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• Qualities/characteristics of information


  • Timely - presented when required
  • Relevant - should be meaningful
  • Complete - contain all the user needs
  • Reliable - can be verified
  • Economical - should not be costly to obtain
• Accuracy

  Information should be accurate
• Validity

  Information should be valid
• Typical desktop personal computer

  • Computers come in different sizes and designs, but the most common is a computer referred to as a personal computer (PC)
  • Personal computers are mostly used in offices, schools, business premises and at home
• Physical parts of a personal computer

  • System unit
  • Monitor
  • Keyboard
  • Mouse
• Peripheral devices


  Devices connected to the system unit using cables called data interface cables that carry data and information to and from the devices
• Keyboard


  Enables the user to enter data and instructions in the computer by pressing keys
• Mouse


  Enables the user to issue instructions to the computer by controlling the mouse pointer displayed on the screen
• Monitor


  Enables the user to see information (output) from the computer
• Historical development of computers

  1. Struggling to invent non-electronic tools that would simplify arithmetic such as Abacus and Napier bones

  2. Analytical engine designed by Charles Babbage in 1832

  3. 1st generation computers (1940-1958)

  4. 2nd generation computers (1958-1964)

  5. 3rd generation computers (1964-1970)

  6. 4th generation computers (1970-1989)

  7. 5th generation computers (circa 1990-present)
• Abacus


  Chinese counting instrument dating back to 3000 BC, with bead-like parts that move along rods
• Analytical engine


  Designed by Charles Babbage in 1832, recognised as the first real computer and Babbage as the father of computing
• 1st generation computers (1940-1958)


  • Huge, expensive and often broke down
  • Slow compared to today's computers, with limited internal storage capacity
  • Used cards to enter data and vacuum tubes to control internal operations
  • Used for payroll processing and building
• 2nd generation computers (1958-1964)

  • Used transistors for internal operations and magnetic cards as primary storage medium
  • Increased storage capacity compared to 1st generation
  • Smaller in size, more reliable, generated less heat, and less prone to hardware failure
• 3rd generation computers (1964-1970)

  • Used integrated circuits, increased storage capacity, more flexibility with input/output, smaller size, and better performance
  • Introduced software industry and operating systems
• 4th generation computers (1970-1989)

  • Used very large scale integrated circuits (VLSI)
  • Large storage capacity and high speed
  • Introduction of microprocessor, microcomputers and supercomputers
• 5th generation computers (circa 1990-present)


  • Characterized by the emerging of telecommunications with computer technology
  • Scientists working on machines with the ability to reason logically and with real-world knowledge
• Types of computers by physical size

  • Supercomputer
  • Mainframe
  • Minicomputer
  • Microcomputer
• Types of computers by functionality

  • Analog computers
  • Digital computers
  • Hybrid computers
• Types of computers by purpose

  • General purpose
  • Special purpose
  • Dedicated
• Supercomputers


  • The fastest, largest and most expensive computers
  • Mainly used in scientific research, simulation, and analysis
• Mainframes


  • More powerful and less expensive than supercomputers
  • Used in government agencies, big companies, and complex mathematical equations
• Microcomputers


  • The smallest, cheapest and least powerful type of computer
  • Used mainly in learning institutions