This document discusses different types of storage devices used in computers. It begins by defining storage devices and distinguishing between primary and secondary storage. Primary storage includes RAM and ROM, which temporarily and permanently store data respectively. Secondary storage devices like hard drives, floppy disks, CDs, DVDs, and USB drives provide larger storage capacities to permanently store data. Newer solid-state storage devices operate faster than traditional magnetic and optical secondary storage as they have no moving parts. The document provides details on the purpose, advantages, and disadvantages of each type of storage device.

1. Storage Devices
For Class IX Students
By IT Teacher Mr. Norser

2. Storage Devices:
A storage device is any
computing hardware that is
used for storing data files
and information.
It can hold and store the
information both temporarily
and permanently, and can
external or internal to a
computer.

3. Types of Storage Devices:
1. Primary storage devices :
Generally smaller in size
Temporarily stores data
Fastest access data speed
2. Secondary storage devices:
Large storage capacity
Store data permanently
They can be both internal and external to the
computer

4. Primary Storage Devices:
Primary storage, also known as main
storage or memory, is the area in a computer
in which data is stored for quick access by
the computer's processor.
Typically, Primary storage devices have an
instance of all the data and applications
currently in use or being processed.

5. Types of Primary Storage Devices:
There are Two main types of
Primary Storage Devices.
RAM (Random Access
Memory)
ROM (Read Only Memory)

6. 1. RAM (Random Access Memory)
Computers store data temporary in
the RAM. It is also known as Main
Memory & Random Access Memory.
These could be operating instructions,
loose data or content from programs
that are running. When the computer
is switched off, all the data is cleared
from the RAM. So it is known as
Volatile Memory.

7. 2. ROM (Read only Memory)
When a computer is first switched on,
it needs to load up the BIOS (Basic
Input/output System) and basic
instructions for the hardware. These
instructions are stored in ROM (Read
Only Memory).
ROM contains the programming that
allows your computer to be “Booted
Up”.
This type of memory is called Non-
Volatile because it retains the data.

8. Secondary Storage Devices:
Secondary Storage, is a Non-
Volatile Memory (does not lose
stored data when the device is
powered down) that is not
directly accessible by the CPU,
because it is not accessed via
the input/output channels.
It is use to store Permanent
Data.

9. Types of Secondary Storage
Devices:
There are Three main types of Secondary
Storage Devices.
Magnetic Storage Devices
Optical Storage Devices
Solid-State Storage Devices

10. 1. Magnetic Storage Devices:
Magnetic storage is the storage of
data on a magnetized medium.
There are Three main types of
Magnetic Storage Devices.
Hard Disk
Floppy Disk
Magnetic Tape

11. Hard Disk Drive:
• Hard disk drive is a data storage device that
uses magnetic storage to stored data
magnetically onto the tracks on the disk.
• The Hard Drive reads & writes the data to
the Hard Disk.
• The platters are used to stored the data and
these data is access by using a magnetic head
• A platter is a hard disk coated with a
magnetic material.

12. Hard Disk Drive:
Uses
Stores all types of media
Stores your data files
Advantages
Large storage capacity up to 10 TB.
Stored items are not lost when the computer is switched off.
Usually fixed inside the computer and not portable.
Disadvantages
Slower than RAM & ROM.
If the hard disk crashes the computer will not work & you have lost
your work!!!

13. External Hard Drive:
An External hard drive is a portable storage device that can be attached
to a computer through a USB cables.
It is usually used to store media that a user needs to be portable, for
backups, and when the internal hard drive of the computer is full memory
capacity.
These devices have a high storage capacity compared to flash drives.

14. Floppy Disk:
Floppy disk is also called Diskette.
It consists of a thin plastic disk coated with magnetic
material.
Uses
To keep personal data
Keep extra copies of data
Advantages
Can be carried with you
Disadvantages
Limited capacity (typically 1.44 Mb)
Unlikely to store your ICT coursework on one disk

15. 2. Optical Storage Devices:
Optical Storage Devices are discs coated with
a reflective metal on which data is record using
laser technology. The data on the storage
medium is read by the laser beam off the
surface of the medium.
Types of Optical devices:
Compact Disc (CD)
Digital Versatile Disc (DVD)
Blu-Ray Disc (BD)

16. Compact Disc( CD ):
Compact Disc is a digital optical disc data
storage format
The average CD allows for up to 700 MB of
data storage. Digital bits are stored as pits
on the reflective material in the disc. A red
wavelength laser detects these pits and
converts them to a digital signal.
Three basic types.
Read only: CD-ROM
Write once: CD-R
Rewriteable: CD-RW

17. CD-ROM (Read Only Memory):
CD-ROM is a optical compact disc which
contains data. Computers can read CD-ROMs, but
cannot write to CD-ROMs, which are not writable
or erasable.
Advantages
Data cannot be erased
Portable
Much larger capacity than floppy disks (about
700Mb)
Disadvantages
Can’t write data to a CD Rom
Data access can be slower than a hard drive.

18. Digital Versatile Disc (DVD):
A Digital Versatile Disc (DVD) is an
optical disc storage medium similar to
a compact disc, but has a larger
storage capacity.
The DVDs allows data storage for up
to 4.7 GB to 9.4 GB.
DVDs used a Red wavelength laser
to read data, much like CDs.
Storing high quality audio & video.

19. Types of DVD:
There are Three main types of DVD.
DVD-ROM:
Read Only Memory DVDs can be only read data but not written or
erased.
DVD-R:
Blank Recordable DVD discs can be recorded once using a DVD
recorder and then function as a DVD-ROM.
DVD-RW:
Rewritable DVDs (DVD-RW, DVD+RW) can be recorded and erased
many times.

20. Blu-Ray Disc ( BD ):
Blu-Ray is the new and more
expansive DVD format.
It provides higher capacity and better
quality than DVD, especially for High-
Definition video.
A Blu-Ray disc can hold up to 25 GB
to 50 GB of data
Blu-Ray used a Blue wavelength laser
to read data.

21. Flash Memory:
Flash Memory is a special types of
memory chip that combines the best
features of RAM & ROM.
It is used for storage and for transferring
data between a digital devices.
Flash Memory is a non-volatile.
It is commonly used in Digital Cameras,
Multimedia Players, USB & Cell Phones.

22. USB Storage Device:
A USB flash drive also known as a USB stick, or pen drive
is a Plug-and-Play portable storage device that uses flash
memory and used for store &
transferring data.
It is lightweight enough to attach to a keychain.
USB Drives now come in capacities ranging between up to
8 GB to 2 TB.
Easy to transfer data from one place to another.

23. 3. Solid-State Storage Devices:
Solid-State Storage is a type of nonvolatile
computer storage that store data
Electronically instead of magnetically or
optical.
Solid-State Devices have no moving
mechanical parts.
SSD operates much faster than other
storage devices, because SSD have no
need to move a head or sensor to find
data or convert it from magnetic or
optical form into electronic form.