Encoder and Decoder Questions and Answers for Viva

Answer-1: An encoder is a digital circuit that converts one or more input signals into a coded output representation. It is used to compress information or data from multiple input lines into a smaller set of output lines, typically in binary form.

Answer-2: An encoder has multiple input lines and a smaller number of output lines. When one or more input lines are activated (usually in binary form), the encoder produces a unique binary code on its output lines corresponding to the active input. The output code represents the position or value of the activated input.

Answer-3: A decoder is a digital circuit that performs the reverse operation of an encoder. It takes coded input and produces multiple output lines, with one output line activated based on the input code. Decoders are used to expand a coded input into a set of output signals.

Answer-4: A binary decoder typically has 'n' input lines and '2^n' output lines. When a binary code is applied to the input lines, the decoder activates one of the output lines, corresponding to the binary value of the input code. All other output lines remain inactive.

Answer-5: Encoders and decoders are used in various digital systems, including:
Memory address decoding in microprocessors.
Data compression and error detection/correction.
Remote control systems (e.g., in television and radio).
Multiplexing and demultiplexing in communication systems.
Keypad scanning in input devices.
Security systems and access control.

Answer-6: In some decoder circuits, there is an additional enable input (EN) that controls the operation of the decoder. When the enable input is activated (typically HIGH), the decoder functions as usual. When it is deactivated (typically LOW), the decoder outputs remain inactive regardless of the input code. This feature is useful for enabling or disabling the decoder as needed in a digital system.