Re: BBR/BBS 65C02 instruction cycle counts

From: Gerrit Heitsch <>
Date: Thu, 30 Jun 2016 00:39:14 +0200
Message-ID: <>
On 06/30/2016 12:28 AM, Segher Boessenkool wrote:
> On Wed, Jun 29, 2016 at 09:09:26PM +0100, smf wrote:
>> It's much more likely to always be 5. Rockwell say it's 5 on one page
>> and imply it's 5/6/7 on another, so one page is definitely wrong as they
>> disagree & the 5/6/7 doesn't make sense. If you go for 4/5/6 then you're
>> assuming that both pages are wrong. Which is possible, but much less
>> likely than them putting an ** on one page when it wasn't meant to be there.
> 4/5/6 does make sense with the cycle descriptions though; or, if it is
> constant time (which I seriously doubt), 4 always.
>> Unless you get hold of some hardware to verify it, or some software that
>> is sensitive to timing that has been developed on real hardware then
>> it's actually not that important.
> Yeah.
>> More important is the 65ce02, where the instructions take less clock
>> cycles as it's the basis for the commodore 65. I don't think commodore
>> used 65c02 in anything.
> 4510...  Not so certain that is the same as 65CE02.

According to

it is... Should be easy enough to verify for someone who has a working 
C65. Does the 4510 have the 16Bit Stackpointer and the Z-Indexregister 
of the 65CE02?


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Received on 2016-06-29 23:00:30

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