Dell LATITUDE D630 PP24L User Manual page 173

U
UAC — user account control— Microsoft Windows Vista®
security feature that, when enabled, provides an added layer
of security between user accounts and access to operating
system settings.
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.
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.
Glossary 175