Author Topic: HD floppy disks stuck on DD format  (Read 540 times)

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Offline gkmaia

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HD floppy disks stuck on DD format
« on: August 28, 2019, 05:32:08 am »
I have a bunch of 2HD 3.5" floppy disks.

The previous owner added a tape to close the HD hole and formatted them as DD 720kb on an old system I do not know what was.

I can only mount them if I close the Hd hole.
I can only format them if I close the Hd hole.
I can only format them to 720kb.

It is like they are stuck in 720kb  format.

Is there a reason for that? Is there a way to bring them back to 1.4kb format?
 

Offline james_s

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Re: HD floppy disks stuck on DD format
« Reply #1 on: August 28, 2019, 05:50:13 am »
Hardware? OS?
 

Online Kleinstein

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Re: HD floppy disks stuck on DD format
« Reply #2 on: August 28, 2019, 06:02:38 am »
Blocking the hole for HD detection is odd, as the HD discs need high write current. The main reason I can imagine is that it was hard to get DD discs and this was done in desperation or not knowing about the difference.

Normally one should be able to reformat a disc no matter what was on it before. Under the new MS-DOS version one may have to call format with an option to disable the undo option. Otherwise it may try to read the disc first and there get an error - at least this happened with discs formatted with larger sectors (AFAIR it crashed DOS 6.x).
 

Offline gkmaia

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Re: HD floppy disks stuck on DD format
« Reply #3 on: August 28, 2019, 06:58:47 am »
I am loading disks with a TEAC FD-05PUW USB external drive.

When I plug the drive on my Mac OsX Mojave I can read disk with the closed HD hole and format them to 720kb. But if I remove the tape to use them as HD disks I cannot read or format them.

When I plug the drive on my old Windows Vista computer I cannot read in any way, neither format with hole closed or open.
 

Offline Towger

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Re: HD floppy disks stuck on DD format
« Reply #4 on: August 28, 2019, 07:09:28 am »
Kleinstien is correct. From memory, later versions of DOSs checked the existing format before reformatting a disk.  You can override this by command line switches.  Well on a PC anyway, Macs are probably another story.
 

Offline Ampera

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Re: HD floppy disks stuck on DD format
« Reply #5 on: August 28, 2019, 08:45:09 am »
USB diskette drives often have problems with anything besides DOS formatted HD diskettes. Try real hardware, with DOS, and do a full format. If you can't do this, then I suggest you spend the insignificant amount of money to simply buy new floppies off Amazon.
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Offline james_s

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Re: HD floppy disks stuck on DD format
« Reply #6 on: August 28, 2019, 07:08:35 pm »
Another thing you can do is use a degaussing wand or coil to completely wipe the disks and then format them.
 

Offline Ampera

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Re: HD floppy disks stuck on DD format
« Reply #7 on: August 29, 2019, 12:50:53 am »
Another thing you can do is use a degaussing wand or coil to completely wipe the disks and then format them.

Ehhh, while I've never done that, it might render the diskette unusable. I'm not sure if even normal diskette drives are capable of redefining the tracks like that, which is essentially the problem being had now. As I said though, I never did this.
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Offline james_s

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Re: HD floppy disks stuck on DD format
« Reply #8 on: August 29, 2019, 01:14:10 am »
Another thing you can do is use a degaussing wand or coil to completely wipe the disks and then format them.

Ehhh, while I've never done that, it might render the diskette unusable. I'm not sure if even normal diskette drives are capable of redefining the tracks like that, which is essentially the problem being had now. As I said though, I never did this.

I've done it numerous times, it works fine. "Modern" diskettes are all soft sectored, prior to the IBM PC some machines used hard sectored disks which made use of the index hole adjacent to the spindle on many 5.25" floppy disks.
 

Offline dexters_lab

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Re: HD floppy disks stuck on DD format
« Reply #9 on: August 29, 2019, 08:00:43 am »
from my own experiences anything after windows xp can have issues reformatting weird floppies, especially when using USB drives

i've just booted my xp machine for you and tried a few combinations, i successfully reformatted a HD disk that was previously formatted as DD with the tape over the hole using:

format a: /u /f:1.44

Also there shouldn't be any issue wiping a disk with a degausser, the formatting process generates all the tracks and sectors needed, back in the 80s and early 90s all floppy disks came raw and entirely unformatted. It wasn't until the proliferation of the PC did disk makers start pre-formatting disks
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Offline Ian.M

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Re: HD floppy disks stuck on DD format
« Reply #10 on: August 29, 2019, 10:26:09 am »
+1 for degaussing.  Conventional floppy disks from the very early low capacity ones all the way up to the 3.2MB capacity ones that were the final iteration of the 3.5" 'stiffy' form factor, didn't use magnetically recorded servo data on the disk for head positioning, (they usually used a stepper with a belt or worm drive to the head carriage) so can reformat totally blank, demagnetised media successfully, and as Dexters_lab just pointed out, before PCs with 1.44MB 3.5" drives dominated the market, all new floppy disks usually came unformatted. 
 

Offline rsjsouza

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Re: HD floppy disks stuck on DD format
« Reply #11 on: August 29, 2019, 06:51:38 pm »
from my own experiences anything after windows xp can have issues reformatting weird floppies, especially when using USB drives
I have the same experience as well. My collection of DD and HD 3-1/2 disks are sometimes not properly acknowledged by the OS, which thinks everything is a single format (generally HD).

Formatting showed up some problems, even when forcing the size of the disk with the option /f:<size>. I had to specify the geometry and it worked with only a few disks.

Oh well... A real FDD connected to the FDD interface worked much better.
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Offline gkmaia

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Re: HD floppy disks stuck on DD format
« Reply #12 on: August 31, 2019, 12:22:57 am »
I ended up buying a $5 old compaq laptop with an internal floppy drive and booted it on DOS 6.0.

I managed to format a few floppies on 1.4 and 720. But several of the floppies could actually be faulty. 
 
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Offline Ampera

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Re: HD floppy disks stuck on DD format
« Reply #13 on: August 31, 2019, 12:53:25 am »
The logic goes, the newer the floppy, the faster it dies.

I have boxes full of CBM formatted 5.25" diskettes with probably few to none dead diskettes.

I also have boxes full of late 90's early 2000's 3.5" diskettes, and had so many of those things die that I had to buy a 10 pack of new ones, because I didn't have enough working diskettes to use for data transfer to older machines.
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Offline rsjsouza

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Re: HD floppy disks stuck on DD format
« Reply #14 on: August 31, 2019, 02:42:52 am »
I have about 100 3-1/2 disks from the early to mid 1990s (mostly 3M, Maxell and Sony) and they are still fit as a fiddle, with just three with bad sectors but none absolutely dead. Actually, two died because they were in a bag with a reused silica-gel that had traces of clorine on it.  :palm:

By the end of the 1990s, our massive collection of 800+ 5-1/4 Nashua DD and HD diskettes was significantly decimated, to the point we ditched pretty much all of them after backing them up to CDs. My Teac 5-1/4 drive is still going strong (bought some DD floppies the other day).

Optical media is proving to be similar to 3-1/2 floppies: I have four 680MB CDs recorded in 1995 (Mitsui-Toatsu) that are still in excellent shape, together with about 150 units recorded in late 1990s and early 2000s that have zero errors. 
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Offline tooki

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Re: HD floppy disks stuck on DD format
« Reply #15 on: September 09, 2019, 02:03:00 am »
Ehhh, while I've never done that, it might render the diskette unusable. I'm not sure if even normal diskette drives are capable of redefining the tracks like that, which is essentially the problem being had now. As I said though, I never did this.
Floppy drives definitely are capable of doing the low-level format. Indeed, floppy disks originally came totally unformatted. Bulk erasing them is fine.

Even early hard disk drives allowed a true low-level format.

The only floppy-like disk I’ve ever used myself that required factory low-level formatting was the Zip disk, which had to be factory formatted on a “servo writer”, so they expressly warned not to bulk erase them.


USB floppy drives are kind of a weird beast, in that they put all the low-level format decoding into the drive firmware, totally isolating the OS from actual drive control. This has some advantages, but makes them incapable of supporting nonstandard formats, which used to be common for copy protection or data density reasons, since software can’t tell a USB drive how to read the format, nor take control of the drive mechanics to do it manually.
 
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