[CSCI150] Lecture 2: Combinational Logic Circuits

Starting from Lecture 2, we will have some separate videos focusing on Tutorials. I will post videos on how to use the software, but sometimes if you do encounter more difficult questions, please contact me for an office hour, or just attend the regular one on Wednesday.

LS4 Part 1 (Lecture): Gates, Operators, Timing Diagram, Truth Table, Gating Delay


  • Gates
    • AND, OR, NOT gates
    • Physical components
  • Operators
    • Differences with physical gates: conceptually speaking, one is mathematical, one is physical simulation
  • Timing Diagram
  • Truth Table
  • Gating Delay
    • Important to know what it is, that it exists

LS4 Part 2 (Tutorial): LogicWorks, Basic circuit drawing and Simulation


  • Basic Interface
    • Simulation I/O, binary switches for inputs, probs for outputs
    • Simulation Gates
  • Timing Diagram control
    • Clock units

LS5 Part 1 (Lecture): Boolean Algebra, Binary Identities

This is one of the slightly longer lecture recordings, it covers some very important things as well as providing some important proofs that you should attempt on your own first.


  • Binary Identities: HS401 handout
    • 17 basic rules, prove using truth table
    • 6 extended rules, prove using the 17 basic rules.
  • Complement using DeMorgan’s Law
    • One should practice the application of DeMorgan’s Law very carefully, as it is quite common to make mistakes
  • Duality
    • The dual of a boolean expression: AND replaced with OR, OR replaced with AND, 0 with 1, 1 with 0
    • Duality principle.
  • Algebraic Manipulation
    • Trial and Error: try all possible binary identities, see if they make the expressions simpler
    • Utilise known conditions wisely, try to compute the values for as much expressions as possible
    • Practice, practice, practice

LS5 Part 2 (Exercise): Boolean Algebra

Here’s what you need before watching this video: bring out a pen/pencil and a few pieces of paper, and do the exercises. Each question is already included in LS5, and will be displayed for 10seconds, during which you should pause the video, attempt to solve it, and only when you have tried sufficient amount of times or have solved it successfully should you proceed to watch my solutions.

The answers will NOT be available in the PDF version of LS5.


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