4:1 multiplexer output?

[sireesha92]

what is the output of this mux??

 

[TrickyDicky]

is the answer 2?

 

[sireesha92]

Answer is 'x'. But i dn't know the reason.. can any one help..?

 

[TrickyDicky]

Are you sure? where did you get that answer?

 

[mrflibble]

I think he may have gotten it from the Wrong Answer Fairy. She's a sneaky one...

I had almost posted a reply "well, I can tell you what it's not. It's not 'x' and not 'z' either.". Good thing I didn't, because mistakes like this maximize the potential for learning.

Anyways, like TrickyDicky asked, where did you get that answer? Suppose the answer is not 'x', what do you think it should be?

 

[sireesha92]

actually i went with the mux equation..

y=s0's1'ip1+s0's1ip2+s0s1'ip3+s0s1ip4

then
according to the inputs given, the equation y= x(unknown value)+0+1+z(high impedance)

addition of any value with unknown(x) results 'x'
so i thought 'x' was the answer..

 

[TrickyDicky]

In my mind, x and z are just logic inputs (poorly chosen names). They are the output of another circuit.

 

[K-J]

what is the output of this mux??

View attachment 88829

The output is 'y'...all the other labels are there just to throw you off the obvious choice.

 

[barry]

I would have GUESSED "1". This makes the assumption that the left-most select input is the low-order bit (I don't know if that's a convention or not).

But I like K-J's answer, too.

I don't see any way that the answer could be "X".

 

[seeker_123]

answer would be either 1 or 0 depends on ur select bit convention.
it would be 0 if u use like
y=s0's1'ip1+s0's1ip2+s0s1'ip3+s0s1ip4

and it would be one if
y=s0's1'ip1+s0s1'ip2+s0's1ip3+s0s1ip4

but answer would never be x or z
because s0's1'ip1 and s0s1ip4 these two terms are zeros
as your select lines are '1' and '0'