O-LevelComputer ScienceBoolean logic2210/11 · May/June 2016 · Q510 Marks
A computer-controlled machine produces plastic sheets. The thickness of each sheet must be within a certain tolerance. The sheets are kept below 50°C as they move over rollers at 10 metres per second. Three parameters need to be monitored all the time. Parameter Description Binary value Conditions D sheet thickness 1 thickness of sheet in tolerance D sheet thickness 0 thickness of sheet out of tolerance S roller speed 1 roller speed = 10 metres/second S roller speed 0 roller speed <> 10 metres/second T temperature 1 temperature < 50 °C T temperature 0 temperature >= 50 °C An alarm, X, will sound if: thickness is in tolerance AND (roller speed <> 10 metres/second OR temperature >= 50°C) OR roller speed = 10 metres/second AND temperature >= 50 °C
- (a)Draw a logic circuit to represent the above monitoring system.[6]
- (b)Complete the truth table for the monitoring system. D S T 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 (May/June 2016). The mark or mark type is shown in brackets.
- [6] (a) 1 mark for each correct gate, with correct source of input(s)
- [4] (b) 4 marks for 8 correct X bits
- [3] (b) 3 marks for 6 correct X bits
- [2] (b) 2 marks for 4 correct X bits
- [1] (b) 1 mark for 2 correct X bits
- [1] (b) X = 0 for D=0, S=0, T=0
- [1] (b) X = 0 for D=0, S=0, T=1
- [1] (b) X = 1 for D=0, S=1, T=0
- [1] (b) X = 0 for D=0, S=1, T=1
- [1] (b) X = 1 for D=1, S=0, T=0
- [1] (b) X = 1 for D=1, S=0, T=1
- [1] (b) X = 0 for D=1, S=1, T=0
- [1] (b) X = 0 for D=1, S=1, T=1
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