Pokhara University
Bachelor of Engineering in Computer Engineering
Semester 1 · PU Spring
Course Title: Digital Logic
Full Marks: 100Pass Marks: 45
Candidates are required to give their answers in their own words as far as practicable.
- 1.15
- a) Define Analog and Digital system. Why digital systems are prefer over analog system.
- b) Perform the Conversion as indicated
- i) (101011) gray = Q2 ii, (561.34)s = (02 iii, (123)10 = Ose
- iv) Find 10’s Complements of (88)10
- 2.15
- a) Why NAND and NOR gate are called Universal Gates? Explain Briefly.
- b) What do you mean by Minterm and Maxterm? Simplify the following expression using Boolean algebra.
- i) (AB’+ABC)'+A(B+AB’)
- ii) ((BC’+A’D) (AB’+CD")”
- 3.60
- a) Discuss the Role of K-Map in Logic Circuit. Minimize the expression mentioned below using K-Map. A Boolean function is given by F(A,B,C,D) = > (3,4,5,7,9,13,14,15) and don’t care condition d(A,B,C,D) = > (0,2,8), and Implement it using NOR gate only. \ b) Design a combinational circuit that transforms decimal digits from 2421 code to BCD. 4, a) Design a comparator circuit that compared two 3 bit numbers. The two numbers being X and Y. It is required to obtain three possible outcomes. i.e. X>Y, X<Y and X= Y.
- b) Implement the following with appropriate MUX:
- i) F(A,B,C)= ¥ (1,3,5,6)
- ii) F(A,B,C,D)= ¥(0,1,3,4,8,9,15) 5. a) Explain operation of SR Flip-flop with its logic diagram, truth table, excitation table, Why JK flip-flop is preferred then SR flipflops?
- b) What is shift register? Explain the operating mechanism of serialin serial out shift register with its circuit diagram. 6. a) Differentiate between synchronous and asynchronous counter. Design a 3-bit synchronous binary down counter using JK Flip Flop.
- b) Design an Arithmetic Logic Unit (ALU) that performs eight Arithmetic Operations and four different logical operations. 7. Write short notes on: (Any two) 2x5
- a) Tristate Logic : b) Parity generator and checker
- c) Nibble Adder a puvensenotes oa
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