I think ability to format DD disks was dropped in Windows 7. You will need an older version of Windows for that.

I assume you're using a USB floppy drive. Some of those have problems with DD disks.

Errius wrote on 2026-09-26, 21:20:

I think ability to format DD disks was dropped in Windows 7. You will need an older version of Windows for that.

I assume you're using a USB floppy drive. Some of those have problems with DD disks.

Do you know the command line to do it please?

Do you have an old computer running Windows XP and with a built in (not USB) floppy drive?

Errius wrote on 2026-09-26, 22:05:

Do you have an old computer running Windows XP and with a built in (not USB) floppy drive?

Yes I do! I also have DOS 6.22. that would be better doing it then windows would

Windows7 CAN format 720k DD floppy disks.
IIRC the ability was removed from the GUI, but you can still do it from the command line, by specifying 80 tracks and 9 sectors/track:

> FORMAT A: /T:80 /N:9

If you want to format non-MS formats, you can do this with ImageDisk - IMD doesn't know about file systems and can only perform a low-level format, however it can read any freshly formatted disk (from any OS) that the PC FDC hardware can access, and recreate that image on another disk (and will format it appropriately while doing so)

On a non-DOS system, you would have to boot the IMD boot disk first - it is possible and can rewrite any diskette the PC FDC hardware can access.

Errius wrote on 2026-09-26, 21:20:

... I assume you're using a USB floppy drive. Some of those have problems with DD disks.

Some USB drives do have trouble, but a lot can do it - In verifying that my above answer is correct (it really has been years since I've done DD under Winblows), I formatted a 720k DD disk on a Win7 system using a USB floppy drive - everything worked!
(and it was a fresh unformatted DD disk)

DaveDDS wrote on Yesterday, 02:08:

Windows7 CAN format 720k DD floppy disks.
IIRC the ability was removed from the GUI, but you can still do it from the command line, by specifying 80 tracks and 9 sectors/track:

> FORMAT A: /T:80 /N:9

I have now managed to do a "3M DS,DD 1.Mb/1.0 Mo" disk and a "3M 3.5, DS double sided 135TPI" disk, using that command that you gave. I then wrote a file to both of them and read it and files are fine!

Then tried to format them both with the "FORMAT A:" command and it would not do it on either disk, then after that I could not read them so I went back to the original command that you quoted and it worked again! I then tried to format in windows and same error again and I had to reformat with the original format command you gave

Question is this format command for formatting non Microsoft disks or is it for formatting DS/DD Disks?

DaveDDS wrote on Yesterday, 02:08:

If you want to format non-MS formats, you can do this with ImageDisk - IMD doesn't know about file systems and can only perform a low-level format, however it can read any freshly formatted disk (from any OS) that the PC FDC hardware can access, and recreate that image on another disk (and will format it appropriately while doing so)

Do you know where I can get image disk from please?

DaveDDS wrote on Yesterday, 02:08:

On a non-DOS system, you would have to boot the IMD boot disk first - it is possible and can rewrite any diskette the PC FDC hardware can access.

Is that the same as above?

DaveDDS wrote on Yesterday, 02:08:

Windows7 CAN format 720k DD floppy disks. IIRC the ability was removed from the GUI, but you can still do it from the command li […]
Show full quote

Windows7 CAN format 720k DD floppy disks.
IIRC the ability was removed from the GUI, but you can still do it from the command line, by specifying 80 tracks and 9 sectors/track:

> FORMAT A: /T:80 /N:9

If you want to format non-MS formats, you can do this with ImageDisk - IMD doesn't know about file systems and can only perform a low-level format, however it can read any freshly formatted disk (from any OS) that the PC FDC hardware can access, and recreate that image on another disk (and will format it appropriately while doing so)

On a non-DOS system, you would have to boot the IMD boot disk first - it is possible and can rewrite any diskette the PC FDC hardware can access.

I was JUST getting ready to suggest this! JUST specify a 720k diskette's tracks and sectors values on the CLI, but I see you beat me to it.

DaveDDS wrote on Yesterday, 02:08:

On a non-DOS system, you would have to boot the IMD boot disk first - it is possible and can rewrite any diskette the PC FDC hardware can access.

Is that the same as above?
[/quote]

I cant seam to edit the posts hear!

I ment is it the same as above or it it a specific boot disk?

Donald Duck wrote on Yesterday, 17:10:

I have now managed to do a "3M DS,DD 1.Mb/1.0 Mo" disk and a "3M 3.5, DS double sided 135TPI" disk, using that command that you […]
Show full quote

DaveDDS wrote on Yesterday, 02:08:

Windows7 CAN format 720k DD floppy disks.
IIRC the ability was removed from the GUI, but you can still do it from the command line, by specifying 80 tracks and 9 sectors/track:

> FORMAT A: /T:80 /N:9

I have now managed to do a "3M DS,DD 1.Mb/1.0 Mo" disk and a "3M 3.5, DS double sided 135TPI" disk, using that command that you gave. I then wrote a file to both of them and read it and files are fine!

Then tried to format them both with the "FORMAT A:" command and it would not do it on either disk, then after that I could not read them so I went back to the original command that you quoted and it worked again! I then tried to format in windows and same error again and I had to reformat with the original format command you gave

Question is this format command for formatting non Microsoft disks or is it for formatting DS/DD Disks?

As per the discussion, Microsoft is making assumptions about the disk drive in question, and trying to format a 1.44mb diskette, when the diskette (or drive) is 720k instead.
They did this as part of their "normal" (for them, anyway) habit of removing features that they think nobody uses/needs/wants anymore.

There are 2 things wrong with that, depending on circumstance:

1) Most common-- The media does not have the right coercivity for high density. More or less, magnetic media is some magnetic particles stuck to the surface of a thin sheet of mylar plastic. Some magnetic particles are more affected by magnets than others. This is their coercivity. low density media is easily affected by magnetic fields, and has a low coercivity. High density media is less affected my magnetic fields, and has a high coercivity. This makes the low density media have bit inversions and other issues from the close track spacing, when you try to format it as 1.44mb. These bits are affected by the nearby magnetic fields of the adjacent track, and they spontaneously flip, and do other strange things.

Since MS is "JUST ASSUMING" the disk should be 1.44mb in capacity, it tries to format it that way, the tracks do bad things to each other when written that close together on low-coercivity media, and the disk is useless.

Reformatting it by manually telling it the CORRECT track and sector geometry, makes the tracks further spread apart, they dont affect each other, and the disk is fine. It's 720kb, just as it should be.

2) Less common-- You put the disk into a low density drive, which physically cannot seek to that track count. Drive stalls out halfway through the format, makes all kinds of nasty sounds when you try. Since we are manually overriding sense features of format by hard specifying the number of tracks and such, windows wont be probing for drive type. It will just be stepping number of tracks as instructed.

Donald Duck wrote on Yesterday, 17:10:

... Then tried to format them both with the "FORMAT A:" command and it would not do it on either disk, then after that I could not read them so I went back to the original command that you quoted and it worked again! I then tried to format in windows and same error again and I had to reformat with the original format command you gave

A 3.5" HD has an extra hole on the side opposite of write-protect - Drive have a sensor and can tell if a diskette is HD or DD ....
But I think Microsoft has stopped recognizing this and always tries to do HD - I think the only reason command line FORMAT still works when specifying tracks/sectors is because they haven't gotten a "round tuit" yet, or they may still want to support some oddball formats.

Question is this format command for formatting non Microsoft disks or is it for formatting DS/DD Disks?

The format command has always been there from DOS on ... MS never "officially" supported non-MS format disks, and DD *was* a valid MS format from DOS-WinXP, but nobody *important* uses DD anymore (or even floppies for that matter), and MS doesn't want to confuse users with subjects actually relating to computers in general - so basic things that were common and expected in a traditional operating system are disappearing.

Donald Duck wrote on Yesterday, 17:12:

Do you know where I can get image disk from please?

DaveDDS wrote on Yesterday, 02:08:

On a non-DOS system, you would have to boot the IMD boot disk first - it is possible and can rewrite any diskette the PC FDC hardware can access.

Is that the same as above?

The "official" release of ImageDisk in on my "Daves Old Computers"site ...

Yes, IMD is a short form reference to IMageDisk (It's called IMD.COM and stores images in .IMD files)

And yes, it runs under DOS and you have to boot the IMD boot disk that I provide to use it on a non-DOS system.

Do be aware that ImageDisk was never designed to be "easy" - It is capable of doing a LOT with floppy disks, but you really have to know what you are doing...

You have a solution to recover your disks working, unless you need to backup/restore etc. completely non DOS/Windows disks, you probably don't need to get into the intricacies of ImageDisk.

Donald Duck wrote on Yesterday, 17:17:

... I ment is it the same as above or it it a specific boot disk?

I provide an "normal" (.IMG) image for a 1.44m HD floppy disk that you can boot on any system (with a 3.5" HD floppy) to run ImageDisk.
I also put some useful tools on the disk, so you can do things like transfer files on/off.

It boots and runs from a RamDisk, meaning you don't have to keep the diskette in after booting (freeing up the drive for creating/recovering images)

You can write that .IMG to an actual floppy with a number of common tools (under DOS my XDISK or IMD itself can do it), under Winblows you can use DskWrite, WinImage etc.

wierd_w wrote on Yesterday, 17:14:

I was JUST getting ready to suggest this! JUST specify a 720k diskette's tracks and sectors values on the CLI, but I see you beat me to it.

Yeah, sorry - I happen to know floppy disk systems VERY well, and knew right away that I could give a useful answer.

but ... it really has been years since I've done this -- fortunately "FORMAT /?" has enough information to remind me ... then I just had to find a system with Win7 and drag out a USB floppy drive to confirm that I wasn't about to give bad information.

DaveDDS wrote on Yesterday, 23:21:

The format command has always been there from DOS on ... MS never "officially" supported non-MS format disks, and DD *was* a valid MS format from DOS-WinXP, but nobody *important* uses DD anymore (or even floppies for that matter), and MS doesn't want to confuse users with subjects actually relating to computers in general - so basic things that were common and expected in a traditional operating system are disappearing.

Bit off topic but windows is disappearing next month! Windows 11 they announced
would be there last OS. And that support for it would be dropped in October this year

DaveDDS wrote on Yesterday, 23:29:

The "official" release of ImageDisk in on my "Daves Old Computers"site ...

Do you have a link to it please?

DaveDDS wrote on Yesterday, 23:29:

You have a solution to recover your disks working, unless you need to backup/restore etc. completely non DOS/Windows disks, you probably don't need to get into the intricacies of ImageDisk.

What are on the disk is of no importance to me. But when formatting I am getting bad
sectors and not full capacity of the disks (please see attachment above)

Donald Duck wrote on Yesterday, 23:49:

DaveDDS wrote on Yesterday, 23:21:

The format command has always been there from DOS on ... MS never "officially" supported non-MS format disks, and DD *was* a valid MS format from DOS-WinXP, but nobody *important* uses DD anymore (or even floppies for that matter), and MS doesn't want to confuse users with subjects actually relating to computers in general - so basic things that were common and expected in a traditional operating system are disappearing.

Bit off topic but windows is disappearing next month! Windows 11 they announced
would be there last OS. And that support for it would be dropped in October this year

This is bit of a misinformation statement, but I dont blame you for it.

More, Microsoft is switching to "Rolling Release" model, instead of "Milestone Release" model.

https://en.wikipedia.org/wiki/Rolling_release

vs

the more traditional milestone release model:
https://en.wikipedia.org/wiki/Software_release_life_cycle

What is "Windows 11" today wont be the same as "Windows 11" 5 years from now. The sub-version number (25H2 et al) is what designates the deployed OS's true identity.

DaveDDS wrote on Yesterday, 02:08:

> FORMAT A: /T:80 /N:9

I wanted to ask you what the T80 and N9 mean?