I am using Linux Mint 17.3 Rosa Cinnamon. The computer is a Dell Dimension 5150.

When I put a floppy disk in the floppy disk drive its small green light lights up. But when I click on its icon in Nemo 2.8.7 file manager, I get a pop-up error message:

"Unable to mount Floppy Disk

Error mounting system-managed device /dev/fd0: Command-line `mount "/media/floppy0"' exited with non-zero exit status 32: mount: /dev/fd0 is not a valid block device".

When I remove the floppy disk and click on the floppy drive icon again I get another pop-up:

"Unable to mount Floppy Disk

An operation is already pending"

A long time later I got another pop-up:

"Unable to mount Floppy Disk

Timeout was reached"

The floppy disk is not actually physically floppy but it a standard plastic-encased 3 1/2 inch wide disk. The text on it says: "KAO MF2HD Double Sided 2 MB Capacity".

I have tried it with two other floppy disks also, same result. One of them makes more noise but still never mounts the drive. All the disks are around 20 years old. Two of them are commercial software disks that were enclosed within a book, the above disk looks like a copy of the same.

What is wrong? Could it be:

a) software not functioning correctly?
b) drive not working or heads dusty/dirty?
c) that the magnetic signal on the disk has faded over 20 years?

Thanks.

Check the /dev directory. Do you actually have a /dev/fd0?

Also look at /var/log/messages? Can you see the kernel recognising the disk?

Do you have CONFIG_BLK_DEV_FD set in the kernel configuration? I suspect it often isn't these days.

Thanks. Looking at the /dev folder with Nemo file manager , I can see a file fd0, but it is zero bytes in length, and described as a "block device". Nearly all the files in the /dev folder are zero bytes in length.

I cannot see anything in the var/log/ folder that has a name anything like "messages", either a file or another folder. Nemo is showing hidden files.

Sorry, I've no idea what that means or how to find it.

OK. First you need to know what the dev folder actually is, for the future. It's an important part of how Linux works. In Linux, all your hardware is managed by the Linux kernel. There are no separate drivers as there are in Windows. Programs communicate with the hardware via the kernel. The files in the /dev directory are pseudo-files; that's why they have zero length. Whenever a program accesses one of these files, the kernel wakes up and does the read or write operation, then passes the result back to the program. As far as the program is concerned, it's just read or written to a file. It doesn't need to know anything about the hardware at the other end. And "block device" is just jargon for a disk or similar because data passes to and from such devices in blocks.

You do have a /dev/fd0 file, so we know now that the kernel can see your floppy drive. Therefore you don't need to do the other things I suggested. But since the mount command doesn't recognise it, you may not have a valid filesystem on the disk. Is it a completely blank disc? Did you format it in any way? I doubt if a purely physical problem with the disk would cause this particular error. You'd more likely be able to mount it but then get read/write errors. So I suspect it's the format that's wrong. Please tell us more about how you used this disk before and what might be on it.

As a frame of reference I have Ubuntu 19 xfce running as a VirtualBox virtual machine and can confirm the floppy drive capability has not been removed from the kernel. I would assume no basic difference between xfce and Cinnamon except for the desktop and also that 17 would be unchanged since it is an older version.

The floppy module was inserted automatically and /dev/fd0 device was created. Try manually mounting the disk from the command line
sudo mount -t vfat /dev/fd0 /media/floppy0
or
sudo mount -t msdos /dev/fd0 /media/floppy0

It is possible the drive has failed or the disks no longer readable.

It's been such a long time since I used floppies that I can't remember if they come with a vfat filesystem on them like USB drives do or if they need to be formatted before use.

It depends:
in the very first time floppies came UNformatted, because you could use them for CP/M, PC-Dos or i.e. Apple // or Commodore 64
And 3.5" floppies were introduced for the Apple MacIntosh (400K 1-side or later 800K double, with varying speed drives) or, say the Apricot computer with about 315 KB (again 1-sided).
But when the PC was about the only actual system left and they introduced HD floppies (with the AT and later), floppies often came pre-formatted with a FAT (fat12, to be exact) filesystem ON them.

But I think the OP was talking about old floppies with data on them, so they should have been formatted with some sort of file-system, most likely thus fat12

If three disks all fail to mount, the problem could be a dirty drive. You can still buy cleaning disks:
https://www.floppydisk.com/floppy-drive-cleaner

The disks themselves may be dirty, and cleaners are available:
https://www.floppycleaner.co.uk/

The disks may have decayed over the years. There are claims of them lasting 20 years, but some people have found them lasting less than 10. You could run gparted and see if it can identify the filing system, then check if it's damaged with fsck.

Note that floppies do not have partitions. Block 0 directly is the boot block.
So the OP could try just to read that block, with dd or so
and look if that succeeds and looks like a fat12 fs bootblock (use wikipedia to find out how that would look if you never did that)

Maybe make a folder for floppy then mount it??

I'm betting this is a file-system thing. As mentioned by a previous poster, floppys back then could be formatted for Apple computers, Amigas, Ataris, MS-DOS systems, Windows ... you name it.

It would help to know what system they were prepared for and then figuring our if a proper file system driver is available.

https://ubuntuforums.org/showthread.php?t=1081430 maybe still works?

I'm inclined to agree with you. I think if the drive was kaput, the kernel wouldn't have recognised the device. And if it was a bad disk surface, you'd expect to get loads of read errors rather than a refusal to mount.
Wouldn't it be simpler just to use mkfs.ext4 on it?

Make image copies of them with dd, & then work on them, by loop mounting them.

Depending on what computer system they were originally formatted for, you will need the corresponding file system to be compiled into the kernel or it's modules.

2MB disks were commonly known as 1.44MB floppies.