VGA Hardware: Difference between revisions
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=== Memory Layout in 256-color graphics modes ===
In this mode, each byte of video memory describes exactly one pixel. Pixels are generated by increasing address in linear mode, with all colors taken from plane 0. In planar mode (Also known as Mode X) each address describes 4 consecutive pixels, one from each plane. Plane 0 describing the first pixel, plane 1 the next, and so on. Technically speaking this is what always happens, but the standard 320x200x256 mode "chains" the planes such that 2 lowest order bits select the plane and the memory thus appears linear.
In linear mode, each byte in host memory corresponds to one pixel on the display, making this mode very easy to use. Mode X requires the use of Plane Write Enable register to select the plane to be written.
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