Question

A priority encoder is only concerned with the value of the MSB in the input lines. Design a priority encoder with 4 input lines and 3 output. One of the output lines corresponds to if there is a 1 in one of the input lines, and if there is the other two lines correspond to the position of the line.

Answer 1

The question involves designing a 4-input priority encoder with 3 outputs, where the outputs indicate if a '1' is present among the inputs, and if so, encode the position of the most significant '1' input.

Step-by-step explanation:

The question is about designing a priority encoder with 4 input lines that produces 3 output lines, which will indicate if at least one of the inputs is a '1', and the position of the highest-priority '1' input. In this context, priority refers to the relative significance of the MSB (most significant bit). The encoder checks the inputs in the order of their priority, starting with the MSB, and generates outputs to represent the position of the first '1' it finds.

An example design for such an encoder could be as follows: Given inputs A (MSB), B, C, and D (LSB), the outputs will be X, Y, and Z. X is active if any input is '1', Y and Z together represent the binary encoding of the position of the highest-priority '1'. If A is '1', Y and Z will be '1' '0', for B they will be '0' '1', for C '1' '1', and for D '0' '0'.

If all inputs are '0', then the outputs should be '0' '0' '0'. The output line X serves as an indication that an input has been detected, and Y and Z encode its position. A truth table can be constructed to clearly specify the output for each input combination for the design of the encoder.