Microsoft KB Archive/148637

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

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Q148637

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The information in this article applies to:


 * Microsoft Windows 95
 * Microsoft Windows 98

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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:

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

For example, if the vendor-specific string is "PVBACKUP" at offset 0003h,  is 03 and  is 00 (because 0003h is written 03 00 in reverse-byte format). In this case, the value for  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:

<pre class="FIXEDTEXT">  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.