Kreisen 3 8 6 X / X E - Manual (Page 102)

How Floppy Disks Work
Floppy disks, or diskettes, are made from a flexible plastic that
is coated with a magnetic oxide. The floppy disk drive encodes
this oxide with the data generated by the computer. After you
turn your system off, unlike electronic RAM, the encoded
oxide retains this data. Your data can then be read by the
floppy disk drive at a later time.
The magnetic oxide coating on the floppy disk will hold its
encoded data almost indefinitely unless you deliberately erase
it. This is done intentionally when you want to update the
information stored on the diskette.
The plastic disk is safely protected by a thin cardboard jacket.
The diskette spins inside this jacket, allowing the entire surface
of the diskette to be scanned by the drive’s circuitry. Data is
read from or written onto the diskette through the oval-shaped
slots in the jacket.
Normally, the computer will write new information onto the
unused space on the diskette. If there is no unused space, your
computer will inform you that the disk is full. You can instruct
the computer to write over the information that is already on
the diskette. You might do this to update an inventory file, or
change an address and phone number in a database.
Caution!
Updating, or overwriting, data stored on a diskette will
erase the old information. Under most circumstances you
cannot get it back.
5-2 Using Floppy Disks