420+ Digital Electronics Solved MCQs

These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering , Bachelor of Science in Computer Science FY (BSc CS) , Bachelor of Computer Applications (BCA) , Bachelor of Science in Computer Science (BSc CS) .

Take a Test

151.	Full subtractor is used to perform subtraction of
A.	2 bits
B.	3 bits
C.	4 bits
D.	8 bits
Answer» B. 3 bits

152.	The output of a full subtractor is same as
A.	half adder
B.	full adder
C.	half subtractor
D.	decoder
Answer» B. full adder

153.	The full subtractor can be implemented using
A.	two xor and an or gates
B.	two half subtractors and an or gate
C.	two multiplexers and an and gate
D.	two comparators and an and gate
Answer» B. two half subtractors and an or gate

154.	Why XOR gate is called an inverter?
A.	because of the same input
B.	because of the same output
C.	it behaves like a not gate
D.	it behaves like a and gate
Answer» C. it behaves like a not gate

155.	Controlled buffers can be useful
A.	to control the circuit’s output into the bus
B.	in comparison of component’s output with its input
C.	in increasing the output from its low input
D.	all of the mentioned
Answer» A. to control the circuit’s output into the bus

156.	A logic circuit that provides a HIGH output for both inputs HIGH or both inputs LOW is
A.	ex-nor gate
B.	or gate
C.	ex-or gate
D.	nand gate
Answer» A. ex-nor gate

157.	What is the first thing you will need if you are going to use a macro-function?
A.	a complicated design project
B.	an experienced design engineer
C.	good documentation
D.	experience in hdl
Answer» D. experience in hdl

158.	What is the major difference between half- adders and full-adders?
A.	full-adders are made up of two half-adders
B.	full adders can handle double-digit numbers
C.	full adders have a carry input capability
D.	half adders can handle only single-digit numbers
Answer» C. full adders have a carry input capability

159.	The binary subtraction of 0 – 0 = ?
A.	difference = 0, borrow = 0
B.	difference = 1, borrow = 0
C.	difference = 1, borrow = 1
D.	difference = 0, borrow = 1
Answer» A. difference = 0, borrow = 0

160.	How many basic binary subtraction operations are possible?
A.	1
B.	4
C.	3
D.	2
Answer» B. 4

161.	When performing subtraction by addition in the 2’s-complement system
A.	the minuend and the subtrahend are both changed to the 2’s-complement
B.	the minuend is changed to 2’s- complement and the subtrahend is left in its original form
C.	the minuend is left in its original form and the subtrahend is changed to its 2’s- complement
D.	the minuend and subtrahend are both left in their original form
Answer» C. the minuend is left in its original form and the subtrahend is changed to its 2’s- complement

164.	The selector inputs to an arithmetic/logic unit (ALU) determine the
A.	selection of the ic
B.	arithmetic or logic function
C.	data word selection
D.	clock frequency to be used
Answer» B. arithmetic or logic function

165.	The inverter can be produced with how many NAND gates?
A.	2
B.	1
C.	3
D.	4
Answer» B. 1

167.	How many shift registers are used in a 4 bit serial adder?
A.	4
B.	3
C.	2
D.	5
Answer» C. 2

171.	The decimal number system represents the decimal number in the form of
A.	hexadecimal
B.	binary coded
C.	octal
D.	decimal
Answer» B. binary coded

162.	What are the two types of basic adder circuits?
A.	sum and carry
B.	half-adder and full-adder
C.	asynchronous and synchronous
D.	one and two’s-complement
Answer» B. half-adder and full-adder

163.	Which of the following is correct for full adders?
A.	full adders have the capability of directly adding decimal numbers
B.	full adders are used to make half adders
C.	full adders are limited to two inputs since there are only two binary digits
D.	in a parallel full adder, the first stage may be a half adder
Answer» D. in a parallel full adder, the first stage may be a half adder

166.	What are carry generate combinations?
A.	if all the input are same then a carry is generated
B.	if all of the output are independent of the inputs
C.	if all of the input are dependent on the output
D.	if all of the output are dependent on the input
Answer» B. if all of the output are independent of the inputs

168.	A D flip-flop is used in a 4-bit serial adder, why?
A.	it is used to invert the input of the full adder
B.	it is used to store the output of the full adder
C.	it is used to store the carry output of the full adder
D.	it is used to store the sum output of the full adder
Answer» C. it is used to store the carry output of the full adder

169.	What is ripple carry adder?
A.	the carry output of the lower order stage is connected to the carry input of the next higher order stage
B.	the carry input of the lower order stage is connected to the carry output of the next higher order stage
C.	the carry output of the higher order stage is connected to the carry input of the next lower order stage
D.	the carry input of the higher order stage is connected to the carry output of the lower order stage
Answer» A. the carry output of the lower order stage is connected to the carry input of the next higher order stage

170.	If minuend = 0, subtrahend = 1 and borrow input = 1 in a full subtractor then the borrow output will be
A.	0
B.	1
C.	floating
D.	high impedance
Answer» B. 1

172.	29 input circuit will have total of
A.	32 entries
B.	128 entries
C.	256 entries
D.	512 entries
Answer» D. 512 entries

173.	BCD adder can be constructed with 3 IC packages each of
A.	2 bits
B.	3 bits
C.	4 bits
D.	5 bits
Answer» C. 4 bits

174.	The output sum of two decimal digits can be represented in
A.	gray code
B.	excess-3
C.	bcd
D.	hexadecimal
Answer» C. bcd

175.	The addition of two decimal digits in BCD can be done through
A.	bcd adder
B.	full adder
C.	ripple carry adder
D.	carry look ahead
Answer» A. bcd adder

420+ Digital Electronics Solved MCQs

Full subtractor is used to perform subtraction of

The output of a full subtractor is same as

The full subtractor can be implemented using

Why XOR gate is called an inverter?

Controlled buffers can be useful

A logic circuit that provides a HIGH output for both inputs HIGH or both inputs LOW is

What is the first thing you will need if you are going to use a macro-function?

What is the major difference between half- adders and full-adders?

The binary subtraction of 0 – 0 = ?

How many basic binary subtraction operations are possible?

When performing subtraction by addition in the 2’s-complement system

What are the two types of basic adder circuits?

Which of the following is correct for full adders?

The selector inputs to an arithmetic/logic unit (ALU) determine the

The inverter can be produced with how many NAND gates?

What are carry generate combinations?

How many shift registers are used in a 4 bit serial adder?

A D flip-flop is used in a 4-bit serial adder, why?

What is ripple carry adder?

If minuend = 0, subtrahend = 1 and borrow input = 1 in a full subtractor then the borrow output will be

The decimal number system represents the decimal number in the form of

29 input circuit will have total of

BCD adder can be constructed with 3 IC packages each of

The output sum of two decimal digits can be represented in

The addition of two decimal digits in BCD can be done through

3 bits full adder contains

The simplified expression of full adder carry is

Complement of F’ gives back

Decimal digit in BCD can be represented by

The number of logic gates and the way of their interconnections can be classified as

What is a multiplexer?

Which combinational circuit is renowned for selecting a single input from multiple inputs & directing the binary information to output line?

It is possible for an enable or strobe input to undergo an expansion of two or more MUX ICs to the digital multiplexer with the proficiency of large number of

Which is the major functioning responsibility of the multiplexing combinational circuit?

6 MULTIPLEXER

One multiplexer can take the place of

A digital multiplexer is a combinational circuit that selects

If the number of n selected input lines is equal to 2^m then it requires select lines.

How many select lines would be required for an 8-line-to-1-line multiplexer?

A basic multiplexer principle can be demonstrated through the use of a

How many NOT gates are required for the construction of a 4-to-1 multiplexer?

In the given 4-to-1 multiplexer, if c1 = 0 and c0 = 1 then the output M is

The enable input is also known as

The word demultiplex means

Why is a demultiplexer called a data distributor?

Most demultiplexers facilitate which type of conversion?

In 1-to-4 demultiplexer, how many select lines are required?

In a multiplexer the output depends on its

In 1-to-4 multiplexer, if C1 = 0 & C2 = 1, then the output will be

In 1-to-4 multiplexer, if C1 = 1 & C2 = 1, then the output will be

176.	3 bits full adder contains
A.	3 combinational inputs
B.	4 combinational inputs
C.	6 combinational inputs
D.	8 combinational inputs
Answer» D. 8 combinational inputs

177.	The simplified expression of full adder carry is
A.	c = xy+xz+yz
B.	c = xy+xz
C.	c = xy+yz
D.	c = x+y+z
Answer» A. c = xy+xz+yz

178.	Complement of F’ gives back
A.	f’
B.	f
C.	ff
D.	ff’
Answer» B. f

179.	Decimal digit in BCD can be represented by
A.	1 input line
B.	2 input lines
C.	3 input lines
D.	4 input lines
Answer» D. 4 input lines

180.	The number of logic gates and the way of their interconnections can be classified as
A.	logical network
B.	system network
C.	circuit network
D.	gate network
Answer» A. logical network

181.	What is a multiplexer?
A.	it is a type of decoder which decodes several inputs and gives one output
B.	a multiplexer is a device which converts many signals into one
C.	it takes one input and results into many output
D.	it is a type of encoder which decodes several inputs and gives one output
Answer» B. a multiplexer is a device which converts many signals into one

182.	Which combinational circuit is renowned for selecting a single input from multiple inputs & directing the binary information to output line?
A.	data selector
B.	data distributor
C.	both data selector and data distributor
D.	demultiplexer
Answer» A. data selector

183.	It is possible for an enable or strobe input to undergo an expansion of two or more MUX ICs to the digital multiplexer with the proficiency of large number of
A.	inputs
B.	outputs
C.	selection lines
D.	enable lines
Answer» A. inputs

184.	Which is the major functioning responsibility of the multiplexing combinational circuit?
A.	decoding the binary information
B.	generation of all minterms in an output function with or-gate
C.	generation of selected path between multiple sources and a single destination
D.	encoding of binary information
Answer» C. generation of selected path between multiple sources and a single destination

185.	6 MULTIPLEXER
A.	to apply vcc
B.	to connect ground
C.	to active the entire chip
D.	to active one half of the chip
Answer» C. to active the entire chip