Re: DSK to NIB Instruction

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

Patrick Schaefer wrote:
> Bryan Parkoff wrote:
>
> >     No, it won't work.  NIB is always write-protected.  Only Apple 
> > Emulator for PC (Apple PC?) can do this, but I tried all the 
> > procedures to copy two dsk images into one nib image using SST in 
> > emulator.  It failed.
>
>
> It works fine with AppleWin running Copy II plus 7.4. I've used this 
> procedure a few years ago to backup my Apple III disks.
>
> Apple used syncronized tracks as a copy protection scheme, therefore a 
> simple .dsk file could not be used.

Since .nib files don't preserve track alignment, and most emulators
don't emulate track alignment in any case, it must not be track
alignment that Apple used for copy protection.

It is much more likely that they used non-standard prolog/epilog
nibbles or an intentional checksum error on some sector.  A .nib
representation would support this simple scheme, while, of course,
a .dsk will not.

No one has mentioned the many programs that used fractional tracks
as part of a protection scheme.  Any new low-level format for Apple
disks should support fractional/spiral track schemes as well.

There is little motivation to move to a new format unless it is truly
universal.

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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