194 Glossary
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.