Secondary storage devices



Secondary storage devices
Hard disc
CD
DVD
Flash
Memory card
Filopy disc




Hard disc:
Permanent storage device.
Consist of circular metalic plates.
Enclosed in a case to prevent from dust and damage.
Can store huge amount of data.
Data is read by a lense placed on the end of a head.
Each dis has a saparate head to read data from it.
Can be connected to computer by IDE or sata cable.


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CD:
Stands for compact disc
It is an optical storage device.
It is usually used as Read only memory.
Portable storage device.
Can store 600 MB of data
Very cheap and easy to handle and use.

Data cannot be edited and also CD may got corrupt.

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DVD:
Digital video disc
Similar to CD but can store bigger amount of data
DVD ROM use laser beam with high frequency to read data.
It can store upto 17GB of data.

CD rom cannot read DVD disc but DVD rom can read both CD and DVD.


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CD-RW:
Rewriteable CD disc.
We need combo drive to write a CD disc.
A special laser is used to erase data by heating up CD portion.
It may store upto 5 GB data.






Smart card:
Image result for Smart card
A special storage device.
Have a small processor and memory to store data.

Card is inserted in a special card reader to work on it.





Floppy Disc.


Not in much use now a days.
Usually comes in 3.5” and can store 1.44MB of data.

Very sensitive to virus.






CPU
Stands for central processing unit.
It is brain of computer.
It do all the processing for computer.
It is a small square chip containing millions of transistors on it.
To keep it cool there is a sink and a fan placed on it.



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