Re: Booting from drive#2

[dempson@actrix.gen.nz (David Empson)]

J. L. Walters <bird@MCS.COM> wrote:

> In article <591inr$2tl@news.ysu.edu>,
> Adalbert Goertz <be404@yfn.ysu.edu> wrote:
> 
> > is it possible ( and how?) to boot GSOS601 from drive#2
> 
> It is NOT possible to boot anything from drive 2 without MASSIVE
> modifications to the boot ROM code. Feel free to do so and post the
> results.

It depends what machine and operating system you are talking about.

DOS 3.3 is heavily dependent on drive 1.  It has to be patched at
several stages in the boot sequence to be able to boot from drive 2.

ProDOS-8 is able to be booted from drive 2, if the firmware supports it.
The original IIc firmware can boot ProDOS from an external 5.25" drive
(S6,D2) if you use PR#7.  Later firmware versions removed this feature.

I'm not sure whether Apple Pascal is able to boot from drive 2 (given
patched firmware, or manually booting), but I doubt it.

GS/OS cannot be booted from drive 2, unless the boot loader (PRODOS file
in the root directory) is modified (and you would still have the problem
of booting from drive 2, which requires firmware changes or manually
loading the boot sector).  There may be problems later in the boot
process when the device drivers start up.

It may also be necessary to patch the boot sector to enable booting off
drive 2 for devices other than 5.25" drives (and GS/OS cannot be booted
from a 5.25" drive).

Some of these issues are avoided if you simply launch the PRODOS file on
drive 2 after booting into ProDOS-8 from drive 1.


In summary: it may be possible to boot GS/OS from drive 2, but doing so
would be very hard, and I don't think you'd gain much out of it.


The only useful reason I can think of for supporting this would be to
have two versions of GS/OS on the computer, and there are programs which
allow this to be done on a single hard drive partition.

If the reason for wanting to boot off drive 2 is because drive 1 is not
booting, then swap the drives over or remove drive 1.

-- 
David Empson
dempson@actrix.gen.nz
Snail Mail: P.O. Box 27-103, Wellington, New Zealand