GATE 2011 ECE Video Solution on Digital Circuits (Digital Electronics)

1. When the output Y in the circuit below is ‘1’, it implies that data has

a. Changed from ‘0’ to ‘1’
b. Changed from ‘1’ to ‘0’
c. Changed in either direction
d. Not changed

Answer: A

Solution : https://www.youtube.com/watch?v=amudsVzHy88


2. The logic function implemented by the circuit below is (ground implies a logic ‘0’)



a. F = AND (P,Q)
b. F = OR (P,Q)
c. F = XNOR (P,Q)
d. F = XOR (P,Q)

Answer:D

Solution : https://www.youtube.com/watch?v=Ko2CWnaQrb0


3. The output Y in the circuit below is always ‘1’, when

a. Two or more of the inputs P,Q, R are ‘0’
b. Two or more of the inputs P,Q, R are ‘1’
c. Any odd number of the inputs P,Q,R is ‘0’
d. Any odd number of the inputs P,Q,R is ‘1’

Answer:B

Solution : https://www.youtube.com/watch?v=vzqfBLVmISE


4. An 8085 assembly language program is given below. Assume that the carry flag is initially unset. The contents of the accumulator after the execution of the program is
MVI A, 07H
RLC
MOV B, A
RLC
RLC
ADD B
RRC

a. 8CH
b. 64H
c. 23H
d. 15H

Answer:C

Solution : https://www.youtube.com/watch?v=GlPuCxCnvws


5. The output of a 3 stage Johnson (twisted ring) counter is fed to a digital to analog (D/A) converter as shown in the figure below. Assume all states of the counter to be unset initially. The waveform which represents the D/A converter output V_o is

Answer:A

Solution : https://www.youtube.com/watch?v=g9vVeVizDIM


6. Two D flip-flops are connected as a synchronous counter that goes through the following Q_B Q_A sequence 00 -> 11 -> 01 -> 10 -> 00-> ………. The connections of the inputs D_A and D_B are

Answer:D

Solution : https://www.youtube.com/watch?v=_9k8tNpWn7w