secondary memory

1. INTRODUCTION TO
SECONDARY STORAGE DEVICES -
HARD DISK,
COMPACT DISK, DVD, FLASH
MEMORY.
PRESENTED BY SAHIL JAKHMOLA

2. SECONDARY STORAGE DEVICES
• Secondary storage is a memory that is stored external to the computer.
• It is mainly used for the permanent and long-term storage of programs
and data.
• Hard Disk, CD, DVD, Pen/Flash drive, SSD, etc, are examples of
secondary storage.

3. HARD DISK
• It is a non-volatile storage device that can be modified or deleted n number of
times without any problem.
• Most of the computers and laptops have HDDs as their secondary storage device.
• It is actually a set of stacked disks, just like phonograph records.
• In every hard disk, the data is recorded electromagnetically in the concentric
circles or we can say track present on the hard disk, and with the help of a head
just like a phonograph arm(but fixed in a position) to read the information present
on the track.
• The read-write speed of HDDs is not so fast but decent.

4. • It is a storage device (HDD) that stores and retrieves data using magnetic
storage
• Hard disks are flat circular plates made of aluminum or glass and coated with
a magnetic material.
• A computer’s hard drive is a device consisting of several hard disks,
read/write heads, a drive motor to spin the disks, and a small amount of
circuitry, all sealed in a metal case to protect the disks from dust. In addition
to referring to the disks themselves, the term hard disk is also used to refer to
the whole of a computer’s internal data storage.

5. CD (COMPACT DISC)
• It is known as Compact Disc. It contains tracks and sectors on its surface to store
data. It is made up of polycarbonate plastic and is circular in shape.
• CD can store data up to 700MB
• It is of two types:
1. CD-R: It stands for Compact Disc read-only. In this type of CD, once the data
is written can not be erased. It is read-only.
2. CD-RW: It stands for Compact Disc read Write. In this type of CD, you can
easily write or erase data multiple times.

6. DIFFERENCE BETWEEN CD-R AND CD-RW
CD-R
• CD-R (Compact disc-recordable)
is a digital optical disc storage
format
• A CD-R disc is a compact disc that
can be written once and read
arbitrarily many times. Compact
disc-recordable.
CD-RW
• A Compact Disc Re-Writable
(CD-RW) is an erasable disc
that can be reused
• The data on a CD-RW disc can
be erased and recorded over
numerous times

7. DVD (DIGITAL VERSATILE DISC)
• It is known as Digital Versatile Disc.
• DVDs are circular flat optical discs used to store data.
• It comes in two different sizes one is 4.7GB single-layer discs and another one is 8.5GB double-
layer discs.
• DVDs look like CDs but the storage capacity of DVDs is more than as compared to CDs.
• It is of two types:
• DVD-R: It stands for Digital Versatile Disc read-only. In this type of DVD, once the data is written
can not be erased. It is read-only. It is generally used to write movies, etc.
• DVD-RW: It stands for Digital Versatile Disc read Write. In this type of DVD, you can easily write
or erase data multiple times.

8. DIFFERENCE BETWEEN DVD-R AND DVD-
RW
DVD-R
• DVD-R stands for Digital
Versatile Disc Recordable
• It can store 4.7 GB on single
layer single sided sided discs,
8.5 GB on dual-layer discs and
9.4 GB on double-sided discs
DVD-RW
• DVD-RW stands for Digital
Versatile Disc Re-Writable
• It can store only 4.7 GB of data
• It is used for storing a small
amount of data

9. FLASH MEMORY DEVICES
• It is a cheaper and portable storage device.
• It is the most commonly used device to store data because it is more reliable and
efficient than other storage devices.
• It has the ability to be electronically reprogrammed and erased.
• It is non-volatile, has a very fast access time and has a higher resistance to kinetic
shock compared to a hard disc drive.
• Flash memory is extremely durable and can withstand intense pressure or extreme
temperatures

10. • Some of the commonly used flash memory devices are:
1. Pen Drive: It is also known as a USB flash drive that includes flash memory
with an integrated USB interface.
2. SSD: It stands for Solid State Drive, a mass storage device like HDD. It is
more durable because it does not contain optical disks inside like hard disks

11. Thanks You
For Your Attention
End
Of Presentation