Digital Logic 2021

Group B

Attempt any six questions.(6*5=30)

2. Subtract 11101.111-10100.101 using 1's and 2's complement.

3. Simplify given Boolean function in both SOP and POS using K-Map  where d represents don't care condition.

F(A,B,C,D)=

4. Define combinational circuit. Write a combinational circuit design procedure. Design a half adder with its truth table, logic diagram and Boolean expression.

5. Define Priority encoder. Design 4:2 priority encoder with its block diagram, truth table, circuit diagram and mathematical expression.

6. Why NAND and NOR gates are called universal gates? Realize NAND gate as universal gate.

7. What is race around condition? Explain how JK master flip flop is used to eliminate race around condition.

8. Differentiate between synchronous and ripple counter. Design mod 7 ripple counter with its state diagram, sequence table,logic diagram and timing diagram.

Group C

9. Define PLA with its block diagram.Realize BCD to gray code converter using PAL.

Attempt any two questions.

10. What is register? Explain types of registers depending on input output with its block diagram and logic diagram.

11. What is state diagram? A sequential circuit with two D flip-flops A and B, one input x and one output z by the following next state and output equations:

A(t+1)= A'+B, B(t+1)=B'x, z= A+B'

i)   Draw the logic diagram of the circuit

ii) Draw the state table

iii) Draw the state diagram of the circuit