I have a collection of vintage computers (Amigas,68k Macs,etc) so I have a pretty big stock pile of 3.5 inch diskettes. However most (if not all) of them are HD, and some computers, such as the Amiga, only have double density drives, so I have formatted many of them as double density in the past...But I want to check my disks to see which are still good (I have everything backed up) so I have been using an old pc with debian to do that. However I have noticed that if I put in a HD disk which is formatted as low-density, I cannot even begin to format it, even though the same disk formats fine in a computer with a low-density drive. I tried like the man page says to do to force it use high density encoding, but I get a message that the device file doesn't exist...

check the write protection of the floppy itself. Otherwise if it was not writable it should not be used (cannot be used at all).

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is the lock tab moved into the locked position ?

No its not locked. It happens with all high density disks that were formatted as double density...

Check to see if /dev/fd0H1440 exists. Use this command to display all of your devices:

ls -l /dev | less

If you haven't used less before then read the man pages for less first:

man less

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Steve Stites

Yeah the device doesn't exist (although fd0 does and it works with disks I haven't previously formatted)...

Linux sets up /dev at boot based on what hardware it finds. If the dual density floppy device does not exist then Linux did not find one during boot. Dual density floppy hardware support consists of both the floppy device and the floppy drive controller chip. Check your bios to see if your floppy drive controller supports dual density. Or you can find out what Linux found in your hardware with the lshw command:

lshw | less

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Steve Stites

For some reason I think there is some small casting mark on the drive that tells it what it is. Maybe if you tape over it? It has been a very long time since I knew this stuff.