Re: Hardware emulation of 6509 using 6502?

From: Jeff Laughton <laughton_at_cyg.net>
Date: Fri, 29 Jun 2018 00:00:39 -0400
Message-ID: <20180629000039.Horde.F3wW6lQwkiGO5pCGh09sqNz@www2.cyg.net>
Quoting Jim Brain <brain@jbrain.com>:

> On 6/28/2018 8:14 AM, Jeff Laughton wrote:
>>
>>
>> Hi, Jim. You'll find some details about timing *differences* in  
>> Table 7-1 of WDC's 65c02 datasheet [1], which makes a comparison  
>> with the NMOS 6502. On the 'C02 the $6C opcode (jmp indirect) takes  
>> one cycle longer. ADC and SBC also apparently take one cycle longer  
>> if you're in decimal mode.
> I am using a Rockwell 65C02.  Any info on those?  I don't know that  
> I have a 65c02s here yet.

Jim -- I'm pretty darn sure the Rockwell and WDC c02's are identical  
in regard to cycle-by-cycle timing.  Certainly that's true regarding  
the $B1 and $91 instructions, and those are all that concern us  
(right?)  The WDC part has a few new pins, and two new instructions  
(STP and WAI), but that shouldn't matter.  Hope that helps.

I'm pretty sleepy so I maybe won't be able to have a proper look at  
those traces tonight...

Jeff

>
> Jim
Received on 2018-06-29 07:00:05

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