Shift Registers(Engineering > Electronics And Communication Engineering ) Questions and answers for exam Preparation

Question 1. On the fifth clock pulse, a 4-bit Johnson sequence is Q0 = 0, Q1 = 1, Q2 = 1, and Q3 = 1. On the sixth clock pulse, the sequence is ________.

Q0 = 1, Q1 = 0, Q2 = 0, Q3 = 0
Q0 = 1, Q1 = 1, Q2 = 1, Q3 = 0
Q0 = 0, Q1 = 0, Q2 = 1, Q3 = 1
Q0 = 0, Q1 = 0, Q2 = 0, Q3 = 1

Explanation:-

Answer: Option C. -> Q0 = 0, Q1 = 0, Q2 = 1, Q3 = 1

Question 2. The bit sequence 0010 is serially entered (right-most bit first) into a 4-bit parallel out shift register that is initially clear. What are the Q outputs after two clock pulses?

0000
0010
1000
1111

Explanation:-

Answer: Option C. -> 1000

Question 3. On the third clock pulse, a 4-bit Johnson sequence is Q0 = 1, Q1 = 1, Q2 = 1, and Q3 = 0. On the fourth clock pulse, the sequence is ________.

Q0 = 1, Q1 = 1, Q2 = 1, Q3 = 1
Q0 = 1, Q1 = 1, Q2 = 0, Q3 = 0
Q0 = 1, Q1 = 0, Q2 = 0, Q3 = 0
Q0 = 0, Q1 = 0, Q2 = 0, Q3 = 0

Explanation:-

Answer: Option A. -> Q0 = 1, Q1 = 1, Q2 = 1, Q3 = 1

Question 4. A bidirectional 4-bit shift register is storing the nibble 1101. Its RIGHT/ LEFT input is HIGH. The nibble 1011 is waiting to be entered on the serial data-input line. After three clock pulses, the shift register is storing
___________________.

1101
0111
0001
1110

Explanation:-

Answer: Option B. -> 0111

Question 5. What is a shift register that will accept a parallel input, or a bidirectional serial load and internal shift features, called?

tristate
end around
universal
conversion

Explanation:-

Answer: Option C. -> universal

Question 6. What does the output enable do on the 74395A chip?

It determines when data can be loaded.
It forces all outputs to go HIGH.
It forces all outputs to go LOW.
It activates the three-state buffer.

Explanation:-

Answer: Option D. -> It activates the three-state buffer.

Question 7. How can parallel data be taken out of a shift register simultaneously?

Use the Q output of the first FF.
Use the Q output of the last FF.
Tie all of the Q outputs together.
Use the Q output of each FF.

Explanation:-

Answer: Option D. -> Use the Q output of each FF.

Question 8. To operate correctly, starting a ring shift counter requires:

clearing all the flip-flops
presetting one flip-flop and clearing all others
clearing one flip-flop and presetting all others
presetting all the flip-flops

Explanation:-

Answer: Option B. -> presetting one flip-flop and clearing all others

Question 9. In a 6-bit Johnson counter sequence there are a total of how many states, or bit patterns?

2
6
12
24

Explanation:-

Answer: Option C. -> 12

Question 10. . A modulus-12 ring counter requires a minimum of ________.

10 flip-flops
12 flip-flops
6 flip-flops
2 flip-flops

Explanation:-

Answer: Option B. -> 12 flip-flops