1.2 Memory & 1.3 Storage

1.2 Memory & 1.3 Storage

1. Secondary Storage

   • Optical
     • Optical readers use lasers to check various indents that hold the data
     • Types of Optical storage include CDs, DVDs and Blu-Ray discs
       • These come in 3 types as well: read only, write once and rewritable
     • Very cheap and secure ways to store data
       • Computer games and DVDs/CDs still use optics to hold data
   • Magnetic
     • Better alternative to HDDs
     • Relatively cheap compared to HDDs
     • Used as archives by large organisations
     • Usually found as plastic cassetes
       • Require extra software to read and write
     • Used to be read from beginning to end until stopped
     • Slow to start but fast when reading and writing
   • Solid State
     • Faster than the HDD to boot up, to read/write and opening programs and files.
     • Better alternative to HDDs, as they both operate as internal storage
     • Most use Flash Memory, a common and efficient non-volatile memory
     • No moving parts, so takes a lot to break it/stop it from working.
     • Has portable variants that can be used to transport data and as a backup device
     • This type of drive doesn't require any form of defragmentation
     • Silent, as opposed to the loud HDDs
   • Virtual Memory
     • Acts as extra RAM
     • Used when too many apps are open at once
     • The CPU cannot read data from the virtual memory, so it must be moved to the RAM first, which makes the process very slow

2. Primary Storage

   • CPU
   • Cache
   • RAM
     • Random Access Memory
     • Main form of memory in the computer
     • Volatile
   • ROM
     • Read-Only Memory
     • Usually unrewriteable
     • Houses the BIOS (Basic Input-Output-System) chip
     • Hold the bootstrap (data used when the PC is off) data, which runs the boot up processes and various scans before the computer starts running
     • Built onto the motherboard (soldered on)
     • Possible to change the programs on the ROM and BIOS
     • Non-volatile (remains intact when the PC is turned off)

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