Dell Precision Workstation 450 User Manual page 324

310 Glossar y
U
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.
U S B — universal serial bus — A hardware interface for a low-speed device such as
a USB-compatible keyboard, mouse, joystick, scanner, set of speakers, or printer.
Devices are plugged directly into a 4-pin socket on your computer or into a multi-
port hub that plugs into your computer. USB devices can be connected and
disconnected while the computer is turned on, and they can also be daisy-chained
together.
U T P — unshielded twisted pair — a type of cable that consists of two unshielded
wires twisted around each other. These cables are used for LANs and telephone
connections.
V
V — The circuitry on a video card or on the system board (in
I D E O C O N T R O L L E R
computers with an integrated video controller) that provides the video capabilities—
in combination with the monitor—for your computer.
V — Memory that consists of memory chips dedicated to video
I D E O M E M O R Y
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.
V — A mode that describes how text and graphics are displayed on a
I D E O M O D E
monitor. Graphics-based software, such as the Windows operating system, 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.
V — See resolution.
I D E O R E S O L U T I O N
V — A program that is designed to inconvenience you or to destroy data
I R U S
stored on your computer. A virus program moves from one computer to another via
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 of the floppy disks that are read or written in that