Re: Write .nib files back to disk

["Antony Mauget" <amauget@hotmail.com>]

Hello Jayson,

Thank you for your explinations but I already know the *big* difference
between DSK and NIB files.

Now, I think, like Andy said in his reply, that the NIB images could be
transfer back to disk. I mean, in real Apple II world, there is no NIB or
DSK format ! Just physical disk and drive... By the way, if I take my two
DSK files and merging them in one NIB file on the emulator, it perfectly
works ! It means there is no lost data.

The real question is what is the process to make a NIB file. I just want to
reverse this process.

Antony

"Jayson Smith" <nospamratguyspambegone@nospamplease.bellsouth.ihatespam.net>
a �crit dans le message de news:
ohfjd.47610$Tq1.2386@bignews1.bellsouth.net...
> Hello,
> First of all, I don't know of a solution to your problem.  However, I'll
try
> to make you understand why the methods you're trying won't work.
> First, you need to understand what a disk image is, and what a nibble
image
> is.  A disk image is 143360 bytes.  This file contains what you might call
> the high-level representation of the contents of the disk.  For example,
on
> track 17, sector 0 of a disk image is the exact sequence of bytes a
program
> would receive when telling DOS to read track 17, sector 0 of the disk.
> There are only the 256 bytes of actual data.  There are no checksum bytes
or
> other data which DOS uses to validate the sector.  On an emulator which
uses
> .dsk files, most likely every disk which is properly inserted is perfect.
> Since there are no checksums, the emulator probably has to generate them
to
> satisfy DOS that the data is OK.
> A nibble file, on the other hand, contains more data.  This type of file
> contains the raw, low-level contents of the disk.  When DOS reads a
sector,
> what it actually gets from the drive itself is this low-level contents.
> This data includes not only the 256 data bytes, but checksum and other
data.
> Any time you get an I/O error, that is because DOS is unable to validate
the
> data on the sector it is trying to read, because either the data itself or
> the validation information has been corrupted.
> The way many copy protection schemes work is to intentionally mess
something
> up about the disk.  This could be in one particular area, or the entire
> disk.  But anyway, the point is that normal DOS can not read the disk, or
at
> least it doesn't think it can.  Something about the low-level data has
been
> messed up.  When a nibble file is converted to a .dsk file, all the
checksum
> data is eliminated so the disk appears to be perfect.  Therefore, when the
> protected program checks to make sure it's legit, the check fails as the
> disk looks perfect so it must be an illegally made copy.  Even if you use
> nibble copiers on the disk image, they won't work for the simple reason
that
> the original disk they're copying from is, for all practical purposes, a
> perfectly ordinary disk.  So the copies won't be any good either.  Even
> converting the copies back to nibble files won't make them good since the
> intentionally messed up information was lost in the original conversion
and
> cannot now be restored.
> I found a program called nib2file for Prodos, but it only works one way,
> converting a disk into a nibble image.  It can not convert a nibble image
to
> a real disk.
> Hope this helps!
> Jayson.
>
> "amauget" <amauget@hotmail.com> wrote in message
> news:418d7040$0$18478$8fcfb975@news.wanadoo.fr...
> > Hi All !
> >
> > I'm currently trying to write .nib (protected) image files back to 5"1/4
> > disks.
> > I can't use the classic ADT solution that works only with .dsk files.
> >
> > I've read FAQs but unfortunately, don't find any method that works. Here
> are
> > the facts :
> >
> > First, I've tried to use convertors such as NIB2DSK.EXE. But the DSK
files
> > aren't working.
> > Then, I've tried to copy the .nib to a .dsk using an emulator and
various
> > copy programs (Locksmith 5.0, Disk Muncher, CopyII+ 7.0, ...). All fail.
> > Finaly, I've tried an interresting (but not working) solution :
> > - load the .nib file into an emulator,
> > - use SST (Saltine's Super Transcopy) to make 2 dsk files from one nib
> file,
> > - send the 2 dsk files (via ADTGS) to my Apple II GS
> > - use SST once again to write the 2 DSK onto 1 disk.
> > Once again, it fails.
> >
> > I'm stuck ! Have you got any clue before I'm going crazy ?
> >
> > Thanx
> >
> > Antony
> >
> >
>
>