Digital circuits is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them.
Digital Circuits MCQs: This section contains multiple-choice questions and answers on the various topics of Digital Circuits. Practice these MCQs to test and enhance your skills on Digital Circuits.
List of Digital Circuits MCQs
1. What is the base of the decimal number system?
- 2
- 8
- 10
- 16
Answer: C) 10
Explanation:
The base of the decimal number system is 10.
2. What is the range of the decimal number system?
- 1-10
- 0-10
- 0-9
Answer: C) 0-9
Explanation:
The range of the decimal number system is 10.
3. Integer part is the part that lies to the ____ of the decimal point in the Decimal number system.
- Right
- Left
Answer: B) Left
Explanation:
The integer part is the part that lies to the left of the decimal point in the Decimal number system.
4. The ____ component is the part of the number to the right of the decimal point.
- Fractional
- Integer
Answer: A) Fractional
Explanation:
The Fractional component is the part of the number to the right of the decimal point.
5. What of the following is the correct representation of a decimal number system?
- 192.146 = (1 × 102) + (9 × 101) + (2 × 100) + (1 × 10-1) + (4 × 10-2) + (6 × 10-3)
- 192.146 = (1 × 103) + (9 × 102) + (2 × 101) + (1 × 10-1) + (4 × 10-2) + (6 × 10-3)
- 192.146 = (1 × 101) + (9 × 102) + (2 × 103) + (1 × 10-1) + (4 × 10-2) + (6 × 10-3)
- None
Answer: A) 192.146 = (1 × 102) + (9 × 101) + (2 × 100) + (1 × 10-1) + (4 × 10-2) + (6 × 10-3)
Explanation:
192.146 = (1 × 102) + (9 × 101) + (2 × 100) + (1 × 10-1) + (4 × 10-2) + (6 × 10-3) is the correct answer.
6. What is the base number of the binary number system?
- 2
- 4
- 6
- 8
Answer: A) 2
Explanation:
The base of the binary number system is 2.
7. What is the range of numbers used in a binary number system?
- 0-2
- 0-1
- 1-2
- None
Answer: B) 0-1
Explanation:
O and 1 numbers are used in the binary number system.
8. What is the base of the Octal number system?
- 2
- 4
- 8
- 16
- 10
Answer: C) 8
Explanation:
The base of the Octal number system is 8.
9. What range of numbers are used in the octal number system?
- 0-8
- 1-9
- 0-9
- 0-7
Answer: D) 0-7
Explanation:
From 0 to 7 numbers are used in the octal number system.
10. What is the base of the hexadecimal number system?
- 10
- 16
- 20
- 18
Answer: B) 16
Explanation:
The base of the hexadecimal number system is = 6.
11. What is the range of the hexadecimal number system?
- 0 to 10 and A to F
- 0 to 9 and A to F
- 1-10 and A to E
- 0-9 and A to E
Answer: B) 0 to 9 and A to F
Explanation:
The range of the hexadecimal number system is: 0 to 9 and A to F.
12. All unsigned numbers are ____.
- Positive
- Negative
Answer: A) Positive
Explanation:
All unsigned numbers are positive.
13. What is the full form of MSB?
- Main significant bit
- Minimum significant bit
- Most significant bit
Answer: C) Most significant bit
Explanation:
MSB stands for the most significant bit.
14. MSB of signed binary numbers is also known as ____.
- Most bit
- Min bit
- Signed bit
- Sign bit
Answer: D) Sign bit
Explanation:
MSB of signed binary numbers is also known as the sign bit.
15. How many types of representation are there for signed binary numbers?
- 5
- 4
- 3
- 2
Answer: C) 3
Explanation:
There are three types of representations for signed binary numbers:
- Sign-Magnitude form
- 1’s complement form
- 2’s complement form
16. 1’s complement of positive number gives a ____ number.
- Positive number
- Negative number
- Both
Answer: B) Negative number
Explanation:
1’s complement of a positive number gives a negative number.
17. 1’s complement of negative number gives a ____ number.
- Positive
- Negative
- Original signed binary number
Answer: A) Positive
Explanation:
1’s complement of a negative number gives a positive number.
18. If you do two times the one’s complement of a binary number including the sign bit, what result you would get?
- Positive
- Negative
- Original signed binary number
Answer: C) Original signed binary number
Explanation:
If you do two times the one’s complement of a binary number including the sign bit, you will get the original signed binary number.
19. The 2’s complement of positive number gives a ____ number?
- Negative number
- Positive number
Answer: A) Negative number
Explanation:
The 2’s complement of a positive number gives a negative number.
20. What will be the 1’s complement of 50 in binary number?
- 110010
- 001101
- 110110
Answer: C) 110110
Explanation:
First step is to convert the decimal 50 into binary which is equal to 110010, now to find the 1’s complement just replace 0 with 1 therefore the final answer is = 001101.
21. What will be the 1’s complement of 30 in binary number?
- 11110
- 00000
- 11111
- 00001
Answer: D) 00001
Explanation:
First step is to convert decimal 30 to binary i.e., 11110, now just change the value of 0 to 1 and 1 to 0 therefore the final answer is = 00001.
22. Binary codes are classified into how many types?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
Binary codes are classified into 2 types:
- Weighted codes
- Unweighted codes
23. Weighted codes are classified into how many types?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
Weighted codes are classified into 2 types: positively weighted codes and negatively weighted codes.
24. What is the full form of BCD?
- Base decimal code
- Binary dialogue code
- Binary coded decimal
- Base-coded decimal
Answer: C) Binary coded decimal
Explanation:
BCD stands for binary coded decimal.
25. How many types of parity codes are there?
- 5
- 4
- 2
- 1
Answer: C) 2
Explanation:
There are two types of parity codes: Even parity code and odd parity code.
26. The value of an even parity bit should be ____ if an even number of ones is present in the binary code.
- 0
- 1
Answer: A) 0
Explanation:
If the binary code has an even number of ones, the value of the even parity bit should be zero.
27. Even parity bit is used only for ____.
- Error detection
- Error correction
Answer: A) Error detection
Explanation:
Even parity bit is used only for Error detection.
28. The value of the odd parity bit should be ____ if an odd number of ones is present in the binary code.
- 0
- 1
Answer: A) 0
Explanation:
If there are an odd number of ones in the binary code, the value of the odd parity bit should be zero.
29. Hamming code is used for ____.
- Error detection
- Error correction
- None
- Both
Answer: D) Both
Explanation:
Hamming code is used for Error detection and Error correction.
30. Which of the following theorem is used to find the complement of the Boolean function?
- Duality theorem
- DeMorgan’s theorem
Answer: B) DeMorgan’s theorem
Explanation:
DeMorgan’s theorem is used to find the complement of a Boolean function.
31. What do you mean by Canonical SoP?
- Canonical sum of products
- Canonical solution of problems
- Canonical solution of products
Answer: A) Canonical sum of products
Explanation:
Canonical SoP stands for Canonical sum of products.
32. Canonical SoP form is also known as ____.
- Sum of Max terms
- Sum of Min terms
Answer: B) Sum of Min terms
Explanation:
Canonical SoP form is also known as the Sum of min terms form.
33. Canonical PoS form is also known as ____.
- Product of Max terms
- Sum of Max terms
- Product of Min terms
- Sum of Min terms
Answer: A) Product of Max terms
Explanation:
Canonical PoS is also known as Product of Max terms.
34. What is the number of cells in 3 variable K-map?
- 5
- 2
- 6
- 8
Answer: D) 8
Explanation:
There are 8 cells in 3 variable K-map.
35. What is the number of cells in 2 variable K-map?
- 4
- 2
- 6
- 8
Answer: A) 4
Explanation:
There are 4 cells in 2 variable K-map.
36. What is the number of cells in 4 variable K-map?
- 32
- 16
- 20
- 14
Answer: B) 16
Explanation:
There are 16 cells in 4 variable K-map.
37. What is the number of cells in 5 variable K-map?
- 40
- 24
- 32
- 20
- 14
Answer: C) 32
Explanation:
There are 32 cells in 5 variable K-map.
38. Ex-OR and Ex-NOR gate comes under which category of the gate?
- Basic gate
- Special gate
- Universal gate
Answer: B) Special gate
Explanation:
Ex-OR and Ex-NOR gate comes under the category of special gate.
39. Which of the following is the universal gate?
- NAND
- NOR
- Both
- None
Answer: C) Both
Explanation:
NAND and NOR both come under the category of universal gate.
40. ____ form is used when the output of a two-level logic realization cannot be achieved using a single logic gate.
- Non-degenerative
- Degenerative
Answer: A) Non-degenerative
Explanation:
Non-degenerative form is used when the output of a two-level logic realization cannot be achieved using a single logic gate.
41. Octal to binary encoder has how many inputs?
- 2
- 8
- 16
- 1
Answer: B) 8
Explanation:
Octal to binary encoder has 8 inputs.
42. A 4*1 mux has how many inputs?
- 5
- 4
- 2
- 1
Answer: B) 4
Explanation:
4*1 mux has 4 data inputs, two selection lines, and one output.
43. What do you mean by PLDs?
- Programmable Logic devices
- Perfect Logic devices
- Prune Logic devices
- Personal Logic devices
Answer: A) Programmable Logic devices
Explanation:
PLDs are known as Programmable Logic devices. These are the integrated circuits.
44. How many types of PLDs are there based on the types of arrays?
- 5
- 4
- 3
- 2
Answer: C) 3
Explanation:
On the basis of type of array there are 3 kinds of PLDs:
- Programmable Read Only Memory
- Programmable Array Logic
- Programmable Logic Array
45. Which of the following statement is correct?
- PROMs are programmable logic devices with fixed AND and programmable OR arrays
- PROMs are programmable logic devices with fixed NAND and programmable OR arrays
- PROMs are programmable logic devices with fixed NOR and programmable OR arrays
Answer: A) PROMs are programmable logic devices with fixed AND and programmable OR arrays.
Explanation:
PROMs are programmable logic devices with fixed AND and programmable OR arrays.
46. Which of the following statement is TRUE about PAL (Programmable array logic)?
- PAL is a programmable logic device with a fixed NOR array and a programmable OR array
- PAL is a programmable logic device with a fixed AND array and a programmable NOR array
- PAL is a programmable logic device with a fixed OR array and a programmable AND array
Answer: C) PAL is a programmable logic device with a fixed OR array and a programmable AND array.
Explanation:
PAL is a programmable logic device with a fixed OR array and a programmable AND array.
47. PAL’s outputs will be in the form of a ____.
- Product of sum
- Sum of products
Answer: B) Sum of products
Explanation:
PAL’s outputs will be in the form of a sum of products.
48. The threshold gate has how many inputs and outputs?
- At least one output and only one input
- At least one input and only one output
- Any number of output and inputs
Answer: B) At least one input and only one output.
Explanation:
The threshold gate has at least one input and only one output.
49. How do you represent the threshold gate?
- Via circle
- Via Square
- Via Combinational circuit
- None
Answer: A) Via circle
Explanation:
A circle represents a threshold gate.
50. Which of the following statement is correct about the combinational and Sequential circuit?
- In sequential circuits Only the current inputs determine the outputs, and in combinational circuits, Outputs are determined by both the current inputs and the current state
- In combinational circuits, Only the current inputs determine the outputs and in sequential circuits, Outputs are determined by both the current inputs and the current state
Answer: B) In combinational circuits, Only the current inputs determine the outputs and in sequential circuits, Outputs are determined by both the current inputs and the current state.
Explanation:
In combinational circuits, Only the current inputs determine the outputs and in sequential circuits, Outputs are determined by both the current inputs and the current state.
51. Among combinational and sequential circuits in which of the following feedback is not present?
- Combinational Circuits
- Sequential Circuits
Answer: A) Combinational Circuits
Explanation:
In combinational circuits, feedback is not present.
52. How many types of sequential circuits are there?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
There are two types of sequential circuits:
- Asynchronous sequential circuits
- Synchronous Sequential circuits
53. If all of the outputs of a sequential circuit change in response to the active transition of the clock signal, the sequential circuit is said to be ____.
- Asynchronous
- Synchronous
Answer: B) Synchronous
Explanation:
If all of the outputs of a sequential circuit change in response to the active transition of the clock signal, the sequential circuit is said to be synchronous.
54. How many types of triggers are used in sequential circuits?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
Two types of triggers are used in sequential circuits:
- Level triggering
- Edge Triggering
55. How many types of level triggering are there?
- 2
- 3
- 4
- 5
Answer: A) 2
Explanation:
There are two types of level triggering:
- Positive level triggering
- Negative level triggering
56. ____ level triggering occurs when the sequential circuit is operated with the clock signal while it is in Logic High.
- Positive level triggering
- Negative level triggering
Answer: A) Positive level triggering
Explanation:
Positive level triggering occurs when the sequential circuit is operated with the clock signal while it is in Logic High.
57. How many types of edge triggering are there based on the transitions of the clock signal?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
There are two types of edge triggering based on the transitions of clock signal:
- Positive level triggering
- Negative level triggering
58. What is the full form of the SR latch?
- Set Reset Latch
- Set Remind Latch
- Save Reset Latch
Answer: A) Set Reset Latch
Explanation:
SR latch stands for Set reset latch.
59. Which of the following is the drawback of the SR latch?
- When both S and R are zero, the next state value cannot be predicted
- When both S and R are one, the next state value cannot be predicted
- When both S and R are one, the next state value can be predicted
Answer: B) When both S and R are one, the next state value cannot be predicted.
Explanation:
SR latch has a drawback i.e., When both S and R are one, the next state value cannot be predicted.
60. What is the full form of a D latch?
- Datagram latch
- Dataset latch
- Database latch
- Data latch
Answer: D) Data latch
Explanation:
Full form of the D latch is the Data latch.
61. Which of the following is the simplest version of the JK flipflop?
- T flip-flop
- SR flip-flop
- D flip-flop
Answer: A) T flip-flop
Explanation:
T flip-flop is the simplest version of JK flip-flop.
62. The ____ is a collection of flip-flops that are used to store binary data.
- Log
- Database
- Ledger
- Register
Answer: D) Register
Explanation:
The register is a collection of flip-flops that are used to store binary data.
63. The register is known as a ____- register if it is capable of moving bits either to the right or to the left.
- Flag
- Shift
- Accumulator
- Stack
Answer: B) Shift
Explanation:
The register is known as a shift register if it is capable of moving bits either to the right or to the left.
64. An ‘N’ bit shift register contains ____ flip-flops.
- N-1
- N+1
- N
- N2
Answer: C) N
Explanation:
An ‘N’ bit shift register contains ‘N’ flip-flops.
65. ____ shift register is a shift register that accepts serial input and outputs serial output.
- SISO
- SIPO
- PISO
- PIPO
Answer: A) SISO
Explanation:
Serial In – Serial Out SISO shift register is a shift register that accepts serial input and outputs serial output.
66. Shift registers are used as ____.
- Parallel to serial converter
- Serial to parallel converter
- Sequence generator
- Counters
- All of the above
Answer: E) All of the above
Explanation:
Shift registers are used as:
- Parallel to serial converter
- Serial to parallel converter
- Sequence generator
- Counters
67. When a counter counts from 0 to 2N -1, it is referred to as a ____ counter.
- Binary down counter
- Binary up counter
Answer: B) Binary up counter
Explanation:
When a counter counts from 0 to 2N- 1, it is referred to as a binary up counter.
68. How many types of counters are there based on the flip-flops?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
There are two types of counters based on the flip flops:
- Asynchronous counter
- Synchronous counter
69. If the flip-flops do not receive the same clock signal, the counter is referred to as ____.
- Asynchronous
- Synchronous
Answer: A) Asynchronous
Explanation:
If the flip-flops do not receive the same clock signal, the counter is referred to as asynchronous.
70. The synchronous sequential circuits is also known as ____.
- Finite state machine
- Regular expression
- Grammar
Answer: A) Finite state machine
Explanation:
Synchronous sequential circuits is also known as Finite state machine.
71. How many types of Finite state machines are there?
- 5
- 4
- 3
- 2
Answer: D) 2
Explanation:
There are two types of FSM:
- Mealy state machine
- Moore state machine
72. A ____ machine is a finite state machine in which the current state and current input symbol determine the future state.
- Moore
- Mealy
Answer: A) Moore
Explanation:
A Moore machine is a finite-state machine in which the current state and current input symbol determine the future state.
73. What is the Mealy machine?
- A Mealy machine is a machine in which the output symbol depends upon the present input symbol and the present state of the machine
- A Mealy machine is a machine in which the output symbol depends upon the present input symbol and the next state of the machine
- A Mealy machine is a machine in which the output symbol depends upon the next input symbol and the next state of the machine
- A Mealy machine is a machine in which the output symbol depends upon the next input symbol and the present state of the machine
Answer: A) A Mealy machine is a machine in which the output symbol depends upon the present input symbol and the present state of the machine.
Explanation:
A Mealy machine is a machine in which the output symbol depends upon the present input symbol and the present state of the machine.
74. What do you mean by ASM charts?
- Algorithmic state machine
- Altar state machine
- Algo state machine
Answer: A) Algorithmic state machine
Explanation:
ASM stands for Algorithmic state machine.
75. In ASM charts state box is represented in which shape?
- Oval
- Cube
- Triangle
- Rectangular
Answer: D) Rectangular
Explanation:
In ASM charts state box is represented in a rectangular shape.
76. In ASM charts decision box is represented in which shape?
- Oval
- Cube
- Triangle
- Diamond
Answer: D) Diamond
Explanation:
In ASM charts decision box is represented in a diamond shape.
77. In ASM charts conditional output box is represented in which shape?
- Oval
- Cube
- Triangle
- Square
Answer: A) Oval
Explanation:
In ASM charts conditional output box is represented in an oval shape.