[Coco] FPGA 63x09
jdaggett at gate.net
jdaggett at gate.net
Fri Mar 27 11:11:41 EDT 2009
That has been looked into.
There are a few issues yet to be resolved, one being my time primarily. Fortunately the busy
season of my line work is almost over and I should get more time to devote around the
middle of May. Of the other issues are which FPGA, which development board and which
design to modify or start from scratch.
In the case of which design to use:
There are four approaches that one can take
1) Modify John Kent's 6809 IP code .
2) Modify one of two 68HC11 IP codes
3) start from scratch
4) start with Fint Wheeler's code and modify it.
I started with approach #3 until I closely looked at the freely available code from Green
Mountain on their version of the 68HC11. I lean to the GM HC11 modification as I am a
hardware engineer as opposed to software engineers. My HDL coding style lends more to
me thinking in terms of hardware rather that more abstract levels. So for some my HDL
coding style may very well be primitive. I personally don't care as it is easier for me to
comprehend what is going on. I do not like long( ten and fifteen page) processes or entities.
To me it is easier to break them up into smaller sections if need be. The GM HC11 is rather
easy for me to read and maybe off an easier route to mdoify. The HC11 archetecture is not
all the dissimilar to the 6809 since both are offshoots of the 6800.
In the case of which FPGA to use
I choose #2 simply because that is the brand I am familiar with and the tools are already
loaded. I am flexible if there is need for another set of tools as long as they are windows
In the case of development board:
There are several out there with many functions added. If XILINX is the choice, then a
Spartan 3E would be the better choice. There are plenty of already boards that range in cost
from about $150 to over $500. My choice is the Digilent Inc Nexsys2 board at $149. It has 8
bit color and has plenty of ram and flash. XESS has a setup that runs about $300 and
includes Networking capabilities. The onboard flash is pretty much dedicated for FPGA
The ideal board would be the Nanoboard. But bundled with Altium's software at $4300 is out
of reach for most. The Nanoboard is very flexible. Then there is the route that theC-ONE
group took that has their own dedicated PCB. The could be even more expensive than a
moderately priced development board.
I hope I have not been to long winded in my reply even though I have. It probably has not
been due to the lack of ability to do a 6309 IP for an FPGA. Instead what to do with it once
one has been developed.
just my thoughts
On 27 Mar 2009 at 8:48, Stephen Adolph wrote:
> I notice that there is a VHDL core for a 6809. Would we know enough
> about 6309 to be able to extend this properly?
> Might be a way to a much faster 6309 capability, not sure if the
> machine could benefit from it though.
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