[Coco] Kip's Single Board Computer

[Dave Philipsen]

Ok, then what would be fetched on the third cycle?



On , Darren A wrote:
> On Tue, Sep 8, 2015 at 9:27 PM, Dave Philipsen wrote:
> 
>> Actually, thinking about it, if it's a two-cycle instruction then the
>> address would just increment once every two cycles.  The CPU only 
>> fetches
>> one byte.  Two cycles later it fetches the next byte at an address 
>> that is
>> just one greater than before. So you'd get address $1212 for the first 
>> NOP,
>> $1213 for the second NOP, etc.  A0 would oscillate at 500 MHz for a 1 
>> MHz
>> clock, A1=250 MHz, etc.
>> 
> 
> 
> Every cycle will be a byte fetch.  The first cycle of a NOP instruction 
> is
> the fetch of the NOP opcode. The second cycle is a fetch of the next
> opcode.  The end-result is the same (the address increments every other
> cycle).
> 
> - Darren