Compact Discs (CDs): A Compact Disc that contains data accessible by a computer. Any data viz. software, games and multimedia can be stored on CDs. CDs have large capacity of 650 to 700 Mb of data storage. CDs are made from a 1.2 mm thick disc of polycarbonate plastic, with a thin layer of aluminium to make a reflective surface. The most common size of Compact discs is 120 mm in diameter. Data is stored on the disc as a series of microsecond indentations "pits" with the gaps between them referred to as "lands". A laser beam is thrown on the reflective surface of the disc to read the pattern of pits and lands. The pattern of changing intensity of the reflected beam is converted into binary data.
Digital Video Discs or Digital Versatile Discs (DVDs): DVD like CD is an optical disc storage media format that can be used for data storage, including movies with high quality video and sound. DVDs resemble Compact Discs in shape and size and both are optical storage media. A DVD player or writer can usually also read CDs, but DVDs are encoded in a different format of much greater density, allowing a much higher data storage capacity then that of a CD. DVDs can store up to 4 GB of data or about 6 times the size of a regular CD.
Compact Disc Read Only Memory (CD ROM): These are only once recordable Compact Discs. No rewriting on the disc is possible.
Compact Disk Recordable and Rewritable (CD R-RW): These are recordable and rewritable compact disks.
CD/DVD Drives: Types of drives:
1. CD-R (Compact Disc Read) Drives: These drives are capable of only reading the prerecorded compact discs.
2. CD-RW (Compact Disk Read Write) Drives: These drives are capable of both reading and recording/burning a compact disk. CD-Recordable drives usually have three different speed ratings, one speed for write-once operations, one for re-write operations, and one for read-only operations.
3. DVD Player RW Combo Drives: These drives are capable of reading and recording CDs and also reading DVDs.
4. DVD R-W Drives: These drives are capable of reading and recording CDs and DVDs both.