END TERM EXAMINATION
Paper Code: BCA-106
SECOND SEMESTER [BCA]
MAY — JUNE 2015
Subject: Digital Electronics
(Batch 2011 onwards)
Note: Attempt any five questions including Q.No 1 which is compulsory.
Select one question from each unit.
(a) State and Prove the Demorgan’s theorems. (4)
(b) Design a full adder using the NAND gates only. (4)
(c) What is a multiplexer? Design a 32 to 1 multiplexer using the 8 to 1 multiplexers. (4)
(d) What is a D ﬂip ﬂop? Show how SR ﬂip ﬂop can be converted to D flip ﬂop.(4)
(e) What is a ripple counter? Explain the difference between the performance of asynchronous and synchronous counters. (4)
(f) Explain the working of bi directional shift register with logic diagram. (5)
Question 2:(a) What is Gray code? Why it is important? List features of BCD and Excess3 codes. (6)
(b) What are Universal gate? Obtain EX-OR operation with universal gates. (3.5)
(c) Convert the following octal numbers to hexadecimal numbers: (3)
(a) Simplify the expression Y = Σm(7,9,10,11,12,13,14,15) using the k-map method.
(b) Realize Y = A + BCD using NAND gates only.
Question 4:(a) Design a 4 bit parallel adder circuit. Give the truth table and explain the operation. (6.5)
(b) What is binary multiplier? Discuss the multiplier using shift method. (6)
(a) Explain the working of BCD to seven segment decoder with diagram. (6)
(b) What is an encoder? Discuss the design of octal to binary encoder. (6.5)
Discuss and explain the working of master slave JK Flip ﬂop. What are its advantages? ( 12.5)
What is shift register? Give its classification and explain the working of each type diagram. (12.5)
What is modulo counter? Design a MOD-6 counter by giving all design steps. (12.5)
Explain the following: (a) RAM (b) PLA (12.5)