input and output

• Hardware

  Physical components that make up the computer system
• Hardware


  • Each piece has a specific role in the computer system
  • Can be internal (fixed inside) or external
• Input devices

  Devices that input data into the computer system
• Input devices

  • Mouse
  • Keyboard
  • Microphone
  • Barcode scanner
• Output devices

  Devices that output data from the computer system
• Output devices

  • Monitor
  • Speakers
  • Printer
  • Projector
• External storage devices

  Provide external storage or backup solutions
• To run computer applications, the computer system must consist of both hardware and software
• Software

  Programs for controlling the operation of the computer or processing electronic data
• Types of software

  • Application software
  • System software
• Application software

  Software with specific tasks (e.g. word processing, spreadsheets, databases, graphics editing, audio/video editing)
• System software

  Provides services to operate the computer system (e.g. operating system, device drivers, utility software)
• System software

  • Operating system
  • Antivirus
  • Performance utilities
• Application software is used for specific tasks, while system software provides the underlying services to operate the computer
• Applets


  Small computer program that performs a specific task within a larger program
• Creating content for presentation

  1. Use word processor to type up text

  2. Use spreadsheet software to create a graph

  3. Use graphic editing application to include pictures
• Producing menus for a restaurant

  1. Use word processing to include text and pictures

  2. Use spreadsheet software to calculate the cost of meals
• Control and measurement systems

  • Measure conditions to maintain an environment (e.g. temperature in a greenhouse)
  • Automatically take action to control the environment (e.g. turn on heater if temperature drops)
• Analog signal


  Continuous range of values collected by sensors
• Digital signal


  Discontinuous values converted from analog signals, understood by computers
• Analog to digital conversion

  Analog signals from sensors are converted to digital signals using an analog to digital converter so computers can understand them
• Measuring and control software

  • Measures conditions in an environment (e.g. temperature in a greenhouse)
  • Compares measurements to preset levels
  • Takes control actions (e.g. turn on heater) to maintain desired conditions
• Sensors placed in a river to check water level, if level rises above 5 meters a flood barrier is raised
• Sensor data


  Cannot be directly read by computer, requires an analog to digital converter
• Measurement systems


  Take readings and store results, can detect changes in the environment
• Control systems


  Change the environment, compare sensor values to preset levels and take action accordingly
• Using computers and sensors to measure temperature of cooling liquid is better than manual readings as it can take measurements outside of school hours, more accurately, and continuously
• Devices used in control systems

  • Computer
  • Sensors
  • Analog to digital converter
  • Actuators (e.g. lights, heater, motor, pump)
• Operating systems


  Manage computer functions including hardware devices, input/output, provide graphical user interface
• Utility software

  Maintain computer resources by running specific tasks (e.g. antivirus, performance optimization)
• Device drivers

  Allow hardware devices to run on a computer
• Linkers and compilers


  Translate programs written in specific languages into executable files that can be run by the computer
• Examples of system software

  • Operating systems
  • Utility software (e.g. antivirus, device drivers)
• Magnetic strip reader


  Device that reads data found on magnetic strips on the back of cards
• Uses of magnetic strip readers

  • Gaining access to a hotel room
  • Topping up credit on an arcade card
  • Reducing the amount on a gift voucher card
  • Inputting bank card details into a system
• Advantages of magnetic strip readers

  • Fast data entry
  • Not affected by water
  • Robust if dropped
  • Can be easily updated
• Disadvantages of magnetic strip readers

  • Strip can become unreadable if scratched
  • Does not work from distance
  • Can be easily lost or misplaced
  • Can be affected by mobile phones
• Chip and pin readers


  Devices used at point of sale to make secure payments using debit or credit cards
• Advantages of chip and pin

  • Secure method of payment
  • Chip is less likely to be damaged than magnetic strip
• Disadvantages of chip and pin


  • Pin could be read by someone watching
  • Fraudulent machines can copy card details