DVD

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DVD (Digital Video Disc, now Digital Versatile Disc) is a format of optical storage. A disc can store up to 4.7GB of data on one side, and it works by reflecting a laser to save and view data.

The writable layer of a DVD disc has a spiral track of data. The track circles from the inside of the disc to outside, and contain pits. There is 740 nanometers (10^-9 m) between one data track and the next.

The track pits are:

  • 320 nanometers wide
  • Minimum of 400 nanometers long
  • 120 nanometers deep

Development

1993
  2 competing developments   
Multimedia CD (MMCD) and Super Disc (SD) 
1995
 2 Developments were combined    
  DVD

Variations

Slight variations of DVD exist due to the widespread support from a range of electronic companies.

  • DVD+ (pronounced "DVD-plus")
  • DVD- (pronounced "DVD-minus")

Differences Between Variations

The differences between DVD+ and DVD- are small, it is a rare case that a DVD- player may not be compatible with a DVD+ disc. DVD- discs are less costly than DVD+ discs to obtain, however require more time to burn data on to.