# Digital Circuits Questions and Answers – Magnitude Comparator

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Magnitude Comparator”.

1. All the comparisons made by comparator is done using ____________
a) 1 circuit
b) 2 circuits
c) 3 circuits
d) 4 circuits

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. Because, all the input is compared to each other, therefore it is possible only by using 1 circuit.

2. One that is not the outcome of magnitude comparator is ____________
a) a > b
b) a – b
c) a < b
d) a = b

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. In a digital comparator, only 3 outputs are possible (i.e. A = B, A > B, A < B). So, a – b is an incorrect option.

3. If two numbers are not equal then binary variable will be ____________
a) 0
b) 1
c) A
d) B

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. In a digital comparator, only 3 outputs are possible (i.e. A = B, A >B, A < B). Other than this, the output will be 0.

4. How many inputs are required for a digital comparator?
a) 1
b) 2
c) 3
d) 4

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. Thus, there are two inputs required for a digital comparator (i.e. A & B).

5. In a comparator, if we get input as A>B then the output will be ____________
a) 1
b) 0
c) A
d) B

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. If A > B, it means that it satisfies one of the condition among three. Hence the output will be 1.

6. Which one is a basic comparator?
a) XOR
b) XNOR
c) AND
d) NAND

Explanation: Generally, an XNOR outputs high for even number of 1s or all 0s and outputs low for otherwise. Thus, an XNOR gate is a basic comparator, because its output is “1” only if its two input bits are equal.

7. Comparators are used in ____________
a) Memory
b) CPU
c) Motherboard
d) Hard drive

Explanation: Comparators are used in the central processing unit (CPUs). Because all the arithmetic and logical operations are performed in the ALU(Arithmetic Logic Unit) part of the CPU.

8. A circuit that compares two numbers and determines their magnitude is called ____________
a) Height comparator
b) Size comparator
c) Comparator
d) Magnitude comparator

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. A circuit that compares two numbers and determine their magnitude is called magnitude comparator.

9. A procedure that specifies finite set of steps is called ____________
a) Algorithm
b) Flow chart
c) Chart
d) Venn diagram

Explanation: A procedure that specifies finite set of steps is called algorithm, While a flowchart is a pictorial representation of the algorithm.

10. How many types of digital comparators are?
a) 1
b) 2
c) 3
d) 4

Explanation: There are two main types of Digital Comparator available and these are: Identity Comparator & Magnitude Comparator. Identity Comparator checks only the equality of the inputs and thus has one output terminal. While Magnitude Comparator checks for greater than, less than as well as equality of the inputs, and thus has 3 output terminals.

11. An identify comparator is defined as a digital comparator which has ____________
a) Only one output terminal
b) Two output terminals
c) Three output terminals
d) No output terminal

Explanation: An Identity Comparator is a digital comparator that has only one output terminal for when A = B either “HIGH” A = B = 1 or “LOW” A = B = 0.

12. A magnitude comparator is defined as a digital comparator which has ____________
a) Only one output terminal
b) Two output terminals
c) Three output terminals
d) No output terminal

Explanation: A Magnitude Comparator is a digital comparator which has three output terminals, one each for equality, A = B greater than, A > B and less than A < B.

13. The purpose of a Digital Comparator is ____________
b) To create different outputs
c) To add a set of different numbers
d) To compare a set of variables or unknown numbers

Explanation: A comparator is a combinational circuit that takes two numbers as input in binary form and results whether one input is greater, lesser or equal to the other input. The purpose of a Digital Comparator is to compare a set of variables or unknown numbers, for example A (A1, A2, A3, …. An, etc) against that of a constant or unknown value such as B (B1, B2, B3, …. Bn, etc) and produce an output condition or flag depending upon the result of the comparison.

14. TTL 74LS85 is a _____________
a) 1-bit digital comparator
b) 4-bit magnitude comparator
c) 8-bit magnitude comparator
d) 8-bit word comparator

Explanation: TTL 74LS85 is a 4-bit magnitude comparator.

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