Fundamental of digital electronics
Question paper:
Unit -I:-
(a) What is number system ? Which number system is the best suitable for computer ? Why ?Explain. 5
(b) Do as directed :
(i) (21F3)16 = (?)2
(ii) (146.10)10 = (?)8
5
OR
(c) Explain how positive and negative numbers are represented in binary with suitable example. 5
(d) What is parity ? What are its types ? How it is useful for detection of error in data ? 5
(a) What is binary code ? Explain ASCII, EBCDIC
and UNICODE. 5
(b) What is gray code ? Explain it with suitable
example :
(i) 11001
(ii) 111011. 5
OR
(c) Explain various methods to represent negative numbers
in binary number system with suitable example.
5
(d) Do as directed :
(i) (277)8 = ( )2
(ii) (A23)16 = ( )10 .
(a) What is data ? Explain signed magnitude and unsigned magnitude number with suitable example.
5
(b) What is excess-3 code ? What are its advantages ? Perform the following addition using excess-3 code : 39 + 45. 5
OR
(c) Do as directed :
(i) (1F38)16 = (?)2
(ii) (734)8 = (?)10 . 5
(d) What is 1’s compliment and 2’s compliment of a number ? Explain with example.
Perform the following subtraction using 2’s compliment method :
(101011)2 – (1110)2. 5
(a) Explain double dabble method of converting decimal number into its binary equivalent.
5
(b) What are binary codes ? Explain gray code with suitable example. 5
OR
(c) Do as directed :
(i) (1101)10 = ( )2
(ii) (234)7= ( )10 . 5
(d) Explain 2’s complement method of number representation. 5
Unit-II:-
(a) What are the different basic gates ? Explain each of them with their truth table and symbols.
5
(b) Explain how NOR gate can be used to construct different gates. 5
OR
(c) What is K-map ? Simplify the following equation using K-map :
f(A, B, C, D) = ∑m (0, 1, 4, 6, 9, 12, 13, 15) 5
(d) State and prove DeMorgon's theorem. 5
(a) Construct various gates using NOR gate. 5
(b) Minimise the following expression using K-MAP and
draw reduce circuit diagram using logic gates :
Y = Sm(0, 1, 2, 4, 6, 7, 9, 10, 14). 5
OR
(c) State the various Boolean laws and prove the
associative laws and commutative laws. 5
(d) Simplify the given equation using K-map and draw
its logic diagram :
y = (A B+ AC+ BC + A B C). 5
(a) Why is NAND gate called Universal gate ? Explain in detail. 5
(b) What is Ex-OR gate ? Explain the construction and working Ex-OR gates with basic gates.
Give the symbol of Ex-OR gate also. 5
OR
(c) State and prove the following laws :
(i) Associative law
(ii) Commutative law. 5
(d) What is k-map ? Simplify the following expression using k-map :
Y = A BC + A BC + A BC + A BC
Draw the logic circuit for simplified expression. 5
(a) Construct AND, OR and NOR gates using only NANO gates. 5
(b) State and prove De-Morgan’s theorem. 5
OR
(c) What is a k-map ? How does it help in reducing the equations in SOP form ? 5
(d) Explain Quine McClusky method. 5
Unit-III:-
(a) Explain the construction and working of 4 bit parallel adder with example. 5
(b) What is decoder ? Explain the construction and working of 3:8 decoder using gates. 5
OR
(c) What is D-flip-flop ? Explain the construction and working of D-ff using logic gates. Why it is
called D-latch ? 5
(d) Explain the construction and working of 3 bit down counter with timing diagram. 5
(a) Draw a full adder circuit and explain its working.
5
(b) Explain the working of 8 : 1 multiplexer circuit with basic gates. 5
OR
(c) Draw the logic diagram of clocked JK Flip-Flop and explain its working. 5
(d) Draw the circuit diagram of 4-bit binary ripple counter and explain its working. 5
(a) What is multiplexer ? Design a 8 : 1 MUX using two 4 : 1 MUX. Give its truth table also.
5
(b) What is half adder ? Explain the construction and working of half adder using logic gates. How
many half adders are required to add 4 bits simultaneously. 5
OR
(c) What is D-flip-flop ? Explain its construction and working with NAND gates. Why is it called
D-latch ? Explain. 5
(d) Explain the construction and working of 4 bit SISO type shift register with its timing diagram.
5
(a) What is a multiplexer ? Explain the working of 4 : 1 multiplexer with circuit diagram.
5
(b) Explain the working of a 3-bit asynchronous counter. 5
OR
(c) What is full adder ? Explain the working of a full adder circuit with neat diagram. 5
(d) Explain the working of JKMSFF with circuit diagram. 5
Unit-IV:-
(a) Give the detail classification of memory with one example of each. 5
(b) What is Cache memory ? Explain. 5
OR
(c) Explain the working of dot matrix printer in detail. 5
(d) What is optical disk ? Explain how data is recorded on it. What are its advantages ? 5
(a) Give the classification of semiconductor memory.
Explain, how data can be stored in static RAM and
dynamic RAM ? 5
(b) Explain the operations of cache memory. 5
OR
(c) Compare semiconductor and magnetic memories.
Describe hard disk in detail. 5
(d) Explain the method of expanding memory size with
suitable example. 5
(a) Differentiate between sequential access and random access memory. 5
(b) What are input and output devices ? Explain any one input device in brief. 5
OR
(c) Write a short note on hard disc. 5
(d) What is cache memory ? Explain. What are its advantages ? 5
(a) Explain ROM and EPROM. 5
(b) Explain the organization of a hard disk. 5
OR
(c) Write a note on any two I/O devices. 5
(d) What is cache memory ? Explain. 5
All 2(1/2) marks question
(a) Write a short note on ASC II code. 2½
(b) Draw the logic diagram of Ex-NOR gates using basics gates and give its truth-table. 2½
(c) Differentiate between synchronous and asynchronous counter. 2½
(d) What is primary and secondary memory ? Explain. 2½
(a) What is hamming code ? Explain with example.
Give one application of it. 2½
(b) State and prove DeMorgans Theorem. 2½
(c) What are JK Flip-Flop and S-R Flip-Flop ? Givea dvantages of JK Flip-Flop over S-R Flip-Flop.2½
(d) What is semiconductor memory ? Why is it used as
primary memory ? Explain. 2½
(a) What is parity code ? What are its types ? Explain with suitable example. 2½
(b) State and prove De-Morgan’s theorem. 2½
(c) Differentiate between synchronous and asynchronous counter. 2½
(d) What is PROM and EPROM ? Explain. 2½
(a) What is an ASCII code ? Explain. 2½
(b) Why NOR gates is called as universal building blocks ? Explain. 2½
(c) What is a demultiplexer ? Explain. 2½
(d) What is RAM ? Explain. 2½
