Re: LZ-Adv: ZShell for TI-82 -- Ideas..
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On 22 Oct 96 at 20:57, Jason C. Wenger wrote:
> >Now, how does this work? At $818d in TI-85 RAM is a pointer to the
> >routine that will hande a keyboard press. The key is to change this
> >address to point at some location where you can put your own asm-code.
> >I achieved this by, in a backup file, changing the VAT-pointer for a
> >real variable to point at this $818d. After transferring the backup to
> >the calc, I can store whatever I want (almost) to this location. In
> >this case I store E145 to the real variable. E145 equals
> >0091FC00000000000000 which means that $818d will contain a pointer to
> >9100. At 9100 it is simple to put a fixed variable containing the
> >asm-code. (I just extended the ZShell string, Quick&Dirty! ) In my
> >backup file
> >the code at 9100 first restores $818d and then the following words
> >(which are also destroyed by storing the real (the values of these
> >words appear not to be critical)). Then I jump to ZShell.
>
> Okay... but how do you keep from rnning ZShell every time a key is
> pressed?
The first thing that the code at $9100 does is to restore $818d back
to its normal value. This makes the calculator function normally after
you've pressed a key once after the E145->A.
Mattias
<pre>
--
Mattias Lindqvist
d96mli@efd.lth.se
www.efd.lth.se/~d96mli
</pre>
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