Message-Id:	<s481fa35.085@calderauk.com>
Date:	Sun, 30 Nov 1997 23:43:40 +0000
From:	Matthias Paul <MPaul AT calderauk DOT com>
To:	opendos AT delorie DOT com, sarlok AT geocities DOT com
Subject:	Re: Booting from 2nd HD
Mime-Version:	1.0

On 97/11/30 Jonathan Anderson asked:
>With all this talk about multi-OS loading, does anyone know how to get
>OpenDOS, MSDOS, or Windows 95 to boot from the second physical hard
>drive?
AFAIK, there s no way with MS-DOS or Windows95. 

But OpenDOS 7.02 BETA2+ in general supports the boot from any physical
drive. The problem is, that most ROM-BIOSes (ROS) only support booting
from C: or A:. If you happen to be one of the lucky ones with a ROS supporting
the boot from other drives, this should work (at least for IBMBIO.COM and 
IBMDOS.COM). There are also some boot loaders that do support loading
the OS from other drives. (I have heart that Linux  LILO does support this, but
I have not tested it myself.) LOADER also has an undocumented option /C
to install on drive D:, but I have not used it myself and cannot supply further tips.
Personally I have developed an utility called BOOTLOAD which is an auxilliary driver for LOADER, displaying a menu with all physical drives to choose from
(including "El Torito" drives like ATAPI/SCSI CD-ROM, ZIP-100, or LS-120).
However, this tool is not yet ready for release.

A general problem when booting from other drives than A: or C: is, that (depending on your boot loader) in most cases you need a MBR and/or
boot sector also supporting this feature. Unfortunately, the current MBR code of
OpenDOS does not fully address this (and the boot sector code depends on
the drive unit been used for its creation), so you usually need to patch at least
the MBR code (My BOOTLOAD can patch the boot sector code in memory,
but cannot patch most of the MBRs). In these cases, the MBR on drive D: 
will usually still load the IBMBIO.COM file from C:, which than - of course - also 
loads IBMDOS.COM and the configuration files from C:. If you find a way to
directly load IBMBIO.COM from D: (not using the MBR, or boot sector code), 
the BIOS kernel will load IBMDOS.COM and the configuration files from D: (or any other drive reported to it as boot unit). 

After all, at the moment you need some expertise to get it running... 

Matthias

------------------------------------------------------------
Matthias Paul
eMail: <Matthias DOT Paul AT post DOT rwth-aachen DOT de>
Web: http://www.rhrz.uni-bonn.de/~uzs180/mpdokeng.html

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