Re: DOS 3.3 File Manager calls - stomping on Track 0, sector 0

["Michael J. Mahon" <mjmahon@aol.com>]

josephoswaldgg@hotmail.com wrote:
> schmidtd wrote:
>
> > I have my trusty copy of Beneath Apple Dos by Worth and Lechner in
> > front of me.  I've modified their sample "copy" program to do my
> > bidding.
>
>
> Have you tried their code out to make sure it doesn't exhibit the same
> bug?
>
>
> > Except... track/sector 0/0 is overwritten with a repeating sequence of
> > (0x00 0x00 0xff 0xff) bytes.  Is there a common trap I'm falling into
> > here?  Code below...
>
>
> Don't know what trap this might be, but that byte pattern looks
> something vaguely like the volume free-sector map. Is your disk's VTOC
> valid?

That was my guess, too--that the updated VTOC is mistakenly being
written back to Tk 0, Sec 0.

> I've never used the file manager directly; I think it was actually
> pretty sensitive to the DOS environment at the time of the call.

Yes, in not fully documented ways...

> Really, the Ctrl-D "BSAVE" solution isn't *that* bad is it?

Exactly.  Is this just an exercise in seeing if it can be done,
or would you rather save time and get the job done reliably (even
with patched versions of DOS)?

-michael

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