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From: dale@boing.UUCP (Dale Luck)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: 14Mhz 68000
Message-ID: <998@boing.UUCP>
Date: 18 Jun 91 15:10:30 GMT
References: <7ABF45A76060644B@BNANDP51> <22508@cbmvax.commodore.com> <1991Jun18.011626.4443@marlin.jcu.edu.au>
Reply-To: dale@boing.UUCP (Dale Luck)
Organization: Boing, Milpitas, Ca.
Lines: 27

In article cpmwc@marlin.jcu.edu.au (Matthew W Crowd) writes:
>
>If you want to build a 16MHz 68000 "accelerator" for the amiga it's a
>big waste of time.
>The speed increase (if any?) is minimal ~10% i think, so why bother?

This really depends on what you are doing. If all you do is increase the
speed of the 68000 chip itself you will see a large improvement if you
use the floating point libraries. After the improved ieee libraries in
1.2  (nearly twice as fast as the previous version), the percentage of
time spent by the processor in mul, div, shift instructions compared to the
rest of the code increased to nearly 50% I believe in some cases. Since
mul, div, shifts are all multiclock instructions which keep the cpu core
real busy, doubling the clock speed of the cpu core will double the speed
of these instructions. So for floating point intensive tasks, there is
much more than a minimal 10% improvement in speed.

The 68010 had about a 5% overall improvement in speed even at 7.14mhz
because of the faster mul and div instructions on the chip. (faster than
the 7.14mhz 68000) that is.

>Matt Crowd        cpmwc@marlin.jcu.edu.au         | "Operator, give me 


-- 
Dale Luck     GfxBase/Boing, Inc.
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