Digital Electronics-Shift Registers
Digital Electronics-Shift Registers
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