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

• cheap

• portable

• slow access times

• fragile - prone to scratches

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, these two states can be represent 1 and 0

  • HHD

  • have a drive head that moves over the surface of the disk

  • high capacity

  • fragile

  • will eventually fail as there are mechanical components

types of magnetic 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

solid state / flash storage

• work by forcing electrons between into floating gates between oxide layers

• this causes a change in the charge of the footing gate, this represents a 0 or 1

• durable

• fast access

• high cost

• limited read/write cycles or 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