1.3 Storage

• the need for secondary storage

• • Primary storage is RAM which is volatile - disappears when power is switched off

  • secondary storage is non-volatile - information and programs are retained even when power is lost

  • secondary storage is generally much bigger than RAM 

• data capacity and calculation of data capacity requirements

• • text files tend to be smaller than images, sound and video files

• common types of storage:

⃝ optical - ie DVD or CD

⃝ magnetic - Hard Drives, Floppy discs, Tape drives

⃝ solid state - SSDs, SD Cards, USB Sticks

• suitable storage devices and storage media for a given application

the advantages and disadvantages of each type will depend on their characteristics:

⃝ capacity  - magnetic holds most

⃝ speed - Solid state is fastest

⃝ portability - Solid state is most portable

⃝ durability - Magnetic is most durable

⃝ reliability - Magnetic or Solid State is most reliable 

⃝ cost - Magnetic is cheapest per MB