secondary storage

WELCOME TO OUR PRESENTATION

Topic: Secondary Storage

To get general idea about secondary storage.

To obtain information concerning the advantages and disadvantages of secondary storage.

To obtain general idea about types of secondary storage.

To know the causes of using secondary storage.

OBJECTIVE OF THE PRESENTATION

CREATED BY HOSSAIN RAJU

OVERVIEW

Introduction What is Secondary Storage? The Advantages of Secondary Storage The Disadvantages of Secondary Storage Evolution of Secondary Storage Devices Types of Secondary Storage Types of Optical Disk Why we use Secondary Storage Devices Conclusion References

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INTRODUCTION

Every computer system consists of a variety of devices to store the instructions and data required for its operation. The instructions and data are stored in the memory (storage) unit of the computer. The memory components of a computer system can be divided into following main groups:

Primary Storage (Main Memory), Secondary Storage (Auxiliary

Memory), and Internal Processor Storage.

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WHAT IS SECONDARY STORAGE?

Secondary storage technology refers to storage devices and storage media that are not always directly accessible by a computer. This differs from primary storage technology, such as an internal hard drive, which is constantly available.

In Computer Science, “Any means of storing and retrieving data external to the main computer itself but accessible to the program.”

SECONDARY STORAGE (CONT…) Used in a computer system to overcome the

limitations of primary storage, Has virtually unlimited capacity because the cost

per bit of storage is very low, Has an operating speed far slower than that of

the primary storage, Used to store large volumes of data on a

permanent basis, Also known as auxiliary memory.

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THE ADVANTAGES OF SECONDARY STORAGE

The advantages of Secondary storage are given below:

Secondary storage devices are safe, reliable and permanent.

High speed storage device. Huge volume data are stored. Less expensive. It is nonvolatile.

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THE DISADVANTAGES OF SECONDARY STORAGE

The Disadvantages of Secondary storage are given below:

While RAM electronic storage devices are fast, secondary storage devices are slower because they are electro-mechanical.

The information on the secondary device has to be first located, then copied and moved to the primary memory or RAM.

Takes more time.

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EVOLUTION OF SECONDARY STORAGE DEVICES

The first hard drive was used in 1956 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 of data.

From 1990 to till now there are many devices is created like card reader, Memory Stick, Multimedia Card etc.

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TYPES OF SECONDARY STORAGE

There are three main types of secondary storage:

Magnetic Tape.Magnetic Disk.Optical Disk.

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TYPES OF SECONDARY STORAGE (CONT…)

Magnetic Tape: Oldest storage device, Used for large computer

like mainframe computers, Made of plastic coated with

magnetic material, Store data permanently, Used to read and write

data, Cost of storing data is

expensive, Used in reels.

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TYPES OF SECONDARY STORAGE (CONT…)

Magnetic Disk: A thin circular metal or plastic

disk coated with magnetic material,

Stored data in the form of magnetic spots,

A random access device, Faster than magnetic tape.

There are three main types of magnetic disk:

i. Hard Diskii. Floppy Diskiii. Zip Disk

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TYPES OF MAGNETIC DISK

Hard Disk: Usually used as secondary

storage, Also called fixed disk, Consists of one or more

metal plates, Metal plates are coated

with magnetic material to store data,

Also have an access arm and read / write heads.

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TYPES OF MAGNETIC DISK (CONT...)

Floppy Disk: A small plastic plate coated

with magnetic material, Stored data in magnetic

spots, Used to transfer data from

one computer to another.

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Zip Disk : Similar to 3 ½ inch

floppy disk, Can store 100 MB or

more data. Used to read and write

data.

TYPES OF MAGNETIC DISK (CONT...)C

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TYPES OF SECONDARY STORAGE (CONT...)

Optical Disk: Used LASER technology to read and write data, LASER stands for Light Amplification through Emission of Radiation,Laser beam writes on the surface of optical disk by creating very small holes. The presence of hole represents a One, and absence of the hole represents a Zero.

TYPES OF OPTICAL DISK

There are following main types of optical disk:

i. CD-ROM.ii. CD-R or WORMiii.CD-RWiv.DVD-ROMv. DVD-Rvi.DVD-RW

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TYPES OF OPTICAL DISK (CONT…)

CD-ROM : Stands for Compact Disk-Read Only Memory, Data stored can only be read, Data can be easily transferred,Commonly can store 650 MB / 700 MB/ 750 MB data.

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CD-R (CD Recordable) Or WORM:

Compact disc recordable, An optical secondary

storage device, Invented by Sony and

Philips, Also known as a WORM

(write once read many), Can store data on it only

once.


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CD-RW ( CD Rewritable ): Stands for Compact Disk

Rewritable, Special type of CD, Can write data on it, CD-Writers are used to store

data.

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DVD - Digital Video Disk (DVD-ROM):

Stands for Digital Video Disk, Used a laser beam with a

short wave length Create very small holes on

the surface of disk. Can store up to 17 GB or

more data.

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DVD-R (DVD-Recordable): Stands for Digital Video Disk Recordable, Initially a blank disk, Can store data only once, Becomes read only,Normally used to store high definition video movies.

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DVD-RW ( DVD Rewritable):

Stands for Digital Video Disk Rewritable.

Can write data many times by erasing the old data.

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WHY WE USE SECONDARY STORAGE DEVICES

It is non volatile and permanent.Used for a very simple task backing up data.Used to serve as an external hard drive.Becoming more and more portable as technology progresses.Many businesses will connect secondary storage devices to share files. Keep data on them for future use.Additional space for data.

CONCLUSION

The primary memory is costly, not a permanent storage media and has limited capacity. The secondary memory is the storage other than main memory, and is used for storing large data files, system programs and the like which are not continuously required by the CPU. It also serves as an overflow memory when the capacity of the main memory is exceeded.

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REFERENCES

Elements of Computer Science by S.K. Sarkar & A. K. Gupta

en.wikipedia.org www.slideshare.net www.techterms.com answers.ask.com

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CREATED BY HOSSAIN RAJU

secondary storage

Technology