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What is DVD-ROM? What are the differences between CD-ROM and DVDROM?

a) DVD (also known as "Digital Versatile Disc" or "Digital Video Disc") is a popular optical
 disc storage media format used for data storage. Primarily uses are for movies, software, and
 data backup purposes, DVDs are of the same form factor as compact discs (CDs), but allow
 for 8 times the data storage capacity (single-layer, single-sided).
 i) Storage capacity: Going by the storage capacity, the DVD specifications have four disk
 configurations, ranging from 4.7 GB to 17 GB. It ranges from single-sided, single-layer
 disks that are much like traditional CD ROM disks to double-sided double-layered DVDs.
 Normally a DVD ROM with a minimum storage capacity can store up to the data of 7 CD
 ROMs. Normally the capacity of a CD ROM is only 650 MB. The capacity of DVD ROM
 starts from 4.4 GB, which is 7 times more than a normal CD ROM. However, this storage
 capacity of DVD ROM relates to single-layer storage. But with double-layer storage, the
 storage capacity of DVD ROM can go up to 8 GB, which is 12.5 times higher than a normal
 CD ROM. Furthermore, double-sided, DVD ROM drives can store 8.8 GB, 14 times greater
 than a CD ROM's capacity. Double-sided, dual-layer DVD-ROM drives store 15.9 GB, 25
 times greater than a CD ROMs capacity. To put it differently a CD ROM can hold the entire
 encyclopedia, but a DVD ROM can hold the encyclopedia, the dictionary, the thesaurus, and
 the phone number/address of everyone in whole India with still a lot of space left! With the
 storage of a DVD ROM, you can see interactive multimedia programs that use hours of fullscreen
 video to help you see movies, play games or even learn your courses.
 ii) Speed of data transfer: DVD ROM scores over the CD ROM. Going by figures the
 minimum transfer rate of CD ROM drives is 150 KB per second. However, the minimum
 transfer rate of DVD ROM drives is 11.08 MB per second. The data transfer rate of DVD
 ROM is approximately equivalent to a 92X CD ROM.
 iii) Reliability: Individually though CD ROMs are very reliable and have a long shelf life
 yet if compared to the DVD, the DVD scores over the CDs in terms of reliability. Since
 DVD ROM discs are made of plastics bonded together, the discs are more rigid than CD
 ROM discs. Though the DVDs can also catch scratch just like CDs yet the scratches in the
 DVD normally do not matter as they are usually out of focus of the laser and therefore it
 does not affect the readability of the DVDs. In case of CDs, scratches could affect the data
 and could also make it useless if the scratches destroy critical tracks. Besides scratches, other
 factors like error correction also makes DVD much better and reliable in comparison to the
 CDs. Normally, in case of the DVD, the error correction is 10 times more effective than the
 CD error correction. Moreover the CDs normally follow RS-CIRC error correction mode,
 whereas DVD have RS-PC error correction. Likewise the error correction overhead in case
 of CD ROM is very high at 34 per cent, whereas it is only 13 per cent in case of DVD drive.

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