Storage

Storage

1. Primary Storage

   • Made up of RAM and ROM
     • This stores programmes and instructions for the CPU to process

2. Secondary Storage

   • Permanently stores data and instructions whilst they are not in use by the CPU.
     • Often provided by a hard disk drive or a solid state drive in a computer.
     • Secondary storage also stores backup data in case originals are lost or damaged.
   • Magnetic Storage
     • Hard disks, magnetic tape, old fasioned floppy disks.
       • Magnetic tape
         • Magnetic tape comes in cassetts that contain a very long reel of magnetic tape
           • These reels can be 1km long
           • Ideally suited to long term storage
           • Downside is that they have a very long access time
     • Magnetic Hard disk drives
       • The value of each bit of data (either 1 or 0) is represented as a positively or negatively charged magnetic particle on a magnetic disc.
       • Magnetic Hard Disks offer a large capacity for a relatively low cost-per-GB and they provide reasonably fast transfer rates (around 120MB/sec).
       • Generaly reliable
   • Flash Memory
     • Solid state drives, USB memory sticks
       • Contain no moving parts
     • Replacing hard rive as main form of secondary storage
     • Mobile devices such as smartphones use flash memory
   • Optical storage
     • CD-Rom, DVD Rom,Blue ray
     • Uses laser light to retrieve data

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