Microsoft Office Tutorials and References
In Depth Information
Computer Hardware
Storing data on magnetic media
Figure 18
magnetic
surface
Before the data is
stored, the
particles in the
magnetic surface
of the disk are
scattered in
random patterns.
mylar disk
The read-write head can reverse polarity to
align the next row of particles in the opposite
direction. The patterns of magnetized
particles represent data.
The read-write
head magnetizes
the particles. The
positive poles of
the magnetized
particles point
toward the
negative pole of
the read-write
head.
The most common magnetic storage devices are floppy disk drives, hard disk drives, and
tape drives. Floppy disks , sometimes called diskettes , are flat circles of iron oxide-coated
plastic enclosed in a hard plastic case (see Figure 19). Floppy disks are sometimes called
3 1 2 " disks because of the size of the hard plastic case. Floppy disks have the capacity to
store 1.44 MB, or 1,440,000 bytes, of data. Although some computers are now manufac-
tured without a floppy disk drive, floppy disks are still very common. The computer shown
in the advertisement in Figure 1 has a floppy disk drive that accepts 3 1 2 " floppy disks with
1.44 MB capacity.
3 1 2 " disk
Figure 19
write-
protect
window
(closed)
write-
protect
window
(open)
Write protection prevents additional files from being stored on the disk and any file
from being erased from the disk. To write protect a 3 1 2 " floppy disk, you open the write-
protect window, as shown in Figure 19.
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