Re: A83: Re: Ion 1.4 vs Ion 1.6

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Re: A83: Re: Ion 1.4 vs Ion 1.6


I have a feeling I know why this happens to Ion, as we went through the
dilemma of whether or not to "fix" this in MirageOS (we ended up deciding to
fix it).

When a program is running, you have to keep track of which program it is
that's running (so you can relocated it back after it's done).  Chances are
Ion just stores the VAT location of the program, and assumes that the
location wont change.  This would work fine, so long as no variables before
it in the VAT are deleted .

To overcome this problem, MirageOS stores the whole program name while the
program is running, and then looks up all the data for it again after it's
finished running.  That way even if the VAT location changes, MirageOS can
still successfully relocate it back to it's proper position.  This is a
tradeoff I guess, since if you change the name of the currently running
program, MirageOS will have problems, but I can't think of a reason why
you'd want to do that.  (And I think the ability to delete programs is more
important).

-Dan Englender

----- Original Message -----
> >
> >a few days before, someone told us ION uses InsertMem and DeleteMem to
> > >load
> >the program --> if that is true, the order in witch programs are >loaded
to
> >the calc doesn't mind for ION too
> >"Sebastiaan Roodenburg" <sebastiaan@rimsystems.nl>
> >
>
> External levels (in the games for instance) can be used without loading
> order problems, as long as you only read them.
>
> But if you try to delete an external program (level or file) within an ION
> program, loaded after the external one, the ION will crash.
> Same thing will happen if you store program to flash (on TI-83 Plus)
> returning it to RAM later and try deleting some "old" external files.
>
> ION will not crash if external programs (to be erased) are loaded after
the
> program (which deletes them).
>
> Don't ask me why this happens.
>
> However MirageOS does not have such problems.
>
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