Logic circuits for boolean functions

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Discussion Overview

The discussion revolves around the construction of a logic circuit for the boolean function ((p+qr)')(pq+r) without simplifying the function first. Participants explore the representation of logic gates and the correct application of boolean algebra in circuit design.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a logic circuit attempt but expresses uncertainty about the correctness of the representation, particularly regarding the application of De Morgan's laws.
  • Another participant points out that the drawn circuit resembles a transmission logic circuit, which lacks a NOT operator, questioning the appropriateness of the implementation.
  • A subsequent reply suggests an alternative drawing but is met with confusion regarding the standard representations of logic gates.
  • Participants discuss the importance of using standard gate shapes to convey the correct function and clarify input-output relationships.
  • There is contention about whether the gates in the drawings have the correct number of inputs and outputs, with some participants asserting that they do not.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the logic circuit representations, and multiple views on the appropriate use of gate shapes and functions remain contested.

Contextual Notes

Some participants express confusion over the representation of logic gates and the implications of their shapes, indicating a potential misunderstanding of standard conventions in logic circuit design.

slain4ever
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Homework Statement



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


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?
 
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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?
 
oh right, that makes sense,

so it would be something like this right? http://screencast.com/t/zIp1V3Lmt
sorry about my handwriting.
 
slain4ever said:
oh right, that makes sense,

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

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
 
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
 
Moderator's note:

This is not a calculus question. Thread moved from Calculus & Beyond to Engineering, Comp Sci, & Technology.
 
slain4ever said:
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

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.
 
slain4ever said:
the gates have the right number of iputs and outputs

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:

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