Got it! (was Re: [CLUE-Tech] X resolution)

[David Anselmi]

Matt Gushee wrote:
[...]
> Some video cards, including mine, can use either a packed 24-bit or a
> sparse 32-bit framebuffer layout. Evidently my card tries to use 32 by
> default, which accounts for X using 32 bits for 24-bit color.

That's interesting.  I'd heard that there was no difference (display 
quality-wise) between 24 and 32bpp.  You get a byte each for red, green, 
and blue either way.

Sparse means that some bits are unused.  You might see reference to 
sparse files (usually related to archiving) that are bigger than the 
space they use on disk (can't say much more about them than that).

Probably there is some reason for using 32bpp like it is faster to 
transfer 32 bits to the card than 24, so the sparse framebuffer gets 
better performance at the expense of memory.

Dave