The MBR *is* different but the articles that you quote are incorrect, or
at least partially incorrect. See inline below.
Timothy Daniels wrote:
[Snip]
(
http://apcmag.com/5485/dualbooting_vista_and_xp):
"The Windows XP bootloader gets installed to the MBR
and Vista can no longer boot." [......]
No it doesn't, that article has technical errors or that particular
passage is incorrect. No one disputes that the MBR is rewritten when
you install a Windows Operating System, that is a well known fact but
the XP boot loader is NTLDR and it does not reside in the MBR. You can
take a Windows 98 boot disk and rewrite/replace the XP MBR with the
Windows 98 MBR and the newly written MBR will still be able to boot
Windows XP, proof enough that the XP boot loader is not installed or
does not reside in the MBR!
And following the link to
http://apcmag.com/5485/dualbooting_vista_and_xp#restoring ,
we have:
"Restoring Vista and dual booting
"Because you can't use the Windows XP bootloader to boot
Vista, we have to reinstate Vista's bootloader to the MBR
and configure it to manage both operating systems."
That is only half ass correct. You have to restore the Vista MBR but
the Vista boot loader itself is not in the MBR. The reason why you need
to change the MBR is not really evident, but it is not completely due to
the boot code requirements.
This view is seemingly supported by Microsoft's own
online documentation
(
http://support.microsoft.com/kb/919529/en-us):
"When you install an earlier version of the Windows operating
system on a Windows Vista-based computer, Setup overwrites
everything from the MBR, the boot sector, and the boot files.
Therefore, the earlier version the Windows operating system
loses forward compatibility with Windows Vista." [.......]
"RESOLUTION
"To resolve these issues, follow these steps.
[snip]
1. Use Bootsect.exe to restore the Windows Vista MBR and
the boot code that transfers control to the Windows Boot
Manager program. To do this, type the following command
at a command prompt: Drive:\boot\Bootsect.exe /NT60 All"
Confusing to say the least. I would have to do some tests to see what
is really going on with the bootsect.exe tool. Keep in mind that
Microsoft is famous for changing terminology and for saying one thing
one day and seemingly the opposite the next day! If you read here:
Bootsect Command-Line Options
http://technet2.microsoft.com/Windo...b66f-4b42-9563-04c218a1a6ac1033.mspx?mfr=true
You will read:
"Bootsect.exe updates the master boot code for hard disk partitions to
switch between BOOTMGR and NTLDR. You can use this tool to restore the
boot sector on your computer. This tool replaces FixFAT and FixNTFS."
The Master Boot Code refers to the MBR IPL and if you search the
Microsoft site you will see that Microsoft specifically refers the
"Master Boot Code" as the MBR IPL too:
http://search.microsoft.com/results.aspx?mkt=en-US&setlang=en-US&q="master boot code"
Yet we know, or we thought that we knew that the Boot Sector is/was the
first sector of a partition or volume! Again, if you search the
Microsoft site for "Boot Sector" you will get all kind of differing
results but as far as booting NT versions the Boot Sector has always
been used to refer to the location of the Partition Boot Code, as
described here:
http://www.microsoft.com/technet/pr...serv/reskit/prork/prcb_dis_stfl.mspx?mfr=true
In that article you can read:
"If the boot device is on a hard disk, the BIOS loads the MBR. The
master boot code in the MBR loads the boot sector of the active
partition, and transfers CPU execution to that memory address. On
computers that are running Windows 2000, the executable boot code in the
boot sector finds Ntldr, loads it into memory, and transfers execution
to that file." (Vista bootstraps in much that same manner, but, for
lack of a better term, there are new "layers" in the MBR.)
So go figure! With conflicting statements like the ones found in the
Bootsect.exe or other Vista articles and Microsoft continually changing
or interchanging the terms it is no small wonder that confusion reigns!
The plain facts are that sometimes you can't know for sure from one
day to the next what Microsoft means when they say something, it's like
going to see your mechanic and from one day to the next he changes the
meaning of the mechanical terms for your car! With that kind of
confusion there is no way of knowing for sure what exactly it is that
bootsect.exe does! The way I read it it appears quite evident that it
changes the (Partition) Boot Sector but it's not clear what exactly, if
anything, it does to the MBR. Maybe it changes both, but at this time I
don't know for sure if it actually changes the MBR. To add yet more
confusion you can read here:
How to use the Bootrec.exe tool in the Windows Recovery Environment to
troubleshoot and repair startup issues in Windows Vista
http://support.microsoft.com/kb/927392
there you will read that the "boot sector" clearly refers to the
Partition Boot Sector.
But it turns out that "bootsect.exe" just restores the boot sector
unless the option "/fixmbr" is added.
There is no /fixmbr switch for bootsect.exe. I think that some of the
conflicting information on the web is due to the fact that much of the
information may have been written when the Vista Release Candidates were
being experimented with.
Bootsect Command-Line Options
http://technet2.microsoft.com/Windo...b66f-4b42-9563-04c218a1a6ac1033.mspx?mfr=true
So at one time, the MBR of Vista differed from the pre-Vista MBRs,
but when Vista was finally released, it had the old MBR.
I'm not sure what you mean by "old MBR", what is the "old MBR"?
As for the new MBR "layers" you might find the information in the white
paper here interesting:
Custom Bootstrap Actions in Windows Vista
http://www.microsoft.com/whdc/system/platform/firmware/OEMBoot_Vista.mspx
In the Vista MBR and the boot process there is a bit more than the old
routine of the Master Boot Code simply passing the instructions to the
Partition Boot Code, there is a whole new element that isn't used at all
on older NT versions! The paper will explain in part why a previous
Microsoft MBR cannot (or might not?) boot Vista. One thing for sure,
with the exception of certain hardware constraints the NT boot process
has changed little from NT3.51 through to XP, the Vista boot process is
entirely different, it brings in some never seen before concepts, at
least never seen before on Microsoft operating systems. This is no
longer the same "old" NT boot process!
John