300+ REAL TIME Digital Circuits Objective Questions & Answers 2023

250+ TOP MCQs on Demultiplexers (Data Distributors) – 1 and Answers

Digital Electronics/Circuits Multiple Choice Questions on “Demultiplexers (Data Distributors) – 1”.

1. The word demultiplex means ___________
A. One into many
B. Many into one
C. Distributor
D. One into many as well as Distributor
Answer: D
Clarification: The word demultiplex means “one into many” and distributor. A demultiplexer sends a single input to multiple outputs, depending on the select lines. It is clear from the diagram:

2. Why is a demultiplexer called a data distributor?
A. The input will be distributed to one of the outputs
B. One of the inputs will be selected for the output
C. The output will be distributed to one of the inputs
D. Single input to Single Output
Answer: A
Clarification: A demultiplexer sends a single input to multiple outputs, depending on the select lines. For one input, the demultiplexer gives several outputs. That is why it is called a data distributor.

3. Most demultiplexers facilitate which type of conversion?
A. Decimal-to-hexadecimal
B. Single input, multiple outputs
C. AC to DC
D. Odd parity to even parity
Answer: B
Clarification: A demultiplexer sends a single input to multiple outputs, depending on the select lines. Demultiplexer converts single input into multiple outputs.

4. In 1-to-4 demultiplexer, how many select lines are required?
A. 2
B. 3
C. 4
D. 5
Answer: A
Clarification: The formula for total no. of outputs is given by 2ⁿ, where n is the no. of select lines. Therefore, for 1:4 demultiplexer, 2 select lines are required.

5. In a multiplexer the output depends on its ___________
A. Data inputs
B. Select inputs
C. Select outputs
D. Enable pin
Answer: B
Clarification: A demultiplexer sends a single input to multiple outputs, depending on the select lines. As the select input changes, the output of the multiplexer varies according to that input.

6. In 1-to-4 multiplexer, if C1 = 0 & C2 = 1, then the output will be ___________
A. Y0
B. Y1
C. Y2
D. Y3
Answer: B
Clarification: It can be calculated from the figure shown below:

For C0 =1 and C1 =0, Y1 will be the output as 0 and 1 are the bit combinations of 1.

7. In 1-to-4 multiplexer, if C1 = 1 & C2 = 1, then the output will be ___________
A. Y0
B. Y1
C. Y2
D. Y3
Answer: D
Clarification: It can be calculated from the figure shown below:

For C0 =1 and C1 =0, Y3 will be the output as 0 and 1 are the bit combinations of 1.

8. How many select lines are required for a 1-to-8 demultiplexer?
A. 2
B. 3
C. 4
D. 5
Answer: B
Clarification: The formula for total no. of outputs is given by 2ⁿ, where n is the no. of select lines. In this case n = 3 since 2³ = 8.

9. How many AND gates are required for a 1-to-8 multiplexer?
A. 2
B. 6
C. 8
D. 5
Answer: C
Clarification: The number of AND gates required will be equal to the number of outputs in a demultiplexer, which are 8.

10. The output Q4 of this 1-to-8 demultiplexer is ____________

A. Q2.(Q1)’.Q0.I
B. Q2.Q1.(Q0)’.I
C. Q2.(Q1)’.(Q0)’.I
D. Q2.(Q1).Q0.I
Answer: C
Clarification: The output Y4 = Q2.(Q1)’.(Q0)’.I. since the bit combinations of 4 are 100.

11. Which IC is used for the implementation of 1-to-16 DEMUX?
A. IC 74154
B. IC 74155
C. IC 74139
D. IC 74138
Answer: A
Clarification: IC 74154 is used for the implementation of 1-to-16 DEMUX, whose output is inverted input.

250+ TOP MCQs on Counters and Answers

Digital Electronics/Circuits Multiple Choice Questions on “Counters”.

1. In digital logic, a counter is a device which ____________
A. Counts the number of outputs
B. Stores the number of times a particular event or process has occurred
C. Stores the number of times a clock pulse rises and falls
D. Counts the number of inputs
Answer: B
Clarification: In digital logic and computing, a counter is a device which stores (and sometimes displays) the number of times a particular event or process has occurred, often in relationship to a clock signal.

2. A counter circuit is usually constructed of ____________
A. A number of latches connected in cascade form
B. A number of NAND gates connected in cascade form
C. A number of flip-flops connected in cascade
D. A number of NOR gates connected in cascade form
Answer: C
Clarification: A counter circuit is usually constructed of a number of flip-flops connected in cascade. Preferably, JK Flip-flops are used to construct counters and registers.

3. What is the maximum possible range of bit-count specifically in n-bit binary counter consisting of ‘n’ number of flip-flops?
A. 0 to 2ⁿ
B. 0 to 2ⁿ + 1
C. 0 to 2ⁿ – 1
D. 0 to 2^n+1/2
Answer: C
Clarification: The maximum possible range of bit-count specifically in n-bit binary counter consisting of ‘n’ number of flip-flops is 0 to 2ⁿ-1. For say, there is a 2-bit counter, then it will count till 2²-1 = 3. Thus, it will count from 0 to 3.

4. How many types of the counter are there?
A. 2
B. 3
C. 4
D. 5
Answer: B
Clarification: Counters are of 3 types, namely, (i)asynchronous/synchronous, (ii)single and multi-mode & (iii)modulus counter. These further can be subdivided into Ring Counter, Johnson Counter, Cascade Counter, Up/Down Counter and such like.

5. A decimal counter has ______ states.
A. 5
B. 10
C. 15
D. 20
Answer: B
Clarification: Decimal counter is also known as 10 stage counter. So, it has 10 states. It is also known as Decade Counter counting from 0 to 9.

6. Ripple counters are also called ____________
A. SSI counters
B. Asynchronous counters
C. Synchronous counters
D. VLSI counters
Answer: B
Clarification: Ripple counters are also called asynchronous counter. In Asynchronous counters, only the first flip-flop is connected to an external clock while the rest of the flip-flops have their preceding flip-flop output as clock to them.

7. Synchronous counter is a type of ____________
A. SSI counters
B. LSI counters
C. MSI counters
D. VLSI counters
Answer: C
Clarification: Synchronous Counter is a Medium Scale Integrated (MSI). In Synchronous Counters, the clock pulse is supplied to all the flip-flops simultaneously.

8. Three decade counter would have ____________
A. 2 BCD counters
B. 3 BCD counters
C. 4 BCD counters
D. 5 BCD counters
Answer: B
Clarification: Three decade counter has 30 states and a BCD counter has 10 states. So, it would require 3 BCD counters. Thus, a three decade counter will count from 0 to 29.

9. BCD counter is also known as ____________
A. Parallel counter
B. Decade counter
C. Synchronous counter
D. VLSI counter
Answer: B
Clarification: BCD counter is also known as decade counter because both have the same number of stages and both count from 0 to 9.

10. The parallel outputs of a counter circuit represent the _____________
A. Parallel data word
B. Clock frequency
C. Counter modulus
D. Clock count
Answer: D
Clarification: The parallel outputs of a counter circuit represent the clock count. A counter counts the number of times an event takes place in accordance to the clock pulse.

250+ TOP MCQs on Introduction of Memory Devices – 5 and Answers

Digital Electronic Circuits Questions & Answers for campus interviews on “Introduction of Memory Devices-5”.

1. When two or more devices try to write data in a bus simultaneously, is known as ______________
A. Bus collisions
B. Address multiplexing
C. Address decoding
D. Bus contention
Answer: D
Clarification: Bus contention is an undesirable state of the bus of a computer, in which more than one memory mapped device or the CPU is attempting to place output values onto the bus at once.

2. A memory is a collection of ____________
A. Unit cells
B. Storage cells
C. Data cells
D. Binary cells
Answer: B
Clarification: A memory is a collection of storage cells with associated circuits needed to transfer information.

3. To transfer the information from input to output and vice versa, the cells used are ____________
A. Storage cells
B. Data cells
C. Unit cells
D. Both data and unit cells
Answer: A
Clarification: To transfer the information from input to output and vice versa, the cells used are called storage cells. The storage cells stores data in the form of binary information.

4. The data stored in a group of bits is called ____________
A. Nibble
B. Word
C. Byte
D. Address
Answer: B
Clarification: The data stored in a group of bits is called word. Usually, a word is a group of 16-bits or 2-bytes.

5. Each word consist of a sequence of ____________
A. Letters
B. Binary numbers
C. Hexadecimal numbers
D. Gray codes
Answer: B
Clarification: Each word consists of a sequence of 0s and 1s (i.e. binary numbers). Usually, a word is a group of 16-bits or 2-bytes.

6. Each word stored in a memory location is represented by ____________
A. RAM
B. ROM
C. Storage class
D. Address
Answer: D
Clarification: Each word stored in a memory location is represented by address. Usually, a word is a group of 16-bits or 2-bytes.

7. The group of each 8-bit is called ____________
A. Nibble
B. Flag
C. Byte
D. Word
Answer: C
Clarification: 1 byte = 8-bit, 4-bits = 1 nibble and 16-bits = 1 word.

8. The capacity of a memory unit is ____________
A. The number of binary input stored
B. The number of words stored
C. The number of bytes stored
D. All of the Mentioned
Answer: C
Clarification: The total number of bytes that can be stored, is the maximum capacity of a memory unit. However, memory unit is the smallest unit of a processor.

9. The communication between memory and its environment is achieved through ____________
A. Control lines
B. Data input/output lines
C. Address selection lines
D. All of the Mentioned
Answer: D
Clarification: Firstly, the data input is needed to transfer the information and it is passed through the address lines and then controlled by control lines. The control lines are responsible for the timing and control of the signals sent and received.

10. One of the most important specifications on magnetic media is the ____________
A. Polarity reversal rate
B. Tracks per inch
C. Data transfer rate
D. Rotation speed
Answer: C
Clarification: The rate of data transfer depends on the properties of magnetic media.

for campus interviews,