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Q148637: Windows 95/98 Overwrites Boot-Sector Field on Floppy Disks

Article: Q148637
Product(s): Microsoft Windows 95.x Retail Product
Version(s): WINDOWS:95
Operating System(s): 
Keyword(s): diskmem win95 kbDiskMemory
Last Modified: 28-JUL-2001

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The information in this article applies to:

- Microsoft Windows 95 
- Microsoft Windows 98 
-------------------------------------------------------------------------------

IMPORTANT: This article contains information about editing the registry.
Before you edit the registry, you should first make a backup copy of the
registry files (System.dat and User.dat). Both are hidden files in the
Windows folder.

SYMPTOMS
========

A floppy disk provided by your computer manufacturer (for example, a system
reference disk or flash BIOS update disk) or a floppy disk created by one of
your programs (for example, a backup disk or a copy-protected program
installation disk) may not be recognized as a valid disk after being accessed in
Windows using Windows Explorer, a command prompt, or another program.

Programs designed to use the disk may report that it is either unrecognizable or
damaged, or you may be asked to insert a valid disk when the correct disk is
already in the disk drive.

This problem is known to occur with the following disks:


- IBM Reference Disks and Flash BIOS Update Disks

  After accessing an IBM Flash BIOS Update Disk in Windows 95, you may receive
  the following error message when you attempt to flash your BIOS with the
  disk:

  Invalid flash diskette


CAUSE
=====

The tool that created the floppy disk uses a boot-sector field that is used by
Windows. On floppy disks that are not write protected, Windows writes a unique
volume identification number to the OEMName field (offset 0x03, or 0003h) of the
boot sector for use by Volume Tracker (Voltrack.vxd). Volume Tracker ensures
that the correct disk is in the drive and reports improper disk removal or
insertion.


RESOLUTION
==========

To prevent this problem from occurring, use one of the following methods.

Write-Protect the Disk
----------------------

If you do not need to write to the floppy disk, set the disk's write- protect
tab. On write-protected disks, Volume Tracker caches the disk's label, serial
number, and BIOS Parameter Block (BPB), instead of writing to the boot-sector
OEMName field.

Add Boot-Sector ID to the NoVolTrack Registry Key
-------------------------------------------------

NOTE: For information about how to edit the registry, view the Changing Keys And
Values online Help topic in Registry Editor (Regedit.exe). Note that you should
make a backup copy of the registry files (System.dat and User.dat) before you
edit the registry.

WARNING: Using Registry Editor incorrectly can cause serious problems that may
require you to reinstall Windows 95. Microsoft cannot guarantee that problems
resulting from the incorrect use of Registry Editor can be solved. Use Registry
Editor at your own risk.

If your hardware vendor or program writes a unique string to the boot sector to
identify the disk, add the string and boot-sector offset location to the
following registry key:

  HKey_Local_Machine\System\CurrentControlSet\Control\FileSystem\ 
  NoVolTrack

To accomplish this, add a binary value (use the hardware vendor or program name
for the value name) to the registry key with the value data in the following
format:

  <xx> <yy> <zz zz zz zz zz zz zz zz>

where <xx> <yy> is the offset in the boot sector where the
vendor-specific string is located (written in reverse-byte format), and <zz
zz zz zz zz zz zz zz> is the vendor-specific string in hexadecimal.

For example, if the vendor-specific string is "PVBACKUP" at offset 0003h,
<xx> is 03 and <yy> is 00 (because 0003h is written 03 00 in
reverse-byte format). In this case, the value for <zz zz zz zz zz zz zz
zz> is 50 56 42 41 43 4b 55 50 (the hexadecimal equivalent of "PVBACKUP").

NOTE: The "PVBACKUP" string in this example is already included in the default
NoVolTrack key created by Windows 95 Setup.

Volume Tracker scans the NoVolTrack key and does not write to the boot- sector
OEMName field of floppy disks specified in the key.


Note that you can create a text file with a .reg extension that includes the
appropriate settings to add to the NoVolTrack key. You can merge the .reg file
into the registry using Regedit.exe or batch Setup (Msbatch.inf). This can be
helpful when you need to add a NoVolTrack entry on multiple computers.

The contents of the .reg file should be

  REGEDIT4

  [HKEY_LOCAL_MACHINE\System\CurrentControlSet\control\FileSystem\ 
  NoVolTrack]
  <VendorName>=hex:<xx>,<yy>,<zz,zz,zz,zz,zz,zz,zz,zz>

where <VendorName> is the manufacturer name and <xx>, <yy>, and
<zz,zz,zz,zz,zz,zz,zz,zz> are as defined above.

NOTE: The registry key should be on one line. It appears on two lines above due
to limited space.

For IBM Flash BIOS Update Disks, the following .reg file should be merged:

  REGEDIT4

  [HKEY_LOCAL_MACHINE\System\CurrentControlSet\control\FileSystem\ 
  NoVolTrack]
  "IBM flash disk"=hex:03,00,49,42,4d,20,35,20,33,66

NOTE: The registry key should be on one line. It appears on two lines above due
to limited space.


Use Only MS-DOS Mode to Access the Disk
---------------------------------------

Do not access the floppy disk from Windows. If you need to access the floppy disk
only in MS-DOS mode, specify MS-DOS mode in the program information file (PIF)
that runs the program you use to access the disk, or boot to a command prompt to
access the disk. Windows does not perform volume tracking in MS-DOS mode.

WARNING: This resolution assumes that you will never access the disk, or view its
contents, from Windows (using Windows Explorer, a command prompt, or another
program). If you do, the OEMName data will be overwritten for Volume Tracker.

MORE INFORMATION
================

If you can no longer access the floppy disk, contact the manufacturer for a
replacement disk.


REFERENCES
==========

Microsoft Windows 95 Resource Kit, "Assigning Drive Letters for Removable
Media," page 652


======================================================================
Keywords          : diskmem win95 kbDiskMemory 
Technology        : kbWin95search kbWin98search kbZNotKeyword3 kbWin98
Version           : WINDOWS:95

=============================================================================

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