logic diagram

[Sadaiyappan]

Hi, please help me with this problem, I have been trying it for hours now and am getting no where.

Imagine a machine with four inputs and one output that functions as follows: the output is on (1) if exactly two of the inputs are on (1) and off (0) otherwise.

 

[Schadenfroh]

I just solved it using a K-Map.

Give it a go.

 

[Sadaiyappan]

ok this is what i get using min terms:

A B C D x

A.B
A.C
A.D
B.C
B.D
C.D

so i get this : (A*B*C'*D') + (A*B'*C*D')+(A*B'*C'*D)+(A'*B*C*D')+(A'*B*C'*D)+(A'*B'*C*D)

now this is confusing me.. am i supposed to draw this out? If i draw it out i will have 16 inputs not 4...

 

[degibson]

Originally posted by: Sadaiyappan
ok this is what i get using min terms:

A B C D x

A.B
A.C
A.D
B.C
B.D
C.D

so i get this : (A*B*C'*D') + (A*B'*C*D')+(A*B'*C'*D)+(A'*B*C*D')+(A'*B*C'*D)+(A'*B'*C*D)

now this is confusing me.. am i supposed to draw this out? If i draw it out i will have 16 inputs not 4...

4 inputs: A, B, C, D
Each input fans out to multiple gates.

 

[Sadaiyappan]

ok but then i get six And statements which = six output not 1 output, so what do i do from there?

 

[Sadaiyappan]

err never mind, i got it...

 

[Ken g6]

Edit: You got it.

P.S. I'm curious, are you allowed to use exclusive-or?

 

[Sadaiyappan]

yes.. well it didn't specify.. i just used six And statements connected to one or statement to create one output at the end..