[Coco] Learning CPU Architecture and Digital Design

[Mark McDougall]

On 17/02/2013 8:30 PM, Kip Koon wrote:

> because there are two versions of the 6x09
> processor core in existence ready to burn into an FPGA chip.

I only know of one version, John Kent's CPU09, which is the core that Gary 
Becker is using in his Coco3FPGA project.

If you say there's another one, I'd be *very* interested, but I suspect 
you're mistaken!?! Hoping not though! :)

> I'd like to expand the
> 6x09 core (not sure which one to pick yet) into a core with a 24-bit address
> bus and keep the same 8-bit data bus while at the same time preserving the
> complete instruction set, if possible.  Has anyone else ever had this idea?

IIRC John himself was looking at enhancing his CPU09 core, though I can't 
recall the exact details of what he was planning. I'm guessing you're 
looking at some sort of 'segment' (for lack of a better word) register(s)?!?

> I'd also like to study this subject in
> detail.  In order to facilitate my studies, which book(s) would you all
> suggest I look into getting?  Thank you all for your help.

There was a book on CPU design in VHDL but I can't recall the title (never 
used it). A quick google search brought up a PDF from opencores on the 
subject, for example.

I think if you have some sort of grounding in CPU architecture you best bet 
would be to dive in and study the CPU09 core itself. I've personally studied 
a few of the cores (6502 & Z80 primarily) and briefly perused John CPU09 
core (to track down an issue) and it's not that difficult to grasp how they 
work if you spend enough time with them. Of course, you still need a 
grounding in CPU architecture first.

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"