how to identify ndos disks

[rare_j]

I've been sorting through some old floppy disks and have come across 3 unlabled disks that come up as df1??? In workbench and when they are booted an amigados requester comes up saying "not a dos disk in df1"
They are old coverdisks that I've overwritten with something many years ago and I'd really like to know what!

What tools can i use to identify what these disks actually are?

[thomas]

Floppy disks which boot but then come up with "not a dos disk" are very suspicious.

If they aren't second or third disks of some game or demo, then they have most likely been infected by a boot block virus.

This means

- the disks have been rendered unusable because the original boot code which is needed to read the ndos data has been overwritten by the virus and

- your Amiga is infected and you risk to infect every other disk you insert, too.

You should switch off the Amiga to remove the virus from memory and put these disks far far away. Then find a boot disk which is surely uninfected, make sure it has the write-protect switch on, start your Amiga from it and check all other disks you might have inserted in the meanwhile.

[zipper]

What about VirusZ bootblock lab?
I had all the time Virusz running and it immediately screamed when a bootblock virus equipped floppy was inserted.

[rare_j]

I had a thought and one of them turned out to be crossdos. I'll try virusz on the other two. If that is a negative, is there any other way I can get a clue as to what the disks are?

Edit: virusz says "disk io error #21" on them both.