Primary and secondary storage.

Authors Avatar

Jennifer Masterton 11T                

Storage Devices

Primary Storage, i.e. random access memory (RAM).  This type of storage holds data and instructions that are being worked on.  When the computer is switched off, the contents of RAM are lost.  This is known as volatile storage.

Secondary storage, such as hard disks, floppy disks, CD’s, DVD and magnetic tape.  This type of storage is non-volatile.

Floppy disks

The standard 31/2” floppy disk is a thin, flexible plastic disk coated in metal oxide enclosed in a rigid plastic casing.  A standard high-density disk has a storage capacity of 1.44 Megabytes.

A diskette consists of two surfaces, each of which contains typically 80 concentric circles called tracks.  Each track is divided into sectors. A floppy disk has to be formatted before it can be used, and this process performs the following tasks:

Join now!

  • Deletes any data already on the disk
  • Divides the disk into the tracks and sectors – one sector holds 512 bytes of data.
  • Set a root directory which lists the files on the disk and which sectors the data for each file is kept in.
  • Finds any bad or damaged sectors on the disk that cannot be used.

Hard Disks

The hard disks used with PC’s consist of one more disk platters permanently sealed inside a casing.  Hard disks typically have a capacity of between 10Gb and 30Gb.  (1Gb = 1,000Mb).

CD-ROM

Compact disk only ...

This is a preview of the whole essay