Digital Circuit and Microprocessor MCQs

Question 1

The voltage levels of a negative logic system

Accepted Answer

may be negative or positive

Answer

must necessarily be negative

Answer

must necessarily be positive

Answer

must necessarily be OV and ?5V

Question 2

The output of a 2-input OR gate is zero only when its

Accepted Answer

both inputs are 0

Answer

either input is 1

Answer

both inputs are 1

Answer

either input is 0

Question 3

When an input electrical signal A = 10100 is applied to a NOT gate, its output signal is

Accepted Answer

1011

Answer

10101

Answer

10100

Answer

101

Question 4

The only function of a NOT gate is to

Accepted Answer

invert an input signal

Answer

stop a signal

Answer

recomplement a signal

Answer

act as a universal gate

Question 5

A NOR gate is ON only when all its inputs are

Accepted Answer

OFF

Answer

ON

Answer

positive

Answer

high

Question 6

For getting an output from an XNOR gate, its both inputs must be``

Accepted Answer

at the same logic level

Answer

high

Answer

low

Answer

at the opposite logic levels

Question 7

In a certain 2-input logic gate, when A = 0, B = 0, then C = 1 and when A = 0, B = 1, then again C = 1. It must be gate.

Accepted Answer

NAND

Answer

XOR

Answer

AND

Answer

NOR

Question 8

The logic symbol shown in Fig. 7.1 represents

Accepted Answer

Answer

single-output AND gate

Answer

NAND gate

Answer

NAND gate used as NOT gate

Question 9

A half-adder can be constructed from

Accepted Answer

one XOR and one OR gate with their inputs connected in parallel

Answer

two XNOR gates only

Answer

one XOR and one OR gate with their outputs connected in parallel

Answer

one XOR gate and one AND gate