SAM HARRIS TECH REVISION

OCR GCSE CS - 2.4 Boolean Logic

2.4 Boolean Logic (OCR J277)

AND Gate: Output is 1 (True) only if BOTH inputs are 1.
OR Gate: Output is 1 (True) if EITHER or BOTH inputs are 1.
NOT Gate: Reverses the input (Inverts 0 to 1, or 1 to 0).
Symbols: Recognising the specific shapes for AND (D-shape), OR (pointed), and NOT (triangle with circle) in logic diagrams.

Function: A table showing all possible combinations of inputs and their resulting outputs.
Two-Input Tables: Handling 4 possible states (00, 01, 10, 11) for gates like AND and OR.
Single-Input Tables: Handling 2 possible states (0, 1) for the NOT gate.

Logic Circuits: Building complex diagrams by connecting multiple gates together.
Logic Expressions: Writing statements like Q = (A AND B) OR (NOT C) to represent a circuit.
Evaluating Outputs: Calculating the final result of a circuit given specific input values.

Year: 2024
Draw the logic gate symbol for an OR gate.
Mark: [1]
Year: 2024
Complete the truth table for the logic circuit: Q = (A AND B) OR C.
Mark: [4]
Year: 2023
Explain the function of a NOT gate in a logic circuit.
Mark: [2]
Year: 2023
Identify which logic gate is represented by the following truth table (Output is 1 only when both inputs are 1).
Mark: [1]
Year: 2022
Draw a logic diagram for the expression: NOT (A AND B).
Mark: [3]
Year: 2022
State why logic gates are used in computer systems.
Mark: [2]
Year: 2021
Complete a 2-input truth table for an XOR gate.
Mark: [2]
Year: 2021
Write the Boolean expression for a circuit that has two inputs, A and B, connected to an AND gate, with the output connected to a NOT gate.
Mark: [2]
Year: 2020
A security alarm (A) activates if a sensor (S) is triggered AND the system is armed (M). Write the Boolean expression for this.
Mark: [1]
Year: Sample Paper
Describe the difference between an AND gate and an OR gate in terms of their inputs and outputs.
Mark: [2]

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