The Compact Disc (CD), as a standardized information carrier, has become one of the most successful consumer products ever marketed. Although the original disc was intended for audio playback, its specific advantages opened very quickly the way towards various computer applications. The standardization of the Compact Disc Read-Only Memory (CD-ROM) and of all succeeding similar products, like Compact Disc interactive (CD-i), Photo and Video CD, CD Recordable (CD-R), and CD Rewritable (CD­ R/W), has substantially enlarged the range of possible applications. The plastic disc represented from the very beginning a removable medium of large storage capacity. The advent of the personal computer accompa­ nied by the