Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!math.fu-berlin.de!fauern!NewsServ!!roell
From: roell@informatik.tu-muenchen.de (Thomas Roell)
Newsgroups: comp.graphics
Subject: Re: 64K colors?
Message-ID: <1991May6.114625.6444@Informatik.TU-Muenchen.DE>
Date: 6 May 91 11:46:25 GMT
References: <1991May2.001518.30298@kuhub.cc.ukans.edu> <10497@labtam.labtam.oz>
Sender: news@Informatik.TU-Muenchen.DE
Organization: Inst. fuer Informatik, Technische Univ. Muenchen, Germany
Lines: 23
In-Reply-To: graeme@labtam.labtam.oz's message of 5 May 91 04: 38:38 GMT

>> While checking out the specs on the 
>> 4000-chip, my eyes bugged as I saw that 
>> it is (in theory anyway)  capable of 
>> producing 65535 colors on screen using 2 
>> bytes to produce a  pixel.
>
>	As I understand it, this is some sort of HAM (Hold And Modify) scheme
>where the chip is put in a special mode, and certain colour values are reserved
>as "instructions" to interpolation hardware to generate colours between two
>of the available palette colours.

No, you are dead wrong. The Et4000 is capable of sequencing 16bit pixels.
There is just the normal timing, except per dot-clock cycle two bytes are send
to the CLUT. Some CLUTs (or call them RAMDAC) can use this to drive their
DACs directly. For example the Sierra RAMDAC uses 5 bits (of these 16) for
each primary color and can thus display 32768 colors simultaneousely.

- Thomas
--
_______________________________________________________________________________
E-Mail (domain):	 roell@lan.informatik.tu-muenchen.de
UUCP (if above fails):   roell@tumult.{uucp | informatik.tu-muenchen.de}
famous last words: "diskspace - the final frontier..."