How to Draw Logic Gate Graphs for NOR and XOR Gates

[Femme_physics]

Homework Statement

Graphs A and B are entries to a NOR gate with 2 inputs. Draw the output C.

Graphs X and are entries to a XOR gate. Draw the output Z.

Homework Equations

The Attempt at a Solution

 

[Max.Planck]

Looks good.

 

[I like Serena]

I'm afraid you've slipped at $\overline{x} \cdot y$.

Tip: XOR means "either the one, or the other (but not both)".

 

[Femme_physics]

I'm afraid you've slipped at $\overline{x} \cdot y$.

Tip: XOR means "either the one, or the other (but not both)".

I'm confused...if XOR mean either this or that, how can u draw it on a single graph?

EDIT: nevermind, I think I figured it out

 

[Femme_physics]

http://img210.imageshack.us/img210/4410/figured.jpg

 

[NascentOxygen]

You are making heavy work of this, Femme_physics. Would you like to start again?

All you need are 3 graphs: x and y, and a blank one for your answer. https://www.physicsforums.com/images/icons/icon3.gif

Now graph the answer following this EXCLUSIVE-OR rule: where x differs from y, draw
logic level 1. (And if x equals y, draw level 0.)

That's all there is to it. Too easy!

I'm not sure why your output trails off to the right at logic 1, where x and y are both at 0 https://www.physicsforums.com/images/icons/icon5.gif

 

[Femme_physics]

I'm not sure why your output trails off to the right at logic 1, where x and y are both at 0

Oops, you're right, but I think this is my only mistake right?

As far as "heavy work" -- well, I think it has an added value, being more thorough allows you to see the whole picture and revise the issue better.

 

[NascentOxygen]

Oops, you're right, but I think this is my only mistake right?

You have made another careless mistake, which will reveal itself.

As far as "heavy work" -- well, I think it has an added value, being more thorough allows you to see the whole picture and revise the issue better.

Exactly right, there is much to be gained by doing it the rigorous way, if only to confirm that the formula jives with the common sense approach. Unfortunately, the more steps you go through, the greater the opportunity to make mistakes. If this were an exam question, I'm sure the time allocation would be for the simple route. It is good to know how to do the task both ways.

If you solve a problem two ways, agreement of answers usually confirms you as being correct. Disagreement can often highlight the error.

 

[Femme_physics]

You have made another careless mistake, which will reveal itself.

Oh yes, I forgot to include that little block in the middle. Thank you

Exactly right, there is much to be gained by doing it the rigorous way, if only to confirm that the formula jives with the common sense approach. Unfortunately, the more steps you go through, the greater the opportunity to make mistakes. If this were an exam question, I'm sure the time allocation would be for the simple route. It is good to know how to do the task both ways.

If you solve a problem two ways, agreement of answers usually confirms you as being correct. Disagreement can often highlight the error.

Completely agree

 

[NascentOxygen]

Congratulations on your 2000th post to physicsforums, Femme_physics!

 

[Femme_physics]

w000t! :) many thanks NacsentOxygen! I'm still trying to catch up with ILS...I used to have bigger post count *Grumbles!*

And for my 2001th post I will (hopefull) present a correct solution!

http://img198.imageshack.us/img198/9691/xyxyxor.jpg

 

[NascentOxygen]

Finally looks right.

 

[Femme_physics]

Thanks :)

 

[Femme_physics]

Trying to get more practice.

Here A and B are Or Gates, with C being the outcome

X and Y are AND Gates, with Z being the outcome

I drew the graphs of the outcome.

Looks good?

http://img85.imageshack.us/img85/4851/18039867.jpg

 

[NascentOxygen]

Trying to get more practice.

Good idea. Don't forget exclusive-OR, too.

Here A and B are Or Gates, with C being the outcome

X and Y are AND Gates, with Z being the outcome

I drew the graphs of the outcome.

Looks good?

yes​

 

[Femme_physics]

Thanks NascentOx :)