Mohan Lal Sukhadia University (MLSU) 2001 COMPUTER SCIENCE - First (Digital Electronics) - Question Paper

First Year exam of the 3 Year
Degree Course, 2001
(Faculty of Science)
COMPUTER SCIENCE
First Paper
(Digital Electronics)
Time - 3 Hours
Maximum Marks - 50
Attempt 5 ques. in all,
choosing 1 ques. from every unit.

UNIT I
1. (a) Convert the the decimal number 45:3125 into binary number. 3
(b) Convert the octal number 5276.128 into binary number. 3
(c) Subtract 1100002 from 100112 using either I's complement or 2's
complement. 4

2. (a) What is a BCD Code? Expresss 1472 into BCD code. 3
(b) obtain largest +ve and -ve numbers with eight bits. 2
(c) Write 1 important difference ranging from ASCII and EBCDIC Codes. 2
(d) Express decimal number -24 in eight bitt`s complement form.
3

UNIT II
3. (a) State and prove De Morgan's theorems for 2 inputs.
(b) Simplify the Boolean expression to its simplest from:
[AB+BD)+ AB)
(c) A circuit has 3 inputs A, B and C. Show its truth table it its output Z is :
Z = ( A+B) ( A+C)
Draw its logic diagram.

4. (a) Use a Karnaugh map to decrease the subsequent expression to a minimum of
products from :-
X= ABC+ABC+ABC+ABC+ABC.
(a) Draw the logic circuit represented by the expression :
AB (C + D).

UNIT III
5. (a) discuss the working of a NAND gate RS Flip - Flop. provide its truth table and times
diagrams.
(b) Discss the working of a pulsed Master-Slave JK Flip-Flop circuit.

6. (a) With the help of a neat circuit, discuss the working of a bi-directional shift register.
(b) define the difference ranging from the serial and parallel methods of entering data
into a register.

UNIT IV
7. (a) What re asynchronous and synchronous counters? discuss them giving
examples.
(b) explain the working, circuit and timing diagrams of a 3-bit asynchronous binary
counter.

8. (a) What is the basic diadvantage of an asynchronous counter?
(b) Disccu the working, circuit and timeing diagrams of EITHER a decade
synchronous counter OR that of a decade asynchronous counter.

UNIT V

9. explain the application of XOR gates in:
(i) Half adder
(ii) Comparator
(iii) Parity checker and generator.

10. Write notes on any 2 of the subsequent :-
(a) Multiplexer ciruits.
(b) Encoder cirucits
(c) Decodercircuits.

Earning:   Approval pending.