Unit I : Evaluation of Computer System
Computers have become a vital part of our life. This Chapter introduces you to the computer and the way computer works. Different parts of the computer and how they work is also covered in this chapter.
Unit II : Hard Disk Drive
Unit III : Optical Media
Unit IV : Processor
Unit V : Hardware & Networking
DVD-ROM & DVD Technology
Now a days computers are equipped with a buit -n DVD-ROM drive to play DVD’s. DVD’s are not only used for playing movies or listening to songs, but also serve as a high capacity storage medium for data.
Every DVD and DVD-ROM drive a specified by a code produced by the manufactures. For a DVD to work in a DVD-ROM drive, the code of the DVD must match the code of the drive. Otherwise, the DVD cannot be used in that DVD-ROM drive. This prevents unahorised distribution of DVDs. The world is catagorized into nine DVD regions and the DVD-ROM drive must be set to correct region code. When a DVD is inserted in a DVD-ROM drive, a decoder checks the code of the drive and the region code of the DVD. If the two match, then the DVD is played.
Table : Region code for DVDs
|DVD Region Code||Geographical Area|
|0||No Region Code (DVD can be played in all regions, that is 1-6 except for 8|
|1||United States of America, Canada|
|2||Europe, South Africa, Greece, Saudi Arabia, Turkey, Egypt and Japan|
|3||North Korea, South Korea, Thailand, Vietnam, Borneo and Indonesia|
|4||Australia, New Zealand, Mexico, Caribbean and South America|
|5||India, former USSR countries, Russia and Africa|
|8||International territories such as airlines and cruise ships|
Storage Capacity of a DVD
The diameter and thickness of a CD and DVD are almost the same. However a DVD can store more data than a CD and a CD-ROM drive cannot read a DVD. This is because of the difference in the arrangement of pits on the surface of the DVD. The pits on a DVD are smaller and more closely spaced in comparison to the pits on a CD. DVD provides high video resolution and good quality of sound and can transfer at the speed of 21.13 megabits per second (Mbps).
|Category||Layer(s) & Side(s)||Capacity|
|DVD-5||single layer on one side (bottom)||4.7 GB|
|DVD-9||two layers on the same side||8.5 GB|
|DVD-10||single layer on both side||9.4 GB|
|DVD-18||two layers on both sides||17.8 GB|
There are two types of DVD technologies that can be used to record or write data on a DVD. These are –
- Recordable DVD (DVD-R and DVD+R)
- Rewritableble DVD (DVD-RW, DVD+RW and DVD-RAM)
Recordable DVD Technology : In the recordable DVD Technology, the data on a DVD cannot be erased once it is written. DVD is created and read with the help of recordable DVD drives. DVD-R and DVD+R are DVD types that use the Recordable DVD Technology.DVD-R is single layered disk and DVD+R is a multi layered disk.
Rewritable DVD Technology: In the Rewritable DVD Technology, the data on a DVD can be written more than once. These days, various types of DVDs using the Rewritable DVD technology are available in the market, such as DVD-RW, DVD+RW and DVD-RAM. DVD-RAM writes faster than DVD-RW/DVD+RW