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Future developments

The amount of data that can be stored on a CD is determined by the wavelength of the laser used to read the data. With shorter wavelength lasers pits can become smaller and can be packed tighter.

The first demonstration of prototypes of double sided high density CDs with capacities of approximately 2.5 gigabyte have been presented in 1995. They will reach the market in 1997.

Rewritable CDs are currently being developed, and prototype systems have been presented already. However, the number of write access to such rewritable CDs is too limited to be of practical use. Also, it is not clear whether rewritable CDs have a future: hard disks are 50 times faster than CD drives, and in many cases the read-only restriction of CDs is absolutely required (e.g. for corpus distribution, copyrighted data, etc.).

Access time and data rate of CD drives will be improved by smaller and thus lighter read heads and higher spin rates of the CD-drives. Currently drives with a spin rate six times as high as in standard CD drives are entering the market, and further improvement can be expected.

EAGLES SWLG SoftEdition, May 1997. Get the book...