A logic expression is a way to write down in letters and symbols a representation of the logic circuit. This section shows how logic statements are formed and the next section shows how logic statements can be used to simplify logic circuits. Whilst there are various ways to represent each logic gate, this section will only deal with OR, AND, NOT, XOR and NAND.
CONVENTIONAL NOTATION
ABC are all ANDed together (3 way and gate) and then the outcome is NOTed.
ABC go through NOT gates individually and then the outcomes are ANDed together(3 way AND gate)
NOTE: Each awarding body may have their own method of representing a Logic Expression. This section gives two different methods, the first method is commonly used at IB and GCSE level and the second method is commonly used at A-Level. Check your course spec for the method expected for your course.
EXAMPLE 1
The logic expression for the circuit above could written as:
IB AND GCSE LEVEL: (A AND B) OR (B AND C) A-LEVEL: (A.B)+(B.C)
EXAMPLE 2
The logic expression for the circuit above could written as:
IB AND GCSE LEVEL: (A AND B) OR (B AND C) A-LEVEL: (A.B)+(B.C)
EXAMPLE 3
The logic expression for the circuit above could written as:
IB AND GCSE LEVEL: (A AND B) OR (B AND C) A-LEVEL: (A.B)+(B.C)
EXAMPLE 4
The logic expression for the circuit above could written as:
IB AND GCSE LEVEL: (A AND B) OR (B AND C) A-LEVEL: (A.B)+(B.C)
DESIGN FROM SCENARIO
TEST YOUR KNOWLEDGE
OTHER USEFUL RESOURCES
Draw your own circuits at : https://logic.ly/demo