# Shift Register Counters MCQ’s

This set of Digital Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Shift Register Counters”.

1. A bidirectional 4-bit shift register is storing the nibble 1110. Its input is LOW. The nibble 0111 is waiting to be entered on the serial data-input line. After two clock pulses, the shift register is storing ________
a) 1110
b) 0111
c) 1000
d) 1001

2. When is it important to use a three-state buffer?
a) When two or more outputs are connected to the same input
b) When all outputs are normally HIGH
c) When all outputs are normally LOW
d) When two or more outputs are connected to two or more inputs

3. What is a recirculating register?
a) Serial out connected to serial in
b) All Q outputs connected together
c) A register that can be used over again
d) Parallel out connected to Parallel in

4. In a parallel in/parallel out shift register, D0 = 1, D1 = 1, D2 = 1, and D3 = 0. After three clock pulses, the data outputs are ________
a) 1110
b) 0001
c) 1100
d) 1000

5. By adding recirculating lines to a 4-bit parallel-in serial-out shift register, it becomes a ________ ________ and ________ out register.
a) Parallel-in, serial, parallel
b) Serial-in, parallel, serial
c) Series-parallel-in, series, parallel
d) Bidirectional in, parallel, series

6. In a 4-bit Johnson counter sequence, there are a total of how many states or bit patterns?
a) 1
b) 3
c) 4
d) 8

7. The group of bits 10110111 is serially shifted (right-most bit first) into an 8-bit parallel output shift register with an initial state 11110000. After two clock pulses, the register contains ______________
a) 10111000
b) 10110111
c) 11110000
d) 11111100

8. What type of register would have a complete binary number shifted in one bit at a time and have all the stored bits shifted out one at a time?
a) Parallel-in Parallel-out
b) Parallel-in Serial-out
c) Serial-in Serial-out
d) Serial-in Parallel-out

9. If a 10-bit ring counter has an initial state 1101000000, what is the state after the second clock pulse?
a) 1101000000
b) 0011010000
c) 1100000000
d) 0000000000

10. How much storage capacity does each stage in a shift register represent?
a) One bit
b) Two bits
c) Four bits
d) Eight bits