Bsc Csit Nepal

2069

Digital Logic

Full Marks: 60
Pass Marks: 24
Time: 3 hours

Attempt any two questions: (2 x 10 = 20)

  1. What is decoder? Implement the following using decoder.
    • (a) F (W X Y Z) = Σ (0,1,3,4,8,9,10)
    • (b) F (W X Y Z) = Σ (1,3,5,6,11,13,14)
  2. What do you mean by asynchronous counter? Design a mod-6 synchronous counter using T flip-flops.
  3. Explain the Master-slave S-R flip-flop with logic diagram, truth table and timing diagram.

Attempt any eight questions: (8 x 5 = 40)

  1. Design a half subtractor using only NOR gates.
  2. Convert the following decimal numbers into hexadecimal and octal number.
    • (a) 220
    • (b) 1020
  3. Design a multiplexer 4x1 using only universal gates.
  4. What is J-K flip flop? Explain.
  5. Write a procedure to reduce K-maps.
  6. What are the various types of shift registers?
  7. Draw a logic diagram of a 4 bit ripple counter using D-flip flop.
  8. Differentiate between combinational logic and sequential logic. List some applications of sequential logic.
  9. Explain the decimal adder.
  10. Write short notes on :
    • (a) Programmable Logic Array
    • (b) Triggering at flip-flop
    • (c) Memory Unit