A-LevelComputer ScienceHardware9618/12 · Oct/Nov 2024 · Q14 Marks
Complete the truth table for the logic expression: X = (A XOR B) NAND (A AND (B XOR C)) [Figure 1.1: Truth table with columns A, B, C, Working space, X, and rows of binary values for A, B, C.] Draw the logic circuit for the logic expression: W = P NAND ((Q OR NOT R) XOR (P XOR Q)) [Figure 1.2: Empty space for drawing a logic circuit.]
- (a)Complete the truth table for the logic expression: X = (A XOR B) NAND (A AND (B XOR C)) Working space A B C 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[2]
- (b)Draw the logic circuit for the logic expression: W = P NAND ((Q OR NOT R) XOR (P XOR Q))[2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.
- [2] 1 mark for each shaded part. A B C X 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 1 1 1 1 1
- [2] 1 mark for (P XOR Q) and (Q OR NOT R) 1 mark for second XOR gate and final NAND gate with appropriate inputs [Diagram of logic circuit: P and Q go into an XOR gate. Q and R go into a NOT gate (for R) and then an OR gate. The output of P XOR Q and the output of Q OR NOT R go into an XOR gate. The output of this XOR gate and P go into a NAND gate to produce W.]
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