UGC NET CSE | July 2018 | Part 2 | Question: 92

Question

In $\text{RS}$ flip-flop, the output of the flip-flop at time $(t+1)$ same as the output at time $t$, after the occurrence of a clock pulse if :

• A. $S=R=1$
• B. $S=0, R=1$
• C. $S=2, R=0$
• D. $S=R=0$

Comments

output of the flip flop at time (t+1) is same as the output at time t, after the occurrence of a clock pulse that means previous o/p is reflecting as present o/p.

this is possible when S=R=0.

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i mark this option but dout on first option

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in S-R flipflop S=R=1  is a invalid combination

Answer 1

Option D. S=R=0

R  S        Q_{t+1
0   0      No Change} 
0  1            0
1  0            1
1  1        *race

Answer 2

S = R = 0 is the normal resting condition of the flip-flop. It has no effect on the output state of the flip-flop. Both $Q$ and $\bar{Q}$ outputs remain in the logic state they were in prior to this input condition.

Answer 3

Option 4 Would Be Correct I.e S=R=0