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O-LevelComputer ScienceBoolean logic2210/12 · Oct/Nov 2019 · Q87 Marks

Consider the logic circuit: [Figure showing a logic circuit with inputs A, B, C and output X. The circuit consists of an XOR gate (inputs A and C), a NOT gate (input C), a NAND gate (inputs B and output of NOT C), and an OR gate (inputs output of XOR and output of NAND). The output of the OR gate is X.]

  1. (a)Write a logic statement to match the given logic circuit.[3]
  2. (b)Complete the truth table for the given logic circuit. A B C Working space X 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1[4]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

  1. [3] (a) X = (A XOR C) OR (B NAND NOTC)
  2. [4] (b) (8 correct outputs) X column: 1, 1, 0, 1, 1, 1, 1, 1

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About this question

Topic
Boolean logic, O-Level Computer Science (syllabus 2210). Structured question, 7 marks.
Source
O-Level Computer Science, Oct/Nov 2019 Paper 1 Variant 2, question 8.

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