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From: ali@rocky.UUCP
Newsgroups: comp.sys.mac
Subject: Re: Bit Blitters
Message-ID: <172@rocky.STANFORD.EDU>
Date: Tue, 10-Mar-87 11:48:49 EST
Article-I.D.: rocky.172
Posted: Tue Mar 10 11:48:49 1987
Date-Received: Wed, 11-Mar-87 20:33:47 EST
References: <43140@beno.seismo.CSS.GOV>
Reply-To: ali@rocky.UUCP (Ali Ozer)
Organization: Stanford University Computer Science Department
Lines: 26

In article <43140@beno.seismo.CSS.GOV> mo@seismo.CSS.GOV (Mike O'Dell) writes:
>The only problem with bit blitters is that none of 
>the chips available actually do what you want in
>all the cases.   ... A vanilla 68K
>can blit faster than any currently known hardware
>chip.

Hmm, a vanilla Amiga (without the 68020 board), containing a vanilla
68K running at 7.2 MHz, can run the game of Life, written in C, at 1.2
Million cells a second. (20 generations a second on a 320 by 190 lo-res 
screen). Just recently someone posted a "super-fast" life game 
to comp.sys.atari.st, written in optimized assembler, and it can crank 
out 400,000 cells/sec. And the atari st is probably the fastest (in terms
on raw computing) 68K micro around ---- Its clock is 8 Mhz (vs 7.2 Mhz for
the Amiga) and it has no multitasking overhead (like the few percent, in the 
Amiga)... Now how can the Amiga do it 3 times faster? The blitter, of course.
Amiga has a 3 source, 1 destination, multiple shift, multiple modulus
blitter that can do almost anything, with the appropriate programming. I 
would never have thought you could run Life on a blitter, but, hey, it runs,
and runs much faster!

One more thing --- Because the game of Life is very blitter oriented on the 
Amiga, it leaves the 68000 free most of the time. Thus I can run my C compiler
concurrently with the game of Life and both run fine, with minimal slowdown...

Ali Ozer, ali@score.stanford.edu,  decwrl!rocky.stanford.edu!ali