Unit 4 Electricity and magnetism


Notes
  • Other common gates in use include NAND and NOR gates. A NAND gate is a combination of a NOT gate and an AND gate. A NOR gate is a combination of a NOT gate and an OR gate.
  • NAND gate
    input
    A
    input
    B
    output
    0 0 1
    1 0 1
    0 1 1
    1 1 0

  • NOR gate
    input
    A
    input
    B
    output
    0 0 1
    1 0 0
    0 1 0
    1 1 0

  • Notice from the truth tables how the NAND and NOR gates are the complete opposite (inverse) of the AND and OR gates, respectively.
  • More than one logic gate can be combined with others to give the desired effect in a particular situation.
    Consider:
    • for a washing machine to work the machine must be on and the door closed
    • a security light will switch on when it is not daylight
    • a fridge alarm will sound when the door is left open or the temperature inside the fridge rises too high.
 
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