Central Processing Unit Part-II

Secondary Storage : -

There are many different type of secondary storage devices. For example: - Magnetic tape,floppy disk, magnetic disk,optical disk.

Magnetic Tape : -

Manetic tape is an older device for secondary storage  though it is very popular even at the present. 

 *  Magnetic tape can virtually staore data of unlimited quantity because many tapes can be used.

 * Magnetic tape is low cost secondary storage device.

 * Magnetic tape reels are easy to store and handle. 

Magnetic Disk : -

Magnetic disk is the most widely used direct-access secondary storage medium today. A magnetic disk is thin, circular metal plate/platter coated  on both sides with a magnetic meterial. There are two kinds of magnetic disk and floppy disk. A hard disk resembles a thin steel platter with an iron oxide coating. Floppy disk is used in microcomputer.

Floppy Disk :-

A floppy disk is used as a medium of direct access secondary storage  for minicomputer systems. A floppy disk is also reffered to as diskettle or floppy, the latterbeing more comman.A floppy disk is made of flexible plastic which is coated with magnetic oxide. The disk is enclosed within a square plastic or card boared  jacket, often reffered to as a cartridge. Floppy disk are typically 3.5, 5.25, or 8 inches in diameter.

Optical Disk : -

Optical disk are increasingly becoming popular for secondary storage. An optical disk also called compact disk or laser optical disk.There are three ways inwhich data are stored-compact disk read only memory (CD-ROM), write once/read many (WORM), and magneto- optical disk.

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

The most common optical disk system used with microcomputers  is known as CD-ROM. It is a 4.75 inch compact disk that can store  upto 660 megabyte. A CD -ROM is read only memory no new data can be written on these but can be only read. That is why CD-ROMs are used for reference materials with massive amount of data, such as encyclopedias, directories, or online databases and for storing multi media  applications that combine text, images, and sound.