Re: PC-card (4)
Date: 2001-04-12 17:43:57

On Thu, 12 Apr 2001, Nicolas Welte wrote:

> wrote:
> > 
> > Hallo,
> > 
> > While writing the article it occured to me that the combination of IO1 or
> > IO2 and $D7xx doesn't sound to bad. This certainly will be atractive to
> > people with a C128 and SCPU.
> > 
> > Another one is IO1 or IO2 and $8000..9FFF. The only disadvantage that I see
> > for the moment is that a write to this area also overwrites the contents of
> > the underlaying RAM. But I thought it is still worth mentioning.
> I think, if you enable Ultimax mode, there is no RAM that can be written to.
> This way you can use about every memory location above $1000 to map in your
> own I/O. I just wonder if the SCPU is compatible with this mode.

After _very_ careful interpretation of the PLA's reverse-engineered
sourcecode, Bogax and I have decided that unless you're writing to the I/O
page, you can't not write to ram.  The only thing that throttles the WE line
on the internal dram is the I/O outputs on the PLA

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