by Secondary memory is non-volatile and has a lower cost per bit. which holds program information permanently. it is also known as Backup/auxiliary Memory.
Types of Secondary memory.
1. magnetic memory:
Floppy Disk, hard disk, and magnetic tape use similar technology for reading and writing data. The surface of these devices is coated with magnetically sensitive material such as iron oxide which reacts to the magnetic field. The disk or tape drive senses the direction of flow as the storage medium passes by the head and data is sent from the READ/WRITE head into the memory.
2. optical memory.
Computer memory uses optical techniques which Generally, involve an addressable laser beam, an à Storage medium that responds to the beam for writing and sometimes for erasing, and a detector that reacts to the altered character medium when it uses the beam to read out stored data.
