Comptia A+ Glossary

  1. %SystemRoot%
    The path where the operating system is installed.
  2. 10BaseT
    Ethernet LAN designed to run on twisted pair cabling. 10BaseT runs at 10 megabits per second. The maximum length for the cabling between the NIC and the switch is 100 meters. It uses baseband signaling.
  3. 100BaseT
    Generic term for an Ethernet cabling system designed to run at 100 megabits per second on twisted pair cabling.
  4. 1000BaseT
    Gigabit Ethernet on UTP.
  5. 110 Block
    The most common connection used with structured cabling, connecting horizontal cable runs with patch panels.
  6. 16-bit (PC Card)
    Type of PC card that can have up to two distinct functions or devices, such as a modem/network card combination.
  7. 3.5-inch Floppy drive
    size of all modern floppy disk drives; the format was introduced in 1986 and is one of the longest surviving pieces of computer hardware
  8. 34-pin ribbon cable
    Type of cable used by floppy drives
  9. 40-pin ribbon cable
    PATA cable used to attach EIDE devices (such as hard drives) or ATAPI devices (such as optical drives) to a system
  10. 64-bit processing
    A type of processing that can run a compatible 64-bit OS and 64-bit applications. 64-bit PCs have a 64-bit-wide address bus, enabling them to use more than 4 GB of RAM.
  11. 8.3 naming system
    File-naming convention that specified a maximum of eight characters for a filename, followed by a three-character file extension. Has been replaced by LFN (Long filename) support.
  12. 80-wire ribbon cable
    PATA cable used to attach fast EIDE devices (such as ATA/100 hard drives) or ATAPI devices (such as optical drives) to a system.
  13. 802.11a
    Wireless networking standard that operations in the 5GHz band with a theoretical maximum throughput of 54 Mbps.
  14. 802.11b
    Wireless networking standard that operates in the 2.4 GHz band with a theoretical maximum throughput of 11 Mbps.
  15. 802.11g
    Wireless networking standard that operates in the 2.4 GHz band with a theoretical maximum throughput of 54 Mbps and is backwards compatible with 802.11b
  16. 802.11n
    Wireless networking standard that can operate in both the 2.4 GHz and 5 GHz bands and use multiple in/multiple out (MIMO) to achieve a theoretical maximum throughput of 100+ Mbps.
  17. AC'97
    Sound card standard for lower-end audio devices; created when most folks listened to stereo sound at best
  18. Accelerometer
    Feature in smartphones and tablets that rotates the screen when the device is physically rotated.
  19. Access control
    Security concept using physical security, authentication, users and groups, and security policies.
  20. ACPI
    Advanced Configuration and Power Interface: Power management specification that far surpasses it predecessor, APM, by providing support for hot-swappable devices and better control of power modes.
  21. Action Center
    A one-page aggregation of event messages, warnings, and maintenance messages in Windows 7.
  22. Active Matrix
    Type of LCD that replaced the passive matrix technology used in most portable computer displays. Also called TFT (thin film transistor).
  23. Active Partition
    On a hard drive, primary partition that contains an operating system
  24. Active PFC (Power Factor Correction)
    Circuitry built into PC power supplies to reduce harmonics.
  25. Activity Light
    An LED on a NIC, Hub or switch that blinks rapidly to show data transfers over the network.
  26. ad hoc mode
    Decentralized wireless mode, otherwise known as peer-to-peer mode, where each wireless node is in meshed contact with every other node.
  27. Address Bus
    Set of wires leading from the CPU to the memory controller chip (traditionally called the Northbridge) that enables the CPU to address RAM. Also used by the CPU for I/O addressing. On current CPUs with built-in memory controllers, the address bus refers to the internal electronic channel from the microprocessor to RAM, alond which the addresses of memory storage locations are transmitted. Like a PO Box, each memory location has a distinct number or address; the address bus provides the means by which the microprocessor can access every location in memory.
  28. Address Space
    Total amount of memory addresses that an address bus can contain
  29. administrative shares
    Administrator tool to give local admins access to hard drives and system root folders
  30. Administrative tools
    Group of Control Panel applets, including Computer Management, Event Viewer, and Reliability and Performance Monitor.
  31. ADSL
    Asymmetric digital subscriber line: Fully digital, dedicated connection to the telephone system that provides average download speeds of 7 Mbps and upload speeds of 512 Kbps.
  32. AES
    Advanced Encryption Standard: A block cipher created in the late 1990s that uses a 128-bit block size and 128-,192, or 256-bit key size. Practically uncrackable.
  33. Advanced Startup Options Menu
    Menu that can be reached during the boot process that offers advanced OS startup options, such as to boot to Safe Mode or boot into Last Known Good Configuration.
  34. Adware
    Type of malicious program that downloads ads to a user's computer, generating undesirable network traffic.
  35. Aero
    The Windows Vista/7 desktop environment. Aero adds some interesting aesthetic effects such as window transparency and Flip 3D.
  36. APG
    Accelerated Graphics Port: 32/64-bit expansion slot designed by Intel specifically for video that runs at 66-MHzand yields a throughput of at least 254 Mbps. Later versions (2x, 4x, 8x) give substantially higher throughput.
  37. ALU
    Arithmetic logic unit: CPU logic circuits that perform basic arithmetic (add, subtract, multiply, and divide).
  38. AMD
    Advanced Micro Devices: CPU and chipset manufacturer that competes with Intel. Produces the popular Phenom, Ahtlon, Sempron, Turion, and Duron microprocessors; also produces video card processors under its ATI brand.
  39. AMI
    American Megatrends, Inc.: Major producer of BIOS software for motherboards, as well as many other computer-related components and software.
  40. Amperes
    Unit of measure for amperage, or electrical current
  41. Amplitude
    Loudness of a sound card
  42. AMR
    Audio Modem Riser: Proprietary slot used on some motherboards to provide a sound interference-free connection for modems, sound cards, and NICs.
  43. Analog
    Device that uses a physical quantity, such as length or voltage, to represent the value of a number. By contrast, digital storage relies on a coding system of numeric units.
  44. Anti-aliasing
    In computer imaging, blending effect that smooths sharp contrast between two regions-e.g., jagged lines or different colors. Reduces jagged edges of text or objects. In voice signal processing, process of removing or smoothing out spurious frequencies from waveforms produced by converting digital signals back to analog.
  45. API
    Application programming interface: Software definition that describes OS calls for application software; conventions defining how a service is invoked.
  46. APIPA
    Automatic Private Internet Protocol Addressing: Feature of Windows that automatically assigns an IP address to the system when the client cannot obtain an IP address automatically.
  47. APM
    Advanced Power Management: BIOS routines that enable the CPU to turn on and off selected peripherals
  48. ARP
    Address Resolution Protocol: Protocol in the TCP/IP suite used with the command-line utility of the same name (arp) to determine the MAC address that corresponds to a particular IP address.
  49. ASCII
    American Standard Code for Information Interchange: Industry-standard 8-bit characters  used to define text characters, consisting of 96 upper- and lowercase letters, plus 32 nonprinting control characters, each of which is numbered. These numbers were designed to achieve uniformity among computer devices for printing and exchange of simple text documents.
  50. Aspect Ratio
    Ratio of width to height of an object. Standard television has a 4:3 aspect ratio
  51. ASR
    Automated System Recovery: Windows XP tool designed to recover a badly corrupted Windows system; similar to the ERD in Windows 2000.
  52. AT
    Advanced Technology: Model name of the second generation, 80286-based IBM computer. Many aspects of the AT, such as BIOS, CMOS, and expansion bus, have become de facto standards in the PC industry. The physical organization of the components on the motherboard is called the AT form factor.
  53. ATA
    AT Attachment: Type of hard drive and controller designed to replace the earlier ST506 and ESDI drives without requiring replacement of the AT Bios-hence, AT attachment. These drives are more popularly known as IDE drives. The ATA/33 standard has drive transfer speeds up to 33 MBps; the ATA/66 up to 66 MBps; the ATA/100 up to 100 MBps; and the ATA/133 up to 133 MBps.
  54. ATA/ATAPI-6
    Also known as ATA-6 or "Big Drive." Replaced the INT13 extensions and allowed for hard drives as large as 144 petabytes (144 million GB).
  55. ATAPI
    ATA Packet Interface: Series of standards that enables mass storage devices other than hard drives to use the IDE/ATA controllers. Popular with optical drives.
  56. ATAPI-compliant
    Devices that utilize the ATAPI standard.
  57. attrib.exe
    Command used to view the specific properties of a file; can also be used to modify or remove file properties, such as read-only, system, or archive.
  58. attributes
    Values in a file that determine the hidden, read-only, system, and archive status of the file.
  59. ATX
    Advanced Technology Extended: Popular motherboard form factor that generally replaced the AT form factor.
  60. Audio Interface
    High-end external sound device used by audio engineers and recording artists.
  61. Authentication
    Any method a computer uses to determine who can access it.
  62. Authorization
    Any method a computer uses to determine what an authenticated user can do.
  63. Autodetection
    Process through which new disks are automatically recognized by the BIOS
  64. Automatic Private IP Addressing
    APIPA: A networking feature of OS's that enables DHCP clients to self-configure an IP address and subnet mask automatically when a DHCP server isn't available.
  65. autorun.inf
    File included on some media that automatically launches a program or installation routine when the media is inserted/attached to a system.
  66. autosensing
    Used by better-quality sound cards to detect a device plugged into a port and to adapt the features of that port
  67. auto-switching power supply
    Type of power supply able to detect the voltage of a particular outlet and adjust accordingly.
  68. Award Software
    Major brand of BIOS software for motherboards. Owned by Phoenix Technologies
  69. Backside Bus
    Set of wires that connects the CPU to Level 2 cache. First appearing in the Pentium Pro, all modern CPUs have a backside bus. Some buses run at full speed of the CPU, whereas others run at a fraction. Earlier Pentium IIs, for example, had backside buses running at half the speed of the processor.
  70. Backup and Restore Center
    Windows Vista/7's backup utility (Windows 7 drops "Center" from the name). It offers two options: create a backup or restore from a back up.
  71. Backup or Restore Wizard
    Utility contained within Windows that allows users to create system backups and set system restore points
  72. Backup Utility
    ntbackup: Windows XP's tool for creating and restoring backups.
  73. Bandwidth
    Piece of the spectrum occupied by some form of signal, such as television, voice, or fax data. Signals require a certain size and location of bandwidth to be transmitted. The higher the bandwidth, the faster the signal transmission, allowing for a more complex signal such as audio or video. Because bandwidth is a limited space, when one user is occupying it, others must wait their turn. Bandwidth is also the capacity of a network to transmit a given amount of data during a given period.
  74. bank
    Total number of SIMMs or DIMMs that can be accessed simultaneously by the chipset. The "width" of the external data bus divided by the "width" of the SIMM or DIMM sticks. DIMM slots that must be populated to activate dual or triple-channel memory.
  75. basic disk
    Hard drive partitioned in the "classic" way with a master boot record (MBR) and partition table.
  76. baud
    One analog cycle on a telephone line. In the early days of telephone data transmission, the baud rate was often analogous to bits per second. Due to advanced modulation of baud cycles as well as data compression, this is no longer true.
  77. bcdedit
    A command-line tool that enables you to view the BCD store, which lists the Windows boot options.
  78. beep codes
    Series of audible tones produced by a motherboard during the POST. These tones identify whether the POST has completed successfully or whether some piece of system hardware is not working properly. Consult the manual for your particular motherboard for a specific list of beep codes.
  79. binary numbers
    Number system with a base of 2, unlike the number systems most of us use that have bases of 10 (decimal numbers), 12 (measurement in feet and inches), and 60 (time). Binary numbers are preferred for computers for precision and economy. An electronic circuit that can detect the difference between two states (on-off, 0-1) is easier and more inexpensive to build than one that could detect the differences among ten states (0-9).
  80. biometric device
    Hardware device used to support authentication; works by scanning and remembering a unique aspect of a user's various body parts by using some form of sensing device such as a retinal scanner.
  81. BIOS
    Basic Input/Output Services: Classically, software routines burned onto the system ROM of a PC. More commonly seen as any software that directly controls a particular piece of hardware. A set of programs encoded in read-only memory on computers. These programs handle startup operations and low-level control of hardware such as disk drives, the keyboard, and monitor.
  82. bit
    Single binary digit. Also, any device that can be in an on or off state.
  83. bit depth
    Number of colors a video is capable of producing. Common bit depths are 16-bit and 32-bit, representing 65,536 colors and 16.7 million colors (plus an 8-bit alpha channel for transparency levels), respectively.
  84. BitLocker Drive Encryption
    Drive encryption software offered in Windows Vista/7 Ultimate and Enterprise editions. BitLocker requires a special chip to validate hardware status and to ensure that the computer hasn't been hacked.
  85. Blu-ray Disc
    Optical disc format that stores 25 and 50 GB of data, designed to be the replacement media for DVD.
  86. Boot
    To initiate an automatic routine that clears the memory, loads the operating system, and prepares the computer for use. Term derived from "pull yourself up by your bootstraps." PCs must do that because RAM doesn't retain program instructions when power is turned off. A cold boot occurs when the PC is physically switched on. A warm boot loads a fresh OS without turning off the computer, lessening the strain on the electronic circuitry. To do a warm boot, press the CTRL-ALT-DELETE keys twice in rapid succession (the three fingered salute).
  87. Boot Configuration Data File
    BCD: File that contains information about the various operating systems installed on the system as well as instructions for how to actually load them.
  88. Boot Sector
    First sector on a PC hard drive or floppy disk, track 0. The boot-up software in ROM tells the computer to load whatever program is found there. If a system disk is read, the program in the boot record directs the computer to the root directory to load the operating system.
  89. boot.ini
    Text file used during the boot process that provides a list of all OS's currently installed and available for ntldr. Also tells where each OS is located on the system. Used in Windows XP and earlier Microsoft operating systems.
  90. bootable disk
    Disk that contains a functional OS; can also be a floppy disk, USB thumb drive, or optical disc.
  91. bootmgr
    Windows Vista/7's Boot Manager
  92. bootrec
    A Windows Recovery Environment troubleshooting and repair tool that repairs the MBR, boot sector, or BCD store. It replaces the fixboot and fixmbr Recovery Console commands used in Windows XP and earlier OSs.
  93. bootstrap loader
    Segment of code in a system's BIOS that scans for an OS, looks specifically for a valid boot sector, and, when one is found, hands control over to the boot sector; then the bootstrap loader removes itself from memory.
  94. bps
    bits per second: Measurement of how fast data is moved from one place to another. A 56K modem can move ~56,000 bits per second.
  95. bridge
    A device that connects two networks and passes traffic between them based only on the node address, so that traffic between nodes on one network does not appear on the other network. For example, an Ethernet bridge only looks at the MAC address. Bridge filter and forward packets based on MAC addresses and operate at Level 2 (Data Link layer) of the OSI seven-layer model.
  96. BTX
    Balanced Technology Extended: Motherboard form factor designed as an improvement over ATX
  97. buffer underrun
    Inability of a source device to provide a CD burner with a constant stream of data while burning a CD-R or CD-RW
  98. buffered/registered DRAM
    Usually seen in motherboards supporting more than four sticks of RAM, required to address interference issues caused by the additional sticks.
  99. bug
    Programming error that causes a program or a computer system to perform erratically, produce incorrect results, or crash.
  100. bus
    Series of wires connecting two or more separate electronic devices, enabling those devices to communicate. Also, a network topology where computers all connect to a main line called a bus cable.
  101. bus mastering
    Circuitry allowing devices to avoid conflicts on external data bus.
  102. bus topology
    Network configuration wherein all computers connect to the network via a central bus cable
  103. byte
    Unit of 8 bits; fundamental data unit of PCs. Storing the equivalent of one character, the byte is also the basic unit of measurement for computer storage.
  104. CAB files
    Short for cabinet files. These files are compressed and most commonly used during OS installation to store many smaller files, such as device drivers.
  105. Cache (disk)
    Special area of RAM that stores the data most frequently accessed from the hard drive. Cache memory can optimize the use of your systems.
  106. cache (L1, L2, L3, etc.)
    Special section of fast memory, usually built into the CPU, used by the on-board logic to store information most frequently accessed by the CPU.
  107. Capacitive touchscreen
    Type of touchscreen that uses electrical current in your body to determine movement of your fingers across the screen.
  108. CardBus
    32-bit PC cards that can support up to eight devices on each card. Electrically incompatible with earlier PC cards.
  109. CAT 5
    Category 5 wire; TIA/EIA standard for UTP wiring that can operate at up to 100 Mb/s.
  110. CAT 5e
    Category 5e wire; TIA/EIA standard for UTP wiring that can operate at up to 1 Gb/s
  111. CAT 6
    Category 6 wire; TIA/EIA standard for UTP wiring that can operate at up to 10 Gb/s.
  112. CAT 6a
    Category 6a wire; augmented CAT 6 UTP wiring that supports 10GBaseT networks at the full 100 meter distance between a node and a switch.
  113. Catastrophic failure
    Describes a failure in which a component or whole system will not boot; usually related to a manufacturing defect of a component. Could also be caused by overheating and physical damage to computer components.
  114. CCFL
    Cold Cathode Fluorescent Lamp: Light technology used in LCDs and flatbed scanners. CCFLs use relatively little power for the amount of light they provide.
  115. cd (chdir)
    Shorthand for "change directory". Allows you to change the focus of the command prompt from one directory to another.
  116. CD Quality
    Audio quality that has a sample rate of 44.4 Khz and bit rate of 128 bits.
  117. CDDA
    CD-Digital Audio: Special format used for early CD-ROMs and all audio CDs; divides data into variable length tracks. A good format to use for audio tracks but terrible for data because of lack of error checking.
  118. Centronics Connector
    Connector used with older printers.
  119. CCNA
    Cisco Certified Network Associate: On of the certifications demonstrating a knowledge of Cisco networking products.
  120. CHAP
    Challenge Handshake Authentication Protocol: Common remote access protocol; the serving system challenges the remote client, usually by means of asking for a password.
  121. Chipset
    Electronic chips, specifically designed to work together, that handle all of the low-level functions of a PC. In the original PC, the chipset consisted of close to 30 different chips; today, chipsets usually consist of one, two, or three separate chips imbedded into a motherboard.
  122. chkdsk
    Checkdisk: Hard drive error detection and, to a certain extent, correction utility in Windows. Originally a DOS command (chkdsk.exe); also the executable for the graphical Error-checking tool.
  123. clock cycle
    Single charge to the clock wire of a CPU
  124. clock-multiplying CPU
    CPU that takes the incoming clock signal and multiplies it inside the CPU to let the internal circuitry of the CPU run faster.
  125. Clock speed
    Speed at which a CPU executes instructions. Measured in MHz or GHz.
  126. Clock (clk) wire
    A special wire that, when charged, tells the CPU that another piece of information is waiting to be processed.
  127. Closed source
    Software that is solely controlled by its creator or distributor.
  128. cluster
    Basic unit of storage on a floppy or hard disk. Multiple sectors are contained in a cluster. When Windows stores a file on a disk, it writes those files into dozens or even hundreds of contiguous clusters. If there aren't enough contiguous open clusters available, the OS finds the next open cluster and writes there, continuing this process until the entire file is saved. The FAT or MFT tracks how the files are distributed among the clusters on the disk.
  129. CMOS
    Complementary Metal-oxide Semiconductor: Originally, the type of nonvolatile RAM that held information about the most basic parts of your PC, such as hard drives, floppies, and amount of DRAM. Today. actual CMOS chips have been replaced by flash-type nonvolatile RAM. The information is the same, however, and is still called CMOS-even though it is now almost always stored on Flash RAM.
  130. CMOS setup program
    Program enabling you to access and update CMOS data.
  131. CNR
    Communications and networking riser: Proprietary slot used on some motherboards to provide a sound interference-free connection for modems, sound cards, and NICs.
  132. Code
    Set of symbols representing characters or instructions in a computer program.
  133. code names
    Names that keep track of different variations within CPU models.
  134. codec
    Compressor/decompressor: Software that compresses or decompresses media streams.
  135. Color depth
    Term to define a scanner's ability to produce color, hue, and shade.
  136. COM port(s)
    Serial communications ports available on your computer.
  137. command
    A request, typed from a terminal or embedded in a file, to perform an operation or to execute a particular program.
  138. command-line interface
    User interface for an OS devoid of all graphical trappings
  139. Command prompt
    Text prompt for entering commands.
  140. CompTIA
    Computer Technology Industry Association
  141. Computer Management
    Applet in Windows' Administrative Tools that contains several useful snap-ins, such as Device Manager and Disk Management.
  142. Computing Process
    Four parts of a computer's operation: Input, processing, output, and storage.
  143. Conditioning charger
    Battery charger that contains intelligent circuitry that prevents portable computer batteries from being overcharged and damaged.
  144. Connectors
    Small receptacles used to attach cables to a system.
  145. Container file
    File containing two or more separate, compressed tracks, typically an audio track and a moving-picture track. Also known as a wrapper.
  146. context menu
    Small menu brought up by right-clicking on objects in Windows
  147. Controller card
    Card adapter that connects devices, such as a disk drive, to the main computer bus/motherboard.
  148. Convergence
    Measure of how sharply a single pixel appears on a CRT; a monitor with poor convergence produces images that are not sharply defined.
  149. copy backup
    Type of backup similar to a normal or full backup, in that all selected files on a system are backed up. This type of backup does not change the archive bit of the files being backed up.
  150. Copy command
    Command in the command-line interface for making a copy of a file and pasting it in another location.
  151. Counter
    Used to track data about a particular object when using the Performance Console in Windows XP
  152. CPU
    Central Processing Unit: "Brain" of the computer. Microprocessor that handles primary calculations for the computer.
  153. CRC
    Cycle Redundancy Check: Very accurate mathematical method used to check for errors in long streams of transmitted data. Before data is sent, the main computer uses the data to calculate a CRC value from the data's contents. If the receiver calculates from the received data a different CRC value, the data was corrupted during transmission and is resent. Ethernet packets use the CRC algorithm in the FCS portion of the frame.
  154. CRIMM
    Continuity RIMM: Passive device added to populate unused banks in a system that uses Rambus RIMMs.
  155. CrossFire
    Technology that combines the power of multiple AMD graphics cards in a system.
  156. CRT
    Cathode Ray Tube: Tube of a monitor in which rays of electrons are beamed onto a phosphorescent screen to produce images. Also, a shorthand way to describe a monitor that uses CRT rather than LCD technology.
  157. CSMA/CA
    Carrier sense multiple access/collision avoidance: Networking scheme used by wireless devices to transmit data collisions, which wireless nodes have difficulty detecting.
  158. CSMA/CD
    Carrier sense multiple access/collision detection: Networking scheme used by Ethernet devices to transmit data and resend data after detection of data collisions
  159. cylinder
    Single track on all the platters in a hard drive. Imagine a hard drive as a series of metal cans, nested one inside another; single can would represent a cylinder.
  160. daily backup
    Backup of all files that have been changed on that day without changing the archive bits of those files.
  161. Daisy-chaining
    Method of connecting several devices along a bus and managing the signals for each device.
  162. Data Classification
    System of organizing data according to its sensitivity. Common classifications include public, highly confidential, and top secret.
  163. Data structure
    Scheme that directs how an OS stores and retrieves data on and off a drive. Used interchangeably with the term file system.
  164. DB connectors
    D-shaped connectors used for a variety of connections in the PC and networking world. Can be male or female and have varying number of pins or sockets. Also called D-sub, D-subminiature, or D-shell connectors.
  165. DDR SDRAM
    Double data rate SDRAM: Type of DRAM that makes two processes for every clock cycle.
  166. DDR2
    Type of SDRAM that sends 4 bits of data in every clock cycle.
  167. DDR3 SDRAM
    Type of SDRAM that transfers data at twice the rate of DDR2 SDRAM.
  168. decibels
    Unit of measurement typically associated with sound. The higher the number of decibels, the louder the sound.
  169. default gateway
    In a TCP/IP network, the nearest router to a particular host. This router's IP address is part of the necessary TCP/IP configuration for communicating with multiple networks using IP.
  170. definition file
    List of virus signatures that an antivirus program can recognize.
  171. defrag
    defragmentation: Procedure in which all the files on a hard disk are rewritten on disk so that all parts of each file reside in contiguous clusters. The result is an improvement in disk speed during operations.
  172. degauss
    Procedure used to break up the electromagnetic fields that can build up on the cathode ray tube of a monitor; involves running a current through a wire loop. Most monitors feature a manual degaussing tool.
  173. DHCP
    Dynamic Host Configuration Protocol: Protocol that enables a DHCP server to set TCP/IP settings automatically for a DHCP client.
  174. differential backup
    Similar to an incremental backup. Backs up the files that have been changed since the last backup. This type of backup does not change the state of the archive bit.
  175. digital certificate
    Form in which a public key is sent from a Web server to a Web browser so that the browser can decrypt the data sent by the server.
  176. DLNA
    Digital Living Network Alliance: Device that connect to a home network, discover each other, and share media. In theory, DLNA devices should work with minimal setup or fuss, even if sourced from different manufacturers.
  177. DIMM
    Dual Inline Memory Module: 32 or 64-bit type of DRAM packaging, similar to SIMMs, with the distinction that each side of each tab inserted into the system performs a separate function. DIMMs come in a variety of sizes, with 184- and 240-pin being the most common on desktop computers.
  178. DirectX
    Set of APIs enabling programs to control multimedia, such as sound, video, and graphics. Used in Windows Vista/7 to draw the Aero desktop.
  179. Disk Cleanup
    Utility built into Windows that can help users clean up their disks by removing temporary Internet files, deleting unused program files, and more.
  180. disk cloning
    Taking a PC and making a duplicate of the hard drive, including all data, software, and configuration files, and transferring it to another PC.
  181. disk duplexing
    Type of disk mirroring using two separate controllers rather than one; faster than traditional mirroring.
  182. disk initialization
    A process that places special information on every hard drive installed in a Windows syste,.
  183. Disk Management
    Snap-in available with Microsoft Management Console that enable techs to configure the various disks installed in a system.
  184. Disk Mirroring
    Process by which data is written simultaneously to two or more disk drives. Read and write speed is decreased but redundancy in case of catastrophe is increased.
  185. disk quota
    Application allowing network administrators to limit hard drive space usage.
  186. disk striping
    Process by which data is spread among multiple drives. Increases speed for both reads and writes of data. Considered RAID level 0 because it does not provide fault tolerance.
  187. disk striping with parity
    Method for providing fault tolerance by writing data across multiple drives and then including an additional drive, called a parity drive, that stores information to rebuild the data contained on the other drives. Requires at least three physical disks; two for the data and a third for the parity drive. This provides data redundancy at RAID levels 3-5 with different options.
  188. disk thrashing
    Hard drive that is constantly being accessed due to lack of available system memory. When system memory runs low, a Windows system will utilize hard disk space as "virtual" memory, thus causing and unusual amount of hard drive access.
  189. diskpart
    A fully functioning command-line partitioning tool.
  190. display adapter
    Handles all the communication between the CPU and the monitor. Also known as a video card.
  191. Display applet
    Tool in Windows XP and 7 used to adjust display settings, including resolution, refresh rate, driver information, and color depth.
  192. Display port
    Digital video connector used by Apple Mac desktop models and some PCs, notable from Dell. Designed by VESA as a royalty-free connector to replace VGA and DVI.
  193. DMA
    Direct Memory Access: Technique that some PC hardware devices use to transfer data to and from the memory without using the CPU.
  194. DMA controller
    Resides between the RAM and the devices and handles DMA requests
  195. DNS
    Domain Name Service: TCP/IP name resolution system that translates a host name into and IP address.
  196. DNS Domain
    Specific branch of the DNS name space. First-level DNS domains include .com, .gov, and .edu.
  197. domain
    Groupings of users, computers, or networks. In Microsoft Networking, a domain is a group of computers and users that share a common account database and a common security policy. On the internet, a domain is a group of computers that share a common element in the hierarchical name.
  198. domain-based network
    Network that eliminates the need for logging on to multiple services by using domain controllers to hold the security database for all systems.
  199. DOS
    Disk Operating System: First popular OS available for PCs. A text-based, single-tasking OS that was not completely replaced until the introduction of Windows 95
  200. dot-matrix printer
    Printer that creates each character from an array of dots. Pin striking a ribbon against the paper, one pin for each dot position, form the dots. May be a serial printer (printing one character at a time) or a line printer.
  201. dot pitch
    Value relating to CRTs, showing the diagonal distance between phosphors measured in millimeters.
  202. double-side RAM
    RAM stick with RAM chips solder to both sides of the stick. May only by used with motherboards designed to accept double-sided RAM. Very common.
  203. DPMS
    Display Power-Management Signaling: Specification that can reduce CRT power consumption by 75% by reducing/eliminating video signals during idle periods.
  204. DRAM
    Dynamic Random Access Memory: Memory used to store data in most personal computers. DRAM stores each bit in a "cell" compose of a transistor and a capacitor. Because the capacitor in a DRAM cell can only hold a charge for a milliseconds, DRAM must be continually refreshed, or rewritten, to retain its data.
  205. DriveLock
    CMOS program enabling you to control ATA security mode feature set.
  206. DSL
    Digital Subscriber Line: High-speed internet connection technology that uses a regular telephone line for connectivity. DSL comes in several varieties, including ADSL, SDSL and many speeds. Typical home-user DSL connections are ADSL with a download speed of 7 Mbps and an upload speed of 512 Kbps.
  207. dual-channel memory
    Form of DDR, DDR2, and DDR3 memory access used by many motherboards that requires two identical sticks of RAM.
  208. dual-core
    CPUs that have two execution units on the same physical chip but share caches and RAM.
  209. dual-scan passive matrix
    Manufacturing technique for increasing display updates by refreshing two lines at a time.
  210. DualView
    Microsoft feature enabling Windows to use two or more monitors simultaneously.
  211. DUN
    Dial-Up Networking: Software used by Widows to govern the connection between the modem and the ISP
  212. Duplexing
    Similar to mirroring in that data is written to and read from two physical drives, for fault tolerance. Separate controllers are used for each drive, both for additional fault tolerance and for additional speed. Considered RAID level 1.
  213. dxdiag
    DirectX Diagnostics Tool: Diagnostic tool for getting information about and testing a computer's DirectX version.
  214. dye-sublimation printer
    Printer that uses a roll of heat-sensitive plastic file embedded with dyes, which are vaporized and then solidified onto specially coated paper to create a high-quality image.
  215. dynamic disks
    Special feature of Windows that enables users to span a single volume across two or more drives. Dynamic disks do not have partitions; they have volumes. Dynamic disks can be striped, mirrored, and striped or mirrored with parity.
  216. ECC
    error correction code: Special software, embedded on hard drives, that constantly scans the drive for bad sectors.
    RAM that uses special chips to detect and fix memory errors. Commonly used in high-end servers where data integrity is crucial.
  218. Effective permisions
    User's combined permissions granted by multiple groups.
  219. EFI
    Extensible Firmware Interface: Firmware created by Intel and HP that replaced traditional 16-bit BIOS and added several new enhancements.
  220. EFS
    encrypting file system: Encryption tool found in NTFS 5 or later.
  221. EIDE
    Enhanced IDE: marketing concept of hard-drive maker Western Digital, encompassing four improvements for IDE drives, including drives larger than 528 MB, four devices, increase in drive throughput, and non-hard drive devices.
  222. Electrical potential
    The voltage differential between any two objects, one of which is frequently ground or earth, resulting in a degree of attraction for the electrons to move from one of the objects to the other. A large difference between a person and a doorknob, for example, can lead to a shocking experience when the two touch.
  223. EMI
    Electromagnetic Interference: Electrical interference from one device to another, resulting in poor performance of the device being interfered with.
  224. ESD
    Electrostatic Discharge: Uncontrolled rush of electrons from one object to another. A real menace to PCs, as it can cause permanent damage to semiconductors.
  225. ERD
    Emergency Repair Disk: Saves critical boot files and partition information and is the main tool for fixing boot problems in Windows 2000.
  226. emulator
    Software or hardware that converts the commands to and from the host machine into an entirely different platform.
  227. encryption
    Making data unreadable by those who do not possess a key or password.
  228. equipment rack
    A metal structure used in equipment rooms to secure network hardware devices and patch panels. Most racks are 19 inches wide. Devices designed to fit in such a rack use a height measurement called units, or simply U.
  229. erase lamp
    Component inside laser printers that uses light to make the coating of the photosensitive drum conductive.
  230. Error-checking
    Windows graphical tool that scans and fixes hard drive problems. Often referred to by the name of the executable, chkdsk, or Check Disk.
  231. eSATA
    Serial ATA-based connector for external hard drives and optical drives.
  232. escalate
    Process used when person assigned to repair a problem is not able to get the job done, such as sending the problem to someone with more expertise.
  233. Ethernet
    Name coined by Xerox for the first standard of network cabling and protocols. Based on a bus topology.
  234. Ethic of Reciprocity
    Golden Rule: Do unto others as you would have them do unto you.
  235. EULA
    End User License Agreement
  236. Event Auditing
    Feature of Event Viewer's Security section that creates an entry in the Security Log when certain events happen, such as a user logging on.
  237. Event Viewer
    Utility made available as an MMC snap-in that enables users to monitor various system events, including network bandwidth usage and CPU utilization.
  238. Expand
    Command-line utility included with Windows used to access files within CAB files.
  239. expansion bus
    Set of wires going to the CPU, governed by the expansion bus crystal, directly connected to expansion slots of varying types.
  240. expansion bus crystal
    Controls the speed of the expansion bus
  241. Expansion Slots
    Connectors on a motherboard that enable users to add optional components to a system.
  242. ExpressCard
    The high-performance serial version of the PC Card that replaced PC Card slots on laptop PCs over the past decade. ExpressCard comes in two widths: 34 mm and 54 mm.
  243. Extended partition
    Type of nonbootable hard disk partition. May only have one extended partition per disk. Purpose is to divide a large disk into smaller partitions, each with a separate drive letter.
  244. EAP
    Extensible Authentication Protocol: Authentication wrapper that EAP-compliant applications can use to accept one of many types of authentication. While EAP is a general-purpose authentication wrapper, its only substantial use is in wireless networks.
  245. Extension
    Two, three, four, five or more letters that follow a filename and identify the type of file. Common file extensions are .zip, .exe, .doc, .java, and .xhtml.
  246. EDB
    External Data Bus: Primary data highway of all computers. Everything in your computer is tied either directly or indirectly to the external data bus.
  247. Fast User Switching
    Account option that is useful when multiple users share a system; allows users to switch without logging off.
  248. FAT
    File Allocation Table: Hidden table that records how files on a hard disk are stored in distinct clusters; the only way DOS knows where to access files. Address of first cluster of a file is stored in the directory file. FAT entry for the first cluster is the address of the second cluster used to store that file. In the entry for the second cluster for the file is the address for the third cluster, and so on until the final cluster, which gets a special "end-of-file" code. There are two FATs, mirror images of each other, in case one is destroyed or damaged. Also refers to the 16-bit file allocation table when used by Windows 2000 and later NT-based OS.
  249. FAT16
    File allocation table that uses 16 bits for addressing clusters. Used as the primary hard drive format on DOS and early Windows 95 machines; currently used with smaller capacity flash media devices.
  250. FAT32
    File allocation table that uses 32-bit for addressing clusters. Commonly used with Windows 98 and Windows Me systems. Some Windows 2000 Professional and Windows XP systems also use FAT32, although most modern Windows systems use the more robust NTFS. Default format for flash media devices larger than 2 GB.
  251. FAT64
    exFAT: A Microsoft-proprietary file system that breaks the 4-GB file-size barrier, supporting files up to 16 exabytes and a theoretical partition limit of 64-zettabytes. Envisioned for use with flash media devices with a capacity exceeding 2 TB.
  252. FCS
    Frame Check Sequence: Portion of an Ethernet frame used for error checking, most commonly with the CRC algorithm.
  253. FDISK
    Disk-partitioning utility used in DOS and Windows 9x systems.
  254. fiber-optic cable
    High-speed cable for transmitting data, made of high-purity glass sealed within an opaque tube.
  255. file
    Collection of any form of data that is stored beyond the time of execution of a single job. A file may contain program instructions or data, which may be numerical, textual, or graphical information.
  256. file allocation unit
    Another term for cluster.
  257. file assocation
    Windows term for the proper program to open a particular file; for example, the file association for opening .MP3 files might be Winamp.
  258. file format
    How information is encoded in a file. Two primary types are binary (pictures) and ASCII (text), but within those are many formats, such as BMP and GIF for pictures. Commonly represented by a suffix at the end of the filename; for example, .txt for a text file or .exe for an executable.
  259. file server
    Computer designated to store software, courseware, administrative tools, and other data on a LAN or WAN. It "serves" this information to other computers via the network when users enter their personal access codes.
  260. file system
    Scheme that directs how an OS stores and retrieves data on and off a drive; FAT32 and NTFS are both file systems. Used interchangeably with the term "data structure"
  261. filename
    Name assigned to a file when the file is a first written on a disk. Every file on a disk within the same folder must have a unique name. Filenames can contain any character except the following: /:*?"<>|
  262. Files and Settings Transfer Wizard
    Windows XP's system for moving files and settings to a new PC
  263. firewall
    Device that restricts traffic between a local network and the Internet.
  264. FireWire
    IEEE 1394: Interconnection standard to send wide-band signals over a serialized, physically thin connector system. Serial bus developed by Apple and TI; enables connection of 63 devices at speeds up to 800 megabits per second.
  265. firmware
    Embedded programs or code stored on a ROM chip. Generally OS-independent, thus allowing devices to operate in a wide variety of circumstances without direct OS support. The system BIOS is firmware.
  266. Flash ROM
    ROM technology that can be electrically reprogrammed while still in the PC. Overwhelmingly the most common storage medium of BIOS in PCs today, as it can be upgraded without a need to open the computer on most systems.
  267. FlexATX
    Motherboard form factor. Motherboards built in accordance with the FlexATX form factor are very small, much smaller than microATX motherboards.
  268. Flip 3D
    In the Aero desktop environment, a three-dimensional replacecment for ALT-TAB. Accessed by pressing the WINDOWS KEY-TAB key combination.
  269. FPU
    Floating point unit: Formal term for math coprocessor circuity inside a CPU. A math coprocessor calculates by using a floating point math. Special CPU circuitry that handles complex numbers.
  270. Floppy Disk
    Removable storage media that can hold between 720 KB and 1.44 MB of data.
  271. floppy drive
    System hardware that uses removable 3.5 inch disks as storage media.
  272. flux reversal
    Point at which a read/write head detects a change in magnetic polarity.
  273. FM synthesis
    Producing sound by electronic emulation of various instruments to more-or-less produce music and other sound effects.
  274. Folders List
    A tree menu in Windows Explorer for Windows 2000 and XP that displays the file structure on the left side of the window; toggled on with the Folders button. In Windows Vista and 7, the Folders list is active by default.
  275. form factor
    Standard for the physical organization of motherboard components and motherboard size. Most common form factors are ATX and BTX
  276. format command
    Command in the command-line interface used to format a storage device
  277. formatting
    Magnetically mapping a disk to provide a structure for storing data; can be done to any type of disk, including a floppy disk, hard disk, or other type of removable disk.
  278. fragmentation
    Occurs when files and directories get jumbled on a fixed disk and are no longer contiguous. Can significantly slow down hard drive access times and can be repaired by using the defrag utility included with each version Windows.
  279. Frame
    A data unit transferred across a network. Frames consist of several parts, such as the sending and receiving MAC addresses, the data being sent, and the frame check sequence.
  280. freeware
    Software that is distributed for free, with no license fee.
  281. Frequency
    Measure of a sound's tone, either high or low.
  282. frontside bus
    Wires that connect the CPU to the main system RAM. Generally running at speeds of 66-133 MHz. Distinct from expansion bus and backside bus, though it shares wires with the former.
  283. FTP
    File Transfer Protocol: Rules that enable two computers to talk to one another during a file transfer. Protocol used when you transfer a file from one computer to another across the Internet. FTP uses port numbers 20 and 21.
  284. Fuel Cells
    Power source that uses chemical reactions to produce electricity. Lightweight, compact, and stable devices expected to replace batteries as the primary power source for portable PCs.
  285. full-duplex
    Any device that can send and receive data simultaneously
  286. Full-Speed USB
    USB standard that runs at 12 Mbps
  287. Fuser Assembly
    Mechanism in laser printers that uses two rollers to fuse toner to paper during the print process.
  288. gain
    Ration of increase of radio frequency output provided by antenna, measured in decibels (dB).
  289. GDI
    Graphical Device Interface: Component of Windows that utilizes the CPU rather than the printer to process a print job as a bitmapped image of each page.
  290. GPF
    General Protection Fault: Error code usually seen when separate active programs conflict on resources or data.
  291. Geometry
    Numbers representing three values: heads, cylinders, and sectors per track; define where a hard drives stores data.
  292. Geotracking
    Feature in cellular phones that enables the cell phone companies and government agencies to use the ID or MAC address to pinpoint where your phone is at any given time.
  293. giga
    Prefix for the quantity 1,073,741,824 (2^30) or for 1 billion. On gigabyte would be 1,073,741,824 bytes, except with hard drive labeling, where it means 1 billion bytes. One gigahertz is 1 billion hertz.
  294. GPS
    Global Positioning System: Technology that enables a mobile device to determine where you are on a map.
  295. GUID GPT
    Globally unique identifier partition table: Partitioning scheme that enables you to create more than four primary partitions without needing to use dynamic disks.
  296. GPU
    Graphics Processing Unit: Specialized processor that helps the CPU by taking over all of the 3-D rendering duties.
  297. Grayscale Depth
    Number that defines how many shades of gray the scanner can save per dot.
  298. grayware
    Program that intrudes into a user's computer experience without damaging any systems or data.
  299. Group
    Collection of user accounts that share the same access capabilities.
  300. Group Policy
    Means of easily controlling the settings of multiple network clients with policies such as setting minimum password lengths or preventing Registry edits.
  301. GUI
    Graphical User Interface: Interface that enables user to interact with computer graphically, by using a mouse or other pointing device to manipulate icons that represent programs or documents, instead of using only text as in text as in early interfaces.
  302. Gyroscope
    Device that can detect the position of the table or phone in 3-D space.
  303. HAL
    Hardware abstraction layer: Part of the Windows OS that separates system-specific devices drivers from the rest of the NT system.
  304. handshaking
    Procedure performed by modems, terminals, and computers to verify that communication has been correctly established.
  305. hang
    When a computer freezes and does not respond to keyboard commands, it is said to "hang" or to have "hung".
  306. hang time
    Number of seconds a too-often-hung computer is airborne after you have thrown it out a second-story window.
  307. hard drive
    Data-recording system using solid disks of magnetic material turning at high speeds to store and retrieve programs and data in a computer.
  308. hardware
    Physical computer equipment such as electrical, electronic, magnetic, and mechanical drives. Anything in the computer world that you can hold in your hand.
  309. Hardware profile
    Feature in Windows XP that enables the user to switch several hardware configurations at once during the Windows boot process.
  310. Hardware protocol
    Defines many aspects of a network, from the packet type to the cabling and connectors used.
  311. HBA
    Host Bus Adapter: Connects SATA devices to the expansion bus.
  312. HDA
    High Definition Audio: Intel-designed standard to support features such as true surround sound with many discrete speakers.
  313. HDMI
    High Definition Multimedia Interface: Single multimedia connection that includes both HD video and audio. One of the best connections for outputting to television. Also contains copy protection.
  314. Head actuator
    Mechanism for moving the arms inside a hard drive on which the read/write heads are mounted.
  315. heads
    Short for read/write heads used by hard drives to store data
  316. hex
    Hexadecimal: Base-16 numbering system using ten digits and six letters. In the computer world, shorthand way to write binary numbers by substituting one hex number digit for a four-digit binary number
  317. Hi-Speed USB
    USB standard that runs at 480 Mbps. Also referred to as USB 2.0.
  318. horizontal cabling
    Cabling that connects the equipment room to the work areas.
  319. host
    On a TCP/IP network, single device that has an IP address-any device that can be the source or destination of a data packet. In the mainframe world, computer that is made available for use by multiple people simultaneously.
  320. hot-swappable
    Any hardware that may be attached to or removed from a PC without interrupting the PC's normal processing.
  321. HRR
    Horizontal Refresh Rate: Amount of time it takes for a CRT to draw one horizontal line of pixels on a display.
  322. HTML
    Hypertext Markup Language: ASCII-based, script-like language for creating hypertext documents such as a those on the www.
  323. HTTP
    Hypertext Transfer Protocol: Extremely fast protocol used for network file transfers in the www environment. Uses port 80.
  324. HTTPS
    HTTP over Secure Sockets Layer: Secure form of HTTP used commonly for Internet business transactions or any time when a secure connection is required. Uses port 443.
  325. Hub
    Electronic device that sits at the center of a star topology network, providing a common point for the connection of network devices. Hubs repeat all information out to all ports and have been replaced by switches, although the term is still commonly used.
  326. Hybrid
    A network topology that combines features from multiple other topologies, such as the star-bus topology.
  327. hyperthreading
    CPU feature that enables a single pipeline to run more than one thread at once.
  328. Hypervisor
    Software that enables a single computer to run multiple operating systems simultaneously.
  329. I/O
    input/output: General term for reading and writing data to a computer. "Input" includes data entered from a keyboard, identified by a pointing device or loaded from a disk. "Output" includes writing information to a disk, viewing it on a CRT, or printing to a printer.
  330. I/O Addressing
    Using the address bus to talk to system devices.
  331. IOAPIC
    I/O advanced programmable interrupt controller: Typically located in the Southbridge, acts as the traffic cop for interrupt requests to the CPU.
  332. I/O base address
    First value in an I/O address range.
  333. ICH
    I/O Controller Hub: Official name for Southbridge chip found in Intel's chipsets.
  334. icon
    Small image or graphic, most commonly found on a system's desktop, that launches a program when selected.
  335. ICS
    Internet Connection Sharing: Windows feature that enables a single network connection to be shared among several machines. ICS was first introduced with Windows 98.
  336. IDE
    Integrated Drive Electronics: PC specification for small- to medium- sized hard drives in which the controlling electronics for the drive are part of the drive itself, speeding up transfer rates and leaving only a simple adapter. IDE only supported two drives per system of no more than 504 MB each, and has been completely supplanted by Enhanced IDE. EIDE supports four drives of over 8 GB each and more than doubles the transfer rate. The more common name for PATA drives.
  337. IEC-320
    Connects the cable supplying AC power from a wall outlet into the power supply.
  338. IEEE
    Institute of Electronic and Electrical Engineers: leading standards-setting group in the US
  339. IEEE 1284
    IEEE standard governing parallel communication
  340. IEEE 1394
    IEEE standard governing FireWire communication.
  341. IEEE 1394a
    Firewire standard that runs at 400 Mbps
  342. IEEE 1394b
    FireWire standard that runs at 800 Mbps.
  343. IEEE 802.11
    Wireless Ethernet standard more commonly known as Wi-Fi.
  344. Image Deployment
    Operating system installation that uses a complete image of a hard drive as an installation media. Helpful when installing an OS on a large number of identical PCs.
  345. Image File
    Bit-by-bit image of data to be burned on CD or DVD-from one file to an entire disc-stored as a single file on a hard drive. Particularly handy when copying from CD to CD or DVD to DVD.
  346. IMAP4
    Internet Message Access Protocol version 4: An alternative to POP3 that retrieves email from an email server, like POP3; IMAP uses TCP port 143.
  347. Impact Printer
    Uses pins and inked ribbons to print text or images on a piece of paper.
  348. impedance
    Amount of resistance to an electrical signal on a wire. Relative measure of the amount of data a cable can handle.
  349. Incremental Backup
    Backs up all files that have their archive bits turned on, meaning that they have been changed since the last backup. Turns the archive bits off after the files have been backed up.
  350. IT
    Information Technology: Field of computers, their operation, and their maintenance.
  351. infrastructure mode
    Wireless networking mode that uses one or more WAPs to connect the wireless network nodes to a wired network segment.
  352. inheritance
    NTFS feature that passes on the same permissions in any subfolders/files resident in the original folder.
  353. instruction set
    All of the machine-language commands that a particular CPU is designed to understand
  354. IMC
    Integrated Memory controller: Memory controller circuitry built into the CPU. An IMC enables faster control over things like the large L3 cache shared among multiple cores.
  355. Interface
    Means by which a user interacts with a piece of software.
  356. INT13
    Interrupt 13 extensions: Improved type of BIOS that accepts EIDE drives up to 137 GB.
  357. Interrupt
    Suspension of a process, such as the execution of a computer program, caused by an event external to the computer and performed in such a way that the process can be resumed. Events of this kind include sensors monitoring laboratory equipment or a user pressing an interrupt key.
  358. iOS
    The operating system of Apple mobile devices.
  359. IP address
    Numeric address of a computer connected to the internet. An IPv4 address is made up of four octets of 8-bit binary numbers translated into their shorthand numeric values. An IPv6 address is 128 bits long. The IP address can be broken down into a network ID and a host ID. Also called Internet address.
  360. IPSec
    Internet Protocol security: Microsoft's encryption method of choice for networks consisting of multiple networks linked by a private connection, providing transparent encryption between the server and the client.
  361. IPv4
    Internet Protocol version 4: Internet standard protocol that provides a common layer over dissimilar networks; used to move packet among host computers and through gateways if necessary. Part of the TCP/IP protocol suite. Uses the dotted-decimal format -
  362. IPv6
    Internet Protocol version 6: Protocol in which addresses consist of eight sets of four hexadecimal numbers, each number being a value between 0000 and FFFF, using a colon to separate the numbers.
  363. IrDA
    Infrared Data Association protocol: Protocol that enables communication through infrared devices, with speeds of up to 4 Mbps.
  364. IRQ
    Interrupt request: Signal from a hardware device, such as a modem or a mouse, indicating that it needs the CPU's attention. In PCs, IRQs are sent along specific IRQ channels associated with a particular device. IRQ conflicts were a common problem in the past when adding expansion boards, but the plug-and-play specification has removed this headache in most cases.
  365. ISA
    Industry Standard Architecture design was found in the original IBM PC for the slots that allowed additional hardware to be connected to the computer's motherboard. And 8-bit, 8.33 MHz expansion bus was designed by IBM for its AT computer and released to the public domain. An improved 16-bit bus was also released to the public domain. Replaced by PCI in the mid-90's.
  366. ISDN
    Integrated services digital network: CCITT standard that defines a digital method for communications to replace the current analog telephone system. ISDN is superior to POTS telephone lines because it supports a transfer rate of up to 128 Kbps for sending information from computer to computer. It also allows data and voice to share a common phone line.
  367. ISO-9660
    CD format to support PC file systems on CD media. supplanted by the Joliet format.
  368. ISO file
    Complete copy of a storage media device, typically used for optical discs.
  369. Joliet
    Extension of the ISO 9660 format. Most popular CD format to support PC file systems on CD media.
  370. joule
    Unit of energy describing how much energy a surge suppressor can handle before it fails.
  371. Jump List
    A Windows 7 menu that shows context-sensitive information about whatever is on the taskbar.
  372. jumper
    Pair of small pins that can be shorted with a shunt to configure many aspects of PCs. Often used in configurations that are rarely changed, such as master/slave settings on IDE drives.
  373. Kerberos
    Authentication encryption developed by MIT to enable multiple brands of servers to authenticate multiple brands of clients.
  374. kernel
    Core portion of program that resides in memory and performs the most essential operating system tasks.
  375. Knowledge Base
    Large collection of documents and FAQs that is maintained by Microsoft. Found on Microsoft's Web site, the Knowledge Base is an excellent place to search for assistance on most OS problems.
  376. KVM
    keyboard, video, mouse
  377. LAN
    Local area network: Group of PCs connected via cabling, radio, or infrared that use this connectivity to share resources such as printers and mass storage.
  378. Laser printer
    Electrophotographic printer in which a laser is used as the light source.
  379. Latency
    Amount of delay before a device may respond to a request; most commonly used in reference to RAM
  380. LBA
    Logical Block Addressing: Translation of IDE drives promoted by Western Digital as a standardized method for breaking the 504-MB limit in IDE drives. Subsequently universally adopted by the PC industry and now standard on all EIDE drives.
  381. LCD
    Liquid crystal display: Type of display commonly used on portable PCs. Also have mostly replaced CRTs as the display of choice for most desktop computer users, due in large part to rapidly falling prices and increasing quality. LCDs use liquid crystals and electricity to produce images on the screen.
  382. LED
    light-emitting diode: Solid-state device that vibrates at luminous frequencies when current is applied.
  383. Level 1 cache
    First RAM cache accessed by the CPU, which stores only the absolute most-accessed programming and data used by currently running threads. Always the smallest and fastest cache on the CPU.
  384. Level 2 Cache
    Second RAM cache accessed by the CPU. Much larger and often slower than the L1 cache, and accessed only if the requested program/data is not in the L1 cache.
  385. Level 3 Cache
    Third RAM cache accessed by the CPU. Much larger than the L1 and L2 caches, and accessed only if the requested program/data is not in the L2 cache. Seen only on high-end CPUs.
  386. LDAP
    Lightweight Directory Access Protocol: Protocol used by many operating systems and applications to access directories.
  387. Live DVD
    The Windows installation media, which loads the Windows Preinstallation Environment (WinPE) directly from disc into memory and doesn't access or modify the hard drive.
  388. Local Security Policy
    Windows tool used to set local security policies on an individual system.
  389. log files
    Files created in Windows to track the progress of certain processes.
  390. logical drives
    Sections of an extended partition on a hard drive that are formatted and assigned a drive letter, each of which is presented to the user as if it were a separate drive.
  391. loopback plug
    Device used during loopback tests to check the female connector on a NIC
  392. Low-speed USB
    USB standard that runs at 1.5 Mbps. Also called USB 1.1.
  393. LPT Port
    Commonly referred to as a printer port; usually associated with a local parallel port.
  394. LPX
    First slimline form factor; replaced by NLX form factor
  395. Lumens
    Unit of measure for amount of brightness on a projector or other light source.
  396. MAC Address
    Media Access Control: Unique 48-bit address assigned to each network card. IEEE assigns blocks of possible addresses to various NIC manufacturers to help ensure that the address is always unique. The Data Link layer of the OSI model uses MAC addresses for locating machines.
  397. MAC Address filtering
    Method of limiting wireless network access based on the physical, hard-wired address of the units' wireless NIC.
  398. Machine Language
    Binary instruction code that is understood by the CPU.
  399. Maintenance kits
    Set of commonly replaced printer components provided by many manufacturers
  400. Matte
    Laptop screen finish that offers a good balance between richness of colors and reflections, but washes out in bright light.
  401. MBR
    Master-Boot Record: Tiny bit of code that takes control of the boot process from the system BIOS
  402. MCC
    Memory Control Chip: Chip that handles memory requests from the CPU. Although once a special chip, it has been integrated into the chipset or CPU on modern PCs.
  403. MCH
    Memory Controller Hub: Intel-coined name for what is now commonly called the Northbridge.
  404. md (mkdir) command
    Command in the command-line interface used to create directories.
  405. mega
    Prefix that stands for the binary quantity 1,048,576 (2^20) or the decimal quantity of 1,000,000. One megabyte is 1,048,576 bytes. One megahertz, however, is a million hertz. Sometimes shortened to Meg, as in a "286 has an address space of 16 Megs.)
  406. Megapixel
    Term used typically in reference to digital cameras and their ability to capture data.
  407. memory
    Device or medium for temporary storage of programs and data during program execution. Synonymous with storage, although it most frequently refers to the internal storage of a computer that can be directly addressed by operating instructions. A computer's temporary storage capacity is measured in KB, MB, or GB of RAM. Long-term data storage on disks is also measured in KB, MB, GB, or TB.
  408. Memory Addressing
    Taking memory address from system RAM and using it to address nonsystem RAM or ROM so the CPU can access it.
  409. Mesh Topology
    Network topology where each computer has a dedicated line to every other computer, most often used in wireless networks.
  410. MFT
    Master File Table: Enhanced file allocation table used by NTFS.
  411. MicroATX
    Variation of the ATX form factor, which uses the ATX power supply. MicroATX motherboards are generally smaller than their ATX counterparts but retain all the same functionality.
  412. microBTX
    Variation of the BTX form factor, MicroBTX motherboards are generally smaller than their BTX counterparts but retain all the same functionality.
  413. microdrive
    Tiny hard drives using the CompactFlash form factor.
  414. microprocessor
    "Brain" of a computer. Primary computer chip that determines relative speed and capabilities of the computer. Also called CPU.
  415. MCITP
    Microsoft Certified IT Professional: An advanced IT certification specifically covering Microsoft products.
  416. MIDI
    Musical Instrument Digital Interface: Interface between a computer and a device for simulating musical instruments. Rather than sending large sound samples, a computer can simply send "instructions" to the instrument describing pitch, tone, and duration of a sound. MIDI files are therefore very efficient. Because a MIDI file is made up of a set of instructions rather than a copy of the sound, modifying each component of the file is easy. Additionally, it is possible to program many channels, or "voices," of music to be played simultaneously, creating symphonic sound.
  417. MIDI-enabled device
    External device that enables you to input digital sound information in the MIDI format; for example, a MIDI keyboard (the piano kind).
  418. migration
    Moving users from one OS or hard drive to another
  419. MIMO
    Multiple in/multiple out: Feature of 802.11n devices that enables the simultaneous connection of up to four antennas, greatly increasing thoughput.
  420. mini connector
    One type of power connector from a PC power supply unit. Supplies 5 and 12 volts to peripherals. Also known as a floppy connector.
  421. mini-DIN
    Small connection most commonly used for keyboards and mice. Many modern systems implement USB in place of mini-DIN connections. Also called PS/2
  422. Mini-ITX
    The largest and the most popular of the three ITX form factors. At a minuscule 6.7 by 6.7 inches, Mini-ITX competes with microATX and proprietary small form factor (SFF) motherboards.
  423. Mini-PCI
    Specialized form of PCI designed for use in laptops.
  424. Mini-PCIe
    Specialized form of PCIe designed for use in laptops
  425. mini power connector
    Connector used to provide power to floppy disk drives.
  426. mirror set
    A type of mirrored volume created by Windows 7 Professional, Enterprise, and Ultimate editions.
  427. Mirroring
    Reading and writing data at the same time to two drives for fault tolerance purposes. Considered RAID level 1.
  428. MMC
    Microsoft Management Console: Means of managing a system, introduced by Microsoft with Windows 2000. The MMC allows an administrator to customize management tools by picking and choosing from a list of snap-ins. Available snap-ins include Device Manager, Users and Groups, and Computer Management.
  429. MMX
    Multimedia extensions: Specific CPU instructions that enable a CPU to handle many multimedia functions, such as digital signal processing. Introduced with the Pentium CPU, these instructions are used on all x86 CPUs.
  430. mode
    Any single combination of resolution and color depth set for a system.
  431. Modem
    modulator/demodulator: Device that converts a digital bit stream into an analog signal (modulation) and converts incoming analog signals back into digital signals (demodulation). Analog communications channel is typically a telephone line, and analog signals are typically sounds.
  432. module
    Small circuit board that DRAM chips are attached to. Also known as a "stick."
  433. Molex connector
    Computer power connector used by optical drives, hard drives, and case fans. Keyed to prevent it from being inserted into a power port improperly.
  434. monaural
    Describes recording tracks from one source (microphone) as opposed to stereo, which uses two sources.
  435. monitor
    Screen that displays data from a PC. Can use either a cathode ray tube (CRT) or a liquid crystal display (LCD) to display images.
  436. motherboard
    Flat piece of circuit board that resides inside your computer case and has a number of connectors on it. Every device in a PC connects directly or indirectly to the motherboard, including CPU, RAM, hard drives, optical drives, keyboard, mouse, and video cards.
  437. mount point
    Drive that functions like a folder mounted into another drive.
  438. move command
    Command in the command-line interface used to move a file from one location to another.
  439. MP3
    Short for MPEG Audio Layer 3. MP3 is a type of compression used specifically for turning high-quality digital audio files into much smaller, yet similar sounding, files
  440. MPA
    Microsoft Product Activation: Introduced by Microsoft with the release of Windows XP, prevents unauthorized use of Microsoft's software by requiring users to activate the software.
  441. MPEG-2
    Moving Pictures Experts Group: Standard of video and audio compression offering resolutions up to 1280x720 at 60 frames per second.
  442. MPEG-4
    Moving Pictures Experts Group: Standard of video and audio compression offering improved compression over MPEG-2
  443. MS-CHAP
    Microsoft's variation of the CHAP protocol, which uses a slightly more advanced encryption protocol. Windows Vista uses MS-CHAP v2 (version 2), and does not support MS-CHAP v1.
  444. msconfig
    System Configuration Utility: Executable file that runs the Windows System Configuration utility, which enables users to configure a system's boot files and critical system files. Often used for the name of the utility, and in "just run msconfig."
  445. MSDS
    material safety data sheet: Standardized form that provides detailed information about potential environmental hazards and proper disposal methods associated with various PC components.
  446. msinfo32
    Provides information about hardware resources, components, and the software environment. Also known as System Information.
  447. Multiboot Installation
    OS installation in which multiple operating systems are installed on a single machine. Can also refer to kicking a device several times in frustration.
  448. Multicore Processing
    Using two or more execution cores on one CPU die to divide up work independently of the OS.
  449. multitasking
    Process of running multiple programs or tasks on the same computer at the same time.
  450. multitouch
    Input method on many smartphones and tablets that enables you to use multiple fingers to do all sorts of fun things, such as using two fingers to scroll or swipe to another screen or desktop.
  451. Nano-ITX
    A 4.7 inch by 4.7 inch variation of the ITX form factor.
  452. NAT
    • Network Address Translation: A means of translating a system's IP address into another IP address before sending it out to a larger network. NAT manifests itself by a NAT program that runs on a system or a router. A network using NAT provides the system on the network with private IP addresses. The system running the NAT software has two interfaces: one connected to the network and the other connected to the larger network.
    • The NAT program takes packets from the client systems bound for the larger network and translates their internal private IP addresses to its own public IP address, enabling many systems to share a single IP address.
  453. native resolution
    Resolution on an LCD monitor that matches the physical pixels on the screen. CRTs do not have fixed pixels and therefore do not have a native resolution.
  454. net command
    Command in Windows that allows users to view a network without knowing view a network without knowing the names of the other computers on the networks
  455. NetBIOS
    Network Basic Input/Output System: Protocol that operates at the Session layer of the OSI seven-layer model. This protocol creates and manages connections based on the names of the computers involved
  456. NetBIOSEUI
    Network Basic Input/Output System Extended User Interface: The default networking protocol for early versions of Windows.
  457. NAS
    Network attached storage: A device that attaches to a network for the sole purpose of storing and sharing files.
  458. network ID
    Number that identifies the network on which a device or machine exists. This number exists in both IP and IPX protocol suites.
  459. network protocol
    Software that takes the incoming data received by the network card, keeps it organized, sends it to the application that needs it, and then takes outgoing data from the application and hands it to the NIC to be sent out over the network.
  460. network technology
    A practical application of a topology and other critical standards to provide a method to get data from one computer to another on a network. It defines many aspects of a network, from the topology, to the frame type, to the cabling and connectors used.
  461. NIC
    Network Interface Card or controller: Expansion card or motherboard interface that enables a PC to connect to a network via a network cable. A wireless NIC enables connection via radio waves rather than a physical cable.
  462. nit
    Value used to measure the brightness of an LCD display. A typical LCD display has a brightness of between 100 and 400 nits.
  463. NLQ
    near-letter quality: Designation for dot-matrix printers that use 24-pin printheads.
  464. NLX
    Second form factor for slimline systems. Replaced the earlier LPX form factor. (NLX apparently stands for nothing; it's just a cool grouping of letters.)
  465. NMI
    non-maskable interrupt: Interrupt code sent to the processor that cannot be ignored. Typically manifested as a BSoD.
  466. NNTP
    Network News Transfer Protocol: Protocol run by news servers that enable newsgroups.
  467. non-system disk or disk error
    Error that occurs during the boot process. Common causes for this error are leaving a nonbootable floppy disk, CD, or other media in the drive while the computer is booting.
  468. nonvolatile memory
    Storage device that retains data even if power is removed; typically refers to a ROM or flash ROM chip, but also could be applied to hard drives, optical media, and other storage devices.
  469. normal backup
    Full backup of every selected file on a system. Turns off the archive bit after the backup.
  470. Northbridge
    Chip that connects a CPU to memory, the PCI bus, Level 2 cache, and AGP activities. Communicates with the CPU through the frontside bus. Newer CPUs feature an integrated Northbridge.
  471. nslookup
    Command-line program in Windows used to determine exactly what information the DNS server is providing about a specific host name.
    One of the critical Windows NT/2000/XP startup files.
  473. NTFS
    NT File System: Robust and secure file system introduced by Microsoft with Windows NT, NTFS provides and amazing array of configuration options for user access and security. Users can be granted access to data on a file-by-file basis. NTFS enables object-level security, long filename support, compression, and encryption.
  474. NTFS permissions
    Restrictions that determine the amount of access given to a particular user on a system using NTFS.
  475. ntldr
    NT Loader: Windows NT/2000/XP boot file. Launched by the MBR or MFT, ntldr looks at the boot.ini configuration file for any installed operating systems.
  476. NVIDIA Corporation
    One of the foremost manufacturers of graphics cards and chipsets.
  477. object
    System component that is given a set of characteristics and can be managed by the operating system as a single entity.
  478. object access auditing
    Feature of Event Viewer's Security section that creates an entry in the Security Log when certain objects are accessed, such as a file or folder.
Card Set
Comptia A+ Glossary
The terms from the glossary of Mike Meyers' study guide for the Comptia A+ Certification.