[Coco] 6309 microprocessor project 01-28-2004

[Paul T. Barton]

--snipped--
> John and Roger,
> 
> I'm not sure why Paul has not replied to this
> thread unless it is 
> because he can't tell from the subject line
> that the Nocan is the topic.
> 
> I own one of Paul's boards, Nocan3 and helped
> him with software testing 
> during the development stages. It is only 8Megs
> and I think Paul got up to 64Megs.
> 
> I can tell you why I did not modify any of my
> programs to use the extra 
> memory. I had no idea how many people bought
> these boards and did not 
> want any software I sold to require exotic
> hardware. Nitros-9 can't yet 
> use this extra memory because it would take a
> major rewrite of the 
> system core to handle the addressing. There
> does not seem to be any good 
> place to but the MMU block address table.

Paul here-

I agree, there's no really good place to put
those MMU additions.

There are really two NoCan styles:

The early (8mb) one uses a different
style of extending the extra DRAM.

The later (64mb) one uses the style
that John wanted to emulate.

This later style was the one that I
really wanted to implement but lacked
the tools to get it done at that time.
Since I now have several that do work
(but without testing software) it seems
worthless to continue. I still want to
see if it can go further just for the
challenge. Besides the GIME may already
be overtaxed as far as the Z0..Zx address
pines and RAS/CAS/WR0/WR1 pins go.

I would like to be able to write a
ramdisk driver to use the unused 62mb
(egad!) under nitros9 l2v320, but
don't have a source sample as yet.

Understanding the MMU was not one of
my special talents but with Robert
Gault's help, I got a little more.

Paul T Barton


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