> >Roberto Safora wrote:
>
> > I have a client who wants to use his video card on 800 x 600,
> 32 bits color.
> > However he is using a CL5446 PCI, 2 MB. In win 95 the most I can see is
> > color 24 bits. I dont understand why we can get 32 bit color,
> nor even in
> > 640 x 480, if we have 2 MB.
> > [log in to unmask]
>
> Is there such a thing as 32 bit color? This is new to me.
> 24 bit color provides 4 million colors and is more colors
> than the human eye can distinguish.  While 4 million
> colors is useful regardless of the limitations of the human
> eye, what could 32 bit color be useful for?
>
> I think your confusing 32 bit graphics with color.  Graphics cards
> can be 32, 64, or 128 bits, but this refers to the "chunks" their
> on-board processors manipulate data, not the depth of the color
> they provide at a given resolution.
>
> I'm using a Diamond Stealth 2000 with 2 meg installed and it lists
> 24 bit truecolor at 800x600 resolution, the same as my 4 meg cards.
> I think there is nothing wrong with your client's system.

        There is such a thing as 32bit colour, but no, they are not 32 bits of real
colour, the 32 bit colour mode is for convenience, there are only 24 bits of
colour, 8 bits are dummies. It is convenient because 32 bits is MUCH easier
to deal with in hardware then 24bits, take this example. Most I/O access to
video is 32bit (This is not true everywhere, but let's just assume it for
now), with 24 bit colour, the video word is aligned with the 32bit storage
only rarely, so you have to calculate with every word gathered where the
video word begins, it is even conceivable that often getting one word of
video information would require TWO data accesses, very wasteful. With 32bit
video words, every word is aligned with the 32bit storage, so there is no
data offset calculation, no multiple data accesses for a single word. Now
this is VERY oversimplified and there are many other things to consider, but
this should get the idea across. BTW I often run at 32bits, and it
benchmarks faster than 24bits! Wasteful memory wise, but my card has enough,
TTYL

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