A circular optical disc made up of thin platted glass and plastic polycarbonate material.
- Standarad size of disc is 12 cm, center hole is of 1.5 cm and 1.2 mm in thickness.
- Storing of data is done on 1 side in a spiral way of valleys (pits) and plains (lands).
- One CD can store upto 600 MB to 700 MB of data, i.e. equivalent to 80 minutes of uncompressed audio files.
- Speed of the disc determines how fast data can be transfered from the CD.
- CD with 24X speed can transfer 3.6 MB/s, 32X speed can transfer 4.8 MB/s and so on.
- Used to store, publish and distribute information.
CD-ROM (CD - Read Only Memory)
- Contents of CD cannot be erased by the user.
- Access only to the data imprinted by the publisher.
- Commercially used in music and software companies to publish large amount of music CD's and application packages.
CD-R (CD - Recordable)
- Contents can be written only once.
- After that they can be read several times, but cannot be written or erased.
CD-RW(CD - Rewritable)
- Contents on the CD can be written on, read and erased several times.
- Made up of alloys of silver, indium, antimony and tellurium.
- Don't bend the disc
- Don't touch it.
- Don't remove cd while rotating or in use.
- Keep away from extreme heat and direct sunglight.
- Store in plastic storage boxes.