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+17 votes

In the following truth table, $V = 1$ if and only if the input is valid.

\begin{array}{|c|c|c|c|} \hline
{D_0}&D_1&D_2&D_3 \\ \hline
0&0&0&0 \\ \hline
1&0&0&0 \\ \hline
\text{x}&1&0&0 \\ \hline
\text{x}&\text{x}&1&0 \\ \hline
\text{x}&\text{x}&\text{x}&1 \\ \hline
\begin{array}{|c|c|c|} \hline
X_0&X_1&V \\ \hline
\text{x}&\text{x}&0\\ \hline
0&0&1\\ \hline
0&1&1\\ \hline
1&0&1\\ \hline
1&1&1\\ \hline
\end{array} \\

What function does the truth table represent?

  1. Priority encoder    
  2. Decoder    
  3. Multiplexer    
  4. Demultiplexer
asked in Digital Logic by Veteran (399k points)
retagged by | 1.7k views

2 Answers

+22 votes
Best answer

Answer is A.

For $2^n \text{ inputs we are having } n \text{ outputs. Here n=2. }$

answered by Active (4.2k points)
selected by
what is significance of don't care here in priority encoder.

To Give priority to Di+1 over Di


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. It is a combinational logic function that has $2^{n}$ (or fewer) input lines and $n$ output lines.

+13 votes


answered by Boss (13.9k points)

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