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>> > Good Morning and a Happy Y2K to all. Not so nice to start the
>> new year with a problem but here it goes... > > I've installed
>> Linux on a second partition on the hard drive. Not on this
>> computer but on a laptop that I also use. Unfortunately I was
>> so STUPID to put the Lilo boot record in the MBR (Master Boot
>> Record) of Windows. So now I can't boot Windows anymore. Linux
>> still recognize the Windows FAT32 partition:
>> IIRC, boot the floppy you made when you installed Win9x. At
>> the command prompt, say: "fdisk /mbr". This will install the
>> Win9x master boot record. YMMV.
Jeff> As I understand it, "fdisk /mbr" will just clear out the
Jeff> mbr. You need to boot from a Windows diskette and do a "sys
Jeff> c:" (or whatever), to get the Windows loader back into the
FDISK /MBR Rewrites the Master Boot Record
The information in this article applies to:
Microsoft MS-DOS operating system versions 5.x, 6.0, 6.2, 6.21, 6.22
Microsoft Windows 95
Microsoft Windows 98
The MS-DOS Fdisk utility usually updates the master boot record only
if no master boot record exists. Repartitioning with Fdisk does not
rewrite this information.
Fdisk has an undocumented parameter called /MBR that causes it to
write the master boot record to the hard disk without altering the
partition table information.
WARNING: Writing the master boot record to the hard disk in this
manner can make certain hard disks partitioned with SpeedStor
unusable. It can also cause problems for some dual-boot programs and
disks with more than four partitions.
What is the MBR?
At the end of the ROM BIOS bootstrap routine, the BIOS reads and
executes the first physical sector of the first floppy or hard disk
drive on the system. This first sector of the hard disk is called
the master boot record (or sometimes the partition table or master
boot block). At the beginning of this sector of the hard disk is a
small program. At the end of this sector is where the partition
information, or partition table, is stored. This program uses the
partition information to determine which partition is bootable
(usually the first primary DOS partition) and attempts to boot from
This program is what is written to the disk by FDISK /MBR and is
usually called the master boot record. During normal operation,
Fdisk writes this program to the disk only if there is no master
Why is the MBR Changed During Setup?
During installation of Microsoft MS-DOS Upgrade, Setup replaces the
master boot record on the hard disk with code to display a message
similar to the following:
The MS-DOS 5.0 Setup was not completed. Insert the UNINSTALL #1
diskette in drive A. Press the ENTER key to continue.
This message should be erased and the master boot code rewritten
before Setup is completed. If a problem occurs during Setup and you
return to the previous version of MS-DOS, UNINSTAL should also
remove this message. However, if Setup or UNINSTAL fails to remove
this message, or if the master boot record becomes corrupted, a new
master boot record can be written to the disk using the following
This option should NOT be used if any of the following conditions
The disk was partitioned using the Storage Dimensions SpeedStor
utility with its /Bootall option.
More than four partitions exist.
Certain dual-boot programs are in use.
The Storage Dimensions SpeedStor utility with the /BOOTALL option
redefines the drive's physical parameters (cylinder, head, and
sector). /BOOTALL stores information on how the drive has been
changed in an area of the master boot record that MS-DOS does not
use. The FDISK /MBR command erases that information, making the disk
Some older original equipment manufacturer (OEM) versions of MS-DOS
and some third-party partitioning utilities can create more than
four partitions. Additional partition information is commonly stored
information on partitions in an area that FDISK /MBR overwrites.
Some dual-boot programs have a special MBR that asks you at startup
which operating system you want to use. FDISK /MBR erases this
program. Dual-boot systems that boot whichever partition is marked
Active are not affected by FDISK /MBR.
For more information on partitioning, query on the following word in
the Microsoft Knowledge Base:
SpeedStor is manufactured by Storage Dimensions, a vendor
independent of Microsoft; we make no warranty, implied or otherwise,
regarding this product's performance or reliability.
More information on partitioning, disk organization, and the boot
sequence can also be found in Chapters 3 and 8 of the "DOS
Programmer's Reference" by Terry Dettmann, published by the QUE
Corporation; Chapters 2 and 10 of "Advanced MS-DOS Programming" by
Ray Duncan, and article 3 of "The MS-DOS Encyclopedia," both
published by Microsoft Press.
Additional query words: 6.22 5.00 5.00a 3rdparty third-party third
party 6.00 6.20 coherent \* yeswin4
Keywords : kbtool msdos win95 win98
Issue type : kbinfo
Article ID: Q69013
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"For example, I've always liked PowerPoint, and I've always thought
that Visual Basic was a good product." -- Linus Torvalds
Michael Powe Portland, Oregon USA
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