Digital Logic 2019

Group B

Attempt any SIX questions. [6x5 = 30]

2. Subtract: 1010.110 – 101.101 using both 2's and 1's complement. [5]

3. Simplify (Using k-map) the given Boolean function in both SOP and POS using the don’t

care condition d:

4. Define decoder. Draw logic diagram and truth table of 3 to 8-line decoder. [1 + 4]

5. Define ROM. Implement the following combinational logic function using ROM: [2 + 3]

6. What are the drawbacks of clocked RS flip flop? Explain the operation of JK Flip flop along with its circuit diagram and characteristic table. [2+3]

7. What is T flip-flop? Explain clocked JK flip-flop with its logic diagram and truth table. [1 + 4]

8. Design MOD - 7 counter with state and timing diagram. [2 + 1 + 2]

Group C

Attempt any TWO questions. [2x10 = 20]

9. Define PLA. Design a PLA circuit with given functions.

F1 (A, B, C) = Σ (3, 5, 6, 7)

F2 (A, B, C) = Σ (0, 2, 4, 7). Design PLA program table also. [3 + 7]

10. Distinguish between sequential and combinational logic with example? Discuss the design procedure of combinational logic. [4+6]

11. A sequential circuit with two D flip-flops, A and B, two inputs x and y, and one output z, is specified by the following next state and output equations [4+3+3]

A(t+1) = x'y + x A

B(t +1) = x'B + x A

z = B

a) Draw the logic diagram.

b) Derive the state table.

c) Derive the state diagram.