[Coco] Learning CPU Architecture and Digital Design

jdaggett at gate.net jdaggett at gate.net
Tue Feb 19 19:34:47 EST 2013


Mark 

I made my judgement based solely on the source code. John makes comments in certain 
areas where the CPU09 does things in one or two cycles faster than the 6809. So I do know 
that it was not 100% cycle accurate.

I have yet to actually use it in a real application. 

Congradulations on the new child. Get sleep when you can. 

james

On 20 Feb 2013 at 8:34, Mark McDougall wrote:

> On 20/02/2013 3:21 AM, jdaggett at gate.net wrote:
> 
> > 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.
> 
> It makes a mess of the Vectrex graphics, so I'm not sure it's that close to 
> being cycle accurate. Either that, or the Vectrex BIOS drawing routines 
> happen to make heavy use of the instructions that aren't accurate!?!
> 
> Regards,
> 
> -- 
> |              Mark McDougall                | "Electrical Engineers do it
> |  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"
> 
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