Digital Logic - Old Question 2025 (BT102CO)

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Purbanchal University

2025

Bachelor of Technology in Artificial Intelligence/First Semester/Final

Time: 03:00 hrs. Full Marks: 60/Pass Marks: 24

BT102CO: Digital Logic

Candidates are required to give their answers in their own words as far as practicable.

Figure in the margin indicate full marks.

Group A

Answer TWO questions. 2 × 12 = 24

1. What is a counter? Explain different types of counter. Discuss synchronous counter with a timing diagram. [2+4+6]

2. Explain the role of multilevel NAND and NOR gates in implementing combinational logic circuits and provide a detailed analysis of the circuit's operation. [12]

3. (a) What is a K-map? Explain the don't care condition in K-map with an example. [6]

3. (b) Simplify the following using K-map: [6]

  • $F(A, B, C, D) = \Sigma(0, 2, 4, 7, 10, 12)$
  • $d(A, B, C, D) = \Sigma(1, 3, 5, 6, 8)$

Group B

Answer SIX questions. 6 × 6 = 36

4. Explain the difference between analog and digital signals. Give real-world examples of each. Why are digital signals preferred in modern electronics? [6]

5. Perform the following: [2+2+2]

  • (a) Subtract $(873)_{10}$ from $(3462)_{10}$ using the 10's complement method.
  • (b) $(2312)_{4} = (?)_{3}$
  • (c) $(32689)_{10} = (?)_{2}$

6. What is a combinational logic circuit? Explain a 4:1 multiplexer with a neat diagram. [6]

7. Analyze the given logic circuit. Determine the output expression and simplify it (if possible). Construct the truth table for the circuit. [6]

graph LR subgraph Inputs A[A] B[B] C[C] D[D] end A --- NOR((NOR)) B --- NOR C --- NOT((NOT)) C --- OR((OR)) D --- OR NOR --- AND{AND} NOT --- AND OR --- AND AND --- OUT[Output]

8. Design a sequential circuit using T flip-flops to implement a 3-bit counter that counts in the sequence $000 \rightarrow 001 \rightarrow 010 \rightarrow 100$ (repeating). Include the state diagram and state equations in your design. [6]

9. What is a Programmable Logic Array (PLA), and how does it differ from a ROM? Explain different types of ROMs. [6]

10. What is a flip-flop? Explain JK-flip-flop with an example. [6]

Practice Quiz