Secondary storage
Types | Technical features | References
CD-Rom

Digital Versatile Disk (DVD)

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Originally Digital video disk.
Promises to put digital video on your TV by end 1997.
Prototype demonstrated Nov 95/Jan 96.
Physical disks resemble CD's only thinner.
DVD players can also play current CDs.
A single-sided, single layer disk using Mpeg-2 compression can hold a 133-minute feature film with 3 sets of surround tracks and four sets of subtitles.
Higher capacity allows video and audio of superior quality to CD-Roms, VHS-tapes and video laser disks.
Supports 6 channels of audio, and users can choose from three types of theatre-quality sound.
Additional tracks will handle up to eight foreign language dubs and subtitles.

Types

DVD-ROM (read only)

DVD-RAM (rewritable)

5.16GB in a dual sided format (2.6 GB single sided), and will include copy protection required by the motion picture industry.Toshiba and Hitachi.

DVD+RW (rewritable)

3Gb on a single-side. Hewlett-Packard, Mitsubishi Chemical, Philips Electronics, Ricoh, Sony and Yamaha.

Technical Features

Each DVD can hold at least 4.7GB on a single side, (double sided DVD capable of 8.5GB) Compromise standard agreed Apr 97 of 5.16GB DS by a consortium of consumer electronics leaders.
Standard rotation slightly slower than 4x CD-ROM, the tightly packed data will give a transfer rate of 1.35MB per second (equal to 9x's CD player, nearly equal to a hard disk)
Video stored using Mpeg-2 - a video compression standard used by todays high-resolution digital TV satellites.
Configurations

References

[Rev: 21/11/98] 27-July-97 © 1997-98 V/2-Com (Verhaart), P O Box 8415, Havelock North, New Zealand.