A new flip flop with inputs X and Y, has the following property. Which of the…

2020

A new flip flop with inputs X and Y, has the following property. Which of the following expresses the next state in terms of X, Y, current state ? ISRO 2020

  1. A.

    X'Q' + Y'Q

  2. B.

    X'Q + Y'Q'

  3. C.

    XQ' + YQ

  4. D.

    XQ' + Y'Q

Attempted by 68 students.

Show answer & explanation

Correct answer: A

To find the correct expression for the next state, we analyze the given truth table row by row to see which Boolean formula fits all cases.

From the table:
1. When X=0, Y=0: Next State is 1.
2. When X=0, Y=1: Next State is Q'.
3. When X=1, Y=1: Next State is 0.
4. When X=1, Y=0: Next State is Q.

Let's test the expression X'Q' + Y'Q:
- Case X=0, Y=0: (1)Q' + (1)Q = Q' + Q = 1. Matches row 1.
- Case X=0, Y=1: (1)Q' + (0)Q = Q'. Matches row 2.
- Case X=1, Y=1: (0)Q' + (0)Q = 0. Matches row 3.
- Case X=1, Y=0: (0)Q' + (1)Q = Q. Matches row 4.

Since the expression X'Q' + Y'Q correctly predicts the next state for all input combinations, it is the correct answer.

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