[Coco] Kip's Single Board Computer
Darren A
mechacoco at gmail.com
Tue Sep 8 23:38:13 EDT 2015
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
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