Compare to cooperative multitasking and preemptive multitasking.
  549. Multithreading
    The ability to pass more than one function (thread) to the OS kernel at the same time, such as when one thread is performing a print job while another reads a file.
  550. NetBEUI (NetBIOS Extended User Interface)
    A network device driver for the transport layer supplied with Microsoft's LAN Manager. A fast, proprietary Microsoft networking protocol used only by Windows-based systems, and limited to LANs because it does not support routing.
  551. NetBIOS (Network Basic Input/Output System)
    In networking, a layer of software, originally developed in 1984 by IBM and Sytek that links a network operating system with specific network hardware. NetBIOS provides an application program interface (API) with a consistent set of commands for requesting lower-level network services to transmit information from node to node.
  552. Network
    A group of computers and associated peripherals connected by a communications channel capable of sharing files and other resources between several users.
  553. Network Address Translation (NAT)
    The process of translating private, non-routable IP addresses into public IP addresses.
  554. Network-Based Firewall
    A firewall designed to protect an entire network of computers instead of just one system. It's generally a stand-alone hardware device with specialized software installed on it to protect your network.
  555. Network Interface Card (NIC)
    In networking, the PC expansion board that plugs into a personal computer or server and works with the network operating system to control the flow of information over the network. The network interface card is connected to the network media (twisted-pair, coaxial, or fiber optic cable, or wireless), which in turn connects all the network interface cards in the network.
  556. Non-dedicated Server
    A computer that can be both a server and a workstation. In practice, by performing the functions of both server and workstation, this type of server does neither function very well. Non-dedicated servers are typically used in peer-to-peer networks.
  557. Nonintegrated System Board
    A motherboard that has no I/O interfaces built in, except for a keyboard and possibly mouse interfaces.
  558. Noninterference Model
    A model intended to ensure that higher-level security functions don't interfere with lower-level functions.
  559. Non-parity Memory
    A memory subsystem that does not support parity checking, possibly resulting in fewer chips populating the memory module.
  560. NWLINK
    The Microsoft implementation of Novell's IPX/SPX protocol.
  561. Name Resolution
    The process of associating a NetBIOS name or host name to an IP address.
  562. Narrow SCSI
    One of the two main SCSI specifications. Narrow SCSI has an 8-bit data bus. The word narrow is not usually included in the names of narrow SCSI devices.
  563. NAT (Network Address Translation)
    A process that converts private IP addresses on a LAN to the proxy server's IP address before a data packet is sent over the Internet.
  564. Native Mode
    A Windows 2000 mode used by domain controllers when there are no Windows NT domain controllers present on the network.
  565. Network Drive Map
    Mounting a drive to a computer, such as drive E, that is actually hard drive space on another host computer on the network.
  566. Network Interface Card (NIC)
    An expansion card that plugs into a computer's motherboard and provides a port on the back of the card to connect a PC to a network. Also called a network adapter.
  567. Network Operating System (NOS)
    An operating system that resides on the controlling computer in the network. The NOS controls what software, data, and devices a user on the network can access. Examples of an NOS are Novell Netware and Windows 2000 Server.
  568. Network Printer
    A printer that any user on the network can access, through its own network card and connection to the network, through a connection to a standalone print server, or through a connection to a computer as a local printer, which is shared on the network.
  569. NLX
    A low-end form factor that is similar to LPX but provides greater support for current and emerging processor technologies. NLX was designed for flexibility and efficiency of space.
  570. Network News Transfer Protoco (NNTP)
    The protocol used by newsgroup server and client software.
  571. Node
    Any computer, workstation, or device on a network.
  572. Noise
    An extraneous, unwanted signal, often over an analog phone line, that can cause communication interference or transmission errors. Possible sources are fluorescent lighting, radios, TVs, lightning, or bad wiring.
  573. Non-interlaced
    A type of display in which the electronic beam of a monitor draws every line on the screen with each pass.
  574. Non-Memory-Resident Virus
    A virus that is terminated when the host program is closed. Compare to memory-resident virus.
  575. Non-parity Memory
    Eight-bit memory without error checking. A SIMM part number with a 32 in it (4 2 8 bits) is non-parity.
  576. Nonvolatile
    Refers to a kind of RAM that is stable and can hold data as long as electricity is powering the memory.
  577. North Bridge
    That portion of the chip set hub that connects faster I/O buses (for example, AGP bus) to the system bus. Compare to South Bridge. The functional part of the chipset that controls local-bus communication among components connected to the frontside bus, such as the CPU and memory.
  578. NTFS (NT File System)
    The file system for the Windows NT/2000/XP operating systems. NTFS cannot be accessed by other operating systems such as DOS. It provides increased reliability and security in comparison to other methods of organizing and accessing files. There are several versions of NTFS that might or might not be compatible.
  579. Ntldr (NT Loader)
    In Windows NT/2000/XP, the OS loader used on Intel systems.
  580. NTVDM (NT virtual DOS machine)
    An emulated environment in which a 16-bit DOS application resides within Windows NT/2000/XP with its own memory space or WOW (Win16 on Win32).
  581. Null Modem Cable
    A cable that allows two data terminal equipment (DTE) devices to communicate in which the transmit and receive wires are cross-connected and no modems are necessary.
  582. Occupational Safety and Health Administration (OSHA)
    A United States federal agency in charge of administering the Occupational Safety and Health Act. OSHA is responsible for ensuring that employees have a safe work environment.
  583. Open Access Point
    A wireless access point that employs no encryption or authentication, allowing any device that receives the signal potential access to the connected network.
  584. Open Systems Interconnection (OSI) model
    A seven-layer theoretical networking model developed by the International Organization of Standardization (ISO).
  585. Octet
    Term for each of the four 8-bit numbers that make up an IP address. For example, the IP address 206.96.103.114 has four octets.
  586. Ohm
    The standard unit of measurement for electrical resistance. Resistors are rated in ohms.
  587. On-Board Ports
    Ports that are directly on the motherboard, such as a built-in keyboard port or on-board serial port.
  588. Operating System (OS)
    Software that controls a computer. An OS controls how system resources are used and provides a user interface, a way of managing hardware and software, and ways to work with files.
  589. Packet
    A group of bits ready for transmission over a network. It includes a header, data, and a trailer.
  590. Page-Description Language
    Describes the whole page being printed. The controller in the printer interprets these commands and turns them into laser pulses or firing print wires.
  591. Page Printer
    A printer that gets its instructions one page at a time, such as a laser printer.
  592. Paper Feed Mechanism
    The portion of the printer that picks up paper from the paper drawer and feeds it into the printer.
  593. Paper Feed Sensors
    The sensors on the paper feed mechanism that detect when the printer has paper or is out of paper.
  594. Paper Pickup Roller
    A D-shaped roller that rotates against the paper and pushes one sheet into a printer.
  595. Parallel Interface
    A legacy port and cable-connector pairing based on a DB25 interface most commonly used for attaching a printer to a computer.
  596. Parity Checking
    Storing an extra bit with and based on each byte in memory. When a byte is accessed, the validity of the parity bit is checked. If the check shows an error, the byte is rejected because there is no way to determine the nature of the error.
  597. Parked
    When the print head is in the locked, resting position.
  598. Partition
    A logical grouping of data organized to fall under a single drive letter for primary partitions and multiple drives for extended partitions.
  599. Partitioning
    The process of assigning part or all of a hard drive for use by the computer.
  600. Passive Hub
    A type of hub that electrically connects all network ports together. This type of hub is not powered.
  601. Password Authentication Protocol (PAP)
    An authentication protocol that offers no true security, but it's one of the simplest forms of authentication. The username and password values are both sent to the server as clear text and checked for a match.
  602. Password Guessing
    Attempting to enter a password by guessing its value.
  603. Patch
    A fix for a known software problem.
  604. Path
    The location to a file or folder.
  605. PC100
    An SDR SDRAM module based on a 100MHz FSB.
  606. PC2-3200
    A DDR2 SDRAM module capable of 3200MBps of throughput and populated with DDR2-400 memory chips and based on a 400MHz FSB.
  607. PC2700
    A DDR SDRAM module capable of 2700MBps of throughput and populated with DDR333 memory chips and based on a 333MHz FSB.
  608. PC3200
    A DDR SDRAM module capable of 3200MBps of throughput and populated with DDR333 memory chips and based on a 333MHz FSB.
  609. Physical Topology
    A description that identifies how the cables on a network are physically arranged.
  610. Pickup Stepper Motor
    The motor that turns the pickup roller in a printer.
  611. Piconet
    A Bluetooth network. A Bluetooth-enabled device can communicate with up to seven other devices in a single piconet. Devices can also be members of multiple piconets.
  612. Platters
    The physical discs on which magnetic or optical data is stored. Hard drive platters, for example, are on a spindle inside a sealed encasement.
  613. Plenum-Rated
    When referring to coaxial covering, a designation that means the coating does not produce toxic gas when burned (as PVC does) and is rated for use in air plenums that carry breathable air.
  614. Plug and Play (PnP)
    A standard set of specifications that was developed by Intel to enable a computer to detect a new device automatically and install the appropriate driver.
  615. Polymorphic
    An attribute of some viruses that allows them to mutate and appear differently each time they crop up. The mutations make it harder for virus scanners to detect (and react) to the viruses.
  616. Port
    The part of an interface found on the computer side to which an opposite-gendered connector from a cable attaches.
  617. Port Assignment
    Configuring an ACL, or setting up rules that determine what gets through a firewall.
  618. Port Forwarding
    Allowing packets that meet the criteria in the ACL to pass through the firewall to their destination.
  619. Port Number
    The logical channel that TCP/IP-based protocols use to communicate.
  620. Port Triggering
    An automated form of port forwarding. It allows traffic to enter the network on a specific port after a computer makes an outbound request on that specific port.
  621. POST Card
    A circuit board that fits into an ISA or PCI expansion slot in the motherboard and reports numeric codes as the boot process progresses. By looking up the number where the card stops, you can identify the source of problems.
  622. Post Office Protocol (POP)
    A TCP/IP protocol optimized for the receiving of e-mail. The current standard is POP3, which uses port 100.
  623. POTS Line
    A Plain Old Telephone Service line, the original analog technology for phone lines still in use today for standard phone service.
  624. Power Circuits
    The set of conductive pathways that converts 110V or 220V house current into the voltages a bubble-jet printer uses (usually 12V and 5V) and distributes those voltages to the other printer circuits and devices that need it.
  625. Power-On Self-Test (POST)
    Part of the boot process controlled by the BIOS that verifies the working condition of the hardware the BIOS knows about.
  626. Power Supply
    A component that converts an external power source to the power required by the other components of the system it powers.
  627. Primary Partition
    The first partition created in an operating system.
  628. Primary Rate Interface (PRI)
    A form of ISDN that contains 23 64-bit B channels and 1 64-bit D channel for a total combined speed of 1536Kbps.
  629. Print Buffer
    A small amount of memory located on the printer used to hold print jobs.
  630. Printer Control Circuits
    Runs a printer's stepper motors, loads paper, and so on. Monitors the health of the printer and reports that information back to the computer.
  631. Printer Controller Assembly
    A large circuit board in a laser printer that converts signals from the computer into signals for the various parts in a printer.
  632. Printer-Resident Fonts
    Fonts that are installed into the onboard memory of the printer.
  633. Printer Ribbon
    A fabric strip that is impregnated with ink and wrapped around two spools encased in a cartridge. This cartridge is used in dot-matrix printers to provide the ink for the print process.
  634. Printers
    Electromechanical output devices that are used to put information from the computer onto paper.
  635. Print head
    The part of a printer that creates the printed image. In a dot-matrix printer, the print head contains the small pins that strike the ribbon to create the image, and in an inkjet printer, the print head contains the jets used to create the ink droplets as well as the ink reservoirs. A laser printer creates images using an electro photographic method similar to that found in photocopiers and does not have a print head.
  636. Print head Alignment
    The process by which the print head is calibrated for use. A special utility that comes with the printer software is used to do this.
  637. Print head Carriage
    The component of a bubble-jet printer that moves back and forth during printing. It contains the physical as well as electronic connections for the print head and (in some cases) the ink reservoir.
  638. Print Media
    Another name for the media being printed on. Examples include paper, transparencies, and labels.
  639. Print Queue
    the documents that are waiting to be printed
  640. Print Server
    A network server that hosts one or more printers for clients to use.
  641. Print Spooler
    A service that formats print jobs in the language that the printer needs.
  642. Propagation Delay
    In satellite Internet, the delay caused by the length of time required to transmit data and receive a response via satellite.
  643. Protocol
    In networking and communications, the specification that defines the procedures to follow when transmitting and receiving data. Protocols define the format, timing, sequence, and error-checking systems used.
  644. Proxy Server
    Also called a proxy, it makes requests of a computer for another computer.
  645. PS/2 Port
    A 6-pin mini-DIN connector named after the second generation of IBM personal computers and still a choice today, trailing behind USB in popularity, for mouse and keyboard attachment.
  646. Public Switched Telephone Network (PSTN)
    The network that carries standard, non-packetized voice and data traffic from subscribers. Traffic can originate from POTS, ISDN, and DSL lines but does not include DSL's data-band traffic.
  647. P1 Connector
    Power connection on an ATX motherboard.
  648. P8 Connector
    One of two power connectors on an AT motherboard.
  649. P9 Connector
    One of two power connectors on an AT motherboard.
  650. Packet
    Segment of network data that also includes header, destination address, and trailer information that is sent as a unit. Also called data packet or datagram.
  651. Page Fault
    An OS interrupt that occurs when the OS is forced to access the hard drive to satisfy the demands for virtual memory.
  652. Pagefile.sys
    The Windows NT/2000/XP swap file.
  653. Page-In
    The process in which the memory manager goes to the hard drive to return the data from a swap file to RAM.
  654. Page-Out
    The process in which, when RAM is full, the memory manager takes a page and moves it to the swap file.
  655. Pages
    4K segments in which Windows NT/ 2000/XP allocates memory.
  656. Parallel Port
    A female 25-pin port on a computer that can transmit data in parallel, 8 bits at a time, and is usually used with a printer. The names for parallel ports are LPT1 and LPT2.
  657. Parity
    An error-checking scheme in which a ninth, or parity, bit is added. The value of the parity bit is set to either 0 or 1 to provide an even number of ones for even parity and an odd number of ones for odd parity.
  658. Parity Error
    An error that occurs when the number of 1s in the byte is not in agreement with the expected number.
  659. Parity Memory
    Nine-bit memory in which the ninth bit is used for error checking. A SIMM part number with a 36 in it (4 2 9 bits) is parity. Older PCs almost always use parity chips.
  660. Partition
    A division of a hard drive that can be used to hold logical drives.
  661. Partition Table
    A table at the beginning of the hard drive that contains information about each partition on the drive. The partition table is contained in the Master Boot Record.
  662. Passive Backplane
    A type of backplane system in which the backplane contains no circuitry at all. Passive backplanes locate all circuitry on a mothercard plugged into a backplane.
  663. Passive Terminator
    A type of terminator for single-ended SCSI cables. Simple resistors are used to provide termination of a signal. Passive termination is not reliable over long distances and should only be used with narrow SCSI.
  664. Patch
    An update to software that corrects an error, adds a feature, or addresses security issues. Also called an update or service pack.
  665. Patch Cable
    A network cable that is used to connect a PC to a hub.
  666. Path
    (1) A drive and list of directories pointing to a file such as C:\Windows\command. (2) The OS command to provide a list of paths to the system for finding program files to execute.
  667. PC Card
    A credit-card-sized adapter card that can be slid into a slot in the side of many notebook computers and is used for connecting to modems, networks, and CD-ROM drives. Also called PCMCIA Card.
  668. PC Card Slot
    An expansion slot on a notebook computer, into which a PC Card is inserted. Also called a PCMCIA Card slot.
  669. PCI (Peripheral Component Interconnect) Bus
    A bus common on Pentium computers that runs at speeds of up to 33 MHz or 66 MHz, with a 32-bit-wide or 64-bit-wide data path. PCI-X, released in September 1999, enables PCI to run at 133 MHz. For some chip sets, it serves as the middle layer between the memory bus and expansion buses.
  670. PDA (Personal Digital Assistant)
    A small, handheld computer that has its own operating system and applications.
  671. Peer-To-Peer Network
    A network of computers that are all equals, or peers. Each computer has the same amount of authority, and each can act as a server to the other computers.
  672. Peripheral Devices
    Devices that communicate with the CPU but are not located directly on the motherboard, such as the monitor, floppy drive, printer, and mouse.
  673. Physical Geometry
    The actual layout of heads, tracks, and sectors on a hard drive. Refer also to logical geometry.
  674. Program Information File (PIF)
    A file used by Windows to describe the environment for a DOS program to use.
  675. Pin Grid Array (PGA)
    A feature of a CPU socket whereby the pins are aligned in uniform rows around the socket.
  676. Ping (Packet Internet Groper)
    A Windows and Unix command used to troubleshoot network connections. It verifies that the host can communicate with another host on the network.
  677. Pinout
    A description of how each pin on a bus, connection, plug, slot, or socket is used.
  678. Pipelined Burst SRAM
    A less expensive SRAM that uses more clock cycles per transfer than nonpipelined burst but does not significantly slow down the process.
  679. Pits
    Recessed areas on the surface of a CD or DVD, separating lands, or flat areas. Lands and pits are used to represent data on a disc.
  680. Pixel
    A small spot on a fine horizontal scan line. Pixels are illuminated to create an image on the monitor.
  681. Plug and Play (PnP)
    A standard designed to make the installation of new hardware devices easier by automatically configuring devices to eliminate system resource conflicts (such as IRQ or I/O address conflicts). PnP is supported by Windows 9x, Windows 2000, and Windows XP.
  682. Polling
    A process by which the CPU checks the status of connected devices to determine if they are ready to send or receive data.
  683. Polymorphic Virus
    A type of virus that changes its distinguishing characteristics as it replicates itself. Mutating in this way makes it more difficult for AV software to recognize the presence of the virus.
  684. POP (Post Office Protocol)
    The protocol that an e-mail server and client use when the client requests the downloading of e-mail messages. The most recent version is POP3. POP is slowly being replaced by IMAP.
  685. Port
    (1) As applied to services running on a computer, a number assigned to a process on a computer 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/O address. (3) A physical connector, usually at the back of a computer, that allows a cable from a peripheral device, such as a printer, mouse, or modem, to be attached.
  686. Port Replicator
    A device designed to connect to a notebook computer in order to make it easy to connect the notebook to peripheral devices.
  687. Port Settings
    The configuration parameters of communications devices such as COM1, COM2, or COM3, including IRQ settings.
  688. Port Speed
    The communication speed between a DTE (computer) and a DCE (modem). As a general rule, the port speed should be at least four times as fast as the modem speed.
  689. POST (Power-On Self Test)
    A self-diagnostic program used to perform a simple test of the CPU, RAM, and various I/O devices. The POST is performed by startup BIOS when the computer is first turned on, and is stored in ROM-BIOS.
  690. Power Conditioner
    A line conditioner that regulates, or conditions, power, providing continuous voltage during brownouts.
  691. Power Scheme
    A feature of Windows XP support for notebooks that allows the user to create groups of power settings for specific sets of conditions.
  692. Power Supply
    A box inside the computer case that supplies power to the motherboard and other installed devices. Power supplies provide 3.3, 5, and 12 volts DC.
  693. Power-On Password
    A password that a computer uses to control access during the boot process.
  694. PPP (Point-to-Point Protocol)
    A protocol that governs the methods for communicating via modems and dial-up telephone lines. The Windows Dial-up Networking utility uses PPP.
  695. PPPoE (Point-to-Point Protocol over Ethernet)
    The protocol that describes how a PC is to interact with a broadband converter box, such as cable modem, when the two are connected by an Ethernet cable, connected to a NIC in a PC.
  696. Preemptive Multitasking
    A type of pseudo-multitasking whereby the CPU allows an application a specified period of time and then preempts the processing to give time to another application.
  697. Primary Domain Controller (PDC)
    In a Windows NT network, the computer that controls the directory database of user accounts, group accounts, and computer accounts on a domain. Also see backup domain controller.
  698. Primary Partition
    A hard disk partition that can contain only one logical drive.
  699. Primary Storage
    Temporary storage on the motherboard used by the CPU to process data and instructions. Memory is considered primary storage.
  700. Printer
    A peripheral output device that produces printed output to paper. Different types include dot matrix, ink-jet, and laser printers.
  701. Printer Maintenance Kit
    A kit purchased from a printer manufacturer that contains the parts, tools, and instructions needed to perform routine printer maintenance.
  702. Private IP Address
    An IP address that is used on a private TCP/IP network that is isolated from the Internet.
  703. Process
    An executing instance of a program together with the program resources. There can be more than one process running for a program at the same time. One process for a program happens each time the program is loaded into memory or executed.
  704. Processor Speed
    The speed, or frequency, at which the CPU operates. Usually expressed in GHz.
  705. Product Activation
    The process that Microsoft uses to prevent software piracy. For example, once Windows XP is activated for a particular computer, it cannot be installed on another computer.
  706. Program
    A set of step-by-step instructions to a computer. Some are burned directly into chips, while others are stored as program files. Programs are written in languages such as BASIC and C++.
  707. Program File
    A file that contains instructions designed to be executed by the CPU.
  708. Protected Mode
    An operating mode that supports preemptive multitasking, the OS manages memory and other hardware devices, and programs can use a 32-bit data path. Also called 32-bit mode.
  709. Protocol
    A set of rules and standards that two entities use for communication.
  710. Protocol.ini
    A Windows initialization file that contains network configuration information.
  711. Proxy Server
    A server that acts as an intermediary between another computer and the Internet. The proxy server substitutes its own IP address for the IP address of the computer on the network making a request, so that all traffic over the Internet appears to be coming from only the IP address of the proxy server.
  712. Public IP Address
    An IP address available to the Internet.
  713. QIC (Quarter-Inch Committee Or Quarter-Inch Cartridge)
    A name of a standardized method used to write data to tape. These backup files have a .qic extension.
  714. Radio Frequency Interference (RFI)
    Another term for electromagnetic interference (EMI).
  715. Rasterizing
    The process of converting signals from the computer into signals for the various assemblies in a laser printer.
  716. Recovery CD/DVD
    A CD-ROM set or DVD that comes with a particular model and brand of computer and usually contains an image of the entire Windows installation, along with applications, utilities, and drivers specifically for that computer. Also called by other names, such as restoration CD or reinstallation DVD.
  717. Remote Computer
    In Remote Desktop, the remote computer is the one that you are not sitting at; it's the one you make a connection to while sitting at the home computer.
  718. Remote Desktop
    A feature of Windows that allows you to connect to another computer and take control over that computer as if you were sitting in front of it. Also the name of the software that lets your computer be a remote computer in a remote desktop connection.
  719. Remote Desktop Connection
    The software that lets a computer act as a home computer in the Remote Desktop application.
  720. replay attack
    Any attack where the data is retransmitted repeatedly (often fraudulently or maliciously). In one such possibility, a user can replay a web session and visit sites intended only for the original user.
  721. Resource
    On a network, any device that clients can access, such as printers or shared drives.
  722. Restore Point
    A copy of your system configuration at a given point in time.
  723. Retrovirus
    A virus that attacks or bypasses the antivirus software installed on a computer.
  724. Riser Card
    A daughter card with expansion slots that inserts into a motherboard; used in low-profile cases.
  725. Root Directory
    The first directory on a logical file system, such as C:\.
  726. Router
    In networking, an intelligent connecting device that can send packets to the correct local area network segment to take them to their destination. Routers link LAN segments at the Network layer of the OSI model for computer-to-computer communications.
  727. RAID (Redundant Array Of Inexpensive Disks Or Redundant Array Of Independent Disks)
    Several methods of configuring multiple hard drives to store data to increase logical volume size and improve performance, and to ensure that if one hard drive fails, the data is still available from another hard drive.
  728. RAM (Random Access Memory)
    Memory modules on the motherboard containing microchips used to temporarily hold data and programs while the CPU processes both. Information in RAM is lost when the PC is turned off.
  729. RAM Drive
    An area of memory that is treated as though it were a hard drive, but works much faster than a hard drive. The Windows 9x startup disk uses a RAM drive. Compare to virtual memory.
  730. RARP (Reverse Address Resolution Protocol)
    A protocol used to translate the unique hardware NIC addresses (MAC addresses) into IP addresses (the reverse of ARP).
  731. Read/Write Head
    A sealed, magnetic coil device that moves across the surface of a disk either reading data from or writing data to the disk.
  732. Real Mode
    A single-tasking operating mode whereby a program has 1024K of memory addresses, has direct access to RAM, and uses a16-bit data path. Using a memory extender (Himem.sys) a program in real mode can access memory above 1024K. Also called 16-bit mode.
  733. Recovery Console
    A Windows 2000/XP command interface utility and OS that can be used to solve problems when Windows cannot load from the hard drive.
  734. Rectifier
    An electrical device that converts AC to DC. A PC power supply contains a rectifier.
  735. Refresh
    The process of periodically rewriting data, such as on dynamic RAM.
  736. Refresh Rate
    As applied to monitors, the number of times in one second an electronic beam can fill the screen with lines from top to bottom. Also called vertical scan rate.
  737. Registry
    A database that Windows uses to store hardware and software configuration information, user preferences, and setup information.
  738. Re-Marked Chips
    Chips that have been used and returned to the factory, marked again, and resold. The surface of the chips may be dull or scratched.
  739. Remote Assistance
    A Windows XP feature that allows a support technician at a remote location to have full access to the Windows XP desktop.
  740. Repeater
    A device that amplifies signals on a network so they can be transmitted further down the line.
  741. Rescue Disk
    A floppy disk that can be used to start up a computer when the hard drive fails to boot. Also called emergency startup disk (ESD) or startup disk.
  742. Resistance
    The degree to which a device opposes or resists the flow of electricity. As the electrical resistance increases, the current decreases. See ohm and resistor.
  743. Resistor
    An electronic device that resists or opposes the flow of electricity. A resistor can be used to reduce the amount of electricity being supplied to an electronic component.
  744. Resolution
    The number of pixels on a monitor screen that are addressable by software (example: 1024 2 768 pixels).
  745. Restore Point
    A snapshot of the Windows Me/XP system state, usually made before installation of new hardware or applications.
  746. REt (Resolution Enhancement technology)
    The term used by Hewlett-Packard to describe the way a laser printer varies the size of the dots used to create an image. This technology partly accounts for the sharp, clear image created by a laser printer.
  747. RIMM
    A type of memory module used on newer motherboards, produced by Rambus, Inc.
  748. Ring Topology
    A network topology in which the nodes in a network form a ring. Each node is connected only to two other nodes, and a centralized hub is not required.
  749. RISC (Reduced Instruction Set Computing) Chips
    Chips that incorporate only the most frequently used instructions, so that the computer operates faster (for example, the PowerPC uses RISC chips).
  750. Riser Card
    A card that plugs into a motherboard and allows for expansion cards to be mounted parallel to the motherboard. Expansion cards are plugged into slots on the riser card.
  751. RJ-11
    A phone line connection found on modems, telephones, and house phone outlets.
  752. RJ-45 Connector
    A connector used with twisted-pair cable that connects the cable to the NIC.
  753. Roaming User Profile
    A user profile for a roaming user. Roaming user profiles are stored on a server so that the user can access the profile from anywhere on the network.
  754. ROM (Read-Only Memory)
    Chips that contain programming code and cannot be erased.
  755. Root Directory
    The main directory created when a hard drive or disk is first formatted. In Linux, it's indicated by a forward slash. In DOS and Windows, it's indicated by a backward slash.
  756. Routable Protocol
    A protocol that can be routed to interconnected networks on the basis of a network address. TCP/IP is a routable protocol, but NetBEUI is not.
  757. Router
    A device that connects networks and makes decisions as to the best routes to use when forwarding packets.
  758. Safe Mode
    Starts Windows using only basic files and drivers, such as mouse (except serial mice), monitor, keyboard, mass storage, base video, and default system services.
  759. Satellite Internet
    A type of Internet connection that uses a satellite dish to receive data from a satellite and a relay station that is connected to the Internet.
  760. Scanner
    An optical device used to digitize images such as line art or photographs, so that they can be merged with text by a page-layout or desktop publishing program or incorporated into a CAD drawing.
  761. Scatternet
    A network of two or more piconets.
  762. SDRAM
    A form of DRAM that is synchronized to the system clock. Varieties include SDR, DDR, DDR2, DDR3, and DRDRAM.
  763. Sector
    A portion of a track that most often stores 512 bytes.
  764. Secure and Fast Encryption Routine (SAFER+)
    The encryption protocol used by Blue-tooth devices.
  765. Secure Digital (SD)
    A solid-state, or flash, memory card format.
  766. Secure Shell (SSH)
    A protocol developed to allow encrypted data exchange between two computers.
  767. Security Log
    A log file used in Windows to keep track of security events specified by the domain's audit policy.
  768. Separator Pads
    Rubber patches that help keep the paper in place so that only one sheet goes into a printer.
  769. Service Packs
    Major patches or upgrades to the Windows operating system are released in groups known as service packs.
  770. Service-Set Identifier (SSID)
    The identifier (name) of a wireless router or wireless access point. The unique name of a wireless network that differentiates it from other wireless networks that are also in range of a wireless client.
  771. Shielded Twisted-Pair (STP)
    Copper network cable which has two or four pairs of twisted wires, shielded by a braided mesh and covered with an outside coating.
  772. SIMM
    A memory module packaging style that features a circuit board with identical pin functions on both sides of the module's card edge.
  773. Simple Mail Transfer Protocol (SMTP)
    A TCP/IP protocol optimized for sending e-mail. It uses port 25.
  774. Single-Channel Memory
    A RAM implementation scheme in which the memory controller allows standard memory modules to be installed one per bank.
  775. Single-Purpose Server
    A server that is dedicated to one purpose (for example, a file server or a printer server).
  776. Single-Sided Memory
    A memory module that has chips and pin functions that match the specification for a single module.
  777. Site License
    A software license that is valid for all installations at a single site.
  778. Smurf Attack
    An attack in which large volumes of ICMP echo requests (pings) are broadcast to all other machines on the network and in which the source address of the broadcast system has been spoofed to appear as though they came from the target computer. When all the machines that received the broadcast respond, they flood the target with more data than it can handle.
  779. Social Engineering
    An attack where an attacker obtains information from people by deceiving them.
  780. SODIMM
    A small-form factor memory module based on DIMM principles and designed for the mobile computing sector.
  781. Solenoid
    In daisy-wheel printers, the small electromechanical hammer that strikes the back of the petal containing the character.
  782. Solid-Ink Printers
    A printer that uses ink in a waxy solid form, rather than in liquid form. This allows the ink to stay fresh and eliminates problems like spillage.
  783. Solid-State Drives (SSD)
    A newer-style drive that has no moving parts, but uses flash memory to emulate a conventional hard disk drive.
  784. Sony/Philips Digital Interface (S/PDIF)
    A digital audio technology that attaches by coaxial or fiber-optic cable.
  785. Southbridge
    The functional part of the chipset that controls non-local bus communication among components connected to the various I/O buses, including PCI, IDE, USB, RS-232, and parallel.
  786. Spam
    Unwanted, unsolicited e-mail sent in bulk.
  787. Special Permissions
    Permissions in Windows operating systems, including Read, Write, Execute, Delete, Change Permissions, Take Ownership, and Full Control.
  788. Spoofing
    An attempt by someone or something to masquerade as someone else.
  789. SRAM
    A faster type of volatile memory that does not require a periodic refresh and is commonly used for cache memory.
  790. Stabilizer Bar
    A small metal bar on a printer that holds the printer carriage as it crosses the page.
  791. Star Topology
    A networking topology characterized by endpoints wiring directly to a central concentrating device, thus not affecting other endpoints when they have connectivity issues.
  792. Static-Charge Eliminator Strip
    The device in EP process printers that drains the static charge from the paper after the toner has been transferred to the paper.
  793. Stealth Virus
    A virus that attempts to avoid detection by masking itself from applications.
  794. Stepper Motor
    A very precise motor that can move in very small increments. Often used in printers.
  795. Straight Tip (ST)
    One of the most common fiber-optic connectors similar in style to the BNC connector used in 10Base2 Ethernet.
  796. Sublimate
    To go from a solid state to a gaseous state without passing through a liquid state.
  797. Subnet Mask
    A Required Part Of Any TCP/IP Configuration, Used To Define Which Addresses Are Local And which are on remote networks.
  798. Subscriber Connector (SC)
    A type of fiber-optic cable connector.
  799. Surge Protectors
    Surge protectors attempt to keep power surges at bay. They often look like a power strip, but they have a fuse inside them which is designed to blow if it receives too much current, and not transfer the current to the devices plugged into it. Surge protectors may have plug-ins for RJ-11 (phone), RJ-45 (Ethernet), and BNC (coaxial cable) connectors.
  800. Swap File
    Also called the page file, the swap file is the virtual memory in Windows.
  801. Switch
    1) A Layer 2 device similar to a hub in its port count but more advanced with the ability to filter traffic based on the destination MAC address of each frame. 2) Option used with commands to specify operations that command should perform.
  802. Syntax
    The correct format for interacting with a command.
  803. System Tray
    Located on the Windows Taskbar, contains a clock by default, but other Windows utilities (for example, screensavers or virus-protection utilities) may put their icons here when running to indicate that they are running and to provide the user with a quick way to access their features.
  804. SBAC (SCSI Bus Adapter Chip)
    The SCSI chip within a device housing that controls data transfer over the SCSI bus.
  805. SCAM (SCSI Configuration Automatically)
    A method of configuring SCSI device settings that follows the Plug and Play standard. SCAM makes installation of SCSI devices much easier, provided that the devices are SCAM-compliant.
  806. Scanning Mirror
    A component of a laser printer consisting of an octagonal mirror that can be directed in a sweeping motion to cover the entire length of a laser printer drum.
  807. SCSI (Small Computer System Interface)
    A fast interface between a host adapter and the CPU that can daisy chain as many as 7 or 15 devices on a single bus.
  808. SCSI ID
    A number from 0 to 15 assigned to each SCSI device attached to the daisy chain.
  809. Secondary Storage
    Storage that is remote to the CPU and permanently holds data, even when the PC is turned off, such as a hard drive.
  810. Sector
    On a disk surface one segment of a track, which almost always contains 512 bytes of data?
  811. Security Accounts Manager (SAM)
    A portion of the Windows NT/2000/XP registry that manages the account database that contains accounts, policies, and other pertinent information about local accounts.
  812. Sequential Access
    A method of data access used by tape drives, whereby data is written or read sequentially from the beginning to the end of the tape or until the desired data is found.
  813. Serial Port
    A male 9-pin or 25-pin port on a computer system used by slower I/O devices such as a mouse or modem. Data travels serially, one bit at a time, through the port. Serial ports are sometimes configured as COM1, COM2, COM3, or COM4.
  814. Session
    An established communication link between two software programs. On the Internet, a session is created by TCP.
  815. System File Checker (SFC)
    A Windows tool that checks to make sure Windows is using the correct versions of system files.
  816. SGRAM (Synchronous Graphics RAM)
    Memory designed especially for video card processing that can synchronize itself with the CPU bus clock.
  817. Shadow RAM or Shadowing ROM
    ROM programming code copied into RAM to speed up the system operation, because of the faster access speed of RAM.
  818. Shell
    The portion of an OS that relates to the user and to applications.
  819. Shielded Twisted-Pair (STP) Cable
    A cable that is made of one or more twisted pairs of wires and is surrounded by a metal shield.
  820. Shortcut
    An icon on the desktop that points to a program that can be executed or to a file or folder.
  821. Signal-Regenerating Repeater
    A repeater that is able to distinguish between noise and signal. It reads the signal and retransmits it without the accompanying noise.
  822. Sigverif.exe
    A Windows 2000/XP utility that allows you to search for digital signatures.
  823. SIMD (Single Instruction, Multiple Data)
    A process that allows the CPU to execute a single instruction simultaneously on multiple pieces of data, rather than by repetitive looping.
  824. SIMM (Single Inline Memory Module)
    A miniature circuit board used in older computers to hold RAM. SIMMs hold 8, 16, 32, or 64 MB on a single module.
  825. Simple Volume
    A type of dynamic volume used on a single hard drive that corresponds to a primary partition on a basic disk.
  826. Single-Ended (SE) Cable
    A type of SCSI cable in which two wires are used to carry a signal, one of which carries the signal itself; the other is a ground for the signal.
  827. Single-Voltage CPU
    A CPU that requires one voltage for both internal and I/O operations.
  828. Slack
    Wasted space on a hard drive caused by not using all available space at the end of clusters.
  829. Sleep Mode
    A mode used in many Green systems that allows them to be configured through CMOS to suspend the monitor or even the drive, if the keyboard and/or CPU have been inactive for a set number of minutes. See also Green Standards.
  830. SLIP (Serial Line Internet Protocol)
    A line protocol used by regular telephone lines that has largely been replaced by PPP.
  831. SMARTDrive
    A hard drive cache program that came with Windows 3.x and DOS and can be executed as a TSR from the Autoexec.bat file (for example, Device=Smartdrv.sys 2048).
  832. SMTP (Simple Mail Transfer Protocol)
    The protocol used by e-mail clients and servers to send e-mail messages over the Internet. See POP and IMAP.
  833. Snap-Ins
    Components added to a console using the Microsoft Management Console.
  834. SNMP (Simple Network Management Protocol)
    A protocol used to monitor and manage network traffic on a workstation. SNMP works with TCP/IP and IPX/SPX networks.
  835. SO-DIMM (Small Outline DIMM)
    A type of memory module used in notebook computers that uses DIMM technology and can have either 72 pins or 144 pins.
  836. Soft Boot
    To restart a PC without turning off the power, for example, by pressing three keys at the same time (Ctrl, Alt, and Del). Also called warm boot.
  837. Soft Switch
    A feature on an ATX system that allows an OS to power down the system and allows for activity such as a keystroke or network activity to power up the system. Also called soft power.
  838. Software
    Computer programs, or instructions to perform a specific task. Software may be BIOS, OSs, or applications software such as a word-processing or spreadsheet program.
  839. Software Cache
    Cache controlled by software whereby the cache is stored in RAM.
  840. SO-RIMM (Small Outline RIMM)
    A 160-pin memory module used in notebooks that uses Rambus technology.
  841. South Bridge
    That portion of the chip set hub that connects slower I/O buses (for example, an ISA bus) to the system bus. Compare to North Bridge.
  842. Spanned Volume
    A type of dynamic volume used on two or more hard drives that fills up the space allotted on one physical disk before moving to the next.
  843. SPI (SCSI Parallel Interface)
    The part of the SCSI-3 standard that specifies how SCSI devices are connected.
  844. Spikes
    Temporary surges in voltage, which can damage electrical components.
  845. Spooling
    Placing print jobs in a print queue so that an application can be released from the printing process before printing is completed. Spooling is an acronym for simultaneous peripheral operations online.
  846. SSE (Streaming SIMD Extension)
    A technology used by the Intel Pentium III and later CPUs and designed to improve performance of multimedia software.
  847. Staggered Pin Grid Array (SPGA)
    A feature of a CPU socket whereby the pins are staggered over the socket in order to squeeze more pins into a small space.
  848. Standby Time
    The time before a Green system will reduce 92 percent of its activity. See also Green Standards.
  849. Standoffs
    Round plastic or metal pegs that separate the motherboard from the case, so that components on the back of the motherboard do not touch the case.
  850. Star Bus Topology
    A LAN that uses a logical bus design, but with all devices connected to a central hub, making a physical star.
  851. Star Ring Topology
    A topology that is physically arranged in a star formation but is logically a ring because of the way information travels on it. Token ring is the primary example.
  852. Star Topology
    A LAN in which all the devices are connected to a central hub.
  853. Start Bits
    Bits that are used to signal the approach of data.
  854. Startup BIOS
    Part of system BIOS that is responsible for controlling the PC when it is first turned on. Startup BIOS gives control over to the OS once it is loaded.
  855. Stateless
    Term for a device or process that manages data or some activity without regard to all the details of the data or activity.
  856. Static IP Address
    An IP address permanently assigned to a workstation.
  857. Static RAM (SRAM)
    RAM chips that retain information without the need for refreshing, as long as the computer's power is on. They are more expensive than traditional DRAM.
  858. Static Vxd
    A VxD that is loaded into memory at startup and remains there for the entire OS session.
  859. Stealth Virus
    A virus that actively conceals itself by temporarily removing itself from an infected file that is about to be examined, and then hiding a copy of itself elsewhere on the drive.
  860. Stop Error
    An error severe enough to cause the operating system to stop all processes.
  861. Streaming Audio
    Downloading audio data from the Internet in a continuous stream of data without first downloading an entire audio file.
  862. Striped Volume
    A type of dynamic volume used for two or more hard drives that writes to the disks evenly rather than filling up allotted space on one and then moving on to the next. Compare to spanned volume.
  863. Subdirectory
    A directory or folder contained in another directory or folder. Also called a child directory or folder.
  864. Subnet Mask
    A subnet mask is a group of four numbers (dotted decimal numbers) that tell TCP/IP if a remote computer is on the same or a different network.
  865. Subsystems
    The different modules into which the Windows NT/2000/XP user mode is divided.
  866. Surge Suppressor Or Surge Protector
    A device or power strip designed to protect electronic equipment from power surges and spikes.
  867. Suspend Time
    The time before a Green system will reduce 99 percent of its activity. After this time, the system needs a warm-up time so that the CPU, monitor, and hard drive can reach full activity.
  868. Swap File
    A file on the hard drive that is used by the OS for virtual memory. Also called a page file.
  869. Switch
    A device used to segment a network. It can decide which network segment is to receive a packet, on the basis of the packet's destination MAC address.
  870. Synchronization
    The process by which files and programs are transferred between PDAs and PCs.
  871. Synchronous DRAM (SDRAM)
    A type of memory stored on DIMMs that runs in sync with the system clock, running at the same speed as the motherboard.
  872. Synchronous SRAM
    SRAM that is faster and more expensive than asynchronous SRAM. It requires a clock signal to validate its control signals, enabling the cache to run in step with the CPU.
  873. SyncLink DRAM (SLDRAM)
    A type of DRAM developed by a consortium of 12 DRAM manufacturers. It improved on regular SDRAM but is now obsolete.
  874. Sysedit
    The Windows System Configuration Editor, a text editor generally used to edit system files.
  875. System BIOS
    BIOS located on the motherboard.
  876. System Bus
    The bus between the CPU and memory on the motherboard. The bus frequency in documentation is called the system speed, such as 200 MHz. Also called the memory bus, front-side bus, local bus, or host bus.
  877. System Clock
    A line on a bus that is dedicated to timing the activities of components connected to it. The system clock provides a continuous pulse that other devices use to time themselves.
  878. System Disk
    Windows terminology for a bootable disk.
  879. System Partition
    The active partition of the hard drive containing the boot record and the specific files required to load Windows NT/2000/XP.
  880. System Resource
    A channel, line, or address on the motherboard that can be used by the CPU or a device for communication. The four system resources are IRQ, I/O address, DMA channel, and memory address.
  881. System Restore
    A Windows ME/XP utility, similar to the ScanReg tool in earlier versions of Windows that is used to restore the system to a restore point. Unlike ScanReg, System Restore cannot be executed from a command prompt.
  882. System State Data
    In Windows 2000/XP, files that are necessary for a successful load of the operating system.
  883. System Tray
    An area to the right of the taskbar that holds the icons of small applets launched at startup.
  884. System.ini
    A text configuration file used by Windows 3.x and supported by Windows 9x for backward-compatibility.
  885. TCP ACK Attack
    An attack that begins as a normal TCP connection and whose purpose is to deny service. It's also known as a TCP SYN flood.
  886. TCP/IP Hijacking
    An attack in which the attacker commandeers a TCP session from a legitimate user after the legitimate user has achieved authentication, thereby removing the need for the attacker to authenticate himself.
  887. TCP Sequence Attack
    An attack wherein the attacker intercepts and then responds with a sequence number similar to the one used in the original session. The attack can either disrupt a session or hijack a valid session.
  888. Temporary File (Temp File)
    A file designed to store information for a short period of time and then be deleted.
  889. Thumb Drive
    A solid-state device with USB attachment that takes the place of older floppy diskettes and holds much more data than floppies ever did.
  890. Token Passing
    A media-access method that gives every NIC equal access to the cable. The token is a special packet of data that is passed from computer to computer. Any computer that wants to transmit has to wait until it has the token, at which point it can add its own data to the token and send it on.
  891. Token Ring
    A local area network with a logical ring structure that uses token passing to regulate traffic on the network and avoid collisions.
  892. Toner
    A carbon substance mixed with polyester resins and iron oxide particles. During the EP printing process, toner is first attracted to areas that have been exposed to the laser in laser printers and is later deposited and melted onto the print medium.
  893. Topology
    The layout of a network. Basic LAN topologies are bus, ring, and star. WAN topologies include full and partial meshes. Topology can describe either the logical or physical layout. See Chapter 10 for more information.
  894. Tracks
    The concentric rings on a platter where data is stored. Tracks are subdivided into sectors.
  895. Transfer Corona Assembly
    The part of an EP process printer that is responsible for transferring the developed image from the EP drum to the paper.
  896. Transferring Step
    The fifth step in the EP print process, when the developed toner image on the EP drum is transferred to the print medium using the transfer corona.
  897. Transformer
    A device that takes one type of electrical current and turns it into a different type of electrical current.
  898. Transmission Control Protocol (TCP)
    A core protocol in the TCP/IP protocol suite that establishes connections and guarantees packet delivery. Part of the TCP/IP protocol suite. TCP guarantees delivery of data for application protocols and establishes a session before it begins transmitting data.
  899. Transmission Control Protocol/Internet Protocol (TCP/IP) Suite
    A set of computer-to-computer communications protocols that encompasses media access, packet transport, session communications, file transfer, e-mail, and terminal emulation. TCP/IP is supported by a very large number of hardware and software vendors and is available on many different computers from PCs to mainframes. It is the protocol of the Internet and the most widely-used communications protocol in existence today.
  900. Tree
    A modified networking topology that interconnects the concentrators of a star topology to form tiers of connectivity for endpoints to reduce the number of concentrators between any two endpoints.
  901. Trojan Horse
    Any application that masquerades as one thing in order to get past scrutiny and then does something malicious. One of the major differences between Trojan horses and viruses is that Trojan horses tend not to replicate themselves.
  902. TV Tuner Card
    A class of internal and external devices that allows you to connect a broadcast signal, such as home cable television, to your computer and display it.
  903. TAPI (Telephony Application Programming Interface)
    A standard developed by Intel and Microsoft that can be used by 32-bit Windows 9x communications programs for communicating over phone lines.
  904. Telephony
    A term describing the technology of converting sound to signals that can travel over telephone lines.
  905. Terminating Resistor
    The resistor added at the end of a SCSI chain to dampen the voltage at the end of the chain.
  906. Termination
    A process necessary to prevent an echo effect of power at the end of a SCSI chain, resulting in interference with the data transmission.
  907. Thread
    Each process that the CPU is aware of; a single task that is part of a longer task or program.
  908. Time To Live (TTL)
    Number of routers a network packet can pass through on its way to its destination before it is dropped. Also called hop count.
  909. Token Ring
    An older LAN technology developed by IBM that transmits data at 4 Mbps or 16 Mbps.
  910. Top-Level Domain
    The highest level of domain names, indicated by a suffix that tells something about the host. For example, .com is for commercial use and .edu is for educational institutions.
  911. Trace
    A wire on a circuit board that connects two components or devices.
  912. Track
    One of many concentric circles on the surface of a hard drive or floppy disk.
  913. Transceiver
    The component on a NIC that is responsible for signal conversion. Combines the words transmitter and receiver.
  914. Transformer
    A device that changes the ratio of current to voltage. A computer power supply is basically a transformer and a rectifier.
  915. Transistor
    An electronic device that can regulate electricity and act as a logical gate or switch for an electrical signal.
  916. Translation
    A technique used by system BIOS and hard drive controller BIOS to break the 504-MB hard drive barrier, whereby a different set of drive parameters are communicated to the OS and other software than that used by the hard drive controller BIOS.
  917. Trojan Horse
    A type of infestation that hides or disguises itself as a useful program, yet is designed to cause damage at a later time.
  918. Terminate-And-Stay-Resident (TSR)
    A program that is loaded into memory and remains dormant until called on, such as a screen saver or a memory-resident antivirus program.
  919. Unattended Installation
    An installation method that does not require human intervention once started and is frequently used when installing over the network. Unattended installations use answer files to supply the necessary parameters to Windows Setup.
  920. Uninterruptible Power Supply (UPS)
    A UPS is designed to protect everything that's plugged into it from power surges, power sags, and even power outages. The device contains one or more batteries and fuses. Energy is stored in the batteries, and if the power fails, the batteries can power the computer for a period of time so the administrator can then safely power it down.
  921. Universal Data Connector (UDC)
    Another name for an IBM data connector.
  922. Unshielded Twisted-Pair (UTP)
    Networking cable that has four twisted pairs of copper wire and a flexible outer coating.
  923. User Datagram Protocol (UDP)
    Part of the TCP/IP suite that performs a similar function to TCP, with less overhead and more speed but with lower reliability. It is a connectionless protocol, meaning that it does not guarantee packet delivery. A connectionless protocol that does not require a connection to send a packet and does not guarantee that the packet arrives at its destination. UDP is faster than TCP because TCP takes the time to make a connection and guarantee delivery.
  924. UART (Universal Asynchronous Receiver-Transmitter) Chip
    A chip that controls serial ports. It sets protocol and converts parallel data bits received from the system bus into serial bits.
  925. Unattended Installation
    A Windows NT/ 2000/XP installation that is done by storing the answers to installation questions in a text file or script that Windows NT/2000/XP calls an answer file so that the answers do not have to be typed in during the installation.
  926. Universal Disk Format (UDF) File System
    A file system for optical media used by all DVD discs and some CD-R and CD-RW discs.
  927. Unshielded Twisted-Pair (UTP) Cable
    A cable that is made of one or more twisted pairs of wires and is not surrounded by a metal shield.
  928. Upper Memory
    In DOS and Windows 9x, the memory addresses from 640K up to 1024K, originally reserved for BIOS, device drivers, and TSRs.
  929. Upper Memory Block (UMB)
    In DOS and Windows 9x, a group of consecutive memory addresses in RAM from 640K to 1MB that can be used by 16-bit device drivers and TSRs.
  930. URL (Uniform Resource Locator)
    An address for a resource on the Internet. A URL can contain the protocol used by the resource, the name of the computer and its network, and the path and name of a file on the computer.
  931. USB (Universal Serial Bus) Port
    A type of port designed to make installation and configuration of I/O devices easy, providing room for as many as 127 devices daisy-chained together.
  932. USB Host Controller
    Manages the USB bus. For the 400 series Intel chip set, the USB host controller is included in the PCI controller chip. The USB uses only a single set of resources for all devices on the bus.
  933. User Mode
    In Windows NT/2000/XP, a mode that provides an interface between an application and the OS, and only has access to hardware resources through the code running in kernel mode.
  934. User State Migration Tool (USMT)
    A Windows XP utility that helps you migrate user files and preferences from one computer to another in order to help a user makes a smooth transition from one computer to another.
  935. Video Capture Card
    A stand-alone device that is often used to save a video stream to the computer for later manipulation or sharing.
  936. Virtual Memory
    A general term for a type of computer technology where hard disk space is used to supplement a computer's physical memory. The memory controller uses a swap file on the hard drive to offload the least recently used contents of RAM to make room for additional applications and data.
  937. Virtual Private Network (VPN)
    A secure network where computers that are not local to the network appear to be local. Used frequently to securely connect LANs together across a WAN or for network users to remotely access the network.
  938. Virus
    A small, deviously genius program that replicates itself to other computers, generally causing those computers to behave abnormally.
  939. Voice-Over IP (VOIP)
    The technology that encapsulates voice traffic into IP packets and transmits it across a TCP/IP network.
  940. Voltage Selector Switch
    The switch on a power supply that allows you to manually change the input voltage between 60Hz, 110VAC to 50Hz, 220VAC.
  941. Vulnerability Scanner
    A software application that checks your network for any known security holes.
  942. V.92
    The latest standard for data transmission over phone lines that can attain a speed of 56 Kbps.
  943. Value Data
    In Windows, the name and value of a setting in the registry.
  944. VCACHE
    A built-in Windows 9x 32-bit software cache that doesn't take up conventional memory space or upper memory space as SMARTDrive did.
  945. VESA (Video Electronics Standards Association) VL Bus
    An outdated local bus used on 80486 computers for connecting 32-bit adapters directly to the local processor bus.
  946. VFAT (Virtual File Allocation Table)
    A variation of the original DOS 16-bit FAT that allows for long filenames and 32-bit disk access.
  947. Video Card
    An interface card installed in the computer to control visual output on a monitor. Also called display adapter.
  948. Virtual Device Driver (Vxd Or VDD)
    A Windows device driver that may or may not have direct access to a device. It might depend on a Windows component to communicate with the device itself.
  949. Virtual Machine
    One or more logical machines created within one physical machine by Windows, allowing applications to make serious errors within one logical machine without disturbing other programs and parts of the system.
  950. Virtual Memory
    A method whereby the OS uses the hard drive as though it were RAM. Compare to RAM drive.
  951. Virtual Real Mode
    An operating mode that works similarly to real mode provided by a 32-bit OS for a 16-bit program to work.
  952. Virus
    A program that often has an incubation period, is infectious, and is intended to cause damage. A virus program might destroy data and programs or damage a disk drive's boot sector.
  953. Virus Signature
    A set of distinguishing characteristics of a virus used by antivirus software to identify the virus.
  954. Virtual Machine Manager (VMM)
    A Windows 9x program that controls virtual machines and the resources they use including memory. The VMM manages the page table used to access memory.
  955. Volatile
    Refers to a kind of RAM that is temporary, cannot hold data very long, and must be frequently refreshed.
  956. Volt (V)
    A measure of potential difference in an electrical circuit. A computer ATX power supply usually provides five separate voltages: +12V, -12V, +5V, -5V, and +3.3V.
  957. Voltage
    Electrical differential that causes current to flow, measured in volts. See volt.
  958. Voltmeter
    A device for measuring electrical AC or DC voltage.
  959. VRAM (Video RAM)
    RAM on video cards that holds the data that is being passed from the computer to the monitor and can be accessed by two devices simultaneously. Higher resolutions often require more video memory.
  960. Watt
    The unit of measure for power, equal to the number of volts in a circuit times the number of amps.
  961. Wide Area Networks (WAN)
    A network that expands LANs to include networks outside of the local environment and also to distribute resources across distances.
  962. Wi-Fi
    A collection of IEEE 802.11x standards.
  963. Wi-Fi Protected Access (WPA)
    An enhancement of 802.11 encryption that secures Wi-Fi communications. The current standard is WPA2.
  964. Windows Catalog
    A list of all the hardware that works with Windows that also details which versions of Windows the hardware works with. The new name for the Hardware Compatibility List.
  965. Wired Equivalency Protocol (WEP)
    An old security protocol developed for Wi-Fi. It has security flaws and is easily compromised.
  966. Wireless Access Point (WAP)
    A central hub that looks nearly identical to wireless routers and provides central connectivity like wireless routers, but doesn't have nearly as many features.
  967. Wireless Personal Area Network (WPAN)
    Another name for a Bluetooth network.
  968. Working Directory
    An area on the hard disk where programs store their temporary files while they work.
  969. Workstation
    1) In networking, any personal computer (other than the file server) attached to the network. 2) A high-performance computer optimized for graphics applications such as computer-aided design, computer-aided engineering, and scientific applications.
  970. Worm
    A program similar to a virus. Worms, however, propagate themselves over a network.
  971. Writing Step
    The third step in the EP print process, during which the items being printed are written to the EP drum. In this step, the laser is flashed on and off as it scans across the surface of the drum. The area on which the laser shines is discharged to almost ground (100V).
  972. Wait State
    A clock tick in which nothing happens, used to ensure that the microprocessor isn't getting ahead of slower components. A 0-wait state is preferable to a 1wait state. Too many wait states can slow down a system.
  973. Wide Area Network (WAN)
    A network or group of networks that span a large geographical area.
  974. Watt (W)
    The unit used to measure power. A typical computer may use a power supply that provides 200W.
  975. Wattage
    Electrical power measured in watts.
  976. WDM (Win32 Driver Model)
    The only Windows 9x Plug and Play component that is found in Windows 98 but not Windows 95. WDM is the component responsible for managing device drivers that work under a driver model new to Windows 98.
  977. Windows File Protection (WFP)
    A Windows 2000/XP tool that protects system files from modification.
  978. Wide SCSI
    One of the two main SCSI specifications. Wide SCSI has a 16-bit data bus.
  979. Wildcard
    A * or ? character used in a command line that represents a character or group of characters in a filename or extension.
  980. Win.ini
    The Windows initialization file that contains program configuration information needed for running the Windows operating environment. Its functions were replaced by the registry beginning with Windows 9x, which still supports it for backward compatibility with Windows 3.x.
  981. Win16 on Win32 (WOW)
    A group of programs provided by Windows NT/2000/XP to create a virtual DOS environment that emulates a 16-bit Windows environment, protecting the rest of the OS from 16-bit applications.
  982. Win386.swp
    The name of the Windows 9x swap file. Its default location is C:\Windows.
  983. WINS (Windows Internet Naming Service)
    A Microsoft resolution service with a distributed database that tracks relationships between NetBIOS names and IP addresses. Compare to DNS.
  984. WinSock (Windows Sockets)
    A part of the TCP/IP utility software that manages API calls from applications to other computers on a TCP/IP network.
  985. Wireless LAN (WLAN)
    A type of LAN that does not use wires or cables to create connections, but instead transmits data over radio or infrared waves.
  986. Workgroup
    In Windows, a logical group of computers and users in which administration, resources, and security are distributed throughout the network, without centralized management or security.
  987. Worm
    An infestation designed to copy itself repeatedly to memory, on drive space or on a network, until little memory or disk space remains.
  988. WRAM (Window RAM)
    Dual-ported video RAM that is faster and less expensive than VRAM. It has its own internal bus on the chip, with a data path that is 256 bits wide.
  989. Zero Insertion Force (ZIF) Socket
    A mechanism on which chip sockets are mounted that allows insertion of the chip with no downward force except gravity. A socket that uses a small lever to apply even force when you install the microchip into the socket.
  990. Zone Bit Recording
    A method of storing data on a hard drive whereby the drive can have more sectors per track near the outside of the platter.

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