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DVD+RW and a 19 cm Dixon Ticonderoga pencil.]] DVD (also known as "'''Digital Versatile Disc'''" and "'''Digital Video Disc'''") is a popular Optical Disc Storage media format used for Data Storage . Its main uses are for Movie s, software, and data archiving. Most DVDs are of the same dimensions as compact discs ( CD s) but store more than 6 times the data. The term DVD is used in describing three ways that data is stored on the disks — DVD-ROM has data which can only be read and not written, DVD-R can be written once and then functions as a DVD-ROM, and DVD-RAM holds data that can be re-written multiple times. In addition, terminology defines the way data is structured on the disk. DVD-Video and DVD-Audio discs respectively refer to properly formatted and structured video and audio content. Everything else, including other types of DVD discs with video content, is referred to as a DVD-Data disc. DVD is also used generically to refer to HD (High Density) video disc formats Blu-ray and HD DVD . HISTORY In the early 1990s two high-density optical storage standards were being developed; one was the MultiMedia Compact Disc, backed by Philips and Sony , and the other was the Super Density disc, supported by Toshiba , Time Warner , Matsushita Electric , Hitachi , Mitsubishi Electric , Pioneer , Thomson , and JVC . IBM's president, Lou Gerstner , acting as a matchmaker, led an effort to unite the two camps behind a single standard, anticipating a repeat of the costly Videotape Format War between VHS , Betamax and Video 2000 in the 1980s. Philips and Sony abandoned their MultiMedia Compact Disc and fully agreed upon Toshiba's SuperDensity Disc with only one modification, namely changing to EFMPlus modulation. EFMPlus was chosen as it has a great resilience against disc damage such as scratches and fingerprints. EFMPlus, created by Kees Immink , who also designed EFM , is 6% less efficient than the modulation technique originally used by Toshiba, which resulted in a capacity of 4.7 GB as opposed to the original 5 GB. The result was the DVD specification, finalized for the DVD movie player and DVD- ROM computer applications in December 1995. 1 In May 1997, the DVD Consortium was replaced by the DVD Forum , which is open to all other companies. Etymology |
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