View Full Version : 3M DS DD RH Disks in a 5150?

July 30th, 2017, 07:15 AM

I recently picked up some 3M DS,DD,RH for my model B 5150 - I formatted the first one, and it made an awful grinding noise - after a while it completed the format with about 160K of bad sectors, I figured that was a bad disk. I tired to format the next disk and it didn't make the grinding noise but when it completed it was only 160kb. I didn't want to try any others with out asking if anyone else encountered something like this. I put a picture of the disk below if it makes a difference.

The drives seem to be working fine with other floppies - is it possible I just have a bad lot of disks?

I've never worked with this particular media before, I otherwise have DS,DD disks and never have any issues with those.


Thanks everyone!

August 3rd, 2017, 12:44 AM
The drives seem to be working fine with other floppies
I notice that you used the word, "seem". If the "other floppies" format without error and you can then write/read across the surfaces, then you should consider the floppies to be good. To be sure, you could use the floppy read/write test found in some diagnostic software.

- is it possible I just have a bad lot of disks?
Yes, possible.

Note that when I come across a box of 'significantly deteriorated' floppies (and I have lots of sealed boxes), sometimes the floppies have left behind a thick coat of oxide on the drive's heads, and then I have to spend some time cleaning the heads before the drive becomes useable again.

I put a picture of the disk below if it makes a difference.
I have one of that exact same media. It formats to 360K in my late model 5150 without problem.

SSDD drive: Early DOS formats to 160K (one side of 8 sectors per track)
SSDD drive: Later DOS formats to 180K (one side of 9 sectors per track)

DSDD drive: Early DOS formats to 320K (two sides of 8 sectors per track)
DSDD drive: Later DOS formats to 360K (two sides of 9 sectors per track)

August 3rd, 2017, 03:53 AM
What DOS version are you using?

August 3rd, 2017, 05:18 AM
Thank you - I'm starting to think my drives are dirty and/or need to be lubricated. I'm the 2nd owner of this particular PC and I know they were never serviced. Since my first post I've noticed a lot of the same behavior on disks that I never had issues with, and they're all intermittent read errors that will clear after a few attempts. I'm going to try cleaning them and see what happens.

August 3rd, 2017, 05:20 AM
I have Dos 2.0 & 2.1 - same issues with both, but now since I'm having similar issues with disks that I've had a long time I'm thinking I just need to clean the drives.

August 3rd, 2017, 05:38 AM
3M is one of the better floppy disk brands, but if a disk was poorly stored or was previously used/abused then it could always fall apart easily.

Before using a newly obtained old disk in a system, even one from a sealed package, it is always a good idea to visually inspect the surface of the disk. Gently turn the disk "cookie" with you fingers through the hub at the center. If you see scratches or spots, or if you hear scraping sounds as the cookie turns, then it is best not to put the disk in a drive without further action.

If it has fouled or damaged the second (top) drive head then some formatters may automatically format the disks as single sided.

And just a reminder, formatting 360k requires a double sided drive with DOS 2.0 or later.

August 3rd, 2017, 06:45 AM
"An awful grinding noise" sounds as if you're making "see through" disks. If, after trying to format one, the disk surface shows visible scoring, you've got a bad disk. Probably due to bad storage conditions. Unless you want to make drink coasters with them, toss them--and then clean your drive heads.

Tandy had a similar problem with a load of 8" SSSD floppies stored in their (un-air conditioned) Fort Worth warehouse. The disks performed well enough new, but after 20-30 years, shed oxide like a dog sheds fur.

Wabash 5.25" floppies were infamous for this, even when fairly new.

August 3rd, 2017, 07:10 AM
Thanks for all the advice - I didn't really know how to describe the sound - for lack of any better description it was much louder and biting than the normal noise the drive makes, that probably doesn't help much - but it was a very atypical from the format/read/write noises my drives were making prior to using these disks. But since my post I've been having read issues with other disks, which I didn't have problems with before so I'm starting to think it's a cleaning issue. Maybe these just happened to clog up the heads and that's where it started going wrong but the media looks like it's in good shape as far as I can tell - these were unused, but I can't vouch for how they were stored.