Thanks for this information, it was exactly what I was looking for.
--
Davey Brain
dsbrain@...
http://www.neosplice.com/~dsbrain/

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--
webrickd@... wrote:
> Davey wrote...
> Hi,
> I'm not real familiar with the
> Atari
> computers, even though I now own 3,
> a 600XL, 800XL and a 130XE. I
> read that
> the Atari computers had 3
> custom chips for graphics and
> sound called
> GTIA, Pokey and Antic. Can
> anyone tell me please exactly
> what aspects
> each chip controlled and what
> the changes were in each during
> the
> successive revisions from the
> original to the XL to the XE? I
> can find
> no detailed explanation thus far.
>
> GTIA handled converting the graphics and text
> information into RGB video data for combining
> to make
> rf and video. I think it is also responsible
> for
> fetching Player/missle data for overlay and in
> collision detection. It supports 16
> color/luminance
> modes the older CTIA did not have.
>
> Antic is responsible for creating the screen
> from the
> display list instructions and pointing to the
> right
> data. It updates memory so GTIA knows what
> mode line
> is being used. A later version added an
> extra bit for accessing
> memory past 64K, for ram upgrades.
>
> Pokey is responsible for audio..sound
> channels, tape
> i/o noise, timer functions, and the keyboard
> scanning.
>
> There are references..Computes Mapping the
> Atari, de re
> Atari, and a FAQ by Michael Current.
>
> Rick D.
>
> ___________________________________________________