[A83] Re: MirageOS remembering program location


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[A83] Re: MirageOS remembering program location




> Van: Dan Englender <dan@calc.org>
> 
> > By the way, did TI allow the 83+ to crash like at the first sign of any
> > danger?  (Because in case of a reset, everything in the archive will
> > be saved, unlike an 86, which doesn't have Flash ROM?)
> 
> ...The 83 Plus will often crash "at the first sign of danger" because of
> the 8.8k limitation.  When code crashes, random stuff is executed, and
> this may very well be in the restricted area, causing the calculator to
> reset.

This resetting 'feature' how is it accomplished? My guess is that there is
some little bit of hardware (inside or outside the Z80) that checks if:

- the highest bit of the adress-bus is set (A0-pin?)
   => read from / write to $8000-$FFFF
- the processor requests data (MREQ- or RD-pin?)
   => we now know the Z80 is reading
- the R register gets an update (RFSH-pin?)
   => gets only updated when an OP-code is requested

And then sets the RESET-pin, simple as that...

Now to see if someone can find the thing ;-)

	Henk Poley <><




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