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Code Converters and Multiplexers MCQ Questions & Answers

Code Converters and Multiplexers MCQs : This section focuses on the "Code Converters and Multiplexers". These Multiple Choice Questions (MCQs) should be practiced to improve the Code Converters and Multiplexers skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

A BCD decoder will have how many rows in its truth table?

A. 10
B. 9
C. 8
D. 3

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Question 2

A binary code that progresses such that only one bit changes between two successive codes is:

A. nine's-complement code
B. 8421 code
C. excess-3 code
D. Gray code

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Question 3

A microcontroller differs from a microprocessor in that it has several ________ ports and ________ built into its architecture, making it better suited for ________ applications.

A. communication, PROMs, control
B. parallel, logic gates, processing
C. input/output, memory, control
D. data, memory, decoding

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Question 4

A principle regarding most IC decoders is that when the correct input is present, the related output will switch:

A. active-HIGH
B. to a high impedance
C. to an open
D. active-LOW

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Question 5

A truth table with output columns numbered 0–15 may be for which type of decoder IC?

A. hexadecimal 1-of-16
B. dual octal outputs
C. binary-to-hexadecimal
D. hexadecimal-to-binary

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Question 6

For the following conditions on a 7485 magnitude comparator, what will be the state of each of the three outputs? A0 = 0B0 = 1IA < B = 0 A1 = 1B1 = 0IA = B = 1 A2 = 1B2 = 0IA > B = 0 A3 = 0B3 = 0 

A. A = B = 0, A < B = 0, A > B = 1
B. A = B = 0, A < B = 1, A > B = 0
C. A = B = 1, A < B = 0, A > B = 0
D. A = B = 0, A < B = 0, A > B = 0

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Question 7

From the following list of input conditions, determine the state of the five output leads on a 74148 octal-to-binary encoder. I0 = 1 I3 = 1 I6 = 1 I1 = 1 I4 = 0 I7 = 1 I2 = 1 I5 = 1 EI = 0

A. GS = L, A0 = L, A1 = L, A2 = H, EO = H
B. GS = L, A0 = H, A1 = L, A2 = L, EO = H
C. GS = L, A0 = L, A1 = H, A2 = L, EO = H
D. GS = L, A0 = H, A1 = H, A2 = L, EO = H

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Question 8

How can the active condition (HIGH or LOW) or the decoder output be determined from the logic symbol?

A. A bubble indicates active-HIGH.
B. A bubble indicates active-LOW.
C. A square indicates active-HIGH.
D. A square indicates active-LOW.

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Question 9

How is an encoder different from a decoder?

A. The output of an encoder is a binary code for 1-of-N input.
B. The output of a decoder is a binary code for 1-of-N input.

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Question 10

How many 74184 BCD-to-binary converters would be required to convert two complete BCD digits to a binary number?

A. 8
B. 4
C. 2
D. 1

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Question 11

How many exclusive-NOR gates would be required for an 8-bit comparator circuit?

A. 4
B. 6
C. 8
D. 10

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Question 12

How many inputs are required for a 1-of-16 decoder?

A. 2
B. 4
C. 8
D. 16

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Question 13

How many inputs will a decimal-to-BCD encoder have?

A. 4
B. 8
C. 10
D. 16

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Question 14

How many outputs are on a BCD decoder?

A. 4
B. 16
C. 8
D. 10

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Question 15

How many possible outputs would a decoder have with a 6-bit binary input?

A. 16
B. 32
C. 64
D. 128

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Question 16

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

A. 2
B. 3
C. 4
D. 8

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Question 17

If two inputs are active on a priority encoder, which will be coded on the output?

A. the higher value
B. the lower value
C. neither of the inputs
D. both of the inputs

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Question 18

In a BCD-to-seven-segment converter, why must a code converter be utilized?

A. to convert the 4-bit BCD into 7-bit code
B. to convert the 4-bit BCD into 10-bit code
C. to convert the 4-bit BCD into Gray code
D. No conversion is necessary.

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Question 19

In a Gray code, each number is 3 greater than the binary representation of that number.


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Question 20

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

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Question 21

One application of a digital multiplexer is to facilitate:

A. data generation
B. serial-to-parallel conversion
C. parity checking
D. data selector

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Question 22

One multiplexer can take the place of:

A. several SSI logic gates
B. combinational logic circuits
C. several Ex-NOR gates
D. several SSI logic gates or combinational logic circuits

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Question 23

One way to convert BCD to binary using the hardware approach is:

A. with MSI IC circuits
B. with a keyboard encoder
C. with an ALU

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Question 24

The expansion inputs to a comparator are used for expansion to a(n):

A. 4-bit system
B. 8-bit system
C. BCD system
D. counter system

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Question 25

The inputs/outputs of an analog multiplexer/demultiplexer are:

A. bidirectional
B. unidirectional
C. even parity
D. binary-coded decimal

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Question 26

The primary use for Gray code is:

A. coded representation of a shaft's mechanical position
B. turning on/off software switches
C. to represent the correct ASCII code to indicate the angular position of a shaft on rotating machinery
D. to convert the angular position of a shaft on rotating machinery into hexadecimal code

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Question 27

Use the weighting factors to convert the following BCD numbers to binary. 0101 0011        0010 0110 1000

A. 01010011    001001101000
B. 11010100    100001100000
C. 110101        100001100
D. 101011        001100001

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Question 28

What control signals may be necessary to operate a 1-line-to-16 line decoder?

A. flasher circuit control signal
B. a LOW on all gate enable inputs
C. input from a hexadecimal counter
D. a HIGH on all gate enable circuits

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Question 29

What do the mathematical symbols A < b and A > B mean?

A. A < B means A is greater than B. A > B means A is less than B.
B. A > B means A is less than B. A < B means A is greater than B.
C. A < B means A is less than B. A > B means A is greater than B.

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Question 30

What is the function of an enable input on a multiplexer chip?

A. to apply Vcc
B. to connect ground
C. to active the entire chip
D. to active one half of the chip

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Question 31

What is the status of the inputs S0, S1, and S2 of the 74151 eight-line multiplexer in order for the output Y to be a copy of input I5?

A. S0 = 0, S1 = 1, S2 = 0
B. S0 = 0, S1 = 0, S2 = 1
C. S0 = 1, S1 = 1, S2 = 0
D. S0 = 1, S1 = 0, S2 = 1

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Question 32

When two or more inputs are active simultaneously, the process is called:

A. first-in, first-out processing
B. priority encoding
C. ripple blanking
D. first-in, first-out processing or priority encoding

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Question 33

Which digital system translates coded characters into a more useful form?

A. encoder
B. display
C. counter
D. decoder

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Question 34

Which of the following is not a weighted value positional numbering system:

A. hexadecimal
B. binary-coded decimal
C. binary
D. octal

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Question 35

Why can a CMOS IC be used as both a multiplexer and a demultiplexer?

A. It cannot be used as both.
B. CMOS uses bidirectional switches.

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Question 36

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.

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Question 37

Why is the Gray code more practical to use when coding the position of a rotating shaft?

A. All digits change between counts.
B. Two digits change between counts.
C. Only one digit changes between counts.

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