mount /dev/fd0 is not a valid block device

[Ioana Glitia <iglitia@linux360.ro>]

I've installed the base system of Debian (from the 20 floppy disks) on 
my IBM 755C Thinkpad (it has no cd-rom and only 20 MB RAM as I said in a 
different mail). When I try to mount a floppy disk it says:

end_request: I/O error, dev 02:00 (floppy), sector 64
/dev/fd0: Input/output error
end_request: I/O error, dev 02:00 (floppy), sector 0
mount: /dev/fd0 is not a valid block device

Did I go wrong somewhere at the installation? Could someone explain me 
what the error means?

Ioana