Secondary Storage

Secondary Storage

1. Magnetic Hard Disk

   • Uses magnetised platter to store data and files
   • Can have up to terabytes of memory
   • Reliable, cost-effective, used in most computer systems
   • Also used as external device to transfer large amounts of data and act as backup
   • Stores OS, installed applications/programs and uses data

2. Optical Disks

   • A CD-ROM/DVD-ROM cannot be overwritten so used for programs and music
   • A CD-RW/DVD-RW can be written to, so used as secondary storage
   • Lasers are used to read/write data to reflective surface
   • Surface has dye layer that is change by shining laser light. Colour difference detected when read
   • Inexpensive and robust

3. Flash memory (solid-state memory)

   • Flexible and can store many GB of data
   • Relatively inexpensive and faster access
   • Used to store data in cameras, mobiles, portable devices, ISB interfaces etc.
   • Small, robust, easy to use