On Tue, Aug 20, 2002 at 01:03:58PM -0700, Bill Studenmund wrote:
> That distinction indicates the one niggle I have with the discussion, that
> there isn't much distinction between memory bits per pixel and chromatic
> (color info) bits per pixel. The above card has 8 memory bits per pixel,
> but only 1 chromatic bit. Also I know there were Apple display cards that
> were 24 bits of cromatic info per pixel, but they took up 32 bits of
> memory (they actually had three 8-bit memory chips that they hooked up to
> three of the four memory byte lanes; there was nothing on the fourth
> byte lane).
> 
> How can we address that? Most users will think in terms of the chromatic
> bits per pixel, not necessarily memory.

XFree86 makes the distinction between "depth" and "bits per pixel".  I
think that is the only sensible way to do it.  On my system,
/var/log/XFree86.0.log says

(**) NV(0): Depth 24, (--) framebuffer bpp 32

The user specifies depth, and the driver picks a fbbpp to suit.
Optionally the user can specify fbbpp as well, but generally it is
unnecessary.

-andy