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274 terms

CompTIA A+ Glossary of Terms A - D

A card set of CompTIA A+ glossary terms from Mike Myer's "CompTIA A+ Certification Exam Guide - 7th Edition" (2010) Covers glossary terms starting with A - D
STUDY
PLAY
10BaseT
Ethernet LAN designed to run UTP cabling. This runs at 10 megabits per second. The maximum length for the cabling between the NIC and the hub (or switch, repeater, etc.) is 100 meters. It uses baseband signaling. No industry standard spelling exists.
100BaseT
Generic term for an Ethernet cabling system designed to run at 100 megabits per second on UTP cabling. It uses baseband signaling. No industry standard spelling exists.
1000BaseT
Gigabit Ethernet on UTP
2.1
Speaker setup consisting of two stereo speakers combined with a subwoofer.
3.5-inch floppy drive
All modern floppy drives are of this size; the format was introduced in 1986 and is one of the longest surviving pieces of computer hardware.
34-pin ribbon cable
Type of cable used by floppy disk drives
3-D graphics
Video technology that attempts to create images with the same depth and texture as objects seen in the real world
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.
5.1 speaker system
Four satellite speakers plus a center speaker and a subwoofer
8.3 naming system
File-naming convention that specified a maximum of eight characters for a filename, followed by a 3-character file extension. Has been replaced by LFN (long filename) support
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 system
802.11a
Wireless networking standard that operates in the 5-GHz band with theoretical maximum throughput of 54 Mbps
802.11b
Wireless networking standard that operates in the 2.4-GHz band with a theoretical maximum throughput of 11 Mbps
802.11g
Wireless networking standard that operates in the 2.4-GHz band with a theoretical maximum throughput of 54 Mbps and is backward compatible with 802.11b
802.11n
Wireless networking standard that can operate in both the 2.4-GHZ and 5-GHz bands and uses MIMO to achieve a theoretical maximum throughput of 100+ Mbps
A/V sync
Process of synchronizing audio and video
AC (alternating current)
Type of electricity in which the flow electrons alternates direction, back and forth, in a circuit
AC'97
Sound card standard for lower-end audio devices; created when most folks listened to stereo sound at best
access control
Security concept using physical security, authentication, users and groups, and security policies.
ACPI (advanced configuration and power interface)
Power management specification that far surpasses its predecessor, APM, by providing support for hot-swappable devices and better control of power modes.
activation
Process of confirming that an installed copy of a Microsoft product (most commonly Windows or a Microsoft Office application) is legitimate. Usually done at the end of software installation.
active matrix
Type of liquid crystal display that replaced the passive matrix technology used in most portable computer displays. Also called TFT (thin film transistor)
active partition
On a hard drive, primary partition that contains on operating system
active PFC (power factor correction)
Circuitry built into PC power supplies to reduce harmonics
ad hoc mode
Decentralized wireless network mode, otherwise known as peer-to-peer mode, where each wireless node is in meshed contact with every other node
Add or Remove Programs
Applet allowing users to manually add or remove a program for the system
address bus
Wires leading from the CPU to the memory controller chip (usually the Northbridge) taht enable the CPU to address RAM. Also used by the CPU for I/O addressing. An internal electronic channel from the microprocessor to random access memory, along which the addresses of memory storage locations are transmitted. Like a post office box, each memory location has a distinct number or address; this thing provides the means by which the microprocessor can access every location in memory.
address space
Total amount of memory addresses that an address bus can contain
administrative shares
Administrator tool to give local admins access to hard drives and system root folders.
Administrative Tools
Group of Control Panel applets, including Computer Management, Event Viewer, and Reliability and Performance Monitor
Administrator account
user account, created when the OS is first installed, that is allowed complete, unfettered access to the system without restriction.
Administrators group
List of members with complete administrator privileges.
ADSL (asymmetric digital subscriber line)
Fully digital, dedicated connection to the telephone system that provides average download speeds of 7 Mbps and upload speed of 512 Kbps
Advanced Startup Options menu
Menu that can be reached during the boot process that offers advanced OS startup options, such as boot in Safe mode or boot into Last Known Good Configuration
adware
Type of malicious program that downloads ads to a user's computer, generating undesirable network traffic
Aero
The Windows Vista desktop environment. This thing adds some interesting aesthetic effect such as window transparency and Flip 3D
AGP (accelerated graphics port)
32/64-bit expansion slot designed by Intel specifically for video that runs at 66 MHz and yields a throughput of at least 254 Mbps. Later versions (2x, 4x, 8x) give substantially higher throughput
algorithm
Set of rules for solving a problem in a given number of steps
ALU (arithmetic logic unit)
CPU logic circuits that perform basic arithmetic (add, subtract, multiply, divide)
AMD (Advanced Micro Devices)
CPU and chipset manufacturer that competes with Intel. Produces the popular Phenom, Ahtlon, Sempron, Turion, and Duron microprecessors; also produces video card processors under it ATI brand
AMI (American Megatrends, Inc)
Major producer of BIOS software for motherboards, as well as many other computer-related components and software
amperes (amps or A)
Unit of measure for amperage, or electrical current
amplitude
Loudness of a sound card
AMR (audio/modem riser)
Proprietary slot used on some motherboards to provide a sound inference-free connection for modems, sound cards, and NICs
analog
Type of 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
anti-aliasing
In computer imaging, blending effect that smooths sharp contrasts 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.
anti-static bag
Bag made of anti-static plastic into which electronics are placed for temporary or long-term storage. Used to protect components from electrostatic discharge.
anti-static mat
Special surface on which to lay electronics. These mats come with a grounding connection designed to equalize electrical potential between a workbench and one or more electronic devices. Used to prevent electrostatic discharge.
anti-static wrist strap
Special device worn around the wrist with a grounding connection designed to equalize electrical potential between a technician and an electronic device. Used to prevent electrostatic discharge.
antivirus program
Software designed to combat viruses by either seeking out and destroying them or passively guarding against them.
API (application programming interface)
Software definition that describes operating system calls for application software; conventions defining how a service is invoked.
APIPA (Automatic Private IP Addressing)
Feature of Windows that automatically assigns an IP address to the system when the client cannot obtain an IP address automatically.
APM (advanced power management)
BIOS routines that enable the CPU to turn on and off selected peripherals
applet
Generic term for a program in the Windows Control Panel
archive
To copy programs and data onto a relatively inexpensive storage medium (disk, tape, etc.) for longterm retention.
archive attribute
Attribute of a file that shows whether the file has been backed up since the last change. Each time a file is opened, changed, or saved, the archive bit is turned on. Some types of backups turn off this archive bit to indicate that a good backup of the file exists on tape.
ARP (Address Resolution Protocol)
Protocol in the TCP/IP suite used with the command-line utility of the same name to determine the MAC address that corresponds to a particular IP address.
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 non-printing control characters, each of which is numbered. These numbers were designed to achieve uniformity among computer devices for printing and the exchange of simple text documents
aspect ratio
Ratio of width to height of an object. Standard television is 4:3
ASR (Automated System Recovery)
Windows XP tool designed to recover a badly corrupted Windows system; similar to ERD
assertive communication
Means of communication that is not pushy or bossy but is also not soft. Useful in dealing with upset customers as it both defuses their anger and gives them confidence that you know what you're doing.
AT (advance technology)
Model name of the second- generation, 80286-based IBM computer. Many aspects of this, such as the BIOS, CMOS, and expansion bus, have become defacto standards in the PC industry. The physical organization of the components on the motherboard is called the AT form factor
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. These drives are more popularly known as IDE drives. (See IDE.) 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. (See Ultra DMA.)
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 GBs).
ATAPI (ATA packet interface)
Series of standards that enable mass storage devices other than hard drives to use the IDE/ATA controllers. Popular with optical drives. (See EIDE.)
ATAPI-compliant
Devices that utilize the ATAPI standards (See ATAPI)
Athlon
Name used for a popular series of CPUs manufactured by AMD
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.
attributes
Values in a file that determine the hidden, read-only, system, and archive status of the file.
ATX (AT eXtended)
Popular motherboard form factor that generally replaced the AT form factor.
authentication
Any method a computer used to determine who can access it.
authorization
Any method a computer uses to determine what a specific user can do.
autodetection
Process through which new disks are automatically recognized by the BIOS.
Automatic Updates
Feature allowing updates to Windows to be retrieved automatically over the Internet.
AutoPlay
Windows 2000/XP/Vista/7 setting, along with autorun.inf, enabling Windows to automatically detect media files and begin using them. (See AUTORUN.INF.)
AUTORUN.INF
File included on some media that automatically launches a program or installation routine when the media is inserted/attached to a system.
autosensing
Better quality sound cards use autosensing to detect a device plugged into a port and to adapt the features of that port.
auto-switching power supply
Type of power supply able to detect the voltage of a particular outlet and adjust accordingly.
Award Software
Major producer of BIOS software for motherboards.
backlight
One of three main components used in LCDs to illuminate an image
backside bus
Set of wires that connect the CPU to Level 2 cache. First appearing in the Pentium Pro, all modern CPUs have a backside bus. Some buses run at the 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. (See also frontside bus and external data bus.)
Backup or Restore Wizard
Utility contained within Windows that allows users to create system backups and set system restore points.
ball mouse
Input device that enables users to manipulate a cursor on the screen by using a ball and sensors that detect the movement and direction of the ball.
bandwidth
Piece of the spectrum occupied by some form of signal, such as television, voice, 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.
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 must be populated to activate dual- or triple-channel memory.
bar code reader
Tool to read Universal Product Code (UPC) bar codes
basic disks
Hard drive partitioned in the "classic" way with a master boot record (MBR) and partition table. (See also dynamic disks.)
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.
BD-RE (Blu-ray Disc-REwritable)
Blu-ray Disc equivalent of the rewritable DVD, allows writing and rewriting several times on the same BD. (See Blu-ray Disc.)
BD-ROM
Blu-ray equivalent of DVD-ROM or CD-ROM (see Blu-ray Disc)
beaming
Term used to describe transferring data from one PDA to another by means of IrDA.
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.
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).
biometric device
Hardware device used to support authentication; works by scanning and remembering unique aspects of a user's various body parts (e.g., retina, iris, face, or fingerprint) by using some form of
sensing device such as a retinal scanner.
BIOS (basic input/output system)
Classically, soft-ware 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 (ROM) on computers.
bit
Single binary digit. Also, any device that can be in an on or off state.
BitLocker Drive Encryption
Drive encryption software offered in Windows Vista/7 Ultimate and Enterprise editions. BitLocker requires a special ship to validate hardware status and to ensure that the computer hasn't been hacked.
bit depth
Number of colors a video card is capable of producing. Common bit depths are 16-bit and 32-bit, representing 65, 536 colors and 16.7 million colors, respectively
Bluetooth
Wireless technology designed to create small wireless networks pre-configured to do specific jobs, but not meant to replace full-function networks or Wi-Fi
Blu-ray Disc (BD)
Optical disc format that stores 25 or 50 GB of data, designed to be the replacement media for DVD. Competed with HD DVD
boot
To initiate an automatic routine that clears the memory, loads the operating system, and prepares the computer for use. Term is derived from "pull yourself up by the 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 finger salute)
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 di- rects the computer to the root directory to load the operating system.
BOOT.INI
Text file used during the boot process that provides a list of all OSs 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
bootable disk
Disk that contains a functional operat-ing system; can also be a floppy disk, USB thumb drive, or optical disc.
bootstrap loader
Segment of code in a system's BIOS that scans for an operating system, 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.
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.
broadband
Commonly understood as a reference to high-speed, always-on communication links that can move large files much more quickly than a regular phone line.
browser
Program specifically designed to retrieve, interpret, and display Web pages.
BSoD (Blue Screen of Death)
Infamous error screen that appears when Windows encounters an unrecoverable error.
BTX (Balanced Technology eXtended)
Motherboard form factor designed as an improvement over ATX.
buffered/registered DRAM
Usually seen in motherboards supporting more than four sticks of RAM, it is required to address interference issues caused by the additional sticks.
buffer underrun
Inability of a source device to pro-vide a CD-burner with a constant stream of data while burning a CD-R or CD-RW.
bug
Programming error that causes a program or a computer system to perform erratically, produce incorrect results, or crash. The term was coined when a real bug was found in one of the circuits of one of the first ENIAC computers.
burn
Process of writing data to a writable optical disc, such as a DVD-R
burn-in failure
Critical failure usually associated with manufacturing defects
bus
Series of wires connecting two or more separate electronic devices, enabling those devices to communicate.
bus mastering
Circuitry allowing devices to avoid conflicts on the external data bus.
bus topology
Network configuration wherein all computers connect to the network via a central bus cable.
byte
Unit of eight bits; fundamental data unit of personal computers. Storing the equivalent of one character, this is also the basic unit of measurement for computer storage.
CAB files
These files are compressed and most commonly used during OS installation to store many smaller files, such as device drivers. Short for cabinet files.
cache (disk)
Special area of RAM that stores the data most frequently accessed from the hard drive. Can optimize the use of your systems.
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.
calibration
Process of matching the print output of a printer to the visual output of a monitor.
card reader
Device with which you can read data from one of several types of flash memory.
card services
Uppermost level of PCMCIA services. This level recognizes the function of a particular PC Card and provides the specialized drivers necessary to make the card work. (See also socket services.)
CardBus
32-bit PC cards that can support up to eight devices on each card. Electrically incompatible with earlier PC cards (3.3 V versus 5 V).
CAT 5
A wire category; TIA/EIA standard for UTP wiring that can operate up to 100 megabits per second.
CAT 5e
A wire category; TIA/EIA standard for UTP wiring that can operate up to 1 gigabit per second.
CAT 6
A wire category; TIA/EIA standard for UTP wiring that can operate up to 10 gigabits per second.
catastrophic failure
Occurs when 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.
CCFL (cold cathode fluorescent lamp)
Light technology used in LCDs and flatbed scanners. These things use relatively little power for the amount of light they provide.
CD (CHDIR)
DOS shorthand for "Change Directory." Allows you to change the focus of the command prompt from one directory to another.
CD (compact disc)
Originally designed as the re-placement for vinyl records, these have become the primary method of long-term storage of music and data.
CD quality
Audio quality that has a sample rate of 44.4 KHz and bit rate of 128 bits
CD-DA (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.
CD-R (compact disc recordable)
Recording media technology that accepts a single "burn" but cannot be erased after that one burn.
CD-ROM (compact disc/read only memory)
Read-only compact storage disk for audio or video data.
CD-RW (compact disc rewritable)
CD technology that accepts multiple reads/writes like a hard drive.
Celeron
Lower-cost brand of Intel CPUs
Cellular WAN
Technology that allows laptops and other mobile devices to access the Internet over a cell phone network.
cellular wireless networks
Networks that enable cell phones, PDAs, and other mobile devices to connect to the Internet.
Centrino
Marketing name for an Intel laptop solution including the mobile processor, support chips and wireless networking.
Centronics connector
Connector used with older printers.
certification
License that demonstrate competency in specialized skill
Cetified Cisco Network Associate (CCNA)
One of the certifications demonstrating a knowledge of Cisco net- working products.
CHAP (Challenge Handshake Authentication Protocol)
Common remote access protocol; serving system challenges, or solicits, the remote client, usually by means of asking for a password.
chassis intrusion detection
Feature offered in some chassis (case) that trips a switch when the chassis is opened.
chipset
Electronic chips, specially designed to work together, that handle all of the low-level functions of a PC. In the original PC, this consisted of close to 30 different chips; today, they usually consist of one, two, or three separate chips embedded into a motherboard.
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.
clean installation
Operating system installed on a fresh drive, following a reformat of that drive. Often the only way to correct a problem with a system when many of the crucial operating system files have become corrupted.
client
Computer program that uses the services of another computer program. Software that extracts information from a server; your auto-dial phone is a client, and the phone company is its server. Also, a machine that accesses shared resources on a server.
client/server
Relationship in which client software obtains services from a server on behalf of a person.
client/server network
Network that has dedicated server machines and client machines.
clock cycle
Single charge to the clock wire of CPU
clock-multiplying CPU
CPU that takes the incoming clock signal and multiples it inside the CPU to let the internal circuitry of the CPU run faster.
clock speed
Speed at which a CPU executes instructions, measured in MHz or GHz. In modern CPUs, the internal speed is a multiple of the external speed. (See also clock-multiplying CPU.)
clock (CLK) wire
Charge on the CLK wire to tell the CPU that another piece of information is waiting to be processed.
cluster
Basic unit of storage on a floppy or hard disk. Multiple sectors are contained in one of these. When Windows stores a file on a disk, it writes those files into dozens or even hundreds of contiguous ___. If there aren't enough contiguous open ___ available, the operating system finds the next open ___ and writes there, continuing this process until the entire file is saved. The FAT or MFT tracks how the files are distributed among the ___s on the disk.
CMOS (complementary metal-oxide semiconductor)
Originally, the type of non-volatile RAM that held in- formation about the most basic parts of your PC, such as hard drives, floppies, and amount of DRAM. Today, actual ____ chips have been replaced by Flash-type non-volatile RAM. The information is the same, however, and is still called ____, even though it is now almost always stored on Flash RAM.
CMOS setup program
Program enabling you to access and update CMOS data
CNR (Communications and Network Riser)
Proprietary slot used on some motherboards to provide a sound inference-free connection for modems, sound cards, and NICs.
coaxial cable
Cabling in which an internal conductor is surrounded by another, outer conductor, thus sharing the same axis.
code
Set of symbols representing characters (e.g., ASCII) or instructions in a computer program (a programmer writes source ___, which must be translated into executable or machine ___ for the computer to use).
codec (compressor/decompressor)
Software that compresses and decompresses media streams
color depth
Term to define a scanner's ability to produce color, hue, and shade.
COM port(s)
Serial communications ports available on your computer. When used as a program extension, .COM indicates an executable program file limited to 64 KB.
command
A request, typed from a terminal or embedded in a file, to perform an operation or to execute a particular program.
command prompt
Text prompt for entering commands
command-line interface
User interface for an OS devoid of all graphical trappings
Compact Flash (CF)
One of the older but still popular flash media formats. Its interface uses a simplified PC Card bus, so it also supports I/O devices.
compatibility modes
Feature of Windows 2000 and beyond to allow software written for previous versions of Windows to operate in newer operating systems.
compliance
Concept that members of an organization must abide by the rules of that organization. For a technician, this often revolves around what software can or cannot be installed on an organization's computer.
component failure
Occurs when a system device fails due to manufacturing or some other type of defect
compression
Process of squeezing data to eliminate redundancies, allowing files to use less space when stored or transmitted.
CompTIA A+ 220-701 (Essentials)
One half of the CompTIA A+ exam, concentrating on understanding terminology and technology, how to do fundamental tasks, and basic Windows operating system support.
CompTIA A+ 220-702 (Practical)
Other half of the CompTIA A+ exam, covering advanced troubleshooting and configuration.
CompTIA A+ certification
Industry-wide, vendor-neutral computer certification program that demonstrates competency as a computer technician
CompTIA Network+ certification
Industry-wide, vendor-neutral certification for network technicians, covering network hardware, installation, and trouble- shooting.
Computer (Vista)
Default interface in Windows Vista and 7 for Windows Explorer; displays drives and net- work locations. (See My Computer.)
Computer Administrator
One of three types of user accounts, the Administrator account has access to all resources on the computer.
Computer Management
Applet in Windows' Administrative Tools that contains several useful snap-ins, such as Device Manager and Disk Management.
computing process
Four parts of a computer's operation: input, processing, output, and storage.
Computing Technology Industry Association (CompTIA)
Nonprofit IT trade association that administers the CompTIA A+ and CompTIA Network+ exams.
conditioning charger
Battery charger that contains intelligent circuitry that prevents portable computer batteries from being overcharged and damaged.
connectors
Small receptacles used to attach cables to a system. Common types of these include USB, PS/2, and DB-25.
consumables
Materials used up by printers, including paper, ink, ribbons, and toner cartridges.
container file
File containing two or more separate, compressed tracks, typically an audio and a moving picture track. Also known as a wrapper.
context menu
Small menu brought up by right-clicking on objects in Windows
Control Panel
Collection of Windows applets, or small programs, that can be used to configure various pieces of hardware and software in a system.
controller card
Card adapter that connects devices, such as a disk drive, to the main computer bus/motherboard.
convergence
Measure of how sharply a single pixel appears on a CRT; a monitor with poor convergence produces images that are not sharply defined.
copy backup
Type of backup similar to Normal or Full, 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.
COPY command
Command in the command line interface for making a copy of a file and pasting it in another location.
core
Name used for the family Intel CPUs that succeeded the Pentium 4
counter
Used to track data about a particular object when using the Performance console
CPU (central processing unit)
"Brain" of the computer. Microprocessor that handles primary calculations for the computer. These are known by names such as Pentium 4 and Athlon.
CRC (cyclic 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 ___ value from the data's contents. If the receiver calculates a ___ value different from the received data, the data was corrupted during transmission and is resent. Ethernet packets have a ___ code.
C-RIMM or CRIMM (continuity RIMM)
Passive device added to populate unused banks in a system that uses Rambus RIMMs.
crossover cable
Special UTP cable used to connect hubs or to connect network cards without a hub. Cross- over cables reverse the sending and receiving wire pairs from one end to the other.
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 this rather than LCD technology.
CSMA/CA (carrier sense multiple access with collision avoidance)
Networking scheme used by wireless devices to transmit data while avoiding data collisions, which wireless nodes have difficulty detecting.
CSMA/CD (carrier sense multiple access with collision detection)
Networking scheme used by Ethernet devices to transmit data and resend data after detecting data collisions.
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; a single can would represent one of these.
daily backup
Backup of all files that have been changed on that day without changing the archive bits of those files. Also called daily copy backup.
Daisy-chaining
Method of connecting several devices along a bus and managing the signals for each device.
data classification
System of organizing data according to its sensitivity. Common classifications include public, highly confidential, and top secret.
data structure
Scheme that directs how an OS stores and retrieves data on and off a drive. Used interchangeably with the term file system. (See also file system.)
DB connectors
D-shaped connectors used for a variety of connections in the PC and networking world. Can be male (with prongs) or female (with holes) and have a varying number of pins or sockets. Also called D-sub, D-subminiature, or D-shell connectors.
DB-15
A two- or three-row DB connector (female) used for 10Base5 networks, MIDI/joysticks, and analog video.
DB-25 connector
DB connector (female), commonly referred to as a parallel port connector.
DC (direct current)
Type of electricity in which the flow of electrons is in a complete circle in one direction.
DDR SDRAM (double data rate SDRAM)
Type of DRAM that makes two processes for every clock cycle. (See also DRAM.)
DDR2 SDRAM
Type of SDRAM that sends four bits of data in every clock cycle. (See also DDR SDRAM.)
DDR3 SDRAM
Type of SDRAM that transfers data at twice the rate of DDR2 SDRAM.
debug
To detect, trace, and eliminate errors in computer programs.
decibels
Unit of measurement typically associated with sound. The higher the number of these, the louder the sound.
dedicated server
Machine that is not used for any client functions, only server functions.
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.
definition file
List of virus signatures that an antivirus program can recognize
defragmentation (DEFRAG)
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 retrieval operations.
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 tool for doing this.
DEL (Erase) command
Command in the command line interface used to delete/erase files
desktop
User's primary interface to the Windows operating system
desktop extender
Portable computer that offers some of the features of a full-fledged desktop computer but with a much smaller footprint and lower weight.
desktop replacement
Portable computer that offers the same performance as a full-fledged desktop computer; these systems are normally very heavy to carry and often cost much more than the desktop systems they replace.
device driver
Program used by the operating system to control communications between the computer and peripherals.
Device Manager
Utility that enables techs to examine and configure all the hardware and drivers in a Windows PC.
DHCP (Dynamic Host Configuration Protocol)
Protocol that enables a server using this to set TCP/IP settings automatically for its client.
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.
digital camera
Camera that simulate film technology electronically
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.
digital zoom
Software tool to enhance the optical zoom capabilities of digital camera
digitally signed driver
All drivers designed specifically for Windows are digitally signed, meaning they are tested to work stably with these operating systems.
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. These come in a variety of sizes, with 184- and 240-pin being the most common on desktop computers.
dipole antennae
Standard stratight-wire antennae that provide the most omnidirectional function.
DIR command
Command used in the command-line interface to display the entire contents of the current working directory.
directory
Another name for a folder
directory service
Centralized index that each PC accesses to locate resources in the domain
DirectX
Set of APIs enabling programs to control multimedia, such as sound, video, and graphics. Used in Windows Vista to draw the Aero desktop.
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.
disk cloning
Taking a PC and making duplicates of the hard drive, including all data, software, and configuration files and transferring it to another PC. (See image installation.)
disk duplexing
Type of disk mirroring using two separate controllers rather than one; faster than traditional mirroring.
Disk Management
Snap-in available with the Microsoft Management Console that enables techs to configure the various disks installed in a system; available in the Computer Management Administrative Tool.
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.
disk quota
Application allowing network administrators to limit hard drive space usage.
disk striping
Process by which data is spread among multiple (at least two) drives. Increases speed for both reads and writes of data. Considered RAID level 0 be- cause it does not provide fault tolerance.
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.
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 an unusual amount of hard drive access.
display adapter
Handles all the communication between the CPU and the monitor. Also known as a video card.
Display applet
Tool in Windows 2000 and Windows XP used to adjust display settings, including resolution, refresh rate, driver information, and color depth.
DMA (direct memory access) modes
Technique that some PC hardware devices use to transfer data to and from the memory without using the CPU.
DMA controller
Resides between the RAM and the devices and handles DAM requests
DNS (domain name system)
TCP/IP name resolution system that translates a host name into an IP address.
DNS domain
Specific branch of the DNS name space. First-level DNS domains include .COM, .GOV, and .EDU.
docking station
Device that provides a portable computer extra features such as a DVD drive or PC Card, in addition to legacy and modern ports. Similar to a port replicator.
documenting
Steps a technician uses to a solve a problem: To record the relevant information. For a technician, this would be recording each troubleshooting job: what the problem was, how it was fixed, and other helpful information.
Documents folder
Windows Vista/7 folder for storing user-created files. Replaces the My Documents folder previously used in Windows 2000/XP. (See My Documents.)
Dolby Digital
Technology for sound reductions and channeling methods used for digital audio.
domain
Groupings of users, computers, or networks. In Microsoft networking, a ___ is a group of computers and users that share a common account database, called a SAM, and a common security policy. On the Internet, a ___ is a group of computers that share a common element in their hierarchical name.
domain-based network
Network that eliminates the need for logging in to multiple servers by using domain controllers to hold the security database for all systems.
DOS (Disk Operating System)
First popular operating system available for PCs. A text-based, single-tasking operating system that was not completely replaced until the introduction of Windows 95.
dot pitch
Value relating to CRTs, showing the diagonal distance between phosphors measured in millimeters
dot-matrix printer
Printer that creates each character from an array of dots. Pins 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.
double-sided RAM
RAM stick with RAM chips soldered to both sides of the stick. May only be used with motherboards designed to accept such RAM. Very common.
DPI (dots per inch)
Measure of printer resolution that counts the dots the device can produce per linear (horizontal) inch.
DPMS (Display Power-Management Signaling)
Specification that can reduce CRT power consumption by 75 percent by reducing/eliminating video signals during idle periods.
DRAM (dynamic random access memory or dynamic RAM)
Memory used to store data in most personal computers. ___ stores each bit in a "cell" composed of a transistor and a capacitor. Because the capacitor in a ___ cell can only hold a charge for a few milliseconds, ___ must be continually refreshed, or rewritten, to retain its data.
DriveLock
CMOS program enabling you to control the ATA security mode feature set.
driver signing
Digital signature for drivers used by Windows to protect against potentially bad drivers.
DS3D (DirectSound3D)
Introduced with DirectX 3.0, this is a command set used to create positional audio, or sounds that appear to come from in front, in back, or to the side of a user. (See also DirectX.)
DSL (digital subscriber line)
High-speed Internet connection technology that uses a regular telephone line for connectivity. This comes in several varieties, including asynchronous (A___) and synchronous (S___), and many speeds. Typical home-user ___ connections are A___ with a download speed of 7 Mbps and an upload speed of 512 Kbps.
D-subminature
Same as DB connector
DTS (Digital Theatre System)
Technology for sound reductions and channeling methods, similar to Dolby Digital.
dual boot
Refers to a computer with two operating systems installed, enabling users to choose which operating system to load on boot.