# How to we do Boolean expreesion.

Discussion in 'Homework Help' started by Ricky Sum, May 7, 2016.

1. ### Ricky Sum Thread Starter New Member

May 6, 2016
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0
Can anyone explain how we do boolean expression. And how to do it.

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2. ### dl324 Distinguished Member

Mar 30, 2015
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Is this homework?

3. ### crutschow Expert

Mar 14, 2008
13,505
3,376
Difficult to explain in a few sentences.
Here are some references.

Mar 30, 2015
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5. ### WBahn Moderator

Mar 31, 2012
18,087
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MOD NOTE: Moved to Homework Help from General Electronics Chat.

6. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
One of the first steps should be to get the original circuit into nothing but one- and two-input gates. Can you change the 3-input AND gate into a subcircuit that uses only 2-input gates (doesn't matter what type).

Next is to translate the different one- and two-input gates into equivalent subcircuits that only use 2-input NAND gates. You can do those off to the side one at a time. At the most basic Boolean expression level, you only have three gates to worry about - NOT, OR, and AND. Can you make each of those out of just 2-input NAND gates? If not, that is the first thing you need to focus on.

7. ### bertus Administrator

Apr 5, 2008
15,806
2,389
Hello,

I have taken your picture, cut out the essential part, adjusted brightness and contrast.

Please cut away any unwanted parts next time.

Bertus

8. ### WBahn Moderator

Mar 31, 2012
18,087
4,917
Check your expression for Z that you have drawn on the diagram. Hint: The middle gate is not and OR gate.

Feb 19, 2010
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10. ### thumb2 Member

Oct 4, 2015
92
6
I am not sure if you're expression for the NOR output is right.

You have a NOR with both its input inverted.
So it should be $(\overline{\bar A + \bar B})$.
Making a thruh table for the 2NOT -> NOR Gate I get:

$\begin{array}{c c | c }
A & B & \overline Y\\
0 & 0 & 0\\
0 & 1 & 0\\
1 & 0 & 0\\
1 & 1 & 1
\end{array}
$

where A and B are the non inverted inputs. So The final output can be reduced to

$Y = (A \wedge B \wedge B)$

For a & b ceck out NAND logic and NOR logic.

Last edited: May 8, 2016
11. ### dl324 Distinguished Member

Mar 30, 2015
3,379
651
There is no Y in the original problem. If you meant Z, you dropped C.

This is the Homework Help forum and members are expected to provide guidance to the OP so they can learn how to do it themselves.

Last edited: May 8, 2016
12. ### thumb2 Member

Oct 4, 2015
92
6
Yes I ment Z and I forgot C ...
Uh OK ...
Regards

Last edited: May 8, 2016