Palette-based color is rarely used on modern PCs, but is common on smaller devices
such as PDAs and cell phones. It may seem absurd to talk about PDAs and phones in
a book about X, but they now have sufficient computing power to viably run an X
server!
The size of a framebuffer in bytes is:
WidthInPixels * HeightInPixels * BytesPerPixel
Therefore, a 1280 ?— 1024 display with 3 bytes (24 bits) per pixel of color information
would take:
1280 x 1024 x 3 = 3932160 bytes = 3.75 MB
Note that since most modern CPUs deal with memory in 32-bit words, many 24-bit
video modes actually devote 32 bits to each pixel to simplify manipulation of the
data. This wastes 8 bits per pixel, but the resulting increase in speed makes it worthwhile.
If the video card in the preceding example used 32 bits per pixel, the memory
required would be 5 MB.
1.11 Displays, Screens, and Xinerama
In X terminology, a display comprises the user interface for one person. That usually
means one keyboard, pointer, video card, and monitor, but for some applications,
more video ???real estate??? is required. Thus, a display can have multiple video cards
and monitors, perhaps with different capabilities and resolutions??”but this is where
the terminology gets tricky.
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