Microsoft Office Tutorials and References
In Depth Information
COM 11
STORAGE DEVICES
STORAGE DEVICES
A storage device is used to store instructions, data, and information when they are not being
used in memory. Four common types of storage devices, sometimes called storage media, are
magnetic disks, optical discs, tape, and miniature mobile storage media. Figure 15 shows how
different types of storage media and memory compare in terms of relative speeds and uses.
FIGURE 15 Comparison of different types of
storage media and memory in terms of relative
speed and uses. Memory is faster than storage, but
is expensive and not practical for all storage
requirements. Storage is less expensive but is
slower than memory.
Magnetic Disks
Magnetic disks use magnetic particles to store items such as
data, instructions, and information on a disk’s surface. Before any
data can be read from or written on a magnetic disk, the disk must
be formatted. Formatting is the process of dividing the disk into
tracks and sectors (Figure 16), so the computer can locate the data,
instructions, and information on the disk. A track is a narrow
recording band that forms a full circle on the surface of the disk.
The disk’s storage locations consist of pie-shaped sections, which
break the tracks into small arcs called sectors . On a magnetic disk,
a sector typically stores up to 512 bytes of data.
Two types of magnetic disks are floppy disks and hard disks.
Some are portable, others are not. Portable storage medium
means you can remove the medium from one computer and carry
it to another computer. The following sections discuss specific
types of magnetic disks.
faster
transfer
rates
Stores…
Memory
(most RAM)
Items waiting to
be interpreted and
executed by the
processor
Hard Disk
Operating system,
application software,
user data and
information, including
pictures, music, and
videos
Flash Memory
Cards and USB
Flash Drives
Digital pictures
or files to be
transported
FIGURE 16 Tracks form circles on the surface of a magnetic
disk. The disk’s storage locations are divided into pie-shaped
sections, which break the tracks into small arcs called sectors.
CDs and DVDs
Software, backups,
movies, music
Tape
Backups
sectors
3
Floppy Disk
Small files to be
transported
track
18
1
slower
transfer
rates
17
2
16
cluster
15
4
5
14
13
6
12
7
11
8
9
10
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