Re: SOS file system information

[schmidtd <schmidtd@my-deja.com>]

On Mar 23, 3:08 pm, Toinet <antoine.vig...@laposte.net> wrote:
> To be honest, the idea is to add a SOS File System Translator for GS/
> OS. Not now, not tomorrow but later. I have so many things to do
> before.
>
> But, SOS disks need to be identified. It can be with a checksum of
> block 0, check some bytes in the volume directory, etc. That's why I
> needed such information.

Define a SOS disk, please?  I would say that there isn't a difference
between SOS and ProDOS, as far as filesystem structures go.  They're
the same thing.  I put out ADTPro for both SOS and ProDOS on the same
disk image.  The same image boots in an Apple /// and in an Apple II.

> I'm a little bit lost with block 0 (ProDOS) vs block 1 (SOS) - Let's
> take an example: imagine I own an Apple I!/ and I also have some
> disks. Am I right to say that the boot driver loads block 0 of the
> disk or are there the two blocks (ProDOS and SOS) on such disks?

I don't know how the /// knows to branch away from block 0 and go and
grab block 1.  The ROM simply loads and runs block 0 from the very
first byte.  There's magick that happens to load up the next block, I
guess.  Must be part of the ProDOS loader...

If you insert a disk that has only a SOS boot block in block 0, it
will just spin in a II.