Data is arranged in a spiral manner
Data is recorded outwards from the center
Each data track is made of millions of data pits
Data pits are incredibly tiny and measured in nanometer
Basic composition of the DVD is made of :
DVD can hold data on single or both the sides
Single-sided single-layered DVD is also known as DVD-5 and has capacity of 4.7 GB
Single-sided dual-layered DVD is also known as DVD-9 and has capacity of 8.5 GB
Double-sided single-layered DVD is also known as DVD-10 and has capacity of 9.4 GB
Double-sided dual-layered DVD is also known as DVD-18 and has a capacity of 17 GB. Provides eight hours of audio or video playback
DVD-ROM - Stores films, computer software in capacity ranging from 4.7 GB to 17 GB
DVD-Video - Stores movies and requires DVD drives with MPEG-2 decoder
DVD-Audio - Stores high-quality music and can also store video content and slide shows
DVD-R and DVD+R - Can be written only once. An organic dye coats the layer of these types of disks
DVD-RW and DVD+RW - Known as phase-change disks
DVD-RAM - Can be accessed in the same manner as a hard drive or floppy disk
DVD-VR and DVD+VR - Used for the creation of movies that can be edited
HD-DVD – Known as Advanced Optical Disc
Tracking system of the DVD player consists of tracking motor and spindle motor
DVD drive reads the data from DVDs with the help of a laser assembly
Laser beam reads the data on the DVD
Laser beam focuses on the reflecting layer of the DVD
Laser is reflected off the reflective layer onto a photosensitive receptor
Photosensitive receptor studies the reflected signal for changes in reflection
The data is then sent to the intended device directly or through a DAC
Pits and lands used by DVD are much smaller than those used by CD
In DVD the pit length is 2.25 times smaller
The track pitch is reduced by 2.16 times
DVD has slightly larger data area on the disc
In DVD the error correction code is 1.32 times more efficient compared to CD
In DVD the sector overhead is less by 1.06 times
DVD drive speed – DVDs rotates counterclockwise and are recorded at a constant data rate called Constant Linear Velocity (CLV) e.g. 4x/24x
Interface – Physical connection of the drive to the PC’s expansion bus e.g. ATAPI, USB
Loading mechanism – Tray, caddy and slot are three distinctly different mechanisms for loading a disc into a DVD drive
Read-only drives, cannot write or record information on a DVD
Speed of the DVD ROM drive is indicated by a number followed by an x
DVD-ROM drives can have two to three speeds listed
Front panel of the DVD ROM drive has a tray that accepts the DVD
Back panel of the DVD player has different ports for the connecting the DVD drive to the computer
Back panel also includes jumper settings
Jumper connections configures the DVD drive as either master or slave
Tape drive – Reads the data and write it to a tape. Has large capacity to store data from hundred megabytes to several gigabytes. Tape drives are sequential access devices. DAT drive was introduced by Hewlett Packard and Sony. It is available in either the Digital Data Storage (DDS-1, DDS-2, and DDS-3) format or the DataDAT format.
The different types of tape drives are :
Pen drive – Called as thumb drives due to their small sizes. Storage size ranges from megabytes to gigabytes. Uses the USB standard
ZIP drive – Proprietary product manufactured by Iomega. Hold 1GB or 2 GB of data and are inexpensive and durable compared to floppy disc . One of the most reliable backup devices of magnetic media. Cannot be used as booting device Magnetic coating on the Zip disk is of better quality. Head that reads the information on the disk (cartridge) is small in size. Therefore there is greater number of track per sector on the cartridge and thus more information can be stored. Uses a variable number of sectors per track
Manage the DVD drive properly in order to avoid problems
Troubleshooting the DVD drive is very important, as a faulty drive can damage the DVD
Problem that may occur are :
