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From: peter@graffiti.UUCP (Peter da Silva)
Newsgroups: net.micro.6809,net.micro.68k
Subject: Re: 68xxx v.s. 80xxx    :-)
Message-ID: <288@graffiti.UUCP>
Date: Fri, 11-Oct-85 17:01:11 EDT
Article-I.D.: graffiti.288
Posted: Fri Oct 11 17:01:11 1985
Date-Received: Mon, 14-Oct-85 05:48:26 EDT
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Xref: watmath net.micro.6809:559 net.micro.68k:1233

>      Actually the 68000 family isn't
> all that fast.  Check some cycle counts
> and you'll find that the 68000 and
> 68008 are cycle hogs.  I don't have
> figures for the 68010, but the 68020
> was a substantial improvement.  I
> think they dropped the mean from over
> 4 cycles to about 3 cycles for most
> instructions.  That plus much higher
> clock speed makes it a very much faster
> processor.

But the 68000 has a more powerful instruction set, so the average number of
cycles per instruction are matched by a larger number of operations per
instruction. The FORTH inner interpreter loop takes up 3 instructions on
the 68000, as compared to about half a dozen on the 80xxx. Other operations
are similarly enhanced. Plus you don't need to waste instructions and opcode
fetches playing around with the DS, CS, SS, and ES registers.