z80 timing... 6502 timing

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sat Apr 17 08:49:39 1999

Kindly give the comments interleaved with your quoted message below a look.

Dick

-----Original Message-----
From: Sellam Ismail <dastar_at_ncal.verio.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Saturday, April 17, 1999 2:45 AM
Subject: Re: z80 timing... 6502 timing


>On Sat, 17 Apr 1999, Mike Ford wrote:
>
>> >Ooh! A machine code competition. I'm in! I'll do the 6502 and whoop
>> >EVERYONE'S ass!
>
Rules are a problem, aren't they?
>
>> And then you woke up. First what are the rules, 6502 or 65C02, code in
Rom
>> or Ram, what is the code supposed to do?
>

Well . . . There's the problem . . . first of all, the code's got to be
executable on something everyone has got available, or it's got to be
simulated on a simulator everyone has available, else there'll be a limit on
interest right away . . . Then, shouldn't there be some consideration of
the coding/debugging time involved? I'd lean in favor of a PC-compatible
simulator. That makes the computation of actual execution time
straightforward. . .

and, of course, it's got to run the code on a "real" processor, not just a
putative "we could build . . ." sort of thing, right? . . . well, maybe . .
. Then there's the question about WHICH 6502 to use. Given a listing, it's
easy enough to compute how long it takes the code to run, but which
instruction set? What about undocumented features? Both these processors
were famous for those. Of course, there doesn't have to be a limitation,
i.e. one could consider ALL available cores.

I'd propose it be a significant problem, but one which is well-defined, i.e.
algorithms are published, hence the problem solution is well-defined, and
I'd propose further that the same algorithm be used so we compare "apples
with apples."

As for the processor core, well, it's also got to be one everybody's got
available, yet it wants to be one which WAS available in 1982. That might
include the Synertek, MOS, and MAYBE the Rockwell core. We can't just say
65C02, because it was buillt in several conflicting versions. What about
the Z-80 core? Whose? Which one? Speed, of course, should be "limited" to
whatever was available in 1982. That certainly includes the Synertek (MOS
Technology-comptible)"4MHz" 6502C (always worked fine at 5 MHz by then), as
well as the Zilog Z-80B (6-MHz). Was the 8MHz part out in 1982?
>
>> My vote goes for something with some graphical element so we can "see"
what
>> is happening. (spinning ball, etc.)


Whereas this might be "cute" it is very limiting, in that it has to be a
graphics-capable environment available with both processors. It should not
"fall" conveniently for either processor, so the graphics array should be
large, and, AFAIK there's no such system for either processor. What should
be done, here? Should we build a board? How do we measure how fast it's
going? Remember, the hardware environment has to be more or less the same
for both processors.

>BRING IT ON, MO FO!
>
>Sellam Alternate e-mail:
dastar_at_siconic.com
>---------------------------------------------------------------------------
---
>Don't rub the lamp if you don't want the genie to come out.
>
>             Coming this October 2-3: Vintage Computer Festival 3.0!
>                   See http://www.vintage.org/vcf for details!
>                        [Last web site update: 04/03/99]
>
Received on Sat Apr 17 1999 - 08:49:39 BST

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