an improvement on the last. You may encounter other video display standards, such as
XGA (Extended Graphics Array) or UVGA (Ultra VGA), which are loosely defined
standards that vary from manufacturer to manufacturer.
The VGA (Video Graphics Array) display standard is considered the base standard
for video display systems today. Virtually all current monitors and video cards support
the VGA standard. It is the default standard for Windows and almost all other operating
systems and device drivers that interact directly with the video system.
Most monitors on the market today claim to be at least SVGA-compatible. What this
actually means is that they have some capabilities that are higher than the VGA standard,
including resolution and color depth. The same holds true for UVGA and XGA, which
are more marketing identities than they are video standards. The Video Electronics Stan-
dards Association (VESA) has recently defined the VESA SVGA standard in an attempt
to standardize the standards above VGA.Video Cards
In general, the video card processes the graphics data produced by software running on
the PC and prepares it for use by the monitor by converting it from digital data to an
analog signal. The video card also sends out the data needed by the monitor to refresh the
image or renew it as it changes.
Video cards, graphics cards, and accelerator cards are all names for the adapter card
inside the PC that is responsible for generating the signals that tell the monitor what to
display. The relationship between the video card and the monitor should be carefully
matched. These two devices must be compatible in terms of the signal used to communicate
to the monitor, the type of connector used to connect them together, the video display
standards they support, and their speed.
For more information on video cards, see Chapter 12.The Cathode Ray Tube (CRT)
The biggest and most expensive part of a conventional PC monitor is the cathode ray tube
(CRT). The CRT applies the same basic technology used in picture tube–based television
sets to display the video output of a personal computer.Painting the Screen
The primary element of the CRT, as illustrated in Figure 16-4, is the electron gun that
shoots a beam of electrons on the back of the display screen, which is lined with millions
of tiny dots of a phosphorous material. The phosphor dots glow when struck by the elec-
trons. If you look very closely at the monitor’s screen, you can see these dots.
Three of the phosphor dots are grouped together to form a pixel (picture element), which
isalsocalledatriad.Ineachpixel(seeFigure16-5),onedotisred,oneisgreen,andoneisblue
in color. How much intensity is used to light each dot of the pixel determines the color your(^380) PC Hardware: A Beginner’s Guide