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Digital Electronics/Circuits Multiple Choice Questions on “Encoders”.
1. How many inputs will a decimal-to-BCD encoder have?
A. 4
B. 8
C. 10
D. 16
Answer: C
Clarification: An encoder is a combinational circuit encoding the information of 2n input lines to n output lines, thus producing the binary equivalent of the input. Thus, a Decimal-to-bcd converter has decimal values as inputs which range from 0-9. So, a total of 10 inputs are there in a decimal-to-BCD encoder.
2. How many outputs will a decimal-to-BCD encoder have?
A. 4
B. 8
C. 12
D. 16
Answer: A
Clarification: An encoder is a combinational circuit encoding the information of 2n input lines to n output lines, thus producing the binary equivalent of the input. Thus, a decimal to BCD encoder has 4 outputs.
3. 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
C. The output of an encoder is a binary code for N-of-1 output
D. The output of a decoder is a binary code for N-of-1 output
Answer: A
Clarification: An encoder is a combinational circuit encoding the information of 2n input lines to n output lines, thus producing the binary equivalent of the input. It performs the opposite operation of a decoder which results in 2n outputs from n inputs. Thus, an encoder different from a decoder because of the output of an encoder is a binary code for 1-of-N input.
4. If we record any music in any recorder, such types of process is called ___________
A. Multiplexing
B. Encoding
C. Decoding
D. Demultiplexing
Answer: B
Clarification: If we record any music in any recorder, it means that we are giving data to a recorder. So, such process is called encoding. Getting back the music from the recorded data is known as decoding.
5. Can an encoder be a transducer?
A. Yes
B. No
C. May or may not be
D. Both are not even related slightly
Answer: A
Clarification: Of course, a transducer is a device that has the capability to emit data as well as to accept. Transducer converts signal from one form of energy to another.
6. How many OR gates are required for a Decimal-to-bcd encoder?
A. 2
B. 10
C. 3
D. 4
Answer: D
Clarification: An encoder is a combinational circuit encoding the information of 2^n input lines to n output lines, thus producing the binary equivalent of the input.
This is clear from the diagram that it requires 4 OR gates:.
7. How many OR gates are required for an octal-to-binary encoder?
A. 3
B. 2
C. 8
D. 10
Answer: A
Clarification: An encoder is a combinational circuit encoding the information of 2n input lines to n output lines, thus producing the binary equivalent of the input. Thus, in octal to binary encoder there are 8 (=23) inputs, thus 3 output lines.
8. For 8-bit input encoder how many combinations are possible?
A. 8
B. 2^8
C. 4
D. 2^4
Answer: B
Clarification: An encoder is a combinational circuit encoding the information of 2n input lines to n output lines, thus producing the binary equivalent of the input. There are 28 combinations are possible for an 8-bit input encoder but out of which only 8 are used using 3 output lines. It is a disadvantage of encoder.
9. The discrepancy of 0 output due to all inputs being 0 or D0, being 0 is resolved by using additional input known as ___________
A. Enable
B. Disable
C. Strobe
D. Clock
Answer: A
Clarification: Such problems are resolved by using enable input, which behaves as active if it gets 0 as input since it is an active-low pin.
10. Can an encoder be called a multiplexer?
A. No
B. Yes
C. Sometimes
D. Never
Answer: B
Clarification: A multiplexer or MUX is a combination circuit that contains more than one input line, one output line and more than one selection line. Whereas, an encoder is also considered a type of multiplexer but without a single output line and without any selection lines.
11. 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
Answer: A
Clarification: An encoder is a combinational circuit encoding the information of 2n input lines to n output lines, thus producing the binary equivalent of the input. If two inputs are active on a priority encoder, the input of higher value will be coded in the output.