Digital Logic 2067
Long Answer Questions:
Attempt any TWO questions. (2x10=20)
1. What is the magnitude comparator? Design a logic circuit for 4 bit magnitude comparator and explain it.
2. What do you mean by full adder and full subtractor? Design a 3 to 8 line decoder using two 2 to 4 line decoder and explain it.
3. What is JK master slave flip-flop? Design its logic circuit, truth table and explain the working principle.
Short Answer Questions:
Attempt any EIGHT questions. (8x5=40)
4. Convert the following hexadecimal number to decimal and octal numbers
(a) 0FFF (b) 3FFF
5. Design a half adder logic circuit using NOR gates only.
6. Proof the 1st and 2nd law of De Morgan’s theorems with logic gate and truth table.
De-Morgans Theorem
De Morgan’s theorem is used to convert OR type of expression into AND type and vice-versa.It is further divided into two different types;
1st law:
It state that the total complement of sum is equal to the product of individual complement. i.e. (A+B)’=A’ ٠B’
Proof:
Input | Output | ||
A | B | (A+B)’ | A’ ٠B’ |
0 | 0 | 1 | 1 |
0 | 1 | 0 | 0 |
1 | 0 | 0 | 0 |
1 | 1 | 0 | |
2nd law:
It state that the total complement of the product is equal to the sum of individual complement. i.e. (A٠B)’ =A’+B’
Proof:
Input | Output | ||
A | B | (A٠B)’ | A’+B’ |
0 | 0 | 1 | 1 |
0 | 1 | 1 | 1 |
1 | 0 | 1 | 1 |
1 | 1 | 0 | 0 |
7. What do you mean by Universal gate? Realize the following logic gates using NOR gates.
(a) OR gate (b) AND gate
An universal gate is a gate which can implement any Boolean function without need to use any other gate type. The NAND and NOR gates are universal gates.
NOR gate as a Universal Gate
To prove that any Boolean function can be implemented using only NOR gates, we will show that the AND, OR, and NOT operations can be performed using only these
Thus, the NOR gate is a universal gate since it can implement the AND, OR and NOT functions.
8. Draw a logic circuit of 4 x 1 multiplexer.
9. What is flip-flop? Mention the application of flip-flop.
10. Explain the Ripple Counter.
11. Design the decimal adder.
12. What do you mean by shift registers? Explain.
13. Write short notes on (any two):
a. Decoder b. Integrated circuit c. PLA.