The capacities of floppy drives goes hand-in-hand with floppy disks. Listed below are a few things to remember when working with floppy drives and disks:
For example, you can't use a 3 1/2" inch disk in a 5 1/4" inch drive. And, you can't use a 5 1/4" inch disk in a 3 1/2" inch drive.
For example, if you try to use a 1.44Mb high density 3 1/2" inch disk in a double density 3 1/2" inch floppy drive, this drive will not be able to read or write to the disk.