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Optical disk

Optical disk is a secondary storage device in which data can be stored permanently. In optical disc, data is stored in binary form and laser beam technology is used to store the data in it. Data can be stored safely for a long time in optical discs. Optical disc is a round and shiny disc whose diameter can range from 3 inches to 12 inches. And its thickness can be up to 0.05 inches.

Optical storage, electronic storage medium that uses a low-power laser beam to record and retrieve digital (binary) data. In optical-storage technology, a laser beam encodes digital data onto an optical, or laser, disk as tiny pits arranged in a spiral track on the disk’s surface.

Types of optical discs –

Compact Disc (CD) –

Compact Disc is a type of optical disc in which data is stored permanently. CD is an optical ROM, in which the data is already stored by the manufacturing companies, and the user can only read the data stored in the CD and cannot write anything in it. The data in CD is read by laser light.

The storage capacity of CD is about 700 MB which is much more than that of Floppy Disk and less than that of DVD and Blue Ray Disc.

VCD –

• CD is also called video CD, preview CD, compact digital video.
• It is a standard digital format for storing video on compact disk.
• The V-CD standard was created in 1993 by Sony, Philips and JVC.
• It can be played in V-CD, V-CD player computers, Advance DVD video players and some video game consoles.
• It was given as white book standard.

CD-R –

• The full name of CD-R is compact disk recordable.
• It is a rewritable disk format by Philips and Sony, that is, the information in it can be re-written.
• In this type of disk, the data already written is erased and the data can be stored again on the same track.

CD-RW –

The full name of CD-RW is compact disk re-writable.
It was introduced in 1997. It is a rewritable disk format, that is, the information in it can be rewritten.
In this type of disk, the data already written is erased and the data can be stored again on the same track.

Digital Versatile Disc (DVD) –

The full name of DVD is Digital Versatile Disc. The storage capacity of DVD is much higher than that of CD. The storage capacity of DVD can be 4.7GB, 8.5GB and up to 20 GB.

The storage capacity of a DVD depends on its layer. The layer of DVD can be of Single, Double, Single Side or Double Side type. Like CD, DVD also uses laser light to store data. Data is stored in each of its layers. The storage capacity of CD was very less, hence the need for DVD.

Blue – Ray Disc –

Blue Ray Disc is a type of Optical Disc in which we can store large size data also. Nowadays Blue Ray Disc is widely used for secondary memory. Like DVD, data is stored in layers in Blue Ray Disc. But 4.7 GB data can be stored in one layer of DVD but 25 GB data can be stored in one layer of Blue Ray Disc. Blue Ray Disc is used to store HD video.

Advantages of optical disc –

• Optical discs last longer than volatile and non-volatile memory. There is no risk of data loss if the power supply is switched off. Optical discs remain safe for many years.
• Optical discs are used in various computers and devices.
• The user can easily create a backup of the data stored in optical disc in his computer.
• The cost of manufacturing optical discs is low because only plastic and aluminum are used.

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