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+16 votes
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In the following truth table, $V = 1$ if and only if the input is valid.
 

Inputs Outputs
$D_0$ $D_1$ $D_2$ $D_3$ $X_0$ $X_1$ $V$
$0$ $0$ $0$ $0$ $x$ $x$ $0$
$1$ $0$ $0$ $0$ $0$ $0$ $1$
$x$ $1$ $0$ $0$ $0$ $1$ $1$
$x$ $x$ $1$ $0$ $1$ $0$ $1$
$x$ $x$ $x$ $1$ $1$ $1$ $1$


What function does the truth table represent?

  1. Priority encoder    
  2. Decoder    
  3. Multiplexer    
  4. Demultiplexer
asked in Digital Logic by Veteran (355k points)
retagged by | 1.3k views

3 Answers

+22 votes
Best answer

Answer is A.

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

http://en.wikipedia.org/wiki/Priority_encoder

answered by Active (4.2k points)
selected by
0
what is significance of don't care here in priority encoder.
0

To Give priority to Di+1 over Di

0

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.

http://www.differencebetween.info/difference-between-multiplexer-and-encoder

+9 votes

....

answered by Boss (12.7k points)
–6 votes
ans b)
answered by Active (5.2k points)
+2
Ans should b A


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