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From: mfriedel@slate.mines.colorado.edu (Friedel Michael)
Newsgroups: comp.sys.next,comp.arch
Subject: Video implementation on NeXTstation color
Keywords: RAMDAC,NeXT
Message-ID: <1991May01.222537.26445@slate.mines.colorado.edu>
Date: 1 May 91 22:25:37 GMT
Sender: mfriedel@slate.mines.colorado.edu (Friedel Michael)
Organization: Colorado School of Mines
Lines: 28

>There is a CLUT in the color slabs, but to answer the first question
>you need to know if the chip has three 16x8 rams or one 4Kx24 ram to
>feed the three 8 bit D/A converters.  This determines if the machine
>is capable of 16 or 256 shades of gray.
>
>Even if it is 4Kx24, the answer to the second question is no.  So an
>answer to the first question is needed before hacking away at how to
>get around the restrictions and answer question three.
>
>Mark Adler
> madler@pooh.caltech.edu

The RAMDAC has 16x8bit for every DAC, it is a Bt463, the basic implementation
is

[VRAM] 4bit -> [Color palette (16 x 8 bit)] 8bits -> [DAC] -> video

for every channel (that is green, red and blue).

Mike

P.S. Does anybody have anymore specs on a Bt463, like max resolution, how to
adress the color palettes .....
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