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From: Terry Lambert <terry@lambert.org>
Message-Id: <199605211803.LAA01534@phaeton.artisoft.com>
Subject: Re: Install boo-boo
To: smbrown@cisco.com (Stephen M. Brown)
Date: Tue, 21 May 1996 11:03:09 -0700 (MST)
Cc: questions@freebsd.org
In-Reply-To: <2.2.32.19960521034453.00a3b888@diablo.cisco.com> from "Stephen M. Brown" at May 20, 96 08:44:53 pm
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> Went through the initial boot from boot.flp, creating a freebsd partion on
> wd1 leaving wd0 untouched but choosing the bootmanager option. Didn't
> actually have the distribution but went through the process anyway, perhaps
> my first mistake?
Choosing the boot manager option when installing on a second drive
is a bad thing. The boot manager is written to the first drive. You
must now recover.
There are two potential types of recovery:
1) wd0 did *not* have OnTrack or another MBR based LBA using
INT 13 geometry translator
Identification: You will see one or more valid partitions
when you boot from floppy and run fdisk.
If this is the case, then the standard MBR was overwritten
by the boot selector from BSD. Then, when it went to mark
a partition active, it couldn't find one, and now you have
no active partition.
Fix: boot a DOS floppy and run fdisk. Mark one of the
partitions active. Problem solved.
2) wd0 *did* have OnTrack or another MBR based LBA using INT 13
geometry translator
Identification: You will see one partition when you boot
from floppy and run fdisk. You will not recognize the
partition ID.
Because the BIOS geometry is unknown to BSD because there
is no way to call INT 13 AH=0x08 AL=0x80 from the kernel
(needs a VM86() call gate), the replacement boot selector
MBR overwrote the first part of the OnTRack or other MBR
based LBA using INT 13 geometry translator. You will
need to reinstall it from the disks which came with your
system. There should be an option to allow you to do
this without overwriting the partition table data.
Once this is done, you need to boot DOS from the repaired
drive do that the translator is installed during the boot
process (remember that it was not installed when BSD
wrote the MBR because BSD does not use BIOS to write the
disk). Once you have booted to a DOS prompt (or, for
Windows95, "Start, Shutdown..., Restart the computer in
MS-DOS mode, Yes"), then you can install OS-BS.EXE from
the DOS command line. This will put it over top of the
real DOS MBR, which is at a translated offset instead of
being at te start of the drive.
> Now when the machine starts I get: NO ROM BASIC, SYSTEM HALTED and hangs.
If the ROM POST initialization portion of the boot can't find a
bootable device (by finding a valid boot record with an active
partition), it will attempt to jump to the ROM BASIC location.
Since most machines do not have the ROM BASIC because of licensing
for BIOS clones, it has been replaces with a little code hunk to
print out that message.
You'd get the same message if you unplugged all the hard drives in
almost any PC (almost, because some of them would start BASIC 8-)).
> How do I make the boot disk (C:) available again? Tried doing fdisk /mbr to
> recreate the MBR on the boot disk but no go. Please help.
Bad plan, but you haven't damaged anything irreversably yet.
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.