Why can’t my computer read my floppy disks? One possibility: disk degradation and/or damage.
Earlier versions of Ensoniq Disk Tools, running on Windows 98 and earlier, were able to makes these calls and read and write and format Ensoniq floppy disks. How, with the advent of the modern Windows operating systems such as XP and Vista, this went away. This is because XP and Vista (and 2000 and NT) no longer use the old MS-DOS operating system. Foolishly, as I have done with other files saved in other formats I thought I could plug my USB floppy drive into my laptop operating Vista and extract and move to my hard drive and hey presto. However on inserting the floppy disk my PC reads that the disks need to be formatted. Not a format that the computer understands.
Note: This article is a quick guide focusing on common floppy disk problems that prevent files being recovered. The target reader is the casual user wanting to check out old disks which have surfaced. If you are a vintage computer hobbyist or enthusiast wanting to take a deep dive into the topic, best check out Herb Johnson’s page.
Figure 1. Forgotten disks from way back. What's on them?
So, you’ve bought one of those cheap USD floppy disk drives to archive those old PC disks which you’ve found at the bottom of the closet. However, things are not going as well as you’d hoped.
Figure 2 - Floppy disk read fail!
You struggle to get even a directory and many times the computer does not recognize the disk is formatted at all. What could be wrong?
Disk, drive or computer?
It’s possible there could be a hardware or driver issue. However, before you start searching the web for hardware solutions and fiddling around with drive alignment etc. consider the MOST likely problem: the media itself. This article discusses disk media and give tips on how to visually assess the health of floppy disks.
What can go wrong with floppy disks
Floppy disks are covered with magnetic storage media. As the years go by this can degrade, lose its magnetic orientation and/or become loose on the mylar surface. Humid conditions can cause fungi to grow on the media. Furthermore, with 3.5 inch floppy disks, the glue sticking the metal hub (at the centre) to the mylar can become unstuck. How quickly all or any of these things happen depends on how well the disks were manufactured in the first place, and how well they have been stored.
So, what are the signs that disk media has a problem? Loose, degraded or damaged media is not always obvious but many times it is! In my experience there are three common visual clues that suggest your disks are not be as good as they once were. These cases are listed below...
Pull back the disk cover (if it has one) so you can see the surface of the disk and rotate it manually. If you see white specs or spots then you have fungi growing on the disk (Figure 3).
Figure 3. Specks of fungi on a 3.5 inch floppy disk
It’s best never to try to read disks that look like this without removing the fungi. This loose material will aggregate on disk drive read/write heads leading to errors. Residue can build up very quickly on the heads, which can then lead to the second problem….
2. Destroyed media (often, but not exclusively, due to problem 1)
Drive heads are only floating a few microns from the disk surface when reading disk contents. Fungi or loose media can build up as a residue on the heads and reduce that gap to zero. Once this occurs the heads make physical contact with the disk! The heads then carve out grooves in the disk, obliterating any magnetic media and with it any data. This damage is often visible on the disk surface as a groove or grooves.
Figure 3a. Grooves carved into a 3.5 inch floppy disk from dirty read/write heads
Figure 3b. Grooves carved into a 5.25 inch floppy disk from dirty drive read/write heads
Often it’s a single groove where the directory track would be. This track is often destroyed first, as a drive with dirty heads will access the same track time and time again looking for directory data. Once the directory is destroyed, files are difficult to reconstruct. Furthermore, a disk drive with dirty read/write heads can become a “destroyer drive” wrecking every subsequent disk which is inserted, even good ones! The heads must be cleaned. If your disks seem free of fungi but suddenly have grooves cut into them after an unsuccessful read, consider that disk drive you bought off e-bay, found in the garage, borrowed from someone or pulled from some ‘90s e-waste might have dirty heads. It just takes one “dirty disk” to turn a drive into a disk destroyer.
3. The hub has come unglued from the mylar disk
This can be a problem with 3.5 disks. Over time the glue used to bind the metal hub in the centre of the disk to the mylar platter can weaken. Eventually, it can become unglued. The hub will spin but the disk won’t.
Figure 4. Detached hub from a 3.5 inch floppy disk
To check, turn the hub manually and check that the disk is moving within its jacket in conjunction with it. Eight and 5.25 inch disks don’t have a metal hub so it’s not an issue with these.
Ok, I have one of these problems. Are the disks a lost cause?
Not necessarily depending on the problem. Fungi can be washed from the surface quite safely using various techniques. Often 100% of the data can be recovered. Destroyed media from a dirty drive head can’t be recovered BUT some files (like text files) can be rebuilt or recovered even if data is missing. I provide a floppy disk file recovery service where I can both remove fungi from disks and/or attempt to recover data from damaged disks. If interested, check it out.
If the hub has come unglued it is virtually impossible to retrieve anything. The hub can be reglued but tolerances are so fine, it’s never in EXACTLY the same place so data is very hard to retrieve. People have done it, but it needs special hardware and software.
As mentioned above, its not always the media that’s at fault and even if it is, there are not always visible signs. However, if the disk media shows the signs described above, then it’s strong evidence the disks rather than the hardware are at fault.
14th January, 2020
When you access a floppy disk, you may receive one of the following error messages:
Disk is not formatted
The disk in drive A is not formatted.
Do you want to format it now?
STOP: The disk media is not recognized, it may not be formatted.
The same disk may work correctly with MS-DOS or Windows 95, or after you re-format the disk with Windows 98, Windows Millennium Edition, Windows NT, Windows 2000, Windows XP, or Windows Server 2003.
Read Old Floppy Disks
This problem occurs on disks that do not contain a media descriptor byte in the BIOS parameter block (BPB) of the boot sector. Some older preformatted floppy disks do not contain a media descriptor byte. Older product disks may also not have the media descriptor byte.
The media descriptor indicates the type of medium currently in a drive. With MS-DOS and Windows 95, you do not have to set the media descriptor byte. Therefore this problem does not occur with these older operating systems.
The media descriptor byte is located in the BPB of the boot sector at offset 21 (15h) and in the first byte of each FAT on the disk.
To resolve this problem, re-format the floppy disk with Windows 98, Windows Millennium Edition, Windows NT, Windows 2000, Windows XP, or Windows Server 2003.
Warning: This workaround is for advanced users only. This workaround involves using a disk sector editor to modify the media descriptor byte on the floppy disk. Misuse of a disk sector editor may make all the data on the drive or volume permanently inaccessible. Disk sector editors function at a level 'below' the file system, so the typical checks for maintaining disk consistency do not apply. This provides you direct access to every byte on the physical disk regardless of access credentials. Therefore, you can damage or permanently overwrite critical on-disk data structures. Use this workaround at your own risk.
To work around this problem, use a disk sector editor to change the BPB media descriptor byte to the appropriate value. For example, you can use the DiskProbe tool to do this on a Windows NT 4.0-based, Windows 2000-based, Windows XP-based, or Windows Server 2003-based computer. DiskProbe (Dskprobe.exe) is included with the Windows Support Tools for Windows XP Professional and Windows XP 64-Bit Edition, the Windows 2000 Support Tools, and Windows NT 4.0 Resource Kit Support Tools.
The following table lists the most common media descriptor bytes:
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 ----- Hard disk
The BPB media descriptor byte is located in sector 0 of the disk, and looks similar to this:
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 hexadecimal 21 (15h).
Read Floppy Disk Without Formatting
For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
301423 HOW TO: Install the Windows 2000 Support Tools to a Windows 2000 Server-Based Computer
306794 How to Install the Support Tools from the Windows XP CD-ROM
Floppy Disk Reader
206848 Windows NT Service Pack 4.0 Tools Not Included on CD-ROM