# MSI Logic Circuits MCQ Questions & Answers

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

Question 1

Why are control inputs included in an HDL magnitude comparator?

A. For cascading the chips
B. For control signal input
C. For signal control
D. For internal interconnections

Question 2

The circuit in Figure 9-8 is defective; data is not appearing on the output lines. A check with the scope shows data pulses on the serial data line and multiplex control lines, S0–S2; no parity error is indicated. A further check with a logic probe indicates that Vcc and ground appear to be present. What might be wrong with the circuit?

A. The demultiplexer may be bad.
B. The parity checker is defective.
C. The parity generator may be bad.
D. The parity checker is defective, or the parity generator may be bad.

Question 3

What are the outputs of a 7485 four-bit magnitude comparator when the inputs are A = 1001 and B = 1010?

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

Question 4

What is the purpose of a decoder's inputs?

A. To allow the decoder to respond to the inputs to activate the correct output gate.
B. To disable the decoder outputs so that all outputs will be inactive.
C. To disable the inputs and activate all outputs.
D. To allow the decoder to respond to the inputs to activate the correct output gate, and to disable the inputs and activate all outputs.

Question 5

Which statement below best describes the function of a decoder?

A. A decoder will convert a decimal number into the proper binary equivalent.
B. A decoder will convert a binary number into a specific output representing a particular character or digit.
C. Decoders are used to prevent improper operation of digital systems.
D. Decoders are special ICs that are used to make it possible for one brand of computer to talk to another.

Question 6

Multiplexing of digital signals is usually required when:

A. moving data internally within a microprocessor.
B. moving data between memory and storage registers in a microprocessor.
C. moving data over long distance transmission lines.
D. moving data internally within a microprocessor or between memory and storage registers.

Question 7

What VHDL techniques are used to describe a priority encoder?

A. Integer outputs and priority coding
B. Signal outputs and priority coding
C. Tristate outputs and priority coding
D. Variables and priority coding

Question 8

The IEEE/ANSI symbol for a decoder has the internal designation bcd/dec. This means the decoder is a:

A. decimal-to-BCD decoder with ten inputs and four outputs.
B. BCD-to-decimal decoder with ten inputs and four outputs.
C. decimal-to-BCD decoder with four inputs and ten outputs.
D. BCD-to-decimal decoder with four inputs and ten outputs.

Question 9

What is an important attribute of the conditional signal assignment statement?

A. Its tristate outputs
B. Its sequential evaluation
C. Its use of library components
D. Its fast activation times

Question 10

Which is the decimal number for the BCD number, 10110110?

A. 182
B. 36
C. 116
D. 10110110 is not a valid BCD number.

Question 11

How is the number one (1) indicated on the outputs of a 7447 BCD-to-seven-segment code converter?

A. Segment a is active.
B. Segment b is active.
C. Segments a and b are active.
D. Segments b and c are active.

Question 12

One can safely state that the output lines for a demultiplexer are under the direct control of the:

A. input data select lines.
B. the internal AND gates.
C. the internal OR gate.
D. Input data line.

Question 13

In an AHDL BCD to binary code converter, how is multiplication by 10 accomplished?

A. By using the shifting of bits
B. By using the library multiplication function
C. By using integer types
D. By using the multiplication operator

Question 14

What is the HDL key issue in the design of the MUX and DEMUX?

A. Having the MUX and DEMUX part of the library
B. Using the case statement in the process
C. Describing the functions
D. Assigning signals under certain conditions