ICT Hardware

ICT Hardware

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
6 China
7 Unused
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

DVD Technologies


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