# Code Converter and Multiplexers in Digital Logic Design MCQs

Q1. 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.

Q2. A basic multiplexer principle can be demonstrated through the use of a:.

A. single-pole relay.

B. DPDT switch.

C. rotary switch.

D. linear stepper.

Q3. How many inputs will a decimal-to-BCD encoder have?.

A. 4.

B. 8.

C. 10.

D. 16.

Q4. 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.

Q5. 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.

Answer= a LOW on all gate enable inputs

Q6. 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.

Answer= several SSI logic gates or combinational logic circuits

Q7. How many exclusive-NOR gates would be required for an 8-bit comparator circuit?.

A. 4.

B. 6.

C. 8.

D. 10.

Q8. How many inputs are required for a 1-of-10 BCD decoder?.

A. 4.

B. 8.

C. 10.

D. 1.

Q9. A BCD decoder will have how many rows in its truth table?.

A. 10.

B. 9.

C. 8.

D. 3.

Q10. How many possible outputs would a decoder have with a 6-bit binary input?.

A. 16.

B. 32.

C. 64.

D. 128.

Q11. Most demultiplexers facilitate which type of conversion?.

B. single input, multiple outputs.

C. ac to dc.

D. odd parity to even parity.

Q12. The inputs/outputs of an analog multiplexer/demultiplexer are:.

A. bidirectional.

B. unidirectional.

C. even parity.

D. binary-coded decimal.

Q13. One application of a digital multiplexer is to facilitate:.

A. data generation.

B. serial-to-parallel conversion.

C. parity checking.

D. data selector.

Q14. 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.

Answer= coded representation of a shaft's mechanical position

Q15. 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. None of the mentioned.

Answer= The input will be distributed to one of the outputs.

Q16. 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.

D. UART.

Q17. 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.

Q18. 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.

Q19. 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.

Q20. Which of the following is not a weighted value positional numbering system:.

B. binary-coded decimal.

C. binary.

D. octal.

Q21. How many inputs are required for a 1-of-16 decoder?.

A. 2.

B. 4.

C. 8.

D. 16.

Q22. A truth table with output columns numbered 0 - 15 may be for which type of decoder IC?.

B. dual octal outputs.

Q23. 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..

Answer= to convert the 4-bit BCD into 7-bit code

Q24. 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..

Q25. 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.

Q26. A circuit that responds to a specific set of signals to produce a related digital signal output is called a(n):.

A. BCD matrix.

B. display driver.

C. encoder.

D. decoder.

Q27. 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.

Q28. How many select lines would be required for an 8-line-to-1-line multiplexer?.

A. 2.

B. 3.

C. 4.

D. 8.

Q29. How many address bits are needed to select all memory locations in the 2118 16K x 1 RAM?.

A. 8.

B. 10.

C. 14.

D. 16.