The document provides information about secondary storage. It begins by defining secondary storage as non-volatile, long-term storage used to store programs and data when a computer is switched off. The main types of secondary storage are magnetic storage devices like hard disk drives. Advantages of secondary storage include safety, reliability, permanence, and ability to store huge volumes of data cheaply. Disadvantages are slower speed compared to primary storage. Common secondary storage devices discussed include hard disks, optical discs like CDs and DVDs, USB flash drives, memory cards, and smart cards.

1. introduction
 NAME Ahsan iftikhar
 ROLL NO 564
 CLASS BSCS 5th EVE
 subject OPERATING SYSTEM

 TOPIC Secondry storage

2. Secondry Storage

3. OBJE CTIVE OF THE
PRESE NTATION
 Togetgeneral ideaabout secondarystorage.
 To obtain information concerning the advantages and
disadvantages of secondarystorage.
 Toobtaingeneral ideaabouttypesofsecondarystorage.
 Toknowthecausesof usingsecondarystorage.

4. Any computing hardware that is used to store data files
and objects is called storage devices. It can store
information both temporarily and permanently.
A storage device may also be known as a storage medium
or storage media.
There are two different types of storage devices,
1) Primary storage device.
2) Secondary storage device.

5. What is Secondry storage ?
Secondary storage is non-volatile , long-term storage.
Without secondary storage all programs and data
would be lost the moment the computer is switched
off. There are three main types of secondary
storage in a computer system: ...
magnetic storage devices, such as hard disk drives.

6. Adnatage of secondry
 Secondary storage devices are safe, reliable and permanent.
 High speed storage device
 Huge volum e d ata are stored.
 Less expensive.
 It is nonvolatile.

7. Disadvantage of secondry
 While RAM electronic storage devices are fast,
 Then secondry
 storage devices are slower because they are
electromechanical.
 The information on the secondary device has to be first
located, then copied and moved to the primary memory
or RAM .
 Takes more time.

8. History of devices
The first hard drive was used in 1 956 which is created by IBM and whose
capacity was 5 MB.
In 1971 , IBM introduced a technology called the floppy disk,
At the beginning of the 1980s the first optical devices were released by
Sony and Philips. This drive can store approximately 650 to 700 MB of data.
From 1990 to til now there are m any devices is created like card reader,
Memory Stick, Multimedia Card etc.

9. Secondry storage devices?
primary storage device are those who use to store data, information and
programs permanently.
It can to store a large amount of data easily. Different storage media are
used to store data, information and programs. It is called non volatile
memory because its contents remain safe if the computer is turned off.
Storage media are available in different sizes and capacities. The
storage media can be a removable, internal or external storage.
Examples of storage media are hard disk , USB flash drive, memory card
and optical discs, smart card and cloud storage
etc.

10. Optical Disc:
Optical disc is a form of removable storage. It includes
CD, DVD and Blu-ray discs. Optical drives use a laser to
read and write data on optical disc. Laser beam writes on
the surface by creating small pit (hole) in the disc.
Optical disc commonly store data in a single track. Most
desktop and laptop computers have at least one optical
drive.
Optical drive reads data by focusing leaser beam on the
surface of the disc. A leaser detects the presence of a pit.
The presence of pit indicates 1 and absence of pit
indicate 0. Leaser beams converts these pits into digital
data. Optical disc storage capacity is from 700 MB to
several GB.

11. CD
SD Stands for Compact Disc . It is mainly used to store photos, audio
and computer software. The contents of CD can be read by CD drive.
CD are available in three types which are read only, recordable and
rewriteable. Different types of CD are follows:
Types of Optical disk

12. 1) CD-ROM
CD-ROM stands for Compact Disc Read Only Memory.
The data stored on CD-ROM can only be read. It
cannot be delete or changed. It can store up to 700MB
of data.
Uses of CD-ROM
CD-ROM is mostly used to store photos and audio.
It is often used to distribute new application software
and games.

13. Advantages of CD-ROM
It is the least expensive way to store data and
information.
CD-ROM discs are durable and easy to handle.
Information can be stored on CD-ROM for many
years.
Disadvantages of CD-ROM
The data cannot be edited.
It retrieves data and information more slowly than
magnetic hard disk.

14. 2)CD-R
CD-R stands for CD Recordable. The user can write data
on CD-R only once but can read it many times. The
data written to CD-R cannot be erased. The process of
recording data on CD-R is called burning. It is also as
WORM(Write Once Read Many).

15. 3)CD-RW
CD-RW stands for Compact Disc Rewritable. It is also
known as erasable optical disc. The user can write data
on CD-RW many times by erasing the existing
contents. The most common type of erasable and
rewritable optical disk is magneto-optical disc (MO).
It use the technology of both magnetic disk and
optical disc.

16. DVD
DVD stands for Digital Video Disc. It is similar to CD.
The storage capacity of DVD is much greater than CD.
It can store up to 17 GB of data. DVD are available in
three types

17. 1)DVD-ROM
DVD-ROM stands for digital video disc read only
memory. It is a high capacity optical disc that the
users can only read but not to write or erase. DVD-
ROM are use to store high definition videos, music and
software etc.

18. 2) DVD-R
DVD-R stands for digital video disc recordable. It is
similar to CD-R discs. The user can write data on it
once but can read it many times. The written data
cannot be erased.

19. 3) DVD-RW
DVD-RW stands for digital video disc rewritable. The
user can write data on CD-RW many times by erasing
the existing contents.

20. Magnetic Disk:
Magnetic disks use magnetic material to store data, information and
instructions on disk surface. The data on magnetic disks is stored in
tracks and sectors. Tracks from circles on the surface of a magnetic
disk. Each track on a disk is divided into sectors. Each sector typically
stores up to 512 bytes of data. Hard disk is the most widely used
magnetic disk.

21. Hard disk:
Hard disk is the primary storage device in a computer to store the
programs and data permanently. It is also known as hard disk
drive(HDD) or hard drive(HD). Most personal computers have at least
one hard disk drive. Some large scale computers contain hundreds of
hard disks. The capacity of hard disk can be up to 8 TB or more.

22. The traditional hard disk is a type of magnetic disk. It is also called
fixed disk because it is fixed in the system unit. It consists of several
circular disks called platters that are coated with magnetic material.
The platters are stacked on the top of one another enclosed in a
sealed case. Each platter has two read/write head, one for each side.
The hard disk also has arms that move the read/write head on the
proper location on the platters to read and write data. The platters
in the hard disk typically spin at a high rate between 5,400 and
15,000 revolutions per minute (RPM).

23. The user can write and read data from the hard disk many times. The
disk must be formatted before any data can be written on a hard
disk. Formatting is a process that creates tracks and sectors on the
disk. Tracks are in the form of circles on the surface of a hard disk.
Each track on a disk is divided into sectors. Each sector typically
store up to 512 bytes of data. Two ore more sectors can be
combined to form a cluster. A cluster is the smallest unit of disk
space that stores data. All tracks in the same position on all surface
of all disks in a hard drive form a cylinder.

24. External and removable Hard Disk
An external hard disk is a separate hard disk that is connected to the USB port
or FireWire port on the system unit. The advantage of external hard disk is
that it can be installed without operating the system unit. Some hard disks
can also communicate with system unit wirelessly. The entire hard disk is
enclosed in a sealed case. The storage capacity of external hard disk is up to
4 TB and more.
A removable hard disk is a type of hard disk that can be inserted and
removable form a drive. The removable hard disk drive is used to read and
write data on the removable hard disk. The storage capacity of removable
hard disk can be up to 4 TB and more.
The data transfer rate of external and removable hard disk is slower than
internal hard disk. However, there are different advantages of these disks
over internal hard disk.

25. Advantages of external disks
However, there are different advantages of these disks over internal
hard disk.
These disks can be used to transfer a large number of files among
computers.
These disks can be used to backup important files or entire internal
hard disk.
These disks can store a large number of audia and video files easily.
These disks can be removed from computer and locked at a secure
lace for the protection of data.
These disks can be used to increase storage space of the computer
without operating the system unit.

26. Floppy Disk or Diskette:
Floppy disk is also called diskette. It consists of a thin plastic disk
coated with magnetic material. This disk is enclosed in a plastic
jacket. It was introduced by IBM in early 1970. It is a portable
storage medium and can be removed from one computer and
inserted into another computer easily. It is not commonly used now
a day. Floppy disk can only store a small amount of data. Data
access speed of floppy disk is slower then hard disk. It is inexpensive
storage media. The standard size of floppy disk is 3.5 inch. The
capacity of floppy disk is 1.44MB.

27. USB Flash Drives
USB Flash Drives is a small and portable
storage device. It is connected to the
computer through USB port. It is commonly
used to transfer documents, photos, music
and videos from one computer to other. It
can be carried in pocket easily. It is available
in different shaped, sizes and capacities. The
storage capacity of USB drive can up to 256
GB or more. It is also called thumb drive, key
drive or jump drive.

28. Memory card
A memory card is a removable flash memory to store data. Most of
these cards are very small. The existing data can be erased and new
data can be written easily. Many cards are available in different
shapes and sizes. They are commonly used with smart phones,
portable media players, digital camera and other portable devices. A
memory card can be inserted into a slot on computer or mobile
devices. However, a card reader can be attached to the computer if
it does not have a slot. The card reader is usually connected to the
USB port of the computer. The card readers are designed to read
multiple types of memory cards.

29. Smart card
It is also a storage device which is used to store data
Smart card is a small card of plastic that contain computer
circuits. Smart card can store a small amount of data
that can be used for payment or identification
purposes. The amount of cash available on the card.
Smart card are also commonly used for national and
student ID cards, credit or debit card etc. They are also
used to store identification data.

30. Why we use secondry storage device
 IT is non voLATiLe AnD peRmAnenT.
 UseD foR veRy simpLe TASk BACkinG up DaTA.
 useD TO SeRve AS An exTeRnAL hARD D Rive.
 Becom inGmoRe AnD moRe poRTABLe AS TechnoLOGy pROGResses.
 MAny Businesses COnnecT SeconDARy sTORAGe Devices TO ShARe
fiLes.
 Keep DATA On Them foR fuTuRe use.
 ADDiTionAL SpACe foR DATA.

31. THANKS FOR WATCHING
ANY QUESTION