Unit 4

• What is a logic gate?


  A device that acts as a building block for digital circuits
• Computers are built up of integrated circuits (ICs). What is an IC?


  They are semiconductor wafers with millions of tiny resistors, capacitors, and other components
• What is a transistor?


  Devices that control the movement of electrons, and consequently, electricity
• What does a capacitor do?


  It temporarily stores electrical energy through distributing charged particles on (usually) two plates to create a potential difference
• What does a resistor do?


  They limit/regulate the flow of electric current in an electronic circuit

  
  

  There are stipes on a resistor, and it indicates how much electricity can pass through it
• What is a motherboard?


  Main circuit board of a computer that connects and allows communication between all hardware components
• What is a combinatorial logic?


  A logic where the results of an operation depends only on the present inputs to the operation
• What is combinatorial logic used for?

  Perform arithmetic, control data movement, compare values for decision making
• What is a sequential logic?


  A logic where the results depend on both the inputs to the operation and the results of the previous operation
• What is a sequential logic used for?


  Counter
• What is boolean algebra?


  Rules that govern constants and variables that can take on 2 values, 1 and 0
• What are the different types of logics and their equations?

  ...

  • NOT --> a'
  • AND --> c = a.b
  • OR --> c = a + b
  • NAND --> c = (a.b)'
  • NOR --> c = (a+b)'
  • Ex-OR --> c = a +o b
  • Ex-NOR --> c = (a +o b)'
• What are the inputs of the logics and their truth table?

  ...

  • NOT - Only 1 input - Inverse of input
  • AND - 2 or more inputs - Both inputs have to be true for the output to be true
  • OR - 2 or more inputs - At least 1 input has to be true for the output to be true
  • NAND - 2 or more inputs - Inverse of AND (when both inputs are 1 output will be 0)
  • NOR - 2 or more inputs - Inverse of OR (is 0 if any inputs are 1)
  • Ex-OR - Only 2 inputs - Both inputs have to be different for output to be true
  • Ex-NOR - Only 2 inputs - Both inputs must be same for output to be true