# Homework Help: Logic circuits for boolean functions

1. Sep 30, 2011

### slain4ever

1. The problem statement, all variables and given/known data

Draw a logic circuit for the boolean function ((p+qr)')(pq+r) do not simplify the function first

3. The attempt at a solution

I got this: http://screencast.com/t/BC4akgo9J
but i'm pretty sure it's wrong because of the first part how the bar goes over the whole first part instead of over each letter, I think I would have to use de morgans laws to remedy this but since it says to not simplify the function I have no idea what to do. or is the first part correct as it is?

2. Sep 30, 2011

### LCKurtz

What you have drawn is a transmission logic circuit. It isn't correct. But how could it be when the NOT operator is not available in transmission logic. Are you sure you aren't supposed to implement the unsimplified function with logic gates?

3. Sep 30, 2011

### slain4ever

oh right, that makes sense,

so it would be something like this right? http://screencast.com/t/zIp1V3Lmt

4. Oct 1, 2011

### LCKurtz

I can't make any sense out of that drawing. The logic gates have standard representations with distinctive shapes. And the AND and OR gates each have two inputs and one output, while the NOT gate has one input and one output. You can see descriptions of them at

http://en.wikipedia.org/wiki/Logic_gate

5. Oct 1, 2011

### slain4ever

the gates have the right number of iputs and outputs I just didn't put the weird shapes, because it's easier for me to remember like this

6. Oct 1, 2011

### Redbelly98

Staff Emeritus
Moderator's note:

This is not a calculus question. Thread moved from Calculus & Beyond to Engineering, Comp Sci, & Technology.

7. Oct 1, 2011

### uart

The shapes have a meaning which is additional to the function (and or not etc), they also make it clear which are the inputs and which is the output.

It's ok to simply draw your logic gates a rectangular box with the function type written in the box, but in this case please make sure you place all the inputs on the left and the output on the right.

8. Oct 1, 2011

### LCKurtz

No they don't. The AND gate on the left does not have two inputs and one output and neither does the OR gate at the lower right.

Last edited: Oct 1, 2011