Logisim ICs

Discussion in 'General Electronics Chat' started by Next State, May 28, 2015.

  1. Next State

    Thread Starter New Member

    May 28, 2015
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    I am brand new to circuits & was hoping someone could answer these two very simple questions regarding Logisim.

    [​IMG]
    In Logisim; is A0 the LSB or the MSB for the above IC? Also, tell me Y5 refers to A2 A1' A0 & Y2 refers to A2' A1 A0'.

    Also, is C the MSB or A the MSB in the following Logisim IC? Again, tell me D5 refers to C B' A and D4 refers to C B' A'.

    [​IMG]

    I'm second guessing because I've built a large counter which displays a sequence on a Hex display... and I'm only getting errors at the MUX / DEMUX points. It's also 2 AM.
     
  2. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    1. Yes, A0 is the address LSB.
    2. Yes, your two conditions are correct.
    3. C is the address MSB.
    4. Yes, your two conditions are correct.

    ak
     
  3. Next State

    Thread Starter New Member

    May 28, 2015
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    Thanks a lot. Also, when using the 74151; I just connect power to the minterms I want to come out of Y (in OR form) and connect ground to the minterms I don't want expressed as part of Y, correct?
     
  4. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Respectfully, one cannot 'connect' a physical entity (CIP power) to a (mathematical) 'abstraction' (CIP minterms):confused: --- Please attempt to rephrase your question sans 'mixing of modes':)

    With constructive intent
    HP
     
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Correct. For an OR gate, power (Vcc, Vss+5, +3.3, whatever) is a logic 1, and ground is a logic 0.

    ak
     
  6. Next State

    Thread Starter New Member

    May 28, 2015
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    The output of this MUX is expressed as "Y" (you could define it with basically any variable). I can select which minterms are generated in that output (in OR form) by placing power / "1" to the inputs associated with those minterms / pins. Power is generally synonymous with "1"...

    Actually, you can definitely map algebraic forms to inputs & outputs of these ICs.
     
    AnalogKid likes this.
  7. Hypatia's Protege

    Distinguished Member

    Mar 1, 2015
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    Please understand, my post was not critical! My intent was merely to 'extol the virtues' of (appropriate, moderate) dichotomization of 'the concrete' (Cip 'hardware') and 'the abstract' (i.e. Mathematical models [CIP Boolean algebra/Karnaugh maps, etc...])

    Trust me! -- As one whose initial approach to engineering was from the 'pure math perspective' I both understand and sympathize with "the temptation"!:rolleyes::)

    Sincerely, best regards
    HP
     
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