Combinational Logic Analysis MCQs

Question 1

The output of an exclusive-NOR gate is 1. Which input combination is correct?

Accepted Answer

A = 0, B = 0

Answer

A = 1, B = 0

Answer

A = 0, B = 1

Answer

none of the above

Question 2

One positive pulse with tw = 75 µs is applied to one of the inputs of an exclusive-OR circuit. A second positive pulse with tw = 15 µs is applied to the other input beginning 20 µs after the leading edge of the first pulse. Which statement describes the output in relation to the inputs?

Accepted Answer

*The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, followed by a 40 s pulse.

Answer

The exclusive-OR output is a 20 s pulse followed by a 40 s pulse, with a separation of 15 s between the pulses.

Answer

The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, with a separation of 40 s between the pulses.

Answer

The exclusive-OR output is a 15 s pulse followed by a 40 s pulse.

Question 3

How many AND gates are required to implement the Boolean expression, X = ABC + ABC + ABC ?

Accepted Answer

3

Answer

1

Answer

2

Answer

4

Question 4

How many NOT gates are required to implement the Boolean expression, X = ABC + ABC ?

Accepted Answer

2

Answer

1

Answer

4

Answer

5

Question 5

The inverter can be produced with how many NAND gates?

Accepted Answer

1

Answer

2

Answer

3

Answer

4

Question 6

A 4-variable AND-OR circuit produces a 0 at its Y output. Which combination of inputs is correct?

Accepted Answer

A = 1, B = 0, C = 1, D = 0

Answer

A = 0, B = 0, C = 1, D = 1

Answer

A = 1, B = 1, C = 0, D = 0

Answer

A = 1, B = 1, C = 1, D = 1

Question 7

A 4-variable AND-OR circuit produces a 1 at its Y output. Which combination of inputs is correct?

Accepted Answer

A = 1, B = 1, C = 0, D = 0

Answer

A = 0, B = 0, C = 0, D = 0

Answer

A = 0, B = 1, C = 1, D = 0

Answer

A = 1, B = 0, C = 0, D = 0

Question 8

Implementation of the Boolean expression X = ABC + AB + AC results in ________.

Accepted Answer

three AND gates, one NOT gate, one OR gate

Answer

three AND gates, one OR gate

Answer

three AND gates, one NOT gate, three OR gates

Answer

three AND gates, three OR gates

Question 9

One possible output expression for an AND-OR-Invert circuit having one AND gate with inputs A, B, and C and one AND gate with inputs D and E is ________.

Accepted Answer

(A + B + C)(D + E)

Answer

ABC + DE

Answer

A + B + C + D + E

Answer

(A + B + C) (D + E)