Digital Logic Past Questions

B.Sc. CSIT - First Semester

Tribhuvan University

Institute of Science and Technology

TU Exam Year: 2080

Bachelor Level: B.Sc. CSIT

Semester: First

Subject: Digital Logic (CSC116)

Full Marks: 60 | Pass Marks: 24

Time: 3 Hours

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

SECTION A

Attempt all questions.

  1. 1.
    What is a combinational circuit?
  2. 2.
    Design a combinational circuit with four input lines that represent a decimal digit in BCD and four output lines that generate the 1's complement of the input binary patterns.
  3. 3.
    What is an asynchronous counter?
  4. 4.
    Design a synchronous counter that counts the sequences of 0-1-4-6-7 using T flip-flop.
  5. 5.
    Implement the Boolean function F(P,Q,R,S) = Σ(3,4,6,8,9,14) using: 8 to 1 multiplexer, PLA, Decoder
  6. 6.
    Perform the operation: (011101)2 - (110011)2 using 2's complement.
  7. 7.
    Perform the operation: (89344)10 - (98654)10 using 9's complement.
  8. 8.
    Simplify f(P,Q,R,S) = Σ(3,4,7,8,14) and d(P,Q,R,S) = Σ(1,6,9,13) using K-map and design a circuit using the minimum number of NAND gates.
  9. 9.
    What is the drawback of an RS Flipflop? Explain D Flip Flop in detail with Logic Diagram, characteristics table, and Characteristics equation.
  10. 10.
    Design a full subtractor with necessary tables and logic diagram.
  11. 11.
    What is a shift register? Explain 4-bit SISO and PIPO with timing diagrams.
  12. 12.
    Design an asynchronous Mod 11 up counter using T flip flop.