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From: dale@boing.UUCP (Dale Luck)
Newsgroups: comp.sys.amiga
Subject: Re: TWO Denise's??
Message-ID: <774@boing.UUCP>
Date: 26 May 89 14:19:11 GMT
References: <2273NU140487@NDSUVM1> <106202@sun.Eng.Sun.COM>
Reply-To: dale@boing.UUCP (Dale Luck)
Organization: Boing, Milpitas, Ca.
Lines: 42

In article <106202@sun.Eng.Sun.COM= cmcmanis@sun.UUCP (Chuck McManis) writes:
=In article <2273NU140487@NDSUVM1> NU140487@NDSUVM1.BITNET (Jason) writes:
=[ya gotta love a mainframe that insists on calling you NU140487!]
=
=>     Upon reading an article appearing in the FMAUG (Fargo-Moorhead Area User
=>Group) newsletter... i'm just curious as to how MUCH we Amiga users are in the
=>dark.
=
=>     In addition to doubling the horizontal resolution, a DD combo would also
=>allow for EXtenden HAM and EX mode. EXtended HAM would allow for HAM to be used
=>in hi-res mode (640X200 and 640X400)... and overscan as well. Also, instead of
=>a mere 16 colors, 256 colors are available. In lower resolution modes (320X200
=>and 320X400) the maximum number of colors is kicked up to 16,777,216 (the
=>article didn't say how many were available on screen at once). There is also
=>a "Landscape mode", which allows for a maximum resolution of 1280X400 (plus
=>overscan)... which for some reason is used when the monitor is placed on it's
=>side.
=
=Hmmmm, So how could these two Denises communicate which pixels were in 
=HAM mode (color gun offset) vs which were simple lookups? Answer : they
=couldn't. And 256 colors? If one Denise has 32 color registers, two
=denises have 64 color registers, how can you get 256? You can't. And
=how could you combine the two sets of color registers so that they were
=each 8 bits wide? Well you might be able to take the digital outputs and
=send those to a brooktree RDAC or something. But uhoh, now you can't load
=the color registers because there isn't any way to access the brooktree's
=registers. Landscape mode? 

I had made a proposal for such a dual denise option. The main feature was
wider color registers. 8 bits each for read/green/blue would be fed directly
into some 8 bit dacs giving us the same number of colors on screen but
from a choice of 16m instead of 4096. The second denise would duplicate
everything that the first denise did except use a bank switch technique to
get at it's color registers without affecting the first denises color
registers.

All the rest of the original posting from Jason had to be stuff for
the National Enquirer.

-- 
Dale Luck     GfxBase/Boing, Inc.
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