# Karnaugh map decomposition

Discussion in 'Homework Help' started by transistortransistor, Jan 21, 2014.

1. ### transistortransistor Thread Starter New Member

Oct 9, 2013
11
0
Hello everyone,

I need to implement the following function:

f(A,B,C) = (sum of the miniterms 2,4,5,6)

I can only use 4 NAND gates with two inputs. A,B,C complement are not available.

The question suggests that I should use K-Map Decomposition.

My question is: how am I supposed to use this technique? should I magically know how each operation looks on a K-map and think of ways to gather them?

2. ### MrChips Moderator

Oct 2, 2009
12,657
3,461
You are supposed to have been shown how to draw Karnaugh maps.

Draw a Karnaugh map for three variables A, B and C.

Show the minterms 2, 4, 5, and 6 on the map. Then we'll guide you from there.

3. ### transistortransistor Thread Starter New Member

Oct 9, 2013
11
0

Ok, whats the next step?

4. ### t06afre AAC Fanatic!

May 11, 2009
5,939
1,222
We do not mind helping in this section of forum. But we will not just serve you a solution on a silver plate. In this case it is quite apparent that you have not done much reading in your books or lecture notes. Anyway try to read this http://www.uotechnology.edu.iq/dep-eee/lectures/1st/Digital techniques/part2.pdf Then feel free to come back with your questions

5. ### MrChips Moderator

Oct 2, 2009
12,657
3,461
Group the 1s in powers of 2 (pairs, quads etc.) and write them down as sums of products.

6. ### transistortransistor Thread Starter New Member

Oct 9, 2013
11
0
Hello MrChips, thanks for helping.

Anyway, I know how K-Maps works.

In this case, I would use 3 NAND's to get the "complement" of the variables + 3 NANDS to the products (BC, AC, AB) + 1 NAND with three inputs to get the final function.

But the question says that I need to use just 4 two input NAND.

And then it suggests K-Map decomposition.

Here a image of an example:

Thats why I said "guess". It's not guessing, but I would need to know beforehand how AND/ORS or any other operation look on K-MAP so I would be able to gather them and get my function.

7. ### MrChips Moderator

Oct 2, 2009
12,657
3,461
If you know how K-Maps work then what is your question?

8. ### transistortransistor Thread Starter New Member

Oct 9, 2013
11
0

Please, take a look at the example of my lecture slide:

http://postimg.org/image/ed1e2mlqn/

9. ### WBahn Moderator

Mar 31, 2012
18,096
4,920
So what on earth is preventing you from drawing the K-Map for A AND B and/or A OR B and seeing what it looks like on a K-MAP?