Digital Design Interview Questions Part 2

Q1. In the sequential circuit shown below,if the initial value of the output Q1Q0 is 00,what are the next four values of Q1Q0?
A) 11, 10, 01, 00
B) 10,11,01, 00
C) 10, 00, 01, 11
D) 11, 10, 00, 01
Q2. Let k = 2n. A circuit is built by giving the output of an n-bit binary counter as input to an n-to-2n bit decoder. This circuit is equivalent to a
A) k bit binary up counter
B) k bit binary ring counter
C) k bit binary down counter
D) k bit binary Johnson counter
Q3.Consider the circuit in the diagram. The ⊕ operator represents EXOR. The D flipflops are initialized to zeroes (cleared).The following data: 100110000 is supplied to the “data” terminal in nine clock cycles. After that the values of q2q1q0 are
A) 000
B) 001
C) 010
D) 101
Q4. 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 and Q'=1
B) Q=1 and Q'=0
C) Q=1 and Q'=1
D) Invalid states
Q5. Consider the partial implementation of a 2-bit counter using T flip-flops following the sequence 0-2-3-1-0, as shown below.To complete the circuit, the input X should be
A) Q2'
B) Q2+Q1
C) (Q1 xor Q2)'
D) Q1 xor Q2
Q6. The minimum number of JK flip-flops required to construct a synchronous counter with the count sequence (0, 0, 1, 1, 2, 2, 3, 3, 0, 0,...) is
A) 0
B) 1
C) 2
D) 3
Q7. How many pulses are needed to change the contents of a 8-bit up counter from 10101100 to 00100111 (rightmost bit is the LSB)?
A) 134
B) 123
C) 124
D) 133
Q8. We want to design a synchronous counter that counts the sequence 0-1-0-2-0-3 and then repeats. The minimum number of J-K flip-flops required to implement this counter is
A) 1
B) 2
C) 5
D) 4
Q9. Design a synchronous counter to go through the following states: 1, 4, 2, 3, 1, 4, 2, 3, 1, 4,...
Q10. Design a synchronous counter to go through the following states: 0->1->3->4->5->7->0..using T flip flop.
Q11. Which of the following input sequences for a cross-coupled R-S flip-flop realized with two NAND gates may lead to an oscillation ?
A) 11,00
B) 01,10
C) 10,01
D) 00,11
Q12. The Boolean function f implemented in the figure shown below, using two input multiplexers is.
B) A'B'C+A'BC'
C) A'BC+A'B'C'
Q13. The functional difference between SR flip-flop and JK flip-flop is that
A) JK flip flop is faster than SR flip flop
B) JK flip flop has a feedback path
C) JK flip flop accepts both inputs 1
D) None of the above
Q14. A modulus 12 ring counter requires a minimum of flip flops.
A) 10 flip flops
B) 12 flip flops
C) 6 flip flops
D) 8 flip flops
Q15. In a three stage counter, using RS flip flops what will be the value of the counter after giving 9 pulses to its input? Assume that the value of counter before giving any pulses is 1
A) 1
B) 2
C) 9
D) 10
Q16. The number of flip-flops required to design a modulo 272 counter is:
A) 8
B) 9
C) 27
D) 11
Q17. Ring counter is analogous to
A) Latch
B) Toggle switch
C) Stepping switch
D) SR flip flop
Q18. How many 3-to-8 line decoders with an enable input are needed to construct a 6-to-64 line decoder without using any other logic gates?
A) 7
B) 8
C) 9
D) 10
Q19. A ROM is used to store the table for multiplication of two 8-bit unsigned integers. The size of ROM required is  
A) 256 x 16
B) 64K x 8
C) 4K x 16
D) 64K x 16
Q20. Consider the equation (123)5 = (x8)y with x and y as unknown. The number of possible solutions is 
A) 1
B) 2
C) 3
D) 4
Q21. The 2’s complement representation of (−539)10 in hexadecimal is
C) DE5
D) 9E7
Q22. Consider the equation (43)x = (y3)8 where x and y are unknown.The number of possible solutions is
A) 3
B) 4 
C) 5
D) 6
Q23. The number of 1's in the binary representation of (3*4096 + 15*256 + 5*16 + 3) are
A) 9
B) 8
C) 10
D) 12
Q24. The number of 1's in the binary representation of (4*4096 + 9*256 + 7*16 + 5) are
A) 9
B) 8
C) 10
D) 12
Q25. Which one of the following expressions does NOT represent exclusive NOR of x and y?
A) xy+x'y'
B) x xor y'
C) x' xor y
D) x' xor y'
Q26. What is the minimum number of gates required to implement the Boolean function (AB+C)if we have to use only 2-input NOR gates?
A) 2
B) 3
C) 4
D) 5
Q27. The total number of prime implicants of the function f(w, x, y, z) = Σ(0, 2, 4, 5, 6, 10) is
A) 2
B) 3 
C) 4
D) 5
Q28. What is the minimum number of NAND gates required to implement a 2-input EXCLUSIVE-OR function without using any other logic gate?
A) 3
B) 4 
C) 5
D) 6
Q29. Logic family popular for low power dissipation.
Q30. What is race-around condition? How can you solve it?
Click here for part 3


Hi I’m Designer of this blog.

    Blogger Comment
    Facebook Comment