Summary: Having problems reading some old 5.25" floppies. Looking for advice on what else I can try before declaring the disks un-retrievable and giving-up.


I recently found a box of old 5.25" DSDD floppy disks dating for the about 1988-89. They are MS-DOS FAT format. They seemed in good physical condition and I don't think they'd been stored near strong magnetic fields or in extreme temperatures, so I decided to have a go a reading them. I acquired an old Compaq Deskpro 5100 XL (which as a 5.25 capable floppy controller and BIOS) that was about to be dumped and bought a reconditioned Canon MD5201 360kb drive and a new floppy cable off ebay.

I fitted the 5.25" drive and connected it and the existing 3.5" using the new cable and replaced the bios battery. The bios recognizes the 5.25" drive as drive B. The PC only has 16mb of memory so I installed NT4 SP6 on the hard drive.

The 5.25" drive spins-up when I insert a disk, and if I try to view the contents of the disk using NT file explorer then the drive access light illuminates. After about a minute I get an error dialog saying "B:\ is not accessible. The device is not ready." This happens for each disk. I decided to sacrifice one of the disks by formatting it but get the same error. If I boot the machine into dos then I get "Not ready reading drive B" when I try to read any of the disks.

I think the most likely explanation is that the disks just aren't readable after all this time. But I find it suspicious that (a) all the drives have completely failed in apparently the same way, and (b) a pack of 3.5" disks that were stored with them are perfectly readable.

I've tried using a different (old) floppy cable and a 1.22MB Teac floppy drive instead, with the same results.

Can anyone suggest anything else I should try (software/hardware) before giving up?

Edit 1: Clarified that they are MS-DOS disks

Edit 2: I had to leave this for a while, but I have now followed-up all the suggestions made by those who helpfully left answers and/or comments. After trying two different drives with every combination of cables, socket positions, and jumper settings, I've come to the conclusion that the floppies just aren't recoverable. Unfortunately this was always the most likely outcome. Thanks to all those who provided advice when there wasn't likely to be a simple answer that I could accept. I have up-voted the answers that were useful.

  • do you get any layout info on them using say Fdisk ? "display partition information" ? or a partition program that could see the layout? – Psycogeek Oct 9 '11 at 17:03
  • After booting in dos, fdisk only gives me information about the hard drive. NT reports the floppies as having an unknown file system. – Andy Johnson Oct 9 '11 at 18:15
  • @Psycogeek: floppy disks do not have a partition table, it's a boot sector + filesystem after that. fdisk won't work on floppies, so this indicates nothing about the problem. – haimg Oct 9 '11 at 18:49
  • @haimg I was trying to think of the oldest tool that would still reside in the newer OS that could show any aspects of the file system. Your right though, it might have run from a floppy and worked with dos disks, but it never partitioned a floppy :-) – Psycogeek Oct 9 '11 at 19:19
  • Keep in mind that the diskettes may be recorded single-sided, even if labeled double-sided, and may be recorded at any one of at least three (maybe 4) different densities. – Daniel R Hicks Oct 9 '11 at 21:24

5 1/4" disks were notorious for losing data. Don't need to store them near a magnetic field, they can self-demagnetize. The next problem is that tracks are located by a stepper motor. This means that you might actually need the original drive that wrote them in order to read them. Tape drives and floppy drives go out of tolerance as they wear. Conversely, they could have been written in a drive that was dead on in calibration, but your current drive is out of spec despite the supposed refurbish and can't read them.

I'd find someone with a known working 5 1/4" drive and see if they can read them. This will tell you if your drive is dead. You've done the only other thing I can recommend and that was to try a different drive and cable. As long as you got the arrow, red stripe and pin 1 lined up on the motherboard header socket (important for the ones that didn't have a key), it was relatively hard to hook up anything wrong on the 5 1/4 drives with the edge connector. 3 1/2" drives were notorious for getting things connected up wrong.

  • Thanks! I can't hear any stepper motors when I try to access the disk - I'd expect the hear them moving the heads as they try to locate the tracks. Unfortunately no-one I know has a working 5.25 drive. – Andy Johnson Oct 9 '11 at 18:05
  • In your bios, check to see if Floppy Drive seek on boot is enabled. With it enabled, you will hear each drive do a track 0 seek on boot. – Fiasco Labs Oct 9 '11 at 22:31

You may have to inspect and configure the floppy drive. Old hardware is not plug-n-play.

There are often four (4) jumpers for drive select. You should (always) use "drive 2", the second of the four positions, when you have a floppy cable that uses the cut & twist on the drive select lines.

There may be terminating resistors, especially if it is a really old floppy drive. Later model floppy drives had electronics that automatically "terminated" the line. Since you have only one floppy, the terminating resistor pack must be installed (if necessary), and the last or end connector of the cable should be used (when there is more than drive connector).

Go into the BIOS setup menu, and verify the the floppy drive is setup for 5 1/4 DS/DD. The "modern" default configuration is for 1.44 MB 3.5".

EDITED drive select jumper info.

  • Thanks for the reply! there are actually two floppies. The 5.25" drive has four jumpers, which I assume are the drive select. Since I'm using it as drive B: I moved the jumper to the second position and plugged it into the FDD cable before the twist. The existing 3.5" drive is A: and is connected to the FDD cable after the cable twist. Is this use of the cable correct? I tried all the other jumper positions but they just resulted in floppy controller errors at power-up, so I assume that the second jumper position is correct. How would I recognise "terminating resistors"? – Andy Johnson Oct 9 '11 at 22:26
  • Often the terminating resistor was a SIP resistor network on the 5 1/4" floppies with last on the chain having termination and middle having none (gently pull it out of the machine pin socket, later drives, set jumper). All the systems from this era that I worked with would always set the drive selects the same on both drives and then use a cable with a half twist on a set of wires between the floppy connectors. Later, when 3 1/2" became defacto standard, they started producing straight cables and changing the jumpers for drive select 0 for A and 1 for B. – Fiasco Labs Oct 9 '11 at 22:27
  • @FisacoLabs I have the 5.25" as B before the twist and the 3.5" as A: after the twist, and the jumper on the 5.25" set to the second position. Are you saying it (maybe) should be on the first position because the cable does the drive select? – Andy Johnson Oct 9 '11 at 22:34
  • Yes, drive select is done by the cable twist. Later floppy cables didn't have a twist, so you had to use the jumpers. – Fiasco Labs Oct 9 '11 at 22:50
  • I tried the jumper on position 1 but then the drive access light didn't even light when I tried to access the B: drive. When I moved it back to position 2 the light comes on again. – Andy Johnson Oct 9 '11 at 22:54

Could be that the data cable connector is not connected properly (turned by 180 degrees). If this is the case, floppies inserted may be erased!

  • Thanks kif. I'm sure its the right way around because the 3.5" drive on the same cable works ok. – Andy Johnson Oct 9 '11 at 16:22
  • Also, when I did try reversing the cable none of the drives were recognised by the bios. – Andy Johnson Oct 9 '11 at 16:29
  • "Same cable"??? 3.5" floppy drives do not have the same type of connector as 5.25" floppy drives. – sawdust Oct 9 '11 at 20:19
  • @sawdust The new cable that I bought has four connectors. A 3.5" connector and 5.25" connector before the cable twist, and a 3.5" connector and 5.25" connector after the twist. I have the 3.25" drive (B:) connected before the wist and the 3.5" (A:) connected after the twist. Is this correct? – Andy Johnson Oct 9 '11 at 22:19
  • Could be possible. 5 1/4" had the card edge connector and all the 3 1/2" when they first came out had an edge card adapter. Later, when 5 1/4" use started to taper off, they quit including the adapter and everyone converted to the easily reversible header pins and sockets which meant you had to always watch out to make sure socket 1 matched to pin 1 (arrow or red stripe) Rule of thumb was no. 1 was next to the power socket except when you got some bright ROC manufacturer who failed to follow any rules which meant you looked for the header pin with the square pad to match up to the cable. – Fiasco Labs Oct 9 '11 at 22:38

From the Wiki http://en.wikipedia.org/wiki/Floppy_disk

There were competing floppy disk formats, with hard and soft sector versions and encoding schemes such as FM, MFM and GCR.

Other data suggest that while the disk structure might be similar, the methods used to read/write were not locked in. Scroll down to the Structure section of the link.

then in FORMAT, where it explains that Apple commodore and IBM were not fully compatable

As far as the magnetics. I have a very old video machine that uses them. they still work. the density was very low. an old Cassette tape will still have some magnetic polarisation left on it, weak but still operational, depending more on how the plastic holds up. not the "metal" ??

Some very old magenetic media (of all types) the plastic flakes off, clogging the heads very quickly, that first layer of heavily oxidised plastic. Take the one you sacraficed and rub your finger across it like a read head might, see if it might be messing up the reader.

  • Thanks Psycogeek. I forgot to mention that they are DOS disks, so they are 40 track MFM. – Andy Johnson Oct 9 '11 at 17:55
  • Thinking about All of the 3.5s and some old data tape I have, there is not a &#^@% thing on any one of mine that has any real value. It was just programs and files work. If there were interesting human things, and pictures and personal documents , then people would want that a lot. but if its 50 dos programs, backups, then what purpose does it serve? museum? lots of that old stuff hangs out on the web, without fighting to get it back – Psycogeek Oct 9 '11 at 18:39
  • One of the disks contains emails (yes, I had internet access in 1989) and a couple of the others contain some image processing software that I wrote back then. Nothing that I haven't been able to survive without for the last 22 years, but I'm just curious... – Andy Johnson Oct 9 '11 at 20:12
  • I hope you have them write protected :-) when we tried to get this video computer thing going, actually found a cleaning disk to use on the machine. ebay.com/itm/Cleaning-Kit-5-1-4-5-25-Floppy-Disk-Drives-/… Leave it to e-bay to be able to find one. The video thing uses a Double density ms-dos disk? – Psycogeek Oct 9 '11 at 20:27

Don't forget to clean the heads often!!!!

Remove any metal covers hiding the head assembly. I set the drive on the table in front of the computer with a long floppy cable.I use 2 wet cleaning system disks 1 with isopropyl alcohol and 1 dry. Use the wet disk first, "retry" the disk a few times to get the head to move back and forth. Use the dry next to "dry off" the heads.

I find some old disks will have trouble reading until the head has touched the whole surface once or twice. Ignore errors and let the head step thru the full 40/80 tracks. Clean the head often during the process because the trash will pile up on the heads. Use a flashlight to inspect the cleanliness of the head surface.

Use a program like WinImage to copy whole disk to image file *.flp or *.vfd , save any copies that make it thru with out ignored errors, you may only get one chance! sometimes the trash will pile up on the head and gouge off the oxide layer...that disk will be trashed. After a few passes the program will often be able to read perfectly in one pass.

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