A question about RS Flip-Flop

Discussion in 'General Electronics Chat' started by Deadeye the assassin, Oct 14, 2010.

  1. Deadeye the assassin

    Thread Starter New Member

    Oct 14, 2010
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    Good day

    I'm fairly new to this, I'm currently earning my bachelor in computer science. The course has just started delving into logic gates and such which I think I understand well. But I'm having trouble understanding RS flip-flops, since according to the truth tables that I have seen only Q is remembered while NOT Q is just forgotten. But every time I look at the picture of the RS I get the nagging feeling that NOT Q should also be remembered since like Q it connects into an OR gate, I asked my teacher and he had no answer why this was.

    Can anyone help me with this?

    PS. I'm using the image on the wikipedia article for my assumption.
     
  2. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Wikipedia states, "Normally, in storage mode, the R and S inputs are both low, and feedback maintains the Q and Q outputs in a constant state, with ~Q the complement of Q. If S is pulsed high while R is held low, then the Q output is forced high, and stays high even after S returns low; similarly, if R is pulsed high while S is held low, then the Q output is forced low, and stays low even after R returns low".

    This doesn't mean that ~Q is forgotten; it will always the the complement of Q and if Q is "remembered", so will ~Q
     
  3. Deadeye the assassin

    Thread Starter New Member

    Oct 14, 2010
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    So are you saying no matter what Q is there is always it's compliment present, for instance if Q is 0 then !Q is 1. Kind of boggles me that this is not in the truth table, since it seems to be quite important.
    So would it make any difference if I would add !Q to the table?

    And thanks for the speed response usually I have to wait 5-6 hours just to get an response :p
     
  4. Wendy

    Moderator

    Mar 24, 2008
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  5. Deadeye the assassin

    Thread Starter New Member

    Oct 14, 2010
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    Ok now I get it, that was a fantastic illustration/explanation about RS flip-flop. Thank you very much.
     
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