Floppy disk guide

Formatting a 720KiB floppy disk in Windows

From a command prompt:
FORMAT A: /T:80 /N:9

Note that some USB floppy drives do not support double density disks.

What is a double density floppy disk?

Typically, floppy disks that are available now are double sided, high density (DS/HD or MF2-HD). They have a capacity of 1.44MiB when formatted in DOS / Windows.

However, an Atari ST cannot read these, as the drive only supports double sided, double density (DS/DD or MF2-DD) disks, which have a capacity of 720KiB when formatted in DOS / Windows.

Identifying a double density / high density floppy disk

Both disk types are physically the same size, but the tracks in their magnetic media are packed more (high density) or less (double density) densely, with higher density disks capable of storing more data.

The easiest ways to tell between the two disk types are:

• High density disks typically have HD printed on them, on or near the metal disk cover.
• High density disks have two holes: one near the left of the disk (which can be blocked to enable writing) and another to the right. Double density disks only have the write-protect hole to the left of the disk.

It is possible to format a double density disk as high density and vice versa, but it will probably not be very reliable.