Shift Registers Questions and Answers
Shift Registers are sequential logic circuits used for data storage and transfer in digital systems. This topic includes digital electronics aptitude questions and answers on serial-in serial-out, parallel-in parallel-out, and bidirectional shift registers. These questions, frequently asked in GATE, DRDO, and ISRO exams, test your conceptual clarity and circuit understanding. Practice these Shift Registers questions with answers to enhance your digital electronics knowledge and improve your competitive exam readiness.
Shift Registers
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69 questions
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
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
3. 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
4. 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
5. A bidirectional 4-bit shift register is storing the nibble 1101. Its 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
6. 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.
7. What is meant by parallel load of a shift register?
- All FFs are preset with data.
- Each FF is loaded with data, one at a time.
8. 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.
9. 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
10. In a 6-bit Johnson counter sequence there are a total of how many states, or bit patterns?
- 2
- 6
- 12
- 24