CD-ROM
CD-ROM stands for Compact Disk Read Only Memory is a type of secondary storage or optical disc that users can read only but not write or erase. Philips and Sony companies invented Compact Disc in year 1982. CD-Rom is a WORM (Write Once Read Many times) device. Typically they can store up to 600-700 MB of data or 70 minutes of audio, also store video, data, and text. The diameter of a Compact Disk is 4.7 inches and its thickness is 0.047 inches. A single Compact Disk equal to : 1500 - 5.25-inch floppy disks, 450 - 3.5 inch floppy disks and 274,000 pages of text.
Types of Compact Disks :
(1) CD-ROM :
Compact Disk Read Only Memory (Write Once Read Many times)
(2) CD-R :
(Compact Disc-Recordable) WORM disks for Well known technology
(3) CD-RW :
(Compact Disc-ReWritable) Rewritable and erasable.
(4) CD Extra :
For Multimedia purpose. Developed by Sony, Philips and Microsoft.
(5) CD-DA :
(Compact Disk Digital Audio) Audio CD, Digital Audio Developed by Philips and Sony companies.
(6) Photo CD :
Developed by Kodak and Philips companies.
(7) Video CD :
Can hold approximately 70 minutes of recorded video.
