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# Big capacity is a must

To store a large amount of diverse information, a disc with a big capacity is essential. The easiest way, but not smartest, is to increase the size of the disc.

One side of a standard 30cm laser disc, for instance, can store 60 minutes of analog images. But a CDV, a CD derivative which uses the same storage system as a laser disc, can store just 5 minutes worth of image information.

At Toshiba we wanted to have our cake and eat it by achieving greater compactness and larger capacity. So, starting from scratch, we set out to create the spec of a new global standard. "How much capacity?" and "What diameter?" were the first questions we had to consider.


Main specifications of DVD

Disc diameter: 120mm
Disc thickness: 1.2mm (0.6mm*2)
Shortest pit length:: 0.4micron meter
Track pitch: 0.74 micron meter
Sector layout: CLV
Logic structure: In accordance with ISO9660 & UDF
Modulation method: 8/16 modulation
Error correction method: RS-PC
Laser wavelength: 650/635nm
Lens (NA): 0.6