Re: Dual Boot Restore

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From: Patti MacLeod (pam120_at_nospamshaw.ca)
Date: 05/05/04 

Date: Wed, 5 May 2004 17:43:22 -0400

You're very welcome, hawk! I'm glad that everything makes sense now, as yes,
it can be very confusing to understand the diference between boot sector and
MBR when the two terms are used interchangeably (much like the confusion
people have when they see the terms "bootdisk" and "startup disk" used
interchangeably).

Regards, 

-- 
Patti MacLeod
Microsoft MVP - Windows Shell/User
"hawk" <hawk@spamex.com> wrote in message
news:109ilpb9jm40a9f@corp.supernews.com...
> Many thanks Dan and Patti! Everything now makes sense. And I completed
>    Doug's fixboot procedure and everything is back to normal. I didn't
> need to use the debug stuff because I had followed a MS procedure for
> making a WinXP "boot" floppy before I formatted "C". So, I had the
> four files for the root of "C", boot.ini, bootsect.dos, ntldr and
> ntdetect.com. Booting with my WinXP CD and following Doug's procedure
> went without a problem.
>
> Regards, hawk
>
> Patti MacLeod wrote:
> > The very first 512 bytes on a hard drive contains the MBR.......this is
> > located prior to C, D or any other logical drives. The debug command
reads
> > the first sector of "C" drive, not the first sector of the hard drive.
> >
> > It is my understanding that when the Linux Loader (LILO) is written, and
one
> > opts to write it to the MBR (as you can have LILO written to the MBR or
to
> > the boot sector of the partition on which Linux will be installed), the
> > loader overwrites the first 4xx (I know it overwrites an amount in the
four
> > hundred range, I just don't know exactly the amount) bytes of the
> > "DOS-style" (for lack of better terminology) MBR with its own code. Thus
> > everything but the partition table and signature bytes is overwritten by
> > LILO.  That was why you had to restore the DOS-style MBR, by running
fdisk
> > /mbr, when you ditched Linux. The DOS-style MBR doesn't know if there is
> > WIN9x or WINNT-style boot code written in any of the boot sectors of any
of
> > the partitions.....it examines the partition table to find an active,
> > bootable partition, loads that partition's boot sector into memory,
verifies
> > the signature bytes at the end of that partition, then passes control
over
> > to the boot sector of that partition.
> >
> > When you formatted and reinstalled 98, it overwrote, without saving it
> > anywhere,  the NT-style boot code required to boot into XP. This is
because
> > WIN9x doesn't understand dual boot. XP, however, does understand dual
boot,
> > and that is why, when it is being installed in a dual-boot situation, it
> > saves the WIN9x-style boot code as bootsect.dos before it overwrites the
> > boot sector with its own code. I believe the same thing would happen
with
> > the NT-style boot code if you simply used the fixboot command from
Recovery
> > Console, without first saving the WIN9x-style code to bootsect.dos The
> > NT-style boot code would overwrite the 9x-style code without saving it
> > first, rendering XP bootable but not 98.
> >
> > Another, allbeit far more lengthy, method of repairing your dual boot
setup
> > would be to perform a repair (in place upgrade) install of XP, as
described
> > here:
> > http://michaelstevenstech.com/XPrepairinstall.htm
> > The drawback of the above method would be that you would have to
reinstall
> > all updates and service packs that you had previously installed. All
other
> > application data plus user settings would be saved.
> >
> > I don't know if I've helped to clear up the confusion or make things
worse.
> > I hope the former.
> >
> >
> >
> > Regards,
> >
>

Relevant Pages

  • Re: bootsect.bak
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    (microsoft.public.windows.vista.general)
  • Re: bootsect.bak
    ... The exact function of this file has changed with successive generations of Windows, so this answer may not be correct for all versions. ... These are the most basic, most primitive instructions that make the system start to "pull itself up by its bootstraps" - that is, to "boot" itself by starting from zero. ... The Partition Table has room for four 16-byte entries; each of these tells where one partition starts and ends, plus a few bits of information about that partition, including whether it is the one Active partition on that HDD. ... The contents of the boot sector vary, depending on which operating system wrote it onto the hard drive. ...
    (microsoft.public.windows.vista.general)
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  • Re: Dual Boot Restore
    ... D or any other logical drives. ... opts to write it to the MBR (as you can have LILO written to the MBR or to ... the boot sector of the partition on which Linux will be installed), ... bootable partition, loads that partition's boot sector into memory, verifies ...
    (microsoft.public.windowsxp.setup_deployment)
  • Re: Are computer forensics people as stupid as they seem?
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