Dell Insp 640 M Manual

							Glossary171
Glossary
Terms in this Glossary are provided for 
informational purposes only and may or may not 
describe features included with your particular 
computer.
A
AC — alternating current — The form of electricity that 
powers your computer when you plug the AC adapter 
power cable in to an electrical outlet.
ACPI — advanced configuration and power interface — 
A power management specification that enables 
Microsoft
® Windows® operating systems to put a 
computer in standby or hibernate mode to conserve the 
amount of electrical power allocated to each device 
attached to the computer.
AGP — accelerated graphics port — A dedicated graphics 
port that allows system memory to be used for video-
related tasks. AGP delivers a smooth, true-color video 
image because of the faster interface between the video 
circuitry and the computer memory.
ALS — ambient light sensor.
antivirus software — A program designed to identify, 
quarantine, and/or delete viruses from your computer.
APR — advanced port replicator — A docking device that 
allows you to conveniently use an external monitor, 
keyboard, mouse, and other devices with your portable 
computer.
ASF — alert standards format — A standard to define a 
mechanism for reporting hardware and software alerts to a 
management console. ASF is designed to be platform- and 
operating system-independent.
B
backup — A copy of a program or data file on a floppy, 
CD, DVD, or hard drive. As a precaution, back up the 
data files from your hard drive regularly.
battery — A rechargeable internal power source used to 
operate portable computers when not connected to an AC 
adapter and an electrical outlet.
battery life span — The length of time (years) during 
which a portable computer battery is able to be depleted 
and recharged.
battery operating time — The length of time (minutes or 
hours) that a portable computer battery holds a charge 
while powering the computer.
BIOS — basic input/output system — A program (or 
utility) that serves as an interface between the computer 
hardware and the operating system. Unless you 
understand what effect these settings have on the 
computer, do not change them. Also referred to as system 
setup.
bit — The smallest unit of data interpreted by your 
computer.
Bluetooth
® wireless technology — A wireless technology 
standard for short-range (9 m [29 feet]) networking 
devices that allows for enabled devices to recognize each 
other.
boot sequence — Specifies the order of the devices from 
which the computer attempts to boot.
bootable CD — A CD that you can use to start your 
computer. In case your hard drive is damaged or your 
computer has a virus, ensure that you always have a 
bootable CD or floppy disk available. Your Drivers and 
Utilities or Resource CD is a bootable CD. 
						

							172Glossary
bootable disk — A disk that you can use to start your 
computer. In case your hard drive is damaged or your 
computer has a virus, ensure that you always have a 
bootable CD or floppy disk available.
bps — bits per second — The standard unit for measuring 
data transmission speed.
BTU — British thermal unit — A measurement of heat 
output.
bus — A communication pathway between the 
components in your computer.
bus speed — The speed, given in MHz, that indicates how 
fast a bus can transfer information.
byte — The basic data unit used by your computer. A byte 
is usually equal to 8 bits.
C
C — Celsius — A temperature measurement scale where 
0° is the freezing point and 100° is the boiling point of 
water.
cache — A special high-speed storage mechanism which 
can be either a reserved section of main memory or an 
independent high-speed storage device. The cache 
enhances the efficiency of many processor operations.
L1 cache — Primary cache stored inside the processor.
L2 cache — Secondary cache which can either be external 
to the processor or incorporated into the processor 
architecture.
carnet — An international customs document that 
facilitates temporary imports into foreign countries. Also 
known as a merchandise passport.
CD — compact disc — An optical form of storage media, 
typically used for audio and software programs.
CD drive — A drive that uses optical technology to read 
data from CDs.
CD player — The software used to play music CDs. The 
CD player displays a window with buttons that you use to 
play a CD.CD-R — CD recordable — A recordable version of a CD. 
Data can be recorded only once onto a CD-R. Once 
recorded, the data cannot be erased or written over.
CD-RW — CD rewritable — A rewritable version of a 
CD. Data can be written to a CD-RW disc, and then 
erased and written over (rewritten).
CD-RW drive — A drive that can read CDs and write to 
CD-RW (rewritable CDs) and CD-R (recordable CDs) 
discs. You can write to CD-RW discs multiple times, but 
you can write to CD-R discs only once.
CD-RW/DVD drive — A drive, sometimes referred to as a 
combo drive, that can read CDs and DVDs and write to 
CD-RW (rewritable CDs) and CD-R (recordable CDs) 
discs. You can write to CD-RW discs multiple times, but 
you can write to CD-R discs only once.
clock speed — The speed, given in MHz, that indicates 
how fast computer components that are connected to the 
system bus operate. 
COA — Certificate of Authenticity — The Windows 
alpha-numeric code located on a sticker on your 
computer. Also referred to as the Product Key or
Product ID.
Control Panel — A Windows utility that allows you to 
modify operating system and hardware settings, such as 
display settings.
controller — A chip that controls the transfer of data 
between the processor and memory or between the 
processor and devices.
CRIMM — continuity rambus in-line memory module 
— A special module that has no memory chips and is used 
to fill unused RIMM slots.
cursor — The marker on a display or screen that shows 
where the next keyboard, touch pad, or mouse action will 
occur. It often is a blinking solid line, an underline 
character, or a small arrow.
D
DDR SDRAM — double-data-rate SDRAM — A type of 
SDRAM that doubles the data burst cycle, improving 
system performance. 
						

							Glossary173
DDR2 SDRAM — double-data-rate 2 SDRAM — A type 
of DDR SDRAM that uses a 4-bit prefetch and other 
architectural changes to boost memory speed to over 
400 MHz.
device — Hardware such as a disk drive, printer, or 
keyboard that is installed in or connected to your 
computer.
device driver — See driver.
DIN connector — A round, six-pin connector that 
conforms to DIN (Deutsche Industrie-Norm) standards; 
it is typically used to connect PS/2 keyboard or mouse 
cable connectors.
disk striping — A technique for spreading data over 
multiple disk drives. Disk striping can speed up operations 
that retrieve data from disk storage. Computers that use 
disk striping generally allow the user to select the data 
unit size or stripe width. 
DMA — direct memory access — A channel that allows 
certain types of data transfer between RAM and a device 
to bypass the processor.
docking device — See APR.
DMTF — Distributed Management Task Force — A 
consortium of hardware and software companies who 
develop management standards for distributed desktop, 
network, enterprise, and Internet environments.
domain — A group of computers, programs, and devices 
on a network that are administered as a unit with common 
rules and procedures for use by a specific group of users. A 
user logs on to the domain to gain access to the resources.
DRAM — dynamic random-access memory — Memory 
that stores information in integrated circuits containing 
capacitors.
driver — Software that allows the operating system to 
control a device such as a printer. Many devices do not 
work properly if the correct driver is not installed in the 
computer.
DSL — Digital Subscriber Line — A technology that 
provides a constant, high-speed Internet connection 
through an analog telephone line. dual display mode — A display setting that allows you to 
use a second monitor as an extension of your display. Also 
referred to as extended display mode.
DVD — digital versatile disc — A high-capacity disc 
usually used to store movies. DVD drives read most CD 
media as well.
DVD drive — A drive that uses optical technology to read 
data from DVDs and CDs.
DVD player — The software used to watch DVD movies. 
The DVD player displays a window with buttons that you 
use to watch a movie.
DVD-R — DVD recordable — A recordable version of a 
DVD. Data can be recorded only once onto a DVD-R. 
Once recorded, the data cannot be erased or written over.
DVD+RW — DVD rewritable — A rewritable version of 
a DVD. Data can be written to a DVD+RW disc, and 
then erased and written over (rewritten). (DVD+RW 
technology is different from DVD-RW technology.)
DVD+RW drive — drive that can read DVDs and most 
CD media and write to DVD+RW (rewritable DVDs) 
discs.
DVI — digital video interface — A standard for digital 
transmission between a computer and a digital video 
display.
E
ECC — error checking and correction — A type of 
memory that includes special circuitry for testing the 
accuracy of data as it passes in and out of memory.
ECP — extended capabilities port — A parallel connector 
design that provides improved bidirectional data 
transmission. Similar to EPP, ECP uses direct memory 
access to transfer data and often improves performance.
EIDE — enhanced integrated device electronics — An 
improved version of the IDE interface for hard drives and 
CD drives.
EMI — electromagnetic interference — Electrical 
interference caused by electromagnetic radiation. 
						

							174Glossary
ENERGY STAR® — Environmental Protection Agency 
requirements that decrease the overall consumption of 
electricity.
EPP — enhanced parallel port — A parallel connector 
design that provides bidirectional data transmission.
ESD — electrostatic discharge — A rapid discharge of 
static electricity. ESD can damage integrated circuits 
found in computer and communications equipment.
expansion card — A circuit board that installs in an 
expansion slot on the system board in some computers, 
expanding the capabilities of the computer. Examples 
include video, modem, and sound cards.
expansion slot — A connector on the system board (in 
some computers) where you insert an expansion card, 
connecting it to the system bus.
ExpressCard — A removable I/O card adhering to the 
PCMCIA standard. Modems and network adapters are 
common types of ExpressCards. ExpressCards support 
both the PCI Express and USB 2.0 standard.
Express Service Code — A numeric code located on a 
sticker on your Dell™ computer. Use the Express Service 
Code when contacting Dell for assistance. Express Service 
Code service may not be available in some countries.
extended display mode — A display setting that allows 
you to use a second monitor as an extension of your 
display. Also referred to as dual display mode.
extended PC Card — A PC Card that extends beyond the 
edge of the PC Card slot when installed.
F
Fa h r e n he it — A temperature measurement scale where 
32° is the freezing point and 212° is the boiling point of 
water.
FCC — Federal Communications Commission — A U.S. 
agency responsible for enforcing communications-related 
regulations that state how much radiation computers and 
other electronic equipment can emit.
floppy — An electromagnetic form of storage media. Also 
known as a floppy diskette or a floppy disk.floppy drive — A disk drive that can read and write to 
floppy disks.
folder — A term used to describe space on a disk or drive 
where files are organized and grouped. Files in a folder can 
be viewed and ordered in various ways, such as 
alphabetically, by date, and by size.
format — The process that prepares a drive or disk for file 
storage. When a drive or disk is formatted, the existing 
information on it is lost.
FSB — front side bus — The data path and physical 
interface between the processor and RAM.
FTP — file transfer protocol — A standard Internet 
protocol used to exchange files between computers 
connected to the Internet.
G
G — gravity — A measurement of weight and force.
GB — gigabyte — A measurement of data storage that 
equals 1024 MB (1,073,741,824 bytes). When used to 
refer to hard drive storage, the term is often rounded to 
1,000,000,000 bytes.
GHz — gigahertz — A measurement of frequency that 
equals one thousand million Hz, or one thousand MHz. 
The speeds for computer processors, buses, and interfaces 
are often measured in GHz.
graphics mode — A video mode that can be defined as x 
horizontal pixels by y vertical pixels by z colors. Graphics 
modes can display an unlimited variety of shapes and 
fonts.
GUI — graphical user interface — Software that interacts 
with the user by means of menus, windows, and icons. 
Most programs that operate on the Windows operating 
systems are GUIs.
H
hard drive — A drive that reads and writes data on a hard 
disk. The terms hard drive and hard disk are often used 
interchangeably. 
						

							Glossary175
heat sink — A metal plate on some processors that helps 
dissipate heat.
help file — A file that contains descriptive or 
instructional information about a product. Some help 
files are associated with a particular program, such as Help 
in Microsoft Word. Other help files function as stand-
alone reference sources. Help files typically have a 
filename extension of .hlp or .chm.
hibernate mode — A power management mode that saves 
everything in memory to a reserved space on the hard 
drive and then turns off the computer. When you restart 
the computer, the memory information that was saved to 
the hard drive is automatically restored.
HTML — hypertext markup language — A set of codes 
inserted into an Internet web page intended for display on 
an Internet browser.
HTTP — hypertext transfer protocol — A protocol for 
exchanging files between computers connected to the 
Internet. 
Hz — hertz — A unit of frequency measurement that 
equals 1 cycle per second. Computers and electronic 
devices are often measured in kilohertz (kHz), megahertz 
(MHz), gigahertz (GHz), or terahertz (THz).
I
IC — integrated circuit — A semiconductor wafer, or 
chip, on which thousands or millions of tiny electronic 
components are fabricated for use in computer, audio, and 
video equipment. 
IDE — integrated device electronics — An interface for 
mass storage devices in which the controller is integrated 
into the hard drive or CD drive.
IEEE 1394 — Institute of Electrical and Electronics 
Engineers, Inc. — A high-performance serial bus used to 
connect IEEE 1394-compatible devices, such as digital 
cameras and DVD players, to the computer. 
infrared sensor — A port that allows you to transfer data 
between the computer and infrared-compatible devices 
without using a cable connection.integrated — Usually refers to components that are 
physically located on the computer’s system board. Also 
referred to as built-in.
I/O — input/output — An operation or device that enters 
and extracts data from your computer. Keyboards and 
printers are I/O devices. 
I/O address — An address in RAM that is associated with 
a specific device (such as a serial connector, parallel 
connector, or expansion slot) and allows the processor to 
communicate with that device.
IrDA — Infrared Data Association — The organization 
that creates international standards for infrared 
communications.
IRQ — interrupt request — An electronic pathway 
assigned to a specific device so that the device can 
communicate with the processor. Each device connection 
must be assigned an IRQ. Although two devices can share 
the same IRQ assignment, you cannot operate both 
devices simultaneously.
ISP — Internet service provider — A company that allows 
you to access its host server to connect directly to the 
Internet, send and receive e-mail, and access websites. 
The ISP typically provides you with a software package, 
user name, and access phone numbers for a fee. K
Kb — kilobit — A unit of data that equals 1024 bits. A 
measurement of the capacity of memory integrated 
circuits.
KB — kilobyte — A unit of data that equals 1024 bytes 
but is often referred to as 1000 bytes.
key combination — A command requiring you to press 
multiple keys at the same time.
kHz — kilohertz — A measurement of frequency that 
equals 1000 Hz. 
						

							176Glossary
L
LAN — local area network — A computer network 
covering a small area. A LAN usually is confined to a 
building or a few nearby buildings. A LAN can be 
connected to another LAN over any distance through 
telephone lines and radio waves to form a wide area 
network (WAN).
LCD — liquid crystal display — The technology used by 
portable computer and flat-panel displays.
LED — light-emitting diode — An electronic component 
that emits light to indicate the status of the computer.
local bus — A data bus that provides a fast throughput for 
devices to the processor.
LPT — line print terminal — The designation for a 
parallel connection to a printer or other parallel device. 
M
Mb — megabit — A measurement of memory chip 
capacity that equals 1024 Kb.
Mbps — megabits per second — One million bits per 
second. This measurement is typically used for 
transmission speeds for networks and modems.
MB — megabyte — A measurement of data storage that 
equals 1,048,576 bytes. 1 MB equals 1024 KB. When used 
to refer to hard drive storage, the term is often rounded to 
1,000,000 bytes.
MB/sec — megabytes per second — One million bytes 
per second. This measurement is typically used for data 
transfer ratings.
memory — A temporary data storage area inside your 
computer. Because the data in memory is not permanent, 
it is recommended that you frequently save your files 
while you are working on them, and always save your files 
before you shut down the computer. Your computer can 
contain several different forms of memory, such as RAM, 
ROM, and video memory. Frequently, the word memory is 
used as a synonym for RAM.
memory address — A specific location where data is 
temporarily stored in RAM.memory mapping — The process by which the computer 
assigns memory addresses to physical locations at start-up. 
Devices and software can then identify information that 
the processor can access.
memory module — A small circuit board containing 
memory chips, which connects to the system board.
MHz — megahertz — A measure of frequency that equals 
1 million cycles per second. The speeds for computer 
processors, buses, and interfaces are often measured in 
MHz.
modem — A device that allows your computer to 
communicate with other computers over analog 
telephone lines. Three types of modems include: external, 
PC Card, and internal. You typically use your modem to 
connect to the Internet and exchange e-mail.
module bay — A bay that supports devices such as optical 
drives, a second battery, or a Dell TravelLite™ module.
monitor — The high-resolution TV-like device that 
displays computer output.
mouse — A pointing device that controls the movement 
of the cursor on your screen. Typically you roll the mouse 
over a hard, flat surface to move the pointer or cursor on 
your screen.
ms — millisecond — A measure of time that equals one 
thousandth of a second. Access times of storage devices 
are often measured in ms.
N
network adapter — A chip that provides network 
capabilities. A computer may include a network adapter 
on its system board, or it may contain a PC Card with an 
adapter on it. A network adapter is also referred to as a 
NIC (network interface controller).
NIC — See network adapter.
notification area — The section of the Windows taskbar 
that contains icons for providing quick access to programs 
and computer functions, such as the clock, volume 
control, and print status. Also referred to as system tray.
ns — nanosecond — A measure of time that equals one 
billionth of a second. 
						

							Glossary177
NVRAM — nonvolatile random access memory — A type 
of memory that stores data when the computer is turned 
off or loses its external power source. NVRAM is used for 
maintaining computer configuration information such as 
date, time, and other system setup options that you 
can set.
O
optical drive — A drive that uses optical technology to 
read or write data from CDs, DVDs, or DVD+RWs. 
Example of optical drives include CD drives, DVD drives, 
CD-RW drives, and CD-RW/DVD combo drives. 
P
parallel connector — An I/O port often used to connect a 
parallel printer to your computer. Also referred to as an 
LPT port.
partition — A physical storage area on a hard drive that is 
assigned to one or more logical storage areas known as 
logical drives. Each partition can contain multiple logical 
drives.
PC Card — A removable I/O card adhering to the 
PCMCIA standard. Modems and network adapters are 
common types of PC Cards.
PCI — peripheral component interconnect — PCI is a 
local bus that supports 32-and 64-bit data paths, 
providing a high-speed data path between the processor 
and devices such as video, drives, and networks.
PCI Express — A modification to the PCI interface that 
boosts the data transfer rate between the processor and 
the devices attached to it. PCI Express can transfer data at 
speeds from 250 MB/sec to 4 GB/sec. If the PCI Express 
chip set and the device are capable of different speeds, 
they will operate at the slower speed.
PCMCIA — Personal Computer Memory Card 
International Association — The organization that 
establishes standards for PC Cards.
PIN — personal identification number — A sequence of 
numerals and/or letters used to restrict unauthorized 
access to computer networks and other secure systems.PIO — programmed input/output — A method of 
transferring data between two devices through the 
processor as part of the data path.
pixel — A single point on a display screen. Pixels are 
arranged in rows and columns to create an image. A video 
resolution, such as 800 x 600, is expressed as the number 
of pixels across by the number of pixels up and down.
Plug-and-Play — The ability of the computer to 
automatically configure devices. Plug and Play provides 
automatic installation, configuration, and compatibility 
with existing hardware if the BIOS, operating system, and 
all devices are Plug and Play compliant.
POST — power-on self-test — Diagnostics programs, 
loaded automatically by the BIOS, that perform basic 
tests on the major computer components, such as 
memory, hard drives, and video. If no problems are 
detected during POST, the computer continues the 
start-up.
processor — A computer chip that interprets and executes 
program instructions. Sometimes the processor is referred 
to as the CPU (central processing unit).
program — Any software that processes data for you, 
including spreadsheet, word processor, database, and 
game packages. Programs require an operating system to 
run.
PS/2 — personal system/2 — A type of connector for 
attaching a PS/2-compatible keyboard, mouse, or keypad.
PXE — pre-boot execution environment — A WfM 
(Wired for Management) standard that allows networked 
computers that do not have an operating system to be 
configured and started remotely.
R
RAID — redundant array of independent disks — A 
method of providing data redundancy. Some common 
implementations of RAID include RAID 0, RAID 1, 
RAID 5, RAID 10, and RAID 50.
RAM — random-access memory — The primary 
temporary storage area for program instructions and data. 
Any information stored in RAM is lost when you shut 
down your computer. 
						

							178Glossary
readme file — A text file included with a software package 
or hardware product. Typically, readme files provide 
installation information and describe new product 
enhancements or corrections that have not yet been 
documented.
read-only — Data and/or files you can view but cannot 
edit or delete. A file can have read-only status if:
 It resides on a physically write-protected floppy disk, 
CD, or DVD.
 It is located on a network in a directory and the 
system administrator has assigned rights only to 
specific individuals.
refresh rate — The frequency, measured in Hz, at which 
your screens horizontal lines are recharged (sometimes 
also referred to as its vertical frequency). The higher the 
refresh rate, the less video flicker can be seen by the 
human eye.
resolution — The sharpness and clarity of an image 
produced by a printer or displayed on a monitor. The 
higher the resolution, the sharper the image.
RFI — radio frequency interference — Interference that 
is generated at typical radio frequencies, in the range of 
10 kHz to 100,000 MHz. Radio frequencies are at the 
lower end of the electromagnetic frequency spectrum and 
are more likely to have interference than the higher 
frequency radiations, such as infrared and light.
ROM — read-only memory — Memory that stores data 
and programs that cannot be deleted or written to by the 
computer. ROM, unlike RAM, retains its contents after 
you shut down your computer. Some programs essential to 
the operation of your computer reside in ROM.
RPM — revolutions per minute — The number of 
rotations that occur per minute. Hard drive speed is often 
measured in rpm.
RTC — real time clock — Battery-powered clock on the 
system board that keeps the date and time after you shut 
down the computer.RTCRST — real-time clock reset — A jumper on the 
system board of some computers that can often be used 
for troubleshooting problems.
S
ScanDisk — A Microsoft utility that checks files, folders, 
and the hard disk’s surface for errors. ScanDisk often runs 
when you restart the computer after it has stopped 
responding.
SDRAM — synchronous dynamic random-access memory 
— A type of DRAM that is synchronized with the optimal 
clock speed of the processor.
serial connector — An I/O port often used to connect 
devices such as a handheld digital device or digital camera 
to your computer.
Service Tag — A bar code label on your computer that 
identifies your computer when you access Dell Support at 
support.dell.com or when you call Dell for customer 
service or technical support.
setup program — A program that is used to install and 
configure hardware and software. The setup.exe or 
install.exe program comes with most Windows software 
packages. Setup program differs from system setup.
shortcut — An icon that provides quick access to 
frequently used programs, files, folders, and drives. When 
you place a shortcut on your Windows desktop and 
double-click the icon, you can open its corresponding 
folder or file without having to find it first. Shortcut icons 
do not change the location of files. If you delete a 
shortcut, the original file is not affected. Also, you can 
rename a shortcut icon.
shutdown — The process of closing windows and exiting 
programs, exiting the operating system, and turning off 
your computer. You can lose data if you turn off your 
computer before completing a shutdown.
smart card — A card that is embedded with a processor 
and a memory chip. Smart cards can be used to 
authenticate a user on computers equipped for smart 
cards. 
						

							Glossary179
software — Anything that can be stored electronically, 
such as computer files or programs.
S/PDIF — Sony/Philips Digital Interface — An audio 
transfer file format that allows the transfer of audio from 
one file to another without converting it to and from an 
analog format, which could degrade the quality of the file.
standby mode — A power management mode that shuts 
down all unnecessary computer operations to save energy.
Strike Zone™ — Reinforced area of the platform base 
that protects the hard drive by acting as a dampening 
device when a computer experiences resonating shock or 
is dropped (whether the computer is on or off).
surge protectors — Prevent voltage spikes, such as those 
that may occur during an electrical storm, from entering 
the computer through the electrical outlet. Surge 
protectors do not protect against lightning strikes or against 
brownouts, which occur when the voltage drops more than 
20 percent below the normal AC-line voltage level.
Network connections cannot be protected by surge 
protectors. Always disconnect the network cable from the 
network connector during electrical storms.
SIM — Subscriber Identity Module. A SIM card contains 
a microchip that encrypts voice and data transmissions. 
SIM cards can be used in phones or portable computers.
SVGA — super-video graphics array — A video standard 
for video cards and controllers. Typical SVGA resolutions 
are 800 x 600 and 1024 x 768.
The number of colors and resolution that a program 
displays depends on the capabilities of the monitor, the 
video controller and its drivers, and the amount of video 
memory installed in the computer.
S-video TV-out — A connector used to attach a TV or 
digital audio device to the computer.
SXGA — super-extended graphics array — A video 
standard for video cards and controllers that supports 
resolutions up to 1280 x 1024.
SXGA+ — super-extended graphics array plus — A video 
standard for video cards and controllers that supports 
resolutions up to 1400 x 1050.
system board — The main circuit board in your computer. 
Also known as the motherboard.system setup — A utility that serves as an interface between 
the computer hardware and the operating system. System 
setup allows you to configure user-selectable options in the 
BIOS, such as date and time or system password. Unless 
you understand what effect the settings have on the 
computer, do not change the settings for this program.
system tray — See notification area.
T
TA P I — telephony application programming interface — 
Enables Windows programs to operate with a wide variety 
of telephony devices, including voice, data, fax, and video.
text editor — A program used to create and edit files that 
contain only text; for example, Windows Notepad uses a 
text editor. Text editors do not usually provide word wrap 
or formatting functionality (the option to underline, 
change fonts, and so on).
travel module — A plastic device designed to fit inside 
the module bay of a portable computer to reduce the 
weight of the computer.
U
UMA — unified memory allocation — System memory 
dynamically allocated to video.
UPS — uninterruptible power supply — A backup power 
source used when the electrical power fails or drops to an 
unacceptable voltage level. A UPS keeps a computer 
running for a limited amount of time when there is no 
electrical power. UPS systems typically provide surge 
suppression and may also provide voltage regulation. 
Small UPS systems provide battery power for a few 
minutes to enable you to shut down your computer.
USB — universal serial bus — A hardware interface for a 
low-speed device such as a USB-compatible keyboard, 
mouse, joystick, scanner, set of speakers, printer, 
broadband devices (DSL and cable modems), imaging 
devices, or storage devices. Devices are plugged directly in 
to a 4-pin socket on your computer or in to a multi-port 
hub that plugs in to your computer. USB devices can be 
connected and disconnected while the computer is turned 
on, and they can also be daisy-chained together. 
						

							180Glossary
UTP — unshielded twisted pair — Describes a type of 
cable used in most telephone networks and some 
computer networks. Pairs of unshielded wires are twisted 
to protect against electromagnetic interference, rather 
than relying on a metal sheath around each pair of wires to 
protect against interference.
UXGA — ultra extended graphics array — A video 
standard for video cards and controllers that supports 
resolutions up to 1600 x 1200.
V
video controller — The circuitry on a video card or on the 
system board (in computers with an integrated video 
controller) that provides the video capabilities—in 
combination with the monitor—for your computer.
video memory — Memory that consists of memory chips 
dedicated to video functions. Video memory is usually 
faster than system memory. The amount of video memory 
installed primarily influences the number of colors that a 
program can display.
video mode — A mode that describes how text and 
graphics are displayed on a monitor. Graphics-based 
software, such as Windows operating systems, displays in 
video modes that can be defined as x horizontal pixels by y 
vertical pixels by z colors. Character-based software, such 
as text editors, displays in video modes that can be 
defined as x columns by y rows of characters.
video resolution — See resolution.
virus — A program that is designed to inconvenience you 
or to destroy data stored on your computer. A virus 
program moves from one computer to another through an 
infected disk, software downloaded from the Internet, or 
e-mail attachments. When an infected program starts, its 
embedded virus also starts.
A common type of virus is a boot virus, which is stored in 
the boot sectors of a floppy disk. If the floppy disk is left in 
the drive when the computer is shut down and then 
turned on, the computer is infected when it reads the 
boot sectors of the floppy disk expecting to find the 
operating system. If the computer is infected, the boot virus may replicate itself onto all the floppy disks that are 
read or written in that computer until the virus is 
eradicated.
V — volt — The measurement of electric potential or 
electromotive force. One V appears across a resistance of 
1 ohm when a current of 1 ampere flows through that 
resistance.
W
W — watt — The measurement of electrical power. One 
W is 1 ampere of current flowing at 1 volt.
WHr — watt-hour — A unit of measure commonly used 
to indicate the approximate capacity of a battery. For 
example, a 66-WHr battery can supply 66 W of power for 
1 hour or 33 W for 2 hours.
wallpaper — The background pattern or picture on the 
Windows desktop. Change your wallpaper through the 
Windows Control Panel. You can also scan in your favorite 
picture and make it wallpaper.
WLAN — wireless local area network. A series of 
interconnected computers that communicate with each 
other over the air waves using access points or wireless 
routers to provide Internet access.
write-protected — Files or media that cannot be changed. 
Use write-protection when you want to protect data from 
being changed or destroyed. To write-protect a 3.5-inch 
floppy disk, slide its write-protect tab to the open 
position.
WWAN — wireless wide area network. A wireless high-
speed data network using cellular technology and covering 
a much larger geographic area than WLAN. 
WXGA — wide-aspect extended graphics array — A video 
standard for video cards and controllers that supports 
resolutions up to 1280 x 800.
X
XGA — extended graphics array — A video standard for 
video cards and controllers that supports resolutions up to 
1024 x 768.