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Re: true color executor/D



>>>>> "Gerald" == Gerald Luther Graef <ggraef@alpha1.csd.uwm.edu> writes:
In article <4e6gsj$16v@uwm.edu> ggraef@alpha1.csd.uwm.edu (Gerald Luther Graef) writes:


    Gerald> In article <4e5gg2$f6@newsstand.cit.cornell.edu>
    Gerald> wmagro@msc.cornell.edu (William Magro) writes:
    >> The catch here is that the 256 colors of VGA are chosen from a
    >> palette of 256k (or fewer) colors with standard VGA cards.
    >> Since each gray must have equal components of red, green, and
    >> blue, this reduces the effective number of true grays to 64
    >> [=262144^(1/3)].  It takes a 24-bit D/A converter (8-bits in
    >> each channel) to generate 256 grays.
    >> 
    >> In the end, the number of grays you can generate depends on the
    >> bitness of your DAC and the smarts of the video driver.

    Gerald> Does this mean that with the right video card it is
    Gerald> possible to get 256 grayscale on executor now?  I ask
    Gerald> because I am thinking about getting a new video card
    Gerald> (leading contender, #9 771).

I've answered this in another post, but with news lag and the
importance of the subject, here's the same story:

Bill's right, the number of bits that your DAC uses is indeed
important, but right now, Executor *won't* do the right thing even if
you have a 24 bit DAC.  That's because we don't yet have a machine
in-house that has a 24 bit DAC *and* a VBE 2.0 driver that will let us
access that DAC.

Because PCs come in so many different configurations, Executor relies
heavily on standards, like the VESA VBE 2.0 standard to access
"special features".  To support 24 bit DACs we'll need to use a VBE
2.0 extension, but to test it we either need to have such a DAC+driver
in house or rely on an Executor Enthusiast to help us test the code.

I believe we do have some video cards in house with 24-bit DACs, so if
the soon to be released new version of UniVBE gives us access to
these, we'll add the functionality and test it in house.  If the new
version of UniVBE *doesn't* support it for our cards, then we'll ask
for help.  Either way we should support this feature by the time
Executor 2 ships, although to use it you'll need a card with a 24-bit
DAC *and* VBE 2.0 extensions to allow us to access it.

Sorry things get so confusing, but that's the way it is in the PC biz.

    Gerald> Thanks...Gerry

--Cliff
ctm@ardi.com


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