CD's and DVD's work in virtually the same style. Both store information as a collection of reflective marks on the surface of the disk. The slim plastic or foil metal layer of the disc gets struck by the laser beam of the writing drive. The laser energy so produced creates little bumps in a spiral pattern similar to that of a long-playing album.
When you set off the disk, it rotates and whilst doing this, a different laser beam shines on the bumps. The laser light flickers off or on because of the bumps and these flickers are changed into ones and zeroes which is basically the language of the computer. The light is reflected back to a sensor and the info is converted into audio, video and general information.
CD's
A Compact Disc or CD is an optical disc originally created to store and play audio but has developed throughout the years into a storage medium for information. Normally CD's can store up to 80 minutes of uncompressed sound identical to 700mb of information.
The CD surface is made from a polycarbonate layer on which is molded spiral tracks. CD info are stored as a series of 'pits ' or minute grooves encoded on these spiral tracks. The field between 'pits ' are known as 'lands'. These pits and lands do not make up the zeroes and ones of binary info. Rather, a change from pit to land (or vice versa) is read as 0 while no change is construed as one. By a method of decoding and reversing, the raw info stored on the disk can be disclosed.
DVD's
A DVD has the same attributes as the CD but offers higher storage capacity.
DVD employs a laser diode light of a 650 nm wavelength which is much shorter than the 780 nm wavelength employed in CD's. This allows for etching of smaller pits on the tracks of the DVD which explains the larger storage capacity of DVD's.
When you set off the disk, it rotates and whilst doing this, a different laser beam shines on the bumps. The laser light flickers off or on because of the bumps and these flickers are changed into ones and zeroes which is basically the language of the computer. The light is reflected back to a sensor and the info is converted into audio, video and general information.
CD's
A Compact Disc or CD is an optical disc originally created to store and play audio but has developed throughout the years into a storage medium for information. Normally CD's can store up to 80 minutes of uncompressed sound identical to 700mb of information.
The CD surface is made from a polycarbonate layer on which is molded spiral tracks. CD info are stored as a series of 'pits ' or minute grooves encoded on these spiral tracks. The field between 'pits ' are known as 'lands'. These pits and lands do not make up the zeroes and ones of binary info. Rather, a change from pit to land (or vice versa) is read as 0 while no change is construed as one. By a method of decoding and reversing, the raw info stored on the disk can be disclosed.
DVD's
A DVD has the same attributes as the CD but offers higher storage capacity.
DVD employs a laser diode light of a 650 nm wavelength which is much shorter than the 780 nm wavelength employed in CD's. This allows for etching of smaller pits on the tracks of the DVD which explains the larger storage capacity of DVD's.
About the Author:
Brian Shaw runs a data recovery business called Kingdom Data Recovery Edinburgh who service all of the United Kingdom. He's got many articles on his web site which refer to issues with storage devices and helpful info about stopping data loss.
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