Types of Storage

• What is primary storage?

  • Where all the data the computer uses is stored

  • AKA main memory

  • faster than secondary storage

  • RAM and ROM
• what is RAM?

  • Random Access Memory

  • holds data and instructions the computer is using (e.g. an application)

  • can be read/written by the CPU

  • volatile - empties when the computer is turned off
• What is ROM?

  • Read-Only Memory

  • contains instructions for boot and BIOS

  • built into the motherboard

  • can only be updated by flashing

  • cannot be changed by CPU

  • non-volatile - data stays when the computer is turned off
• What is virtual memory?

  secondary storage is used as extra memory when the RAM is full, which stores the app which has not been used for the longest time
• What are the disadvantages of virtual memory?


  • CPU needs to transfer data back to RAM to read/write it, meaning something else has to move

  • can slow down the performance
• what is secondary storage?

  where the OS, programs and any other data is stored long-term, as it is non-volatile
• What are the 3 types of secondary storage?

  optical, magnetic, solid state
• How does optical storage work?

  lasers are used to read and write data while a disk spins, by detecting whether light reflects or scatters in a pit. e.g. CD, DVD, Blu-Ray
• Advantages of optical storage

  • cheap

  • durable

  • portable
• disadvantages of optical storage

  • low capacity

  • easily damaged

  • low read and write speeds
• how does magnetic storage work?

  magnets are used to charge particles on the surface to represent bits. the two types are hard disk drives (HDD) and magnetic tape
• what are the advantages of HDDs?

  • can act as internal and external storage

  • greater capacity

  • still common
• what are the disadvantages of HDDs?

  • noisy

  • energy inefficient

  • easily damaged (e.g. bumped while on)
• what is the advantage of magnetic tape?

  very high capacity and value
• what is the disadvantage of magnetic tape?

  slow access as it is sequential
• what are magnetic tapes mostly used for?

  long-term backup
• what is the main advantage of solid state storage?

  much faster than other options
• what are the disadvantages of solid state storage?


  • more expensive

  • limited in write number