Bsc Csit Nepal

2066

Digital Logic

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

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

  1. Design the 4-bit synchronous up/down counter with timing diagram, logic diagram and truth table.
  2. Design a full subtractor with truth table and logic gates.
  3. Design a decimal adder with logical diagram and truth table.

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

  1. Differentiate between Analog and Digital system.
  2. Convert the following octal numbers to hexadecimal.
    • a. 1760.46
    • b. 6055.263
  3. Which gates can be used as inverts in additional to the NOT gate and how?
  4. Draw a logic gates that implements the following
    • $ A = ( Y_1 \oplus Y_2) (Y_3 \odot Y_4) + ( Y_5 \oplus Y_6 \oplus Y_7 ) $
    • $ A = ( X_1 \odot X_2) + (X_3 \odot X_4) + ( X_4 \odot X_5) \oplus ( X_4\odot X_7 ) $
  5. State and prove De-Morgan’s theorem 1st and 2nd with logic gates and truth table.
  6. Reduce the following expressions using K-map $ \overline{A} + B(A+ \overline{B}+D) (\overline{B}+C) (B+C+D) $
  7. Differentiate between a MUX and a DEMUX.
  8. Explain the operation of Decoder.
  9. What are the various types of shift registers?
  10. What do you mean by Synchronous counter?