FLOPPY DISK & DRIVE
ITS CONSTRUCTION & WORKING
What is a floppy disk ?
A floppy disk, or diskette, is
a disk storage medium
composed of a disk of thin
and flexible magnetic
storage medium, sealed in a
rectangular plastic carrier
lined with fabric that removes
dust particles. They are read
and written by a floppy disk
Usage of Floppy Disk :
Floppy disks are used for emergency boots in systems
lacking support for other bootable media, and
for BIOS can still be executed from bootable floppy
disks. If BIOS updates fail or become corrupt, floppy
drives can sometimes be used to perform a recovery.
The floppy disk was the primary external writable
storage device used.
Types of Floppy Disk :
According to the size, floppy disks
are generally classified into two:
• 5 .25 -inch diskette
• 3 .5- inch diskette
A normal 3½ inch disk can store
1.44 megabytes of data.
Zip drives were introduced by the
Iomega corporation in the mid
1990s. A zip disk was capable of
storing 100 megabytes, 250
megabytes and even 750 megabytes
on a single disk. Zip drives were
mainly available as a peripheral that
could be added to an existing system.
Types of Floppy disk cont.
Abbr. Floppy DiskType Capacity Info
SS/SD or 1S/1D Single Sided,
100 K First generation.
SS/DD or 1S/2D 5-1/4 inch Single
DD/DD or 2D/2D 5-1/4 inch Double
360 K Most common type
in the early 1980's
DD/HD or 2D/HD 5-1/4 inch Double
DD 3.5 inch Micro
720 K Hard plastic case
HD 3.5 inch Micro
1.44 Mb or
Hard plastic case
Floppy disk Construction
A floppy is made up of a circular thin Mylar plastic material
coated with magnetic particles sealed into 90x94 mm plastic
case. Every magnetic particles holds one data bit.
The Shutter with spring is present to avoid dust particles from
Inserting inside the drive, the shutter opens allows magnetic
media expose to Read / Write head.
Hub is a hole through which floppy disk is rotated by spindle
or stepper motor.
Paper ring Clean the disk by removing microscopic bits of
Floppy drive construction :
Made of ferrite type to make them electromagnetic.
Head contacts much closer compared to HDD due to
low rpm [300 rpm]
3.5 Floppy disk has only 80 tracks per side so the
actuator doesn’t need to be much precise as HDD.
Unlike HDD, FDD has 3 heads :
One is Read/Write head
And other two is tunnel –erase head to clean up after r/w head
as there is a magnetization that overlaps two adjacent tracks
Working of Floppy disk drive :
1) Exposing the
2) Sending Signals
From the Circuit
3) Checking for
4) Positioning the
5) Writing the Data
Disk presence switch is the mechanism called
diskette changeline signal to form controller board
that disk has been removed.