1.1.3

• an input device can be used to input data and information into a computer
• likewise, an output device can be used to send information from the computer
• examples of input devices:

  • keyboard
  • webcam
  • magnetic stripe reader
  • barcode reader
• examples of output devices:

  • speakers
  • printers
  • projector
• there are a variety of different methods of storing information, each of with is suited to a particular type of information
• optical storage:

  • read from and written to by lasers
  • binary information is represented by portions of the disc which either reflect or scatter the laser light
• CD:

  • use optical technology to store small quantities of information
  • most commonly used for audio files, text and digital images.
  • small, thin and light
• DVD:

  • optical devices that have a higher storage capacity than CDs
  • this means they are suited to storing digital videos which require more storage space than audio files or photos
• blu-ray:

  • have more than 5 times more storage than traditional DVDs, making them more suited to sore high-resolution films
• magnetic storage:

  • represents binary information with 2 states - polarised and unpolarised
  • these two states can represent 1 and 0, allowing information to be represented in binary form
• hard disk drives:

  • typically have high capacities of 500GB to 5TB
  • work by rotating magnetic platters at high speeds
• advantages of optical storage:

  • durable and immune to environmental conditions
  • easy to transport
  • suitable for transporting software, music or movies
• disadvantages of optical storage:

  • low storage capacity
  • slower read/write speeds
  • can be easily scratched or damaged
• magnetic tape:

  • long stretched of tape were passed through readers that would check the polarity of the tape and read off a binary value
• advantages to magnetic storage:

  • high storage capacity
  • low cost per gigabyte
  • suitable for long term storage and backup
• disadvantages of magnetic storage:

  • slower read/ write times compared to flash storage
  • susceptible to physical damage
  • moving parts can wear out over time
• flash storage:

  • fast and compact
  • uses silicon semiconductors that form the logic gates NAND and NOR to store an electrical charge in either high or low
  • these states can be used to represent the binary values True or False, which is used to represent information
• advantages to flash memory:

  • can be erased and reprogrammed electronically
  • non-volatile
  • fast read/write speeds
  • no moving parts so less likely to fail
• disadvantages to flash memory:

  • higher cost per gigabyte
  • flash memory cells can wear out after a certain number of write cycles
• solid state drives:

  • extremely light and portable
  • have no moving parts - makes them more resistant to damage
  • high data transfer rates
• RAM:

  • random access memory
  • type of fast main memory used to store data and programs that the computer is currently using
  • this speed up the execution as RAM has higher access speeds than flash memory
• disadvantages of RAM:

  • more expensive per gigabyte than secondary storage devices
  • RAM is volatile, meaning it loses its information when the power is lost
  • therefore, RAM isnt used for storing personal files but as a temporary storage while the computer is running
• ROM:

  • read only memory - cannot be modified
  • once programmed, the state of them memory cells inside cannot be changed
  • useful for storing fixed sequences of instructions
  • non-volatile - so retains data even when computer is powered off
• virtual storage:

  • storing information remotely so that it can be accessed by any computer with access to the same system
  • often an abstraction of multiple drives acting as one
• advantages of virtual storage:

  • easy to increase storage as needed
  • data can be accessed from anywhere with an internet connection
  • data redundancy protects data loss due to hardware failure
  • pay for only the storage used
• disadvantages of virtual storage:

  • access to data can be slow with little to no data connection
  • storing sensitive data off site can pose a security risk
  • expensive and costs can add up over time