Re: Questions about IIGS, hard drives, and booting different OSes...

["Warren Ernst" <wernst@gmail.com>]

Well, to wrap this up (at least from my perspective), after conducting
many, MANY tests with GS.OS 6.01, I can state, with high certainty,
that GS/OS 6 (and therefore, probably 5.04, and 4.x) is hard-coded to
look at Drive 1 from an actual, non-phantom slot when booting.

My evidence:

I installed GS/OS 6 onto all 4 partitions on a CFFA card. I manually
booted into ProDOS and then manually executed the "PRODOS" file that
gets installed by the GS/OS installer on each of the 4 partitions.

When GSOS on partition 1 was intact, I could execute "PRODOS" on all
the partitions and get a boot. However, if I renamed Partition 1's
/SYSTEM folder to something else, then I would get that file error
described above, even when all the other partitions' /SYSTEM folders
were intact. Furthermore, I could restore Partition 1's /SYSTEM foler
and *delete* all the other partitions' /SYSTEM folders, manually
execite "PRODOS" on the other partitions, and get a working GSOS boot.

Conclusion: the GSOS Boot Loader is automatically looking to Drive 1 on
the booting slot for the /SYSTEM folder, and files therein.

Now things may be different with an Apple SCSI card, RamFast,
MicroDrive controller, Vulcan, Sider, or other hard drive controller,
but I feel pretty confident in this being the case with the CFFA.

Anyway, thanks all, for the assistance and insight.

-Warr



David Wilson wrote:
> David Empson wrote:
> > It has been a while since I looked into this, but I think the
> > fundamental problem is that there is no information available to the
> > PRODOS bootstrap loader which tells it the drive from which the file was
> > loaded. It can find out which slot was being used courtesy of some zero
> > page variables left behind by the block 0 bootstrap loader (which have
> > to be replicated if the PRODOS file is launched directly).
>
> ProDOS 8 can boot from drive 2 in one circumstance (that I know of).
> According to the IIc technical reference manual, a IIc with the
> original ROM and an external 5.25" drive supports this functionality.
> It does this with PR#7 which results in the following code being
> executed:
>
> c700 dfb $ff ; make it look like slot is empty (1 byte NOP on 65C02)
> c701 lda #$e0 ; slot 6 drive 2
> c703 ldy #1 ; drive 2
> c705 bra $c6fb
> c6fb jmp $c60b
> c60b stx $2b ; SLOTZ
> c60d sta $4f ; BOOTDEV
>
> It looks like the Zero Page location BOOTDEV ($4F) is where the ProDOS
> 8 boot block code looks to find the boot device number and if  the high
> bit is set it knows it was booted from drive 2. I do not know of any
> other controller cards with firmware that support booting from anything
> but drive/partition 1. I am sure it could be written for the CFFA
> firmware if anyone wanted it.