O-LevelComputer ScienceBoolean logic2210/21 · May/June 2025 · Q78 Marks
Consider the logic expression: X = (A AND B) XOR (B OR NOT C)
- (a)Draw a logic circuit for this logic expression. Each logic gate must have a maximum of two inputs. Do not simplify the logic expression. A B C X[4]
- (b)Complete the truth table for the given logic expression. A B C 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 Working space X[4]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2025). The mark or mark type is shown in brackets.
- [1] (a) One mark for each correct gate, with the correct input(s) as shown. (Circuit: A and B go to AND gate. C goes to NOT gate. B and NOT C go to OR gate. Output of AND and output of OR go to XOR gate, which outputs X.)
- [4] (b) 4 marks for 8 correct outputs
- [3] (b) 3 marks for 6/7 correct outputs
- [2] (b) 2 marks for 4/5 correct outputs
- [1] (b) 1 mark for 2/3 correct outputs
- Truth Table (b): A B C X 0 0 0 1 0 0 1 0 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0
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