Write A Note On DVD-ROM

• Short for Digital Versatile Disc or Digital Video Disc, a DVD or DVD-ROM, is a disccapable of storing large amounts of data on one disc the size of a standard Compact Disc. 
• DVD drives were first sold in 1997, today they are widely used for storing and viewing movies and other data. 
• To play a DVD on a computer a user must have a DVD drive as well as a DVD player, which is a software program designed to play and control a DVD disc. 
• The movie Twister became the first featured film put on DVD on March 25, 1996. In the picture to the right, is an example of what a DVD movie may look like, in this example it's a picture of the Matrix movie.

How much data can a DVD hold?

There are several capacities a single DVD disc is capable of holding. Below is a listing of the different types of DVD's and each of their total capacity.

• One of the most common DVD's is the single-sided, single-layer disc, capable of holding 4.7 GB.
• The single-sided, double-layer disc is capable of holding between 8.5-8.7 GB.
• The double-sided, single-layer disc is capable of holding 9.4 GB.
• Although rare, the double-sided, double-layer disc is capable of holding up to 17.08 GB.

What is the difference between a DVD and a CD?

Physically, a DVD and CD look the same. Both discs are the same size and typically have one side with a label and the other side that the laser reads, unless it is a double-sided DVD. However, the technology that makes up a DVD allows for the same size disc to hold a lot more data than a CD.

Standard DVD formats

The official specifications for DVD are divided into five books:

• Book A for DVD-ROM;
• Book B for DVD Video;
• Book C for DVD Audio;
• Book D for writeable (DVD-R) and rewritable (DVD-RW) DVDs. The DVD-R format is Write-Once, while DVD-RW is a rewritable format, which lets data be rewritten using a phase-change metallic alloy;
• Book E for rewritable DVDs (also called DVD-RAM, for DVD Random Access Memory). DVD-RAM is a rewritable medium which uses phase-change technology to record data. DVD-RAMs are actually cartridges which are composed of a case and a DVD. Some cartridges are removable, so that a DVD-RAM can be played in a DVD player.