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Second storage device

Members : Mohd. Ibrahim , Patricia Antai , Nurfarahin , Nur Ezzati , Yamunaa

Patricia Antai Robin

on 23 July 2013

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Transcript of Second storage device

Secondary Storage Devices
What is Secondary storage device?
Alternatively referred to as external memory and auxiliary storage.

a storage medium that holds information until it is deleted or overwritten regardless if the computer has power.

provides permanent/nonvolatile storage

the data that are stored inside it are not deleted or erased even when the power is switched off.

-whenever it is necessary for us, we can retrieve the information/the data from the secondary storage device and use it.

Compact Discs/ CD-ROM
•Compact Disks most popularly known as cds
•They are Read only memory device as without the CD writers we cannot store our files and folders on the
•The diameter of the CD ranges from 10 cms to 30 cms. A typical CD is of 13 cm diameter.
•CD comprises of a transparent thin layer of aluminium covering the pitted surface for reflectivity.
• One CD can store 600 MB to 750 MB data on it.
• Laser reads the normally used cds
• So once the data is stored into the CD ROM it cannot be erased.
• Recently writable cds are also introduced in the market but they are not so common.
• The read/write speed of a CD-ROM is average access tune is 125 milliseconds.
• The data may be in the form of text, image, sound, video clips, animated movies or their combinations.
• The CD Rom drive are mostly used to keep back ups & access the data for reading

Examples of Secondary Storage Device
Floppy Disks
USB drives
• USB drives are known by a myriad of names, including thumb drives (since the most common size is that of your thumb), jump drives and flash drives.
• USB drives are currently available in USB 2.0 with USB 3.0 hitting the market now.
• These small plug-and-play drives are removable, re-writable, and great for storing personal and professional data, as many are hardware-encrypted devices for ultimate security
• Is a circular piece of plastic material

• Coated with particles, which are magnetized. This thin plastic sheet is protected

• From outside by a plastic cover to prevent the sensitive data stored on them.

• Commonly used floppy disks are of 3.5 ” diameter

• Used to store data and transfer them from one computer to another

• The data inside the floppies are stored in tracks and sectors

• The outer plastic cover has read / write hole covered by a metal sheet

• A hard disk is fixed inside the cabinet of CPU (Central Processing Unit)
• It is made up of many rigid metal platters coated to store data magnetically.
• The hard disk rotates while recording data.
• This rotation speed is measured in the unit of revolutions per minute (rpm).
• The normal speed of hard disks is 3600 revolutions per second.
• The read/write head of the hard disks moves across its surface.
• The storage capacity of the hard disks is many times more than the floppy disks

Memory Card
• A memory card (sometimes called a flash memory card or a storage card) is a small storage medium used to store data such as text, pictures, audio, and video, for use on small, portable or remote computing devices.

• Most of the current products use flash memory, although other technologies are being developed.

• There are a number of memory cards on the market, including the SD card (secure digital card), the CF card (Compact Flash card), the Smart Media card, the Memory Stick, and the Multimedia Card.

Five major advantages of secondary storage:
1. Convenience: secondary storage allows you to locate and retrieve stored data, programs and information easily and quickly.

2. Economy: storing data, programs and information on a secondary storage medium is relatively inexpensive.

3. Reliability: data, programs and information stored on a secondary storage medium are safe and protected

4. Capacity: when one secondary storage medium is filled with data, another can always be added, forming libraries of data and information with considerably less bulk than traditional system of data and information storage

5. Portability: secondary storage mediums may be transported to other sites for future processing.
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