[A83] Re: Last free mem byte

To: <assembly-83@lists.ticalc.org>
Subject: [A83] Re: Last free mem byte
From: "Tijl Coosemans" <tijl@ulyssis.org>
Date: Wed, 5 Dec 2001 14:20:12 +0100
References: <F202T2cMGeHwwne32uW00005e11@hotmail.com>
Reply-To: assembly-83@lists.ticalc.org


> From: "SUCKER from the old days" <sucker_pvn@hotmail.com>
>
> > > Van: Tijl Coosemans <tijl@ulyssis.org>
> > >
> > > > From: "SUCKER from the old days" <sucker_pvn@hotmail.com>
> > > >
> > > > Where is the last byte of the free mem? (Ti-83-)
> > > > (there were all the vars change places and stuff like that,
> > > > so right before the last block of TI-OS)
> > > >
> > > >            SUCKER
> > >
> > >
> > > On the 83-, free mem starts at (930Dh) and ends at (9311h).
> > >
> > > The 83+'s dev guide has some good information about that, ram
structure
> > > and such (chapter 2 page 5).
>
> I just want to know where the last block of TI-OS begins,
> so I can put a pointer right before it.
> There's no chance that the mem is completely used.
> (as found in the check ram screen)
>
> Or ain't this possible?
>        SUCKER

Well, an interpretation of the dev guide can be: free mem doesn't have a
start point nor an end point and yet it has. Meaning, the location of the
start and end of free mem aren't fixed and change a lot during TIOS
execution. If you store a pointer at (9311h)-1, which would be the end of
free mem at some time, it most likely gets overwritten at some time later.

Why not store your pointer in a safeRam location or something? You're busy
with interrupts right? so why not store your pointer in the same ram
location as where you put your interrupt routine?

mvg,

tijl

References:

[A83] Re: Last free mem byte

From: "SUCKER from the old days" <sucker_pvn@hotmail.com>