# Digital Circuits Questions and Answers – Parity Generators/Checkers – 1

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Parity Generators/Checkers – 1”.

1. How many outputs are present in a BCD decoder?
a) 4
b) 5
c) 15
d) 10

Explanation: A binary decoder is a combinational logic circuit which decodes binary information from n-inputs to a maximum of 2n outputs. A BCD to Decimal decoder has 10 number of outputs because the decimal digit’s range is from 0 to 9.

2. Which digital system translates coded characters into a more useful form?
a) Encoder
b) Display
c) Counter
d) Decoder

Explanation: A binary decoder is a combinational logic circuit which decodes binary information from n-inputs to a maximum of 2n outputs. Decoder converts the coded characters into our required data form.

3. 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

Explanation: A LOW on all gate enable inputs is necessary to operate a 1-line-to-16 line decoder because enable pins are usually, active-low pins.

4. How many inputs are required for a 1-of-10 BCD decoder?
a) 4
b) 8
c) 10
d) 2

Explanation: A binary decoder is a combinational logic circuit which decodes binary information from n-inputs to a maximum of 2n outputs. Therefore, for a BCD to decimal decoder, No. of inputs = 4 such that number of outputs is <= 2n.

5. A BCD decoder will have how many rows in its truth table?
a) 10
b) 9
c) 8
d) 3

Explanation: A binary decoder is a combinational logic circuit which decodes binary information from n-inputs to a maximum of 2n outputs. Thus, BCD decoder will have 10 rows as it’s input ranges from 0 to 9.
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6. How many possible outputs would a decoder have with a 6-bit binary input?
a) 32
b) 64
c) 128
d) 16

Explanation: The possible outputs would be: 2n = 64 (Since n = 6 here).

7. Which is the way to convert BCD to binary using the hardware approach?
a) By using MSI IC circuits
b) By using a keyboard encoder
c) By using an ALU
d) By using UART

Explanation: One way to convert BCD to binary using the hardware approach is MSI (medium scale integration) IC circuits.

8. How many inputs are required for a 1-of-16 decoder?
a) 2
b) 16
c) 8
d) 4

Explanation: A binary decoder is a combinational logic circuit which decodes binary information from n-inputs to a maximum of 2n outputs. Here, number of outputs = 16.
16 = 24 = 2n. Thus, number of inputs is 4.

9. A truth table with output columns numbered 0–15 may be for which type of decoder IC?
b) Dual octal outputs

Explanation: A binary decoder is a combinational logic circuit that decodes binary information from n-inputs to a maximum of 2n outputs. A truth table with output columns numbered 0–15 may be for Hexadecimal 1-of-16. Because hexadecimal occupies less space in a system.

10. 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 triangle indicates active-HIGH
d) A triangle indicates active-LOW

Explanation: A bubble indicates active-LOW in a decoder always. Enable pin of the decoder is usually active-LOW and is triggered on the input being at 0.

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