1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Boolean Logic design help

  1. Mar 25, 2010 #1
    1. The problem statement, all variables and given/known data

    Using NAND, AND OR, &/or NOR gates build a vote counting machine. It should light an LED when majority votes are true (or answer "yes"). Assume 4 input votes only.


    2. Relevant equations

    Boolean Logic

    3. The attempt at a solution

    So I know the solution in terms of algebra, which is ABC + ABD + ACD + BCD (where ABCD are the 4 input votes) and I know at the end I need two OR gates summing up to one single OR gate. Not sure how to design the beginning though.

    I am also looking for a way to simplify it since I have to build the whole thing out of NAND gates only.
     
  2. jcsd
  3. Mar 25, 2010 #2

    berkeman

    User Avatar

    Staff: Mentor

    Your problem statement doesn't confine you to 2-input gates. It only takes two levels of logic to do it with AND-OR logic, right?

    Are you constrained to only using 2-input NANDs for the final circuit? How do you make an OR out of a NAND? Have you looked at the inverted function in case it offers some optimization? Please show us more work...
     
  4. Mar 28, 2010 #3
    Yeah we can have 4 inputs, but I am still not sure about you saying using the two level AND-OR logic.
    I know how to construct the different kind of gates from NAND gates now, just need a clear concept how to solve this problem.
     
  5. Mar 29, 2010 #4

    berkeman

    User Avatar

    Staff: Mentor

    Show us your initial truth table and initial logic implementation.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook