Def. and Uses
Magnetic backing storage media
Stores the binary data on a disk or tape coated with a material that can be magnetised differently, depending on whether a 0 or 1 is stored. used for tertiary and off-line storage.
Data stored in backing storage is permanent so it is NOT lost when the computer is turned off.
It is always slower to access data from backing storage than from internal memory.
Fixed hard disks
A hard-drive built into the case of the computer is known as ‘fixed’. Most computers have one.
Fixed hard-drives act as the main backing storage device. They provide almost instant accsess to files (random access and high access speeds)
Large storage capacity
Stores and retrieves data much faster than a floppy disk or CD-ROM
Data is not lost when you switch off the computer
Usually fixed inside the computer so it can’t get mislaid.
Can be replaced and upgraded as necessary
Can have two hard disks in a machine, one can act as a mirror of the other and create a backup copy.
Hard disks eventually fail which stops the computer from working.
Regular 'head' crashes can damage the surface of the disk, leading to loss of data in that sector.
The disk is fixed inside the computer and cannot easily be transferred to another computer.
Portable hard discs
A portable hard-drive is one that’s placed into a small case along with some electronics that allow the hard-drive to be accessed using a USB or similar connection.
e.g. Many portable music players (iPods and stuff) contain tiny hard-drives.
Allows very large amounts of data to be transported from computer to computer.
Prone to damage easier than fixed hard disks
Magnetic tape stores data in a plastic tape coated with a magnetic layer. Magnetic tape is used in any application where extremely large storage capacity is needed and the speed of access is not important. They provide serial access.
It’s generally the cheapest option