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Conference hydra::amiga_v1

Title:AMIGA NOTES
Notice:Join us in the *NEW* conference - HYDRA::AMIGA_V2
Moderator:HYDRA::MOORE
Created:Sat Apr 26 1986
Last Modified:Wed Feb 05 1992
Last Successful Update:Fri Jun 06 1997
Number of topics:5378
Total number of notes:38326

341.0. "4096 colors without HAM mode?" by BAGELS::BRANNON (Dave Brannon) Fri Feb 20 1987 20:44

    Has anybody played around with the Copper display list to get a 
    4096 color screen? (not HAM mode)
    
    My Atari 400 can do 256 colors with a custom display list and
    the ST can do 512 with raster interrupts.  It should be possible
    to get 4096 without the limitations of HAM mode.
    
    My pet peeve with the Atari 400 was the display list that just
    sat there, waiting to be used.  Very few programs took advantage
    of it, they just used the 4 colors available.  Only one paint
    program - Fun With Art, i think, could use it.
    
    There is a comment in the ST notesfile that says Tom Hudson, of
    DEGAS fame, is trying to get a standard mechanism established
    for displaying 512 colors on the ST.
    
    Any comments?
    -dave
T.RTitleUserPersonal
Name		DateLines
341.1Amiga has it NOW!TLE::RMEYERSRandy MeyersSat Feb 21 1987 12:5017
Re: .0

The problem with using the copper list (or on the ST, line interrupts)
to get more colors it that it is somewhat kludgy.  The Amiga has an
advantage over the ST in doing this sort of thing because the only way
of handling this on the ST is for the 68000 to run itself to death
fielding interrupts.

Anyway, Intuition already supports the use of the Copper list to display
more than 32 colors.  Remember that one of the features of the Intuition
is that you can display overlapping screens with different resolutions
and colors.  For example, run dpaint, and pull the dpaint screen down using
the screen drag bar to reveal the workbench screen underneath.  What you
have in that situation is a high resolution screen with four colors
being displayed simultaneously with a low resolution screen of 32 different
colors.  (Well, actually, the whites on both color pallets are the same
so that there is only 35 different colors on that display.)
341.2BAGELS::BRANNONDave BrannonMon Feb 23 1987 14:1512
    re:.1  depends on what you consider kludgy, i think HAM mode fuzziness
    is somewhat kludgy :-)
    
    The Copper will cycle steal from the 68000 when processing a complex
    display list, but that is a lot better than having the 68000 doing
    it.  Intuition support of independent color registers per screen
    is nice, but takes too much memory to get the 4096 colors.  But
    it does prove the Amiga can do it (Intuition modifying the display
    list).  The catch is how to tie a custom display list to a custom
    screen, and still let Intuition have it's sliding screens.
    
    -dave