Secondary storage devices

1. Dr B T Sampath Kumar
Professor
Department of Library and Information Science
Tumkur University, Tumakuru, INDIA
www.sampathkumar.info
Secondary Storage Devices

2. Secondary storage devices
• Secondary storage devices are storage devices
that operate alongside the computer’s
primary storage, RAM and cache memory.
• Secondary storage is a non-volatile memory,
which has the capability to hold data until and
unless it has either been deleted or
overwritten.

3. Different secondary storage
Different secondary storage devices are:
• Floppy Disc
• Hard disc
• Compact Disc
• Digital Versatile Disc
• Blu-ray disc
• Pen drive
• Memory cards

4. Floppy Disc (FD)
• It is a thin flexible circular plastic plate coated
with magnetic oxide.
• The data is stored on the floppy disc in terms
of magnetized spots.
• The surface of floppy disc is divided into a
number of concentric circles called tracks and
these tracks are further divided into sectors.

5. Hard Disc (HD)
• A hard disc is a group of round flat metal
plates, which are coated with magnetic
material.
• Because of the use of metal in place of thin
plastic plate, they are called hard disc.

6. Compact Drive (CD)
• CD is a circular plastic plate, which is coated
with a highly reflective material.
• The data is recorded on this disc by focusing a
laser beam on the surface of the disc.

7. Cont..
• The storage density of CD-ROM is about 700
MB.
• They are used to store reference sources viz.,
encyclopedia, dictionary, testbooks etc., as
well as songs and movies.

8. Digital Versatile Disc (DVD)
• A DVD looks just like a CD but has higher data
storage capacity.
• Like a CD, data is recorded on DVD in a spiral
trail of tiny pits and the discs are read using a
laser beam.

9. Cont..
• The DVD's larger capacity is achieved by
making the pits smaller and the spiral tighter
and by recording the data in as many as four
layers two on each side of the disc.

10. Blu-ray Disc (BD)
• Blu-ray disc, often known simply as Blu-ray, is
a digital optical disc data storage device.
• It is designed to supersede the DVD and is
capable of storing several hours of video in
high-definition.
• A double-layer Blu-ray disc can store up to 200
GB.

11. Pen drive
• Pen drive is typically removable and
rewritable.
• It offers potential advantages over other
portable storage devices.
• They are more compact, faster and hold much
more data.

12. Memory card
• It is an electronic data storage device used for
storing digital information, typically using flash
memory.
• These are commonly used in portable
electronic devices, such as:
– digital cameras
– mobile phones
– computers
– tablets, PDAs
– portable media players