in Digital Logic edited by
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Consider the following multiplexer where $I0, I1, I2, I3$ are four data input lines selected by two address line combinations $A1A0=00,01,10,11$ respectively and $f$ is the output of the multiplexor. EN is the Enable input.

The function $f(x,y,z)$ implemented by the above circuit is 

  1. $xyz'$
  2. $xy + z$
  3. $x + y$
  4. None of the above
in Digital Logic edited by
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1 comment

It could be done via Table and K-map but that will be more time consuming.
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2 Answers

61 votes
 
Best answer
As $x$ is connected to $I0$  & $I1$, $y$ connected to $I2,$ $y'$ connected to $I3$ & $A1,$ $z$ connected to $A0$ and $z'$ connected to ENABLE $(EN),$

$f= ( {\overline{A1}}.{\overline{A0}}.I0+ {\overline{A1}}.A0.I1 +A1.{\overline{A0}}.I2 + A1.A0.I3 ).EN$

$\implies f = (xyz' +xyz + y'z'y + zy')z'$
$\qquad= (xyz' +xyz + zy')z' =xyz'$

Correct Answer: $A$
edited by

20 Comments

how to simply this:

F = (XYZ' +XYZ + Y'ZY + ZY')Z'

= (XYZ' +XYZ + ZY')Z'  //this step to final step XYZ'

=XYZ'

2
z*z' =0
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@karthik

  (XYZ' +XYZ + Y'ZY + ZY')Z'

=XYZ'Z'+XYZZ'+Y'ZYZ' + ZY'Z'

=XYZ'+0+0+0

=XYZ'
1
Where is X,Y,Z in the circuit diagram?
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why is EN  multiplied in characteristic equation? Kindly explain . Thanks

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yes it will multiply

When EN = 1, themultiplexer performs its operation depending on the selection line

1

Thanks :)

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in the above question enable will be in complemented form
1

enabled at  0 and disabled at 1?

0
yes for the above circuit because inverter is present there
1

As you mentioned - "Z is connected to A"

then how could you substitute A0as Z for the third min-term.

It should be Y'Z'Y instead of Y'ZY.

Correct me if I am wrong. Although I know that it won't affect the final answer by doing so.

1
how you write this function in xyz form from A1, A0??????????
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@raj see in circuit...  A1 is getting y' and AO is getting z..
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@gari thank u

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how we know "X connected to I0  I1 .Y connected to I2  "

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I think u should look at the diagram carefully
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This is totally due to depression .. thanks @akanshadewangan24
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I want to know, why you multiply enable with the all the input ??

What the reason for that ?
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edited by

how come ZY' for A1.A0.I3  why not Y'ZY'

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ZY' equals to ZY'Y' @sandeep verma
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8 votes

Option A

Answer:

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