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From: jmueller@umaxc.weeg.uiowa.edu (Jim Mueller)
Newsgroups: comp.sys.apple2
Subject: Re: 3200+ colors
Message-ID: <6642@ns-mx.uiowa.edu>
Date: 24 Jun 91 22:03:49 GMT
References: <9106241405.AA21887@apple.com> <1991Jun24.143726.10040@en.ecn.purdue.edu>
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Reply-To: jmueller@umaxc.weeg.uiowa.edu (Jim Mueller)
Organization: U of Iowa, Iowa City, IA
Lines: 46

In article <1991Jun24.143726.10040@en.ecn.purdue.edu> cmm@en.ecn.purdue.edu (Chris M McKinsey) writes:
>In article <9106241405.AA21887@apple.com> PYC121@URIACC.BITNET (Andy Kress) writes:
>>
>>    Ok....we can now change the pallet for everline on the screen.  But
>> can we change the pallet of a line while the beam is scanning across
>> that line in order to get more than 16 colors on the line?
>>

>
>Yes, it's possible. Anything is possible, though. You can monitor the
>softswitch at $E0C03E/3F to read the horizontal beam location. Now whether
>or not you can get the GS to read this beam fast enough as to change the
>palette at the exact same pixel everytime around is another story. I would
>have to say: no. But I think only experimentation will yield the truth. So
>to answer your question, yes, it is possible to change the palette while the
>beam is in mid-line. But, it may not look all that well.

    Well, I think that would work a little bit better if you were reading
$E0C02E/2F.  But at any rate that won't help you.  The VGC in the IIgs doesn't 
check to see what colors are stored in the video ram for a particular
palette more than once per scan line, in short, it is *>NOT<* possible
to change colors Mid-Scan, because the video hardware doesn't allow it.

     In the Tool Box reference #2, it says that you may change colors
in between scan lines (hinting at 3200 capabilities), at any rate, I
tested to see if its possible, and determined that it's not.

>On another side, a friend of mine claims to be working on a 4096 color viewer
>for the IIgs. He mentioned it had 3 unfolded code segements each 64k in size
>to do the palette/color switches. I'm anxious to see if he can pull it off.

    There is not a way to show more than 3200 TRUE colors on the SHR
screen in a given screen refresh.

>Chris M. McKinsey
>AOL: McKinsey
>GEnie: A2pro.Chris

Jason Andersen
AOL: DWS Jason
InterNet: jgandersen@icaen.uiowa.edu
--
|Jim Mueller								     |
|Internet: jmueller@umaxc.weeg.uiowa.edu                                     |
|The University of Iowa                            			     |
|"Many truths we cling to...greatly to our own point of view do they depend."|