From: Greg King (gngking_at_erols.com)
Date: 2006-04-05 07:57:31
From: William Levak <wlevak@grex.cyberspace.org>
Date: Thursday, March 30, 2006, 12:47 AM -0500
>
> On Wed, 29 Mar 2006, Spiro Trikaliotis wrote:
> >
> > I know the 1581 is known to lose data in some ROM versions. Anyway, I
> > did not find any details in how this can happen.
> >
> > Today, I encountered the following problem:
> >
> > 1. I have a disc which contained some files:
> >
> > 0 ."test " 45 3d
> > 83 "f0" prg
> > 83 "f1" prg
> > 83 "f2" prg
> > 83 "f3" prg
> > 83 "f4" prg
> > 83 "f5" prg
> > 83 "f6" prg
> > 83 "f7" prg
> > 83 "f8" prg
> > 83 "f9" prg
> > 83 "f10" prg
> > [...]
> > 83 "f33" prg
> > 83 "f34" prg
> > 83 "f35" prg
> > 83 "f36" prg
> > 83 "f37" prg
> > 6 blocks free.
> >
> > That is, it contained 38 files, each 83 blocks, that it was almost
> > full; only 6 blocks were unused.
> >
> > 2. I copied some file on the disc; the file did not have enough room;
> > thus, I got the following new contents:
> >
> > 0 ."test " 45 3d
> > 83 "f0" prg
> > 83 "f1" prg
> > [...]
> > 83 "f36" prg
> > 83 "f37" prg
> > 0 "test" *prg
> > 0 blocks free.
> >
> > 3. Now, I validated the disc to free the blocks used
> > by the half-written file (the equivalent to OPEN 1,8,15,"V0")
> >
> > 4. After this, my directory only contained the first 8 files:
> > 0 ."test " 45 3d
> > 83 "f0" prg
> > 83 "f1" prg
> > 83 "f2" prg
> > 83 "f3" prg
> > 83 "f4" prg
> > 83 "f5" prg
> > 83 "f6" prg
> > 83 "f7" prg
> > 2496 blocks free.
> >
> > That is, the validate deleted the files "f8" to "f37", along with
> > "test".
> >
> > Has anyone seen exactly this behaviour? Is the validate command in the
> > 1581 known to delete files it should not delete? Or, was the structure
> > on the 1581 wrong?
>
> I have had that problem. It seems to lose directory sectors.
>
> The latest revision of ROM, 318045-02, does not have that problem.
Maybe, the directory's file-chain was truncated, by mistake.
Try looking at sector 40,4 ($28,$04) with a disk editor. If the next eight
file-names still are there, then link the previous sector to it. Next,
walk through the directory sectors; make sure that the file-names' numbers
keep going up. If they ever go down, then you have a circular directory
(fix it, of course)! When you reach that "test" name, make sure that its
sector has 0,255 ($00,$FF) as the link bytes.
List the directory; then, try validating again.
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