What Is optic Disk?

Optical Disk

Optical disk is an electronic data storehouse medium from which data is read and written to by using a low-powered laser beam. It is flat, circular, plastic or glass disk on which data is stored in the form of light and dark pits. The laser beam reads the pits and the data can be accessed. There are three basic types of optic disks:

Scsi To USB

o Read-only optic disks: The optic disks, which are recorded at the time of make and cannot be erased. Cd, Cd-Rom, Dvd-Rom, and Dvd-Video are the read-only disks.

o Worm: Worm stands for write-once, read many. The optic disks that can be recorded by the user only once but cannot be erased. After they have been recorded once, they behave like a read-only optic disk Cd-R, Dvd-R, and Worm disks are write-once.

o Rewritable/Magneto-optic disks: The optic disks that can be erased and written to with the new information. Cr-Rw, Dvd-Ram, Dvd-Rw, and magneto-optic disks and Data play are rewritable. Rewritable disks use magneto-optic or phase turn technology.

An optic disk offers many advantages over magnetic storehouse media.

o top storehouse capacity

o Low cost per Megabyte of storage

o Environmental health tolerance

o High data stability

o Long media life

An optic disk has much more storehouse capacity on the order of gigabytes, than a magnetic disk. It can hold up to 6Gb of data in comparison to 1.44 Mb of a diskette. optic disks are reasonable to manufacture. Data stored on optic disks is resistant to power surges or magnetic disturbances, such as head crashes or corruption form stray magnetic fields. Hence, they furnish high data stability. optic disks are less vulnerable to extremes of hot and cold as
compared to the magnetic disks. optic disks have long media life than magnetic disks.

Optical storehouse Devices

Cd-Rom

Cd-Rom: is an abbreviation of ageement Disc Read-Only Memory. A Cd-Rom is a Cd that contains computer data, which cannot be read or rewritten. In
computers, Cdrom is the most commonly used optic storehouse technology. Cd-Rom is a ageement disc that contains information, which is accessible by a computer. It is composed of polycarbonate plastic, thin reflective metal layers, made of aluminium and a lacquer coating. Data is stored on the disc as a series of light and dark pits; the light part refers to the spaces in the middle of the pits. A laser beam reads the pits and the data can be accessed.

Cd-Rom is an adaptation/Extension of the ageement disc that is designed for music storehouse and playback. The format of Cd-Rom is very similar to an audio Cd; the only contrast being the standards used to store data. A appropriate 120 mm Cd-Rom holds up to 700 Mb of data, or about 70 minutes of audio. This may mean that One Cd can consist of over one thousand novels; an mean novel being composed of 60, 000 words. Once the data is written to a appropriate Cd-Rom disc, it cannot be altered or rewritten.

A Cd-Rom can be read using a Cd-Rom drive, which is approximately base on the personal computers. A Cd-Rom drive may be connected to the computer in some separate ways depending on the type of interface, such as:

o Ide (Ata)

o Scsi

o Sata

o Firewire

o Usb

Almost all modern Cd-Rom drives can play audio as well as video Cds.

Cd-Rom Standards

Cd-Rom format provides an outstanding solution to the problem of storing large digital files. some formats are used for data stored on Cd-Roms. These consist of Red book standards for audio-Cd, White Book and Yellow Book for Cd-Rom. An Iso 9960, which defines the appropriate file theory of a Cd-Rom is due to be replaced by Iso 13490.

Cd-Rom Format

One Cd-Rom sector contains 2352 bytes, which is further divided into 98 24-byte frames. A Cd-Rom contains a third layer of Reed-Solomon error revision in order to accomplish improved error revision and detection.

Mode-1 Cd-Rom: It has full three layers of error revision data, which contains 2048 bytes of the available 2352 per sector.
Mode-2 Cd-Rom: It is mostly used for video files, which contains 2336 user-available bytes per sector.

Cd-Rom Speeds And Uses

+ Early Cd-Rom drives were known as single-speed and could read the data at the speed of 150 Kbps.

+ Cd-Rom drives can change data up to the speed of 7800 Kbps

+ Cd-Rom can store audio, video, text and schedule instructions. It is used to store software programs.

Dvd-Rom

Dvd-Rom: is an abbreviation of Digital Versatile Disc- read only memory. Dvd-Rom is an optic disc storehouse media format that can be used for data storage, which includes movies with high video and sound quality. Dvd-Rom is a non-volatile optic storehouse medium similar to Cd-Rom, which contains computer data that cannot be erased or rewritten. These Dvds are read-only disks that have storehouse capacity for 133 minutes of high capability video, in format, and audio full- length highlight film. The discs are pressed in a similar fashion as the Cds. The reflective exterior is gold or silver colored.

Dvd-Rom can be accessed using a Dvd-Rom drive attached to the personal computer. Dvd-Rom drives are backward compatible, i.e. They are also capable of reading Cd-Roms and audio Cds as well. The Dvd-Rom supports disks with capacities of 4.7 Gb to 17 Gb and way rates of 600 Kbps to 1.3 Mbps. A appropriate Dvd disc store up to 9.4 Gb of data. Dvd-Roms are of same size as a ageement disc, but holds data about 7 times more. Dvd can store that much of data because both the sides of a disc are used, with sophisticated data compression technologies.

Dvd-Rom is a contrast of Cd-Rom that is being used in place of Cd-Roms in many personal computers. All Dvd-Roms consist of a file system, Udf, which is an extension of the Iso 9660 appropriate used for data Cds.

Cd-Rw

Cd-Rw is an abbreviation of ageement disc-rewritable. It is a recordable Cd format that can be erased and rerecorded many times, just like a floppy disk or a hard disk. It is a rewritable version of Cd-Rom. Cd-Rw disc is round plastic, about 5 inches in diameter. Cd-Rw disks can be played or recorded in the Cd-Rw drive only. These disks behave unusable when put in a quarterly Cd-drive or a Cd-R drive cannot be played. A Cd-Rw drive can read all things except a Dvd.

A Cd-Rw can hold 650 Megabytes of data (unlimited estimate of times) written by a Cd-Rw drive. Cd-Rw cannot be selectively overwritten but can be extended. Cd-Rws must be finished before they can be read in a normal Cd-Rom drive. Cd-Rw disks cannot be read using a Cd-Rom drive built before 1997. Cd-Rws can be randomly read and written because of the contrast of Udf format. Cd-Rw disks and drives are more expensive than a quarterly Cd-Rom drive or media. A Cd-Rw disc can be read optically by laser light.

Dvd-Rw

Dvd-Rw: stands for Digital Versatile Disk-Rewritable. It is a re-recordable optic disc, which can report up to 4.7 Gb per side in a similar fashion to a Cd-Rw. Dvd-Rw supports sequential read/write way i.e. The gismo may need to wait for the exact location in a constantly revolving medium. The facts stored on Dvd-Rw can be erased and rerecorded over many times without damaging the medium.

Dvd-Rw is a phase-change erasable format based on Dvd-R, using similar mark length, track pitch and rotation control. The format is supported by the Dvd Forum. Dvd-Rw is also called "Dvd Dash Rw" and "Dvd Minus Rw".

Dvd-Rw can be played in many Dvd drives and players. Depending on quality, recording time varies from 1 hour to 6 hours.

If these optic disk gets damaged then the stored data becomes in accessible, these lost or damaged data can be recovered by usinig Stellar Phoenix Cd Data salvage Software