This course introduces the basic tools for the design of digital circuits and introducing methods and procedures suitable for a variety of digital design applications.
Tribhuvan University
Institute of Science and Technology
2080
Bachelor Level / first-semester / Science
Computer Science and Information Technology( CSC116 )
Digital Logic
Full Marks: 60 + 20 + 20
Pass Marks: 24 + 8 + 8
Time: 3 Hours
Candidates are required to give their answers in their own words as far as practicable.
The figures in the margin indicate full marks.
Section A
Attempt any two questions.
What is combinational circuit? Design a combinational circuit with four inputs that represent a decimal digit in BCD and four output lines that generate the 1’s complement of the input binary patterns.
What is asynchronous counter? Design asynchronous counter that counts the sequence of 0-1-4-6-7 using T flip-flop.
Implement the Boolean function F(P,Q,R,S) = ∑ (3,4,6,8,9,14) using:
a. 8 to 1 multiplexer
b. PLA
c. Decoder
Section B
Attempt any eight questions.
Perform the following operations:
a. (011101)2 – (110011)2 using 2’s complement
b. (89344)10– – (98654)10 using 9’s complement.
If f(P,Q,R,S) = ∑(3,4,7,8,14) and d(P,Q,R,S) = ∑(1,6,9,13). Simplify using K-map and design the circuit using minimum number of NAND gates.
What is the drawback of RS Flipflop? Explain D Flip Flop in detail with a logic diagram, characteristics table, and characteristics equation.
Design a full subtractor with necessary tables and logic diagram.
What is shift register? Explain 4 bit SISO and PIPO with timing diagram.
Design an asynchronous mod 11 up counter using T flip flop.
How race condition in JK flipflop can be resolved? Explain.
What is decoder circuit? Design 3 to 8 decoder circuit.
Write short notes on: