From: wallmann@backus.pu.informatik.th-darmstadt.de (Natuerlich!)
Subject: Re: A4000 at WOC
Date: Sun, 27 Sep 1992 21:47:37 GMT
Organization: MSD software vault #9 @THD

In article <1992Sep25.175523.20771@klaava.Helsinki.FI> lindblad@klaava.Helsinki.FI (Jarkko Lindblad) writes:
>wallmann@backus.pu.informatik.th-darmstadt.de (Natuerlich!) writes:
>: In article <1992Sep24.195307.19082@klaava.Helsinki.FI> lindblad@klaava.Helsinki.FI (Jarkko Lindblad) writes:
>: >gerrymon@eng.umd.edu (Gerry Mon) writes:
>: >: In article <19r8nrINN2sk@uwm.edu> gblock@csd4.csd.uwm.edu (Gregory R Block) writes:
>: [ stuff deleted]
>: I don't know where you got that crazy idea from. GEM windows never were
>: forced to be byte or even wordaligned. Some programmers (including me)
>
>Hmm....Hmmmmmmm....HMMMMMMMMMMMMMMMMMM....(oops, forgot the caps lock
>on...:)
>	There was a review on some magazine many years (it was
>probably 1985 or 1986) (can't remember what magazine it was) ago,
>which said this.
Well it was wrong.

>: like it this way since the output to the window is faster if the workspace
>: of the window is byte aligned.
>
>Just wondering, by how much faster?
The best I can say (from memory) is perceptible.

>: >Well, at least the atar blitter found in ST(e's I guess) are simply
>: >s l o w. Also the inability to concurrently use CPU and blitter is a
>: >flaw in the design of the ST-series (including Falcon).
>: If this isn't ever so typical of c.s.a.a, no clue what your talking 
>: about but giving what you guess away as facts.
>
>Well, Dave Haynie said that it is/was roughly 25 to 50% of the speed of
>Amiga blitter. Somehow I usually trust him...
That's why you buy Amigas (har). I don't have both machines, I just have
the two reference manuals. Just from the paper I'd say the 25% to 50% would
be best case, when you are mixing three sources into one destination. Which
the Atari blitter can only do successively.
For your 'normal' operation scrolling windows and the like, the speed of
both is limited by the buswidth, which in comparison between the A1000 and
the ST is really the same. Now taking into consideration that the ST runs
10% faster anyhow... Somewhere someone oughta have made some tests
giving some figures about pixel blit rate per second, of both blitters
this would be a lot more informative than guessing (guilty!).

>: The truth is: the Blitter does DMA it does share the bus with the
> [ stuff deleted]>
>: CPU and can blit concurrently. TOS in its singletasking incarnation didn't
>
>Hmm, everyone else say it does not do anything concurrently with CPU -
>and I also may easily say that - however even if it did, it'd had to
Everyone else in your case are Amigoids who think on the level "what
must not be, can not be". The hardware design is like this if both
want to access the bus, 50% go to the blitter and 50% to the CPU 
(ignoring disk DMA for now).

>share the same bus with CPU and therefor neither of the ones could
>operate at full speed. Blitteri that is slower than CPU is not
>practical in single bus systems like Atari ST, Falcon and Commodore 64.
And AMIGA 1000 you forgot...

>: make use of this, I am curious whether they will use this in MTOS.
>
>I guess the next thing you will say about me is that I lie when I say
>that neither the CPu or the blitter can operate at full speed
>concurrently if they share the same bus.
I'd only do this if I was as clueless as you...

Nat!
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