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Re: [vox-tech] rescuing winxp?
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Re: [vox-tech] rescuing winxp?

On Friday 24 September 2004 12:48, Peter Jay Salzman wrote:
> On Fri 24 Sep 04, 12:21 PM, Mark K. Kim <lugod@cbreak.org> said:
> > On Fri, 24 Sep 2004, Rick Moen wrote:
> > > That is correct.  SYS.COM copies several files (io.sys, command.com,
> > > msdos.sys, and at least one other that I've mercifully forgotten about)
> > > with the read-only, hidden, and system flags set, to the indicated FAT
> > > filesystem.  One of those gets written to a specific physical location
> > > so as to be findable by the Int13h boot service, early in the boot
> > > process
> >
> > [snip]
> >
> > Starting at some DOS version, the physical location thing became no
> > longer necessary.  I'm not sure which version but somewhere around DOS
> > 4-ish. Apparently the DOS bootstrap code became smarter and figured out
> > ways to search for those files in the FS.  As a consequence, the "system"
> > flag on those system files (which tells the OS and utility tools like
> > Norton and PC Tools not to move those files from their physical location)
> > no longer became necessary as they were before.
> >
> > To re-install the MBR, another important component for booting DOS and
> > Windows, uses FDISK's *undocumented* flag:
> >
> >   FDISK /MBR
> >
> > Once I told someone to do that over the phone and he freaked out (because
> > "FDISK is dangerous!")  I'm not sure if he had the guts to go through
> > with it...
> >
> > -Mark
> >
> >From Rick's earlier posts, it sounds like all the nameless MS 0th order
> bootloader does is pass control to the zeroth sector of the bootable
> partition.
> Does that mean that XP has the same MBR as Win95?
> What I'm getting at is, can I use an old DOS fdisk to rewrite a MBR on a
> Win XP machine?

As I recall, all fdisk /mbr does is takes a copy of master boot record from 
some backup location and places it in the master boot record of the drive.  

I think this is why fdisk /mbr won't remove lilo very easily(as lilo installs 
itself into the mbr as well as the backup location) 

or maybe I'm clueless, but when my mind saw "fdisk /mbr" it came up with that.  

Mike Wenk
vox-tech mailing list

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