Backing Storage

Magnetic Storage Hard and floppy Disks

tracks

Sector

Block – track 3 sector 1

Magnetic Storage - Disks

• Disk surfaces coated with iron coating• Particles can be magnetised to point North(1)

or South(0)• When a file is saved the operating system

makes a note of the filename and which track/sector block it is saved to

• File can be found again by direct (random) access – going straight to the block

Magnetic Tape

• Used for Backup• Sequential (Serial) Access– Must read through all earlier files to find one

File 1File 2File 3File 4File 5File 6

Optical Storage

Land Land

Pit

Laser

Sensor

Laser

Sensor

Laser

Sensor

Aluminium Layer

1 10