CD-ROM

CD-ROM (Compact  Disk - Read Only Memory) :

CD-ROM is also one of the commonly used secondary storage devices. The main advantages of CD-ROM is, they can store large volumes of data i.e., 700 MB to 1.4 GB and also they are cheaper and easy to handle. It is made up of small plastic disk, coated with aluminium or silver for magnetization. A layer of transparent plastic is further deposited on the disk. The data is recorded in spiral tracks and the data once recorded cannot be deleted or rewritten, but can be read any number of times.

In this technology, a high power laser is beam is used to record data by burning tiny pits in the surface of the hard plastic disk. To read the data, a low power laser beam is used to scan the disk surface. The data are stored in binary digits. When the laser beam reflects from the smooth surface of the disk it is interpreted as a 1 bit and when the beam enters the tiny pits it is interpreted as a 0 bit.

Advantages :

1. High storage capacity.

2. Easy to use in multimedia application.

3. Handled easily.

4. Can Read/Rewrite using CD-RW's.

5. Widely used.

Disadvantages :

1. CD Writing can be done carefully.

2. Should be kept free from dust and heat.