HP Vectra XU 6/XXX Optimization Manual page 44

Pixel Data
8-Bit pixel data in video memory
Pixel displayed in one of
256 displayable colors
1 Your PC's Performance Features
More Video Performance
The graphics controller stores screens of data for output to the display
in video memory. These screens of data are called frames and so your
video memory is also known as a frame buffer.
The pixel data stored by the graphics controller defines the color to be
displayed for each pixel. The amount of data required for each pixel is
determined by the number of displayable colors; if you are using only
256 displayable colors, each pixel needs eight bits to define its color
(eight bits gives 256 possible combinations), while in true color modes,
each pixel can require up to four bytes (32-bits).
The screen resolution determines how many pixels make up a screen
for the display. The number of pixels required is typically very large.
Even a standard VGA screen at 640
300,000 pixels. Consequently, when writing a screen of pixel data to
the video memory, the video controller is manipulating very large
amounts of data.
38 English
24-Bit pixel data in video memory
Pixel displayed in one of 16,7 M
displayable colors
480 resolution consists of over