z80 timing... 6502 timing - test-drb@ccmp.vtda.org

19 Apr 1999

While what you say is certainly true, the page-zero usage is not dynamic,
so, unless your task is very large and complex, page zero usage is therefore
under the coder's control.  I agree with your observation that the rate of
memory usage is a good indicator of the rate at which a processor gets work
done.  The 6502 shines in that respect, in that the internal operations are
generally overalpped with the fetch of the next instruction, with a few
notable exceptions.

Generally speaking, I've chosen processors with foreknowledge of what the
device's most frequent tasks would be.  For example, I picked a 65C02 for an
application for which my boss had expressed a profound preference for the
Z-80.  I had to prove to him that, for OUR task, the 65C02 had a couple of
features we could use very effectively and which the Z-80 didn't offer.
It's always case specific.

Dick
-----Original Message-----
From: Dwight Elvey &lt;elvey(a)hal.com&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Monday, April 19, 1999 2:55 PM
Subject: Re[2]: z80 timing... 6502 timing

...
 "Richard Erlacher" &lt;edick(a)idcomm.com&gt;
wrote:
> I don't know why this has to be so complicated.  There need to be
> constraints in order to ensure a level playing field, but since there are
> two related objectives, (1) to  find out which of the two processors in the
...
 > title of this message is "faster" and
(2) to generate the fastest code for
...
   them for
comparison. 
Hi
 I always have to wonder about the meaning of faster.
Although I like the 6502 for a lot of things and would
say that it is often faster than a 8080 for many things,
I also know that resources like page zero get used up
quickly. Once these are gone, things tend to slow down.
 I think we will continue to see that, like in the past,
most processors with about the same memory access speeds
will do about the same amount of work ( same bit count ).
On chip cache has changed that some but that just makes
another category. I would say any processor was superior
to another on small benchmarks unless the numbers were
in the 5X magnitude or more. Large application are more
useful in comparisons but it is hard to come up with
enough cross platform examples to make meaningful judgments.
 I've always said, one should stick with what makes you happy.
Dwight