1.1.3 input, output and storage

input device

• used to put data and information into a computer

• examples

  • keyboard

  • webcam

output device

• used to send information from the computer

• examples

  • speakers

  • monitor

optical storage

• read and written to using laser

• pits represent 0

• lands represent 1

types of optical storage

• CD

  • compact disk, mostly used for audio files but can store text and images, fragile and portable

  • limited storage capacity, slow transfer speeds

• DVD

  • digital video disk, higher capacity than CDs

• Blu Ray

  • more capacity than DVDs, useful for storing high resolution films

magnetic storage

• devices which store information magnetically represent binary information using two magnetic states

  • polarised and unpolarised, if a portion of a magnetic material is polarised, all magnetic poles align and can be read by a read/write head passing over

  • if an area is not polarised, magnetic poles are randomly scattered and produce a different reading on a read/write head

  • these two states can be represent 1 and 0

types of optical storage

• hard disk (HDD)

  • high capacities

  • have rotating magnetic platters under a read/write head on an actuating arm

• magnetic tape

  • stretches of tape are passed through readers which cheat the polarity of the tape and read off binary

• floppy disk

  • thin magnetic disk

  • portable

  • small capacity

flash storage

• fast and compact

• uses silicon semiconductors forming NAND and NOR gates to store electrical charges in a high or low state that represent binary values

• erased and reprogrammed electronically

• non-volatile, stores data when power is lost

• expensive

• NOR for small quantities of data, NAND for larger files

solid state drive (SSD)

• light and portable - no moving parts

• high data transfer speeds

• high cost

• limited lifespan

random access memory (RAM)

• random access memory

• fast main memory used to store data and programs the computer is currently using

• speeds up the computers execution as RAM has higher access speeds than flash memory

• more expensive per gigabyte than secondary storage

• volatile meaning it loses its information when power is lost

  • its only used for storming tempery files

primary storage

• used by the OS to run the computer

• store information like code instructions to execute files which are required by running programs

read only memory (ROM)

• cannot be modified

• useful for storing fixed sequences of instructions like a computers start-up (bootstrap) routine

• non-volatile so data remains when computer is powered off

virtual storage

• storing information remotely so it can be accessed by any computer with access to the same system

• cloud storage

• convenient to access and share

• limitations of users network speed - needs internet connection

• high cost