[Coco] Kip's Single Board Computer

[Dave Philipsen]

You could also use a BRN as a no-operation.  That instruction has an 
opcode of $21 and takes three cycles to complete.


> On , RETRO Innovations wrote:
> 
>>> This is correct except that NOP is actually a 2-cycle instruction.  
>>> The 2nd
>>> cycle of each NOP will read the following location.  The sequence of
>>> addresses presented will be $1212 and $1213 for the first NOP, then 
>>> $1213
>>> and $1214 for the second NOP, etc..  So, following the first NOP, the
>>> address bus will increment on every other CPU cycle.
>> Would it really increment the address bus counter like that on the
>> external pins?  6502 is a 2 cycle NOP, but the address lines do not do
>> that, they just (as you note) increment at clock/2.
>> 
>> Jim
>> 
>>> 
>>> - Darren
>>> 
>> 
>> 
>> --
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