Re: floppy disk change (was Re: 1.15 kernel)

[Julian Reschke-FJR010 <Julian_Reschke-FJR010@email.mot.com>]

A.Kielhorn@tu-bs.de%INTERNET wrote:
> 
> At 1:21 Uhr +0200 20.05.1998, Konrad Kokoszkiewicz wrote:
> 
> >To not screw up the filesystem on a changed diskette when you copy
> >something to it while the system doesn't even know you changed it. Which
> >occurs actually quite often (or: would if you weren't aware that disk
> >change detection is broken in most ataris).
> 
> Save one wire, we can always do it in software!
> 
> >> TOS uses a checksum for sector 0-6 (IIRC) to decide if the disk was really
> >> changed or not. Sector 0 alone is not a sure indication, as it may be
> >> identical on different disks.
> >
> >Yes, I know the theory about TOS behaviour (I read the doc for FLOPFIX).
> >The problem is that it DOES NOT WORK. And it is quite unlikely for the
> >sector zero to be identical on two diskettes (each has 32 bit random
> >serial number generated while formatting).
> 
> Many early formatters used *the same* serial number for every disc. And I'm
> sure I still have some old discs with identical numbers.

Please be aware that where GEMDOS expects a "serial number", MS DOS
expects a disk name. This will be identical for all floppies formatted
under the same DOS version, or bought in one package as "preformatted".
If disk exchange with DOS machines is supposed to work, never never
rely on the serial number.

Regards, jr