[Coco] Learning CPU Architecture and Digital Design

[jdaggett at gate.net]

Commercial cores could be cycle accurate and also run at faster speeds. 

A lot depends on how accurate to the specifications of the 6809 that the designer wants to 
be.  Most I have seen state that they are source code and opcode compatible. That is they 
will run the same code without compiling or assembly. Naturally when you run one of these 
cores at 10 or 15MHz, timing loops will need adjusting.

John Kent's open source core is widely accepted. It is now very stable and while not 100% 
cycle accurate, it is very close as of the last time I looked at it. There were a few opcodes that 
executed one or two cycles faster. 


james


On 19 Feb 2013 at 15:16, T. Franklin wrote:

> Curious, Do these "commercial" cores do a better job of emulating the clock timing of the 6809 vs the "open source" cores? I'm just wondering if paying for a core would result in any bennifit over the open sours models.
> 
> -Tim
> 
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