Re: A86: Re: LCD stuff
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Re: A86: Re: LCD stuff
Hmm, I never thought about that before :) I took a quick look at the ROM,
and it appears to reset the calc immediately on startup at $0000, so I guess
the CPU _dos_ always have to have power. A very unlikely alternative (but
still possible) is that the calc has a very small boot ROM that takes care
of this, so that it doesn't start at $0000 unless all the batteries are
pulled (but if it had a boot ROM, why would it set everything up in the main
ROM? It wouldn't...).
> On that note: If, say, the ROM were executed from the very beginning,
> as I believe it is when the calc is turned on after ALL batts have been
> pulled, doesn't it reset the calc? (i.e., flush the VAT and system
> memory???) And the internal CPU registers, PC in particular, are RAM,
> and thus power-dependent, correct? If so, then if power were removed
> from the CPU, the PC would reset to $0000 and the next time it turned on
> the calc would reset. Then, if the CPU were totally dependent on the
> primary batteries, and absolutely does not run off the backup batt, then
> when you change your batteries the calc should reset. This does not
> happen, thankfully. So wouldn't that mean that the CPU is powered, and
> thus running, even when only the backup battery is in the calc?
>
> Cassady Roop
>
> David Phillips wrote:
> >
> > What do you mean? It always uses regular batteries...
> >
> > The lithium battery merely holds current for the RAM, the same as
batteries
> > in say a Game Boy cart (the case for Super Mario DX is clear, so you can
> > actually see the lithium battery in there).
> >
> > > Is it relying on the back-up or regular batteries when
> > > the LCD is off using this method?
>
>
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