# Mumbai University Previous year question papers

## III Sem Electronics Examination June 2006

## Digital System Design-I

N. B. : (1) Question NO.1 is compulsory. .

(2) Solve any four out of remaining six questions.

1. (a) Find Hexadecimal Equivalent of

1) (2338.122)10

2) (326)7

3) (761.514)8

(b) Rerform the following operations

1) (F88)16 + (D89)16

2) (762)BCD+ (348)BCD

3) (246)10

(435)10using 2’s complement method.

(c) What are self complementing codes? Explain with 2 examples.

(d Perform the following operations

1) , (1101.11)2 X (101.1001)2.

2) (10000111)2 + (1101)2

2. (a) Simplify u sing Boo–lean Theo–rems and implement using AOI gates only

1) ABC + ABC + ABC + ABC.

2). [(C + CD) (C + CD)] [(AB + AS) + (A EBB.)]

(b) Given logic expression.

=AS + AC + C + ABC +.ABC.

1) Express in Standard SOP form and simplify using boolean theorems.

2) Draw K map and simplify

3) Draw a logic diagram using NANDgates only.

3. (a) Implement BCD Adder using 7483, 4 bit binary adder IC. Explain its operation.

(b) What is SR Flip Flop? Explain its operation. Write truth table, characteristic equation and excitation table for the same.

4. (a) There are four adjacent parking slots in a company. Each slot is equipped with a special sensor whose output is asserted low when a car is occupying a slot, otherwise the sensor’s output is high. Design and draw a schematic for a system, which will generate a low output if §nd only if there are two or more than two adjacent slots vacant.

(b) Explain the working of IC 7485, 4 bit comparator and hence implement a 5 bit comparator using the same IC.

5. (a) Using Quine McClusky method of minimization solve,

F=*L *m

(8,9,10,11,13,15,16,18,21,24,25,26,27,30,31)

(b) Write a VHDL program for decoder like 74LS138 (3:8 decoder) 8

6. (a) Explain what is tristate gate. Draw the symbol, truth table and circuit diagram of the same.

(b) Draw a neat circuit diagram of 2 in’puts TTL NANDgate and explain its operation. ‘Draw transfer Characteristics and give specifications of the same.

7.

(a) What is a multiplexer? Implement,

F=1t M(0,1,4,5,7) using 4:1 multiplexer.

(b) Write short notes on (any **two) :-**

1) Master slave JK flip flo’p

2) Static hazards

3) 74180 Parity generator and Checker.