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From: melling@cs.psu.edu (Michael D Mellinger)
Subject: Re: Blitter vs. 040 (was: Computer Architecture question
In-Reply-To: mykes@amiga0.SF-Bay.ORG's message of 11 May 91 23:37:31 GMT
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	<vbcH!4p@cs.psu.edu> <mykes.2510@amiga0.SF-Bay.ORG>
Date: Sun, 12 May 91 20:27:07 GMT
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In article <mykes.2510@amiga0.SF-Bay.ORG> mykes@amiga0.SF-Bay.ORG (Mike Schwartz) writes:

   The blitter provides parallel computing power.  You can decide whether to
   use the 68040's cycles to render graphics or to do heavy calcuations, whichever
   the application requires.  Another way to describe how this works:

   The blitter has a shared bus with the CPU.  The CPU has 3 buses (at least on
   an A2500) - CHIP (shared with blitter), ZORRO (slots), and FAST memory bus.
   While the Blitter blits, the CPU can be accessing either of the other 2 buses
   to its heart's content.

How fast are the Amiga buses?  If you use the 040 to render graphics,
it must access the chip RAM correct?  So there will be bus contention?
Wouldn't it be better to let the 68040 just have the bus?  How much
memory does video RAM take up in the 680x400(4096 colors) graphics
mode or a better graphics mode.  When you fill up chip RAM you have a
problem.  Do all the current Amiga's ship with the 2MB RAM chip set?

-Mike