10 questions🇬🇧English
🔌 Logic Gates & Boolean Algebra – A-level
Computer Science · A-level — practise truth tables, De Morgan's laws, simplifying expressions, Karnaugh maps and adders.
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Questions
How many of the four rows in the truth table of a 2-input NOR gate give an output of 1?
3
0
1
2
20s
A logic circuit has 3 inputs. How many rows does its complete truth table need?
9
6
16
8
20s
In a half adder, which logic gate produces the carry output?
OR
NAND
XOR
AND
20s
Using ¬ for NOT, · for AND and + for OR, De Morgan's law states that ¬(A + B) is equivalent to:
A · B
¬A + ¬B
¬A · ¬B
¬A · B
30s
Using · for AND and + for OR, what does the expression A + A · B simplify to?
A
A · B
B
A + B
30s
Inputs A and B go into an AND gate. Its output and input C go into a NOR gate giving Q. Which expression gives Q?
Q = ¬((A · B) + C)
Q = ¬(A + B + C)
Q = (A · B) + ¬C
Q = ¬(A · B) + C
30s
A full adder has inputs A = 1, B = 1 and carry-in = 1. What are its outputs?
Sum = 1, Carry out = 1
Sum = 0, Carry out = 1
Sum = 0, Carry out = 0
Sum = 1, Carry out = 0
30s
Using ¬ for NOT, · for AND and + for OR, what does (A + B) · (A + ¬B) simplify to?
1
B
A
A · B
60s
In a 4-variable Karnaugh map, how many variables are eliminated by a valid group of four adjacent 1s?
3 variables
1 variable
4 variables
2 variables
30s
When does a positive edge-triggered D-type flip-flop update its output Q?
Whenever the D input changes
On the falling edge of the clock
On the rising edge of the clock
While the clock is held high
20s