[A83] Re: MirageOS remembering program location
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[A83] Re: MirageOS remembering program location
> > ...Actually, it needs to be a bit more complicated because it's actually
> > dependant on what page the code is actually running from, not the mapped
> > address. IE. if you load RAM page 0 into 4000h, and run some code
there,
> > it'll still crash. The same applies for the Flash ROM execution
> protection.
>
> That means that the adress-bus part changes. But would cutting the
RFSH-pin
> help? That pin isn't used all (might even not be connected, but then my
> theory isn't correct anyway), since Ti's don't have dynamic RAM.
>
> And what is this Flash ROM execution protection?
...I have no clue on the RFSH pin. As for the Flash ROM execution
protection, code can only be run from 00-08, and 16h-1Fh, plus the pages
your apps are on. If you've got an SE, you can see the particular bounds
for execution of code from flash ROM by looking at ports 22h (lower bound),
and 23h (upper bound). If you try to run code from any page in between
these, the calculator will crash. Not to do with the execution protection,
but of course you also, if you want to disable the flash ROM protection (so
you can write, etc), need to have code executing from pages 1Fh, 1Dh, or
1Ch, regardless of where they're mapped.
> > On a side note, here's a nifty quick way to "disable" the 8.8k limit on
> the
> > SE:
> > [..]
>
> Just put another RAM page at $CFFF-$FFFF. That definately works :-)
...Yeah, but it depends with RAM page. Some will still crash.
-Dan Englender
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