1. Primary Storage Devices

--are those devices where the data is stored temporarily. Analogous to our memory cells where we keep the data temporarily before we enter them into permanent storage devices. The data stored in these places should be recorded or entered into secondary storage or permanent storage devices, as they are volatile. Ex: Random Access Memory

2. Secondary Storage Devices

--are those devices where the data is stored permanently. Analogous to our note book, text books, video tapes, vcds, DVDs etc in our daily life.

SECONDARY STORAGE: Sequential or direct access.

CD-ROM

Magneto-optical disk

Network storage

Switched storage.

Floppy disks are normally 3.5-inch diskettes, made of polyester film with a magnetic coating.

Hard disks are made up of several rigid platters, a read/write head mechanism, and an electronic device interface. Hard disks access data more quickly and efficiently than floppy disks and are highly reliable

Data, collecting, organising , combining, sorting, manipulating , summarising,

Bits, bytes, fields, records, files, databases

Batch processing, online processing, Sequential and direct access

Data is recorded on disks in circular bands referred to as tracks. A disk is divided up into sectors or equal wedge shaped areas used for storage reference purposes. Magnetic tape is used for starting historical data or for keeping backups of important files. Magnetic tape as a sequential storage media that is well suited for batch applications

CD-ROM is a special kind of optical disk on which data are recorded using laser devices and read using CD-ROM drives.