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Combinational Circuit PYQ quiz GATE CS
Question 1
In the following truth table, V = 1 if and only if the input is valid.
What function does the truth table represent?
- A
Priority encoder
- B
Decoder
- C
Multiplexer
- D
Demultiplexer
Question 2
Consider a carry lookahead adder for adding two n-bit integers, built using gates of fan-in at most two. The time to perform addition using this adder is
- A
Θ(1)
- B
Θ(Log (n))
- C
Θ(√ n)
- D
Θ(n)
Question 3
Consider a 4-to-1 multiplexer with two select lines S1 and S0, given below
The minimal sum-of-products form of the Boolean expression for the output F of the multiplexer is
- A
P\'Q + QR\' + PQ\'R
- B
P\'Q + P\'QR\' + PQR\' + PQ\'R
- C
P\'QR + P\'QR\' + QR\' + PQ\'R
- D
PQR\'
Question 4
Consider the circuit above. Which one of the following options correctly represents f (x, y, z)?
- A
xz' + xy + y'z
- B
xz' + xy + (yz)'
- C
xz + xy + (yz)'
- D
xz + xy' + (yz)'
Question 5
The switching expression corresponding to f(A, B, C, D) = Σ (1, 4, 5, 9, 11, 12) is
- A
BC'D' + A'C'D + AB'D
- B
ABC' + ACD + B'C'D
- C
ACD' + A'BC' + AC'D'
- D
A'BD + ACD' + BCD'
Question 6
In an SR latch made by cross-coupling two NAND gates, if both S and R inputs are set to 0, then it will result in
- A
Q = 0, Q' = 1
- B
Q = 1, Q' = 0
- C
Q = 1, Q' = 1
- D
Indeterminate states
Question 7
A circuit outputs a digit in the form of 4 bits. 0 is represented by 0000, 1 by 0001, ..., 9 by 1001. A combinational circuit is to be designed which takes these 4 bits as input and outputs 1 if the digit ≥ 5, and 0 otherwise. If only AND, OR and NOT gates may be used, what is the minimum number of gates required?
- A
2
- B
3
- C
4
- D
5
Question 8
Which are the essential prime implicants of the following Boolean function? f(a, b, c) = a'c + ac' + b'c
- A
a'c and ac'
- B
a'c and b'c
- C
a'c only
- D
ac' and bc'
Question 9
Consider a multiplexer with X and Y as data inputs and Z as control input. Z = 0 selects input X, and Z = 1 selects input Y. What are the connections required to realize the 2-variable Boolean function f = T + R, without using any additional hardware ?
- A
R to X, 1 to Y, T to Z
- B
T to X, R to Y, T to Z
- C
T to X, R to Y, 0 to Z
- D
R to X, 0 to Y, T to Z
Question 10
Consider the following multiplexor where 10, 11, 12, 13 are four data input lines selected by two address line combinations A1A0 = 00, 01, 10, 11 respectively and f is "the output of the multiplexor. EN is the enable input.
The function f(x, y, z) implemented by the above circuit is :
- A
xyz'
- B
xy + z
- C
x + z
- D
None of these
There are 19 questions to complete.
