Digital Design Interview Questions Part 3

1. A ring counter consisting of five Flip-Flops will have.
a) 5 states
b) 32 states
c) 10 states
d) None of the above
2. The 2’s complement of the number 1101101 is.
a) 0111110
b) 0110010
c) 0010011
d) 0101110
3. Which of the following is the fastest logic?
a) TTL
b) ECL
d) None of the above
4. If the input to T-flipflop is 100 Hz signal, the final output of the three T-flipflops in cascade is.
a) 1000Hz
b) 12.5Hz
c) 500Hz
d) None of the above
5. The digital logic family which has the lowest propagation delay time is.
a) TTL
b) ECL
d) None of the above
6. A 4-bit synchronous counter uses flip-flops with propagation delay times of 15 ns each. The maximum possible time required for change of state will be.
a) 60ns
b) 45ns
c) 30ns
d) 15ns
7. Words having 8-bits are to be stored into computer memory. The number of lines required for writing into memory are.
a) 1
b) 2
c) 4 
d) 8
8. How many flip flops are required to construct a decade counter?
a) 4
b) 10
c) 2
d) None of the above
9. How many flip-flops are required to construct mod 30 counter?
a) 30
b) 5
c) 4
d) 6
10. An eight stage ripple counter uses a flip-flop with propagation delay of 75 nanoseconds. The pulse width of the strobe is 50ns. The frequency of the input signal which can be used for proper operation of the counter is approximately.
a) 1MHz
b) 2MHz
c) 4MHz
d) None of the above
11. Which of following consume minimum power?
a) TTL
b) ECL
d) None of the above
12. The Boolean expression A'.B+ A.B'+ A.B is equivalent to.
a) A+B
b) (A+B)'
c) A'B
d) AB
13. Data can be changed from special code to temporal code by using.
a) Combinational Circuits
b) A/D Converters
c) Shift Registers
d) Counters
14. The code where all successive numbers differ from their preceding number by single bit is.
a) Binary Code
b) Gray Code 
c) BCD
d) None of the above
15. The A/D converter whose conversion time is independent of the number of bits is.
a) Successive approximation
b) Parallel conversion
c) Dual Slope
d) None of the above
16. 1’s complement representation of decimal number of -17 by using 8 bit representation is.
a) 1100 1100
b) 1101 1101
c) 0001 0001
d) 1110 1110
17. The number of digit 1 present in the binary representation of
          3 x 512 +7 x 64+5 x 8+3
a) 8
b) 9
c) 10
d) None of the above
18. Which of the following binary number is the same as its 2's complement?
a) 1000
b) 1010
c) 1001
d) None of the above
19. The output expression of the following gate network is
a) X.Y
b) X+Y
c) XY+X'Y'
d) None of the above
20. Consider the following boolean function of four variables, f (w, x, y,z) = Σ(1, 3, 4, 6, 9, 11, 12, 14), the function is.
a) Independent of one varible
b) Independent of two variable
c) Independent of three variable
d) None of the above
Answers:  1.a  2. c  3. b  4. b  5. b  6.d  7. d  8. a  9. b  10. a  11. c  12. a  13. c  14. b  15. b  16. d  17. b  18. a  19. c  20. b.
Click here for part 4


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