The document provides a comprehensive overview of external storage devices, specifically focusing on floppy disks and floppy disk drives (FDD). It details the history, types, components, and functioning of floppy disks as well as their advantages and disadvantages. Floppy disks served as a primary data storage medium in the early days of computing, with various sizes and structures evolving over the years.

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2. EXTERNAL MEMORY
An external storage device, also referred to as auxiliary storage
and secondary storage, is a device that contains all the addressable data
storage that is not inside a computer's main storage or memory. An
external storage device can be removable or non-removable, temporary
or permanent, and accessible over a wired or wireless network.
FLOPPY DISK
Definition
A floppy disk is a magnetic storage medium for computer systems.
The floppy disk is composed of a thin, flexible magnetic
disk sealed in a square plastic carrier. In order to read and write data
from a floppy disk, a computer system must have a floppy disk drive
(FDD). A
floppy disk is
also referred
to simply as a
floppy. Since
the early days
of personal
computing,

3. floppy disks were widely used to distribute software, transfer files, and
create back-up copies of data. When hard drives were still very
expensive, floppy disks were also used to store the operating system of
a computer.
TYPES OF FLOPPY DISK DRIVES
Floppy disk drives are available in different sizes. The
floppy disk drive shares the name with the size of the floppy disk that it
uses.
 5.25 Inch Floppy Disk Drive
 3.5 Inch Floppy Disk Drive
 5 ¼ -Inch Drive
A 5 ¼-inch floppy disk drive was common on personal
computers that were produced during the 1980's and were still included
on computers in the early 1990's. A 5 ¼ -inch floppy disk could store
between 360 kilobytes and 1.2 megabytes of data. Some 5 ½-floppy
disks could be modified and used to write data to both sides of the
disk. This led to manufacturers producing double-sided drives that
could read both sides of the disk.
5 ¼-inch floppy disk drive

4.  3 ½ -Inch Drive
A 3 ½-inch floppy drive is considered a floppy drive
because the diskette uses a magnetic floppy disk that is encased in
plastic. A 3 ½-inch floppy disk is capable of storing 730 kilobytes on a
double density disk and 1.44 megabytes on a high density disk. On
older computers the only way to load programs such as Windows 3.0
was to use multiple disks to install the program.
3 ½-inch floppy drive
HISTORY OF THE FLOPPY DISK DRIVE
The floppy disk drive (FDD) was invented at IBM by Alan
Shugart in 1967. The first floppy drives used an 8-inch disk (later called
a "diskette" as it got smaller), which evolved into the 5.25-inch disk that
was used on the first IBM Personal Computer in August 1981. The
5.25-inch disk held 360 kilobytes compared to the 1.44 megabyte
capacity of today's 3.5-inch diskette.
The 5.25-inch disks were dubbed "floppy" because the
diskette packaging was a very flexible plastic envelope, unlike the rigid
case used to hold today's 3.5-inch diskettes.
By the mid-1980s, the improved designs of the read/write
heads, along with improvements in the magnetic recording media, led
to the less-flexible, 3.5-inch, 1.44-megabyte (MB) capacity FDD in use
today. For a few years, computers had both FDD sizes (3.5-inch and
5.25-inch). But by the mid-1990s, the 5.25-inch version had fallen out

5. of popularity, partly because the diskette's recording surface could
easily become contaminated by fingerprints through the open access
area.
PARTS OF FLOPPY DISK DRIVE

6. MAJOR PARTS OF FLOPPY DISK DRIVE
Let us know about the important parts of this Disk Drive.
 Read/Write Heads
They are located in both parts of a diskette, they move
simultaneously in the same assembly. Their heads are not directly
opposite , the second is a foam, which is a Fayyad that protects it from
being written together in every media surfaces. In the same head used
for reading and writing, one is to use a second wider head to erase the
track. This allows it to write data in a wider “clean slate”, with the
analog data of the adjacent track without any interfering.
Read/write heads
 Drive Motor
A very small spindle motor engages the metal hub in the
center of the diskette, which spines it into 300 or 360 rotations per
minute (RPM).
Drive motor

7.  Stepper motor
This motor assesses the stepped revolutions of a precise number,
from which to move into the read/write head assembly, the proper
track position. It goes fastened to the read/write head assembly with
stepper motor shaft.
Stepper Motor
 Mechanical from
This is a system that opens the levers of the little protective window
in the diskette, which allows read/write heads to touch with the dual-
sided diskette media. An external button allows the diskette to eject, at
a point where the spring-loaded protective window is close in the
diskette.
 Circuit Board
It contains all the electronics used in reading or writing data, in
Diskette, it also handles these things together. It also controls these
stepper-motor control circuits, which is used to move read/write heads
to each track.
Circuit board

8. WORKING OF THE FLOPPY DISK DRIVE
The floppy disk drive reads data from a floppy disk just as a
cassette player reads music from a cassette. The magnetic particle on
the surface of the floppy disk holds the stored data, the head moves
over these magnetic particles and reads the data. The data is stored on
the sectors and tracks of the floppy disk. The tracks are concentric
circles on the floppy disk.
The steps followed by the floppy disk drive to read data from the
floppy disk:
1. The user executes a command, or disk. The program requests
information from the floppy disk.
2. The spindle motor in the floppy disk drive rotates the floppy disk.
3. The stepper motor moves the read write head over the required
track and the read write head reads the data from the floppy disk.
4. The floppy disk drive sends the data to the microprocessor for
processing.
5. The spindle motor stops rotating the floppy disk in the floppy disk
drive.
The steps followed by the floppy disk drive to write data on the floppy
disk:
1. The user executes a command, or the program sends data to be
written on the floppy disk.
2. The spindle motor in the floppy disk drive rotates the floppy disk.
3. The stepper motor moves the read write head over the required
track for the read write head to read the track address from the floppy
disk for storing the data.
4. The erase coils located on the read write head erases the data from
the track.

9. 5. The write head is wound up.
6. The write head converts the binary data into electromagnetic
impulses and writes the data on the floppy disk.
7. The spindle motor stops rotating the floppy disk in the floppy disk
drive.
ADVANTAGES & DISADVANTAGES OF FLOPPY DISK
 Advantages
1. Portable – small and light weight.
2. Allow random access of data.
3. Can provide a valuable means of backing up data.
4. It is an inexpensive.
5. Useful for transferring file between computers or home and
school.
6. Private data can store securely.
 Disadvantages
1. Easy to be damaged.
2. Small storage capacity.
3. Many computers don’t have floppy disk.
4. Can transport a virus from one machine to another.
5. Data can be erased if the disk comes into contact with a magnetic
field.
6. Slow to access.