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From: OC.TREI@CU20B.COLUMBIA.EDU
Newsgroups: net.micro.amiga
Subject: Blitter speed.
Message-ID: <1651@caip.RUTGERS.EDU>
Date: Thu, 27-Mar-86 05:10:48 EST
Article-I.D.: caip.1651
Posted: Thu Mar 27 05:10:48 1986
Date-Received: Fri, 28-Mar-86 06:45:22 EST
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Organization: Rutgers Univ., New Brunswick, N.J.
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From: Peter G. Trei <OC.TREI@CU20B.COLUMBIA.EDU>



	While waiting for my official Commodore doc kit to arrive, I
borrowed a friend's hardware manual and started reading about the
blitter. It seems like a wonderful chip, and I conceived an
application which makes EXTREMELY heavy use of it. Which leads to my
question:

     Just how fast is the blitter? How many clock cycles per processed
word? How do the number of inputs, the presence of an output, and the
use of modulos and/or barrel shifts effect the speed? I cant find
anything to pin this down in the Hardware manual with any accuracy. My
estimates range from 7 million words/sec (This is the clock speed.
After all, this is a pipelined device) to a mere 62,500 words/sec (in
line with a claim that it can lay down lines at 'over 1 M pixels/sec').

    I guess I'll find out when I write the program, but I really think
this sort of nitty-gritty stuff should be in the hardware manual. If
it is in one of the volumes I have not obtained yet, I would
appreciate a pointer. If it is not in the docs, I hope CBN will post
the data here and put it in the next edition. I'd really like to pin down
the speed with better accuracy than a >100x range.

'Inquiring minds want to know!'

							Peter Trei
							oc.trei@cu20b
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