John Barnes

The mbr looks up in its tables the active partition and reads the boot
sector for the bootloader, which has to be on that (system drive) for
Windows. If it is XP it points to ntldr, if Vista to the boot file. As far
as ntldr is concerned, that performs several functions one of which is to
read the boot.ini and either goes driectly to the boot drive in the boot.ini
or presents the menu to select from multiple boot drives. On the boot
partition it loads the ntoskrnl.exe and hal.dll starting XP. Don't know
the process for Vista.


"David Wilkinson" <no-reply@effisols.com> wrote in message
news:OLQaTv49GHA.4468@TK2MSFTNGP05.phx.gbl...
> John Barnes wrote:
>
>> Don't stay out of responding. The sources I have read indicate the mbr
>> is different so I suggested adding that step. Very little information
>> about the Vista boot process seems to be available still, let alone
>> authoritative.
>>
>
> When XP alone is installed, the MBR on the first bootable disk points to
> the boot sector of the XP partition. If you now install Vista on another
> partition (perhaps on a different hard drive) then (as I understand it)
> the boot files on the XP partition get modified, but the MBR still points
> to the boot sector of the XP partition (as it has to, or nothing would
> boot). Now there may be technical differences in the MBR after Vista is
> installed, but the key information on where to look for the boot files
> must be the same.
>
> Otherwise, boot managers like Ranish ot BootIt NG (BING) would not work,
> because they operate by modifying the MBR to a "standard MBR" which points
> to the boot sector of the selected OS. Any other info in the MBR (except
> the partition table of course) cannot therefore be crucial.
>
> BTW, all these things are much easier to do if you use a third party boot
> manager. I highly recommend BING. You can just forget about NTDLR and the
> Vista boot loader and all that stuff. Each OS is installed separately, and
> you can install or reinstall them in any order. I'm not sure if BING can
> recover from a situation where both XP and Vista are already installed,
> but it is possible. Certainly you can use it if you already have one OS
> installed.
>
> David Wilkinson