Error Accessing Floppy Disks Using Windows NT

• Microsoft Windows NT operating system version 3.1
• Microsoft Windows NT Advanced Server version 3.1
• Microsoft Windows NT Workstation versions 3.5 and 3.51
• Microsoft Windows NT Server versions 3.5 and 3.51

SYMPTOMS

When you access a floppy disk from your Windows NT computer, following error message appears:

   STOP: The disk media is not recognized, it may not be formatted.

CAUSE

This occurs on disks that are preformatted or are from a product where the disk manufacturer failed to write the media descriptor byte to the disk.

MS-DOS and Windows 95 do not require the media descriptor byte be set, hence this problem does not show up with these operating systems.

In most versions of MS-DOS, the first sector contains the media descriptor field.

The media descriptor field specifies a value that identifies the type of media that the disk is. Some device drivers use the media descriptor to determine quickly whether the removable media in the drive has changed.

Following are the valid media descriptor bytes for MS-DOS:

   Byte   Capacity   Media Size and Type
   -------------------------------------------------

   F0     2.88 MB    3.5-inch, 2-sided, 36-sector
   F0     1.44 MB    3.5-inch, 2-sided, 18-sector
   F9     720K       3.5-inch, 2-sided, 9-sector
   F9     1.2 MB     5.25-inch, 2-sided, 15-sector
   FD     360K       5.25-inch, 2-sided, 9-sector
   FF     320K       5.25-inch, 2-sided, 8-sector
   FC     180K       5.25-inch, 1-sided, 9-sector
   FE     160K       5.25-inch, 1-sided, 8-sector
   FE     250K       8-inch, 1-sided, single-density
   FD     500K       8-inch, 2-sided, single-density
   FE     1.2 MB     8-inch, 2-sided, double-density
   F8     -----      Fixed disk

   addr  data:
   0000  EB 3C 90 4D 53 44 4F 53 35 2E 30 00 02 01 01 00
   0010  02 E0 00 40 0B F0 09 00 12 00 02 00 00 00 00 00
                        xx <---- This byte above XX is the media descriptor
                                 byte and is at offset hex 15.