Topic 1a
Logic Gates

Learning Objectives

By the end of this topic students should be able to:

  • Explain the general functionality of a(n) [AND | OR | NOT | XOR] gate.
  • Given two inputs to an [AND | OR] gate, identify the output of the gate.
  • Given one input to a NOT gate, identify the output of the gate.
  • Given up to three inputs to a circuit consisting of a combination of up to three gates, identify the output of the circuit.

 

The notation used above is used to combine similar Learning Objectives.   When you see:

  • Explain the general functionality of a(n) [AND | OR | NOT | XOR] gate.
This means that any ONE of those four words could go in the blank to complete the objective.

  • Explain the general functionality of an AND gate.
  • Explain the general functionality of an OR gate.
  • Explain the general functionality of a NOT gate.
  • Explain the general functionality of an XOR gate.”

 

Learning Materials

Checking for Understanding

Answer the following questions.

  1. "If a 0 goes in, a 0 comes out" is the rule for which logic gate?
     
  2. "If a 1 goes in, a 1 comes out" is the rule for which logic gate?
     
  3. "If a 0 goes in, a 1 comes out" and "if a 1 goes in, a 0 comes out" are the rules for which logic gate?
     
  4. What input patterns will cause the following circuit to produce an output of 1?

     
  5. What input patterns will cause the following circuit to produce an output of 1?

     
  6. What input patterns will cause the following circuit to produce an output of 1?

 

To check your understanding of the answers to these question please refer to this answer key.

 

Additional Guidance

If you are still struggling with the material in this topic, the following video may help.

Further Information

If you understand this material and are using this in your own courses, you might find the following material beneficial. This material is a supplement to this course and your understanding of this is not assessed.
  • Basic Gates vs. Universal Gates
    • While we talk about seven types of gates, we can actually build several of these from combinations of the others.
    • In this reading we explain the typical concept of Universal Gates
  • Flip-flops
    • We don't think it is essential that you understand flip-flops for this course. But you may have heard about them. And you may even be teaching a course that discusses them with your students. In this case, you might want read the explanation for this topic from your textbook.
      • Reading: Section 1.1 in your textbook, pp 28-32.