Re: Dual booting ProDOS and SOS

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

On May 19, 12:22 pm, "Jeff Blakeney"
<jeff.blake...@a2central.com.remove-z5i-this> wrote:
> If I remember the thread about this, block 0 is the ProDOS boot block
> and block 1 is the SOS boot block.  On normal ProDOS disks, only block 0
> has any code in it and block 1 is empty so you need to copy the SOS boot
> block 1 from an SOS disk onto a disk which has the ProDOS boot block 0
> (or vice versa).
If your newsreader supports it, here's the deep link to the thread in
question:
http://groups.google.com/group/comp.sys.apple2/tree/browse_frm/thread/d59664f6b69fff97/a71df049fd3e7818

And the interesting part of that thread:
<quote>
SOS doesn't use block 0 and ProDOS doesn't use block 1.

A "dual boot" disk will have the ProDOS boot code in block 0, and the
SOS boot code in block 1.

A ProDOS-only boot disk will have ProDOS boot code in block 0 and
probably zeros in block 1.

A SOS-only boot disk will have SOS boot code in block 1 and probably
zeros in block 0.

A disk which isn't set up to boot either OS (formatted and has a
directory, but no boot blocks) could have arbitrary junk in both
blocks
0 and 1.
</quote>

My problem is... I can't get a disk to actually behave that way.
It'll boot on a II, and it'll get started on a /// - and even complain
of a lack of SOS.KERNEL if one's not present.  If I add one, though,
plus a SOS.DRIVER and SOS.INTERP for it to use, the /// just goes into
a hard loop with a blank screen.  Same behavior on real and virtual
hardware.  I have a dedicated SOS disk with those same three files
that will work just fine in a real ///.