## Digital Principles and System Design - Dec 2014

### First Year Engineering (Semester 2)

TOTAL MARKS:

TOTAL TIME: HOURS

**1** State the principle of duality.(2 marks)
**10** What is volatile memory? Give example.(2 marks)

### Answer any one question from Q11 (a) & Q11 (b)

**11 (a)** Simplify the function F(w,x,y,z)=∑m(2, 3, 12, 13, 14, 15) using tabulation method. Implement the simplified function using gates.(16 marks)
**11 (b) (i)** Simplify the Boolean function in Sum of Products (SOP) and Product of Sums (POS) F(A, B, C, D)=∑m(0,1,2,5,8,9,10).(10 marks)
**11 (b) (ii)** Plot the following Boolean function in Karnaugh map and simplify it. F(w, x, y, z)=∑m (0, 1, 2, 4, 5, 6, 8, 9, 12, 13, 14).(6 marks)

### Answer any one question from Q12 (a) & Q12 (b)

**12 (a)** Design and implement a 8421 to gray code converter. Realize the converter using only NAND gates.(16 marks)
**12 (b)** Design 2-bit Magnitude Comparator and write a Verilog HDL code.(16 marks)

### Answer any one question from Q13 (a) & Q13 (b)

**13 (a)** Design a MOD-10 Synchronous counter using JK flip-flops. Write execution table and state table.(16 marks)
**13 (b) (i)** How race condition can be avoided in a flip flop?(8 marks)
**13 (b) (ii)** Realize the sequential circuit for the state diagram shown below.

(8 marks)

### Answer any one question from Q14(a) & Q14 (b)

**14 (a)** An asynchronous sequential circuit is described by the following excitation and output function.

Y=X_{1}X_{2}+(X_{1}+X_{2})Y

Z=Y.

i) Draw the logic diagram of the circuit.

ii) Derive the transition table and output map.

iii) Describe the behaviour of the circuit.(16 marks)
**14 (b)** Design a synchronous counter using JK flip flop to count the following sequence 7, 4, 3, 1, 5, 0, 7, ....(16 marks)

### Answer any one question from Q15 (a) & Q15(b)

**15 (a)** Design a BCD to Excess-3 code converter and implement using suitable PLA.(16 marks)
**15 (b)** Discuss on the concept of working and applications of semiconductor memories.(16 marks)
**2** Implement AND gate using only NOR gates.(2 marks)
**3** Implement the following Boolean function using 8:1 multiplexer F(A,B,C)=∑m(1, 3, 5, 6).(2 marks)
**4** Define hazard.(2 marks)
**5** Distinguish Moore and Mealy circuit.(2 marks)
**6** With reference to a JK flip flop, what is racing?(2 marks)
**7** How many states are there in a 3-bit ring counter? What are they?(2 marks)
**8** What is a Priority Encoder?(2 marks)
**9** Whether PAL is same as PLA? Explain.(2 marks)