Storage

secondary storage

non-volatile storage devices that retains data when power is turned off

types of secondary storage

magnetic, solid state, optical

characteristics of magnetic

• usually the highest capacity

• usually the cheapest

• if kept stable then reliable

• heavy and bulky

• moving parts

characteristics of solid state

• more durable, no moving parts

• portable (USB stick)

• limited lifespan

• quickest read/write speed

characteristics of optical

• relatively cheap

• light and portable

• drive used to read the disc is considered unreliable

primary storage

• holds the data and instructions that the CPU needs to access while the computer is turned on

• includes RAM and ROM

RAM

• Random Access Memory

• holds the instructions that are currently in use

• is volatile, contents are lost when power is turned off

• has very fast read-write speed

• larger capacity than ROM

• can be edited

ROM

• Read Only Memory

• holds the first instructions a computer needs in order to start up

• contains BIOS (Basic Input Output System) and stores boot sequence

• fast read-write speed but slower than RAM

• is non-volatile, contents are not lost even when the power is turned off

• is read only, data can only be read and can’t be edited

virtual memory

• an extension of RAM located in secondary storage

• when RAM is close to being full, virtual memory is used so the computer remains operational

• data currently not in use is transferred here

• much slower read-write speed and negatively impacts system performance