The GATE Grind

GATE 2011 CS (CS1) – Question 60

Digital Logic · Sequential Circuits · 2 marks · Multiple choice

The three D flip-flops form the shown counter. Immediately before a clock edge P,Q,R=0,1,0. Find PQR after the edge.

Diagram for GATE 2011 CS (CS1) question 60
  1. 000
  2. 001
  3. 010
  4. 011

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (D) 011

Explanation

Trace the D inputs: $P^+=R$, $Q^+=\overline{P+R}$, $R^+=Q\bar R$. At PQR=010 these evaluate to 0,1,1. Synchronous D flip-flops load those values together, giving 011, D.

More Sequential Circuits questions

All Sequential Circuits questions →