65816 and I/O

From: Ruud Baltissen (Ruud.Baltissen_at_abp.nl)
Date: 2001-01-19 08:22:14

Hallo allemaal,

In my previous mail I also had the plan to ask you what the best way is to
expand a C=. (that's what the subject "memory expansion" originaly was meant
for). But personal circumstances forced me to stop writing so I sent it with
the question.

FUNET provides a way to expand, the memmory of a C64 or C128. The big
problem is you won't find SW to support it. Looking from the SW side, you'll
find three systems: 1) GEOS-RAM 2) the REU and 3) CMD.
CMD is capable of expanding up to 16 MB. My first thought was to use the
same trick until I realised that the trick was the fact they used the 65816.
This is not exiting as I already made a design based on this principle. But
it triggered a chain reaction: if they use the 65816, how about the I/O area
of the 6510? There are, AFAIK, only two solutions:
1) the 65816 tells the 6510 in some way to perform the needed actions.
2) even if the 6510 is disabled, it is possible to adress the I/O area.

I think it  is solution #2. Is this a known fact, or can this be checked?
This would mean I can simplify my own design.
And if it can be simplified, why not designing using the known specs of CMD.
What kind of technical info of the Super-CPU is available?

Thanks for any info.

Groetjes, Ruud

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