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From: kbad@atari.UUCP (Ken Badertscher)
Newsgroups: comp.sys.atari.st
Subject: Re: Blitter disappointment (was: Time to create comp.sys.atari.flames)
Message-ID: <1819@atari.UUCP>
Date: 27 Nov 89 19:01:56 GMT
References: <1989Nov8.182505.11625@uunet!unhd> <23996@cup.portal.com> <24111@cup.portal.com> <1261@atha.AthabascaU.CA> <5312@sdcc6.ucsd.edu>
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Organization: Atari Corp., Sunnyvale, CA
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pa1329@sdcc13.ucsd.edu (pa1329) writes:

| Hmmm,.  I wonder why is the Atari blitter so ineffective.

"Ineffective" is a pretty strong word.  As has been mentioned, software
speeder-uppers like TurboST and QuickST give a dramatic speed
improvement because they solve the real bottleneck: software overhead.

The BLiTTER chip does what it was designed to do very well.  That is,
BitBlt operations are sped up tremendously.  A large part of the
graphics processing being done by many ST's is TEXT bit block transfer
operations.  As has been demonstrated by Wayne Buckholt and Darek
Mihocka, it is possible, given room, to speed these up significantly.
Fast, resolution specific blit dispatching and code combined with
the BLiTTER chip is phenomenal.

As an aside, I should point out that our VDI guy has put a lot of work
into the blit code for the TT, and it's pretty phenomenal _without_
hardware assist.  One other thing that will give a noticeable improvement
is the lack of Line F compression in STE and TT ROMs.  The Line F
compression adds a bit of overhead to AES operations, and desktop/window/
dialog operations are noticeably sped up when the compression is gone.

| Its speed is no where comparable to the Amiga's blitter.

As I said above, I think the real problem is a software bottleneck.  If
it were possible to put the Ami blitter in ST's, you'd probably get
similar results - albeit with a chip more powerful in terms of variety
of operations.

-- 
   |||   Ken Badertscher  (ames!atari!kbad)
   |||   Atari R&D System Software Engine
  / | \  #include <disclaimer>