No single gate compares: the truth...

Discussion in 'Off-Topic' started by rbaulbin, Jan 23, 2011.

  1. rbaulbin

    Thread Starter New Member

    Jan 4, 2011
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    beenthere -

    I was in the process of editing the last post when you closed the previous thread to actually involve an agreement to the concept that no single gate compares... I prematurely posted the message beforehand. Sorry about that... :)

    It is an absolute fact that no single gate compares 2 inputs to "determine" which one is greater, equal or less. To anyone confused due to my previous posting, the reason it is true that no comparison is being made is because the gate does not determine WHICH of the inputs has "something" on it vs. "nothing" on it: It only "favors" "something" over "nothing" due to being physically set up that way to function predictably. In fact, I don't think you can use "favors" -- I'm not sure which term can be used to describe it without ascribing decision-making or volitional capacity to the thing. Even the term "evaluates" is a little bizarre to me.

    The real question now I'm trying to figure out is how comparison, which seems to be the fulcrum of "decision-making" capacity *IS* capable of being carried out by *multiple* gates, such as seen in that comparator chip. This seems very strange to me that logic condition evaluation can effect quantity comparison.

    But that's for another forum perhaps -- unless someone feels like talking about it.

    Thanks.

    j
     
    Last edited: Jan 23, 2011
  2. Wendy

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    Mar 24, 2008
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    Again, it is a science. If you try to make up your own language with an established science you won't get very far. The language already exists and is well established.

    We have had other people with your approach here on AAC. They are either here to learn (which includes learning the lingo) or argue. The ones who were here to argue are gone, banned, as they liked to mess with people who were new and here to learn. Those who were trying to learn learned, and are still here.

    How much background do you have in Boolean Algebra? I paid my dues well over 30 years ago. I routinely design with gates and counters. I have built computers as kits, and programmed in machine code. I know and understand the subject, as did most of the people in the last thread. You were arguing with centuries of experience, yet dismissing their input casually and substituting your own ideas. Not a good start here.

    We have one young man who is trying to build his own CPU from scratch. Most of the guys here respect that highly, as this is how you truly learn a subject. Nothing beats hands on experience. Philosophy, on the other hand, does not work in these subjects. I will argue a point if I think the other side is listening, but I detest argument for its own sake. I will not indulge it either, and will speak up when I see it.

    How many projects have you built, and how often do you do it? Do you really want to understand gates, and how to put them together to make real world things out of them?
     
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    Well, the truth table might be a little hairy to draw up, but that schematic has everything you need to draw one.
    Greater than/less than/equal decisions, in hardware anyhow, are a tiny part of the universe of digital systems.
    Or maybe I am entirely missing your point, or maybe I am being sucked in by someone who gets off on getting fools like me to play his game.:rolleyes:
     
  4. rbaulbin

    Thread Starter New Member

    Jan 4, 2011
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    Bill -

    I appreciate the candor. I have no pretense, and I too can't stand arguing for argument's sake -- if you're not trying to get to a truth, I would also affectionally call it insanity. :)

    The truth is, in the previous topic, more than one person had used the term compare or "comparison". And then I came across a wiki article that was most certainly written by very learned individuals, and they used the word compare. I had a hard time believing the word "compare" was part of the science if many seemed to be using it to describe gates. It seemed like it was a natural bent linguistically to use the term. After hearing the input from everyone here and also doing a lot of independent thought, I came to the conclusion semantically "compare" is not a proper term. I think someone should edit that article, as Wikipedia is a go-to source for a lot of information. I felt a real legitimate issue was there which was more about linguistics than circuits. I felt I was in a position to discuss or even argue it because it was more in my purview rather than the nitty gritty of circuits.

    Plainly and simply, I'm more interested in "new concepts" rather than existing science, though there is an intersection there. A lot of Einstein's ideas were born out of philosophical muse. Boolean Algebra started out as a philosophy and became a science. I understand Boolean Algebra -- I'm not any expert in it, but I'm familiar enough with it to understand how it impacts what I'm after. I do not have an electronics background, nor do I seek one. Am I interested in building circuits? Not really. I'm trying to get at things conceptually in the frame of thinking that Boole was on when pulling apart things such as the laws of thought. So this is where my mind hangs out. I can understand if such talk doesn't belong here, though I can't help but think others here would be interested in such things due to the intersection of science and philosophy.
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    One start is to learn the symbology and function of some basic gates. Then, obtain the data sheet of a 7485 magnitude comparator that has the internal logic illustrated. You can work it out on paper - apply two four bit inputs and see what state each logic gate takes from those inputs. As long as the inputs are maintained, the internal logic will hold its state.

    From my data sheet (from a Motorlola Schottky TTL Data manual), the internal logic consists of a few NOR gates and a mix of AND and NAND gates, some with more than two inputs. The gates at pins 5 & 7 can be viewed as 6 input NOR gates, if that helps.

    You're in luck - if you can run Java applets, the linked site will do the work for you - http://tams-www.informatik.uni-hamb...20-arithmetic/45-compare/7485-comparator.html
     
  6. Wendy

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    Mar 24, 2008
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    http://en.wikipedia.org/wiki/Logic_gate

    Didn't jump out at me, but I only did a cursory search of the article. Mostly they referred to gates as Boolean functions.

    Thing is, there are analog parts called comparators. They compare two DC voltages and output a 1 or a 0 depending. They are a single bit A/D converter.

    The language is precise for a reason, it is a very deep subject.
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    rbaulbin - are you related to someone called Loosewire?
     
  8. Ron H

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    In post #3, I made a similar comment about about the 7485. Rbaulbin totally ignored my post.
     
  9. rbaulbin

    Thread Starter New Member

    Jan 4, 2011
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    Did not at all ignore your post... did not yet have time to reply to it (was going to reply today sometime).
     
  10. Ron H

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    OK, sorry for jumping to conclusions.
     
  11. Robin Mitchell

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    Oct 25, 2009
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    Are you talking about me???
     
  12. Wendy

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    Mar 24, 2008
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    Yep, I love your projects, and won't hesitate to brag on you.

    You may have noticed I spend a bit of time on my replies, and try to keep it constructive, more constructive than most.

    Keep it up, and you will go far.
     
  13. Robin Mitchell

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    Oct 25, 2009
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    that means sooo much to me Bill, thanks :)

    You have been promoted to nbf (new best friend XD )
     
  14. Georacer

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    Nov 25, 2009
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    Does the username BestFriend say anything to the senior members? Why can't we just say to those "philosoraptors" that if they want to judge electronics they have to study it first? No exceptions!
     
  15. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    So the gist of the topic is that logic ICs are sentient?
     
  16. rbaulbin

    Thread Starter New Member

    Jan 4, 2011
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    Now THAT is a welcoming, rational, friendly, and dare I say relevant reply. Lots of humanity in it, I'll tell you. Most CERTAINLY in the context of everything that has been said. Feel free to post more like this -- adds to the topic tremendously.
     
  17. Wendy

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    Mar 24, 2008
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    I think I've mentioned discussions like the other thread were not the first, and they leave scars.

    Gates are much simpler than neurons. I am a minority view, and have no problem with it, but my speculation is that we're very close to synthetic intelligence. We have all the hardware we need (or are very close to having it), but have no basic theory how to put it all together. When we do, we'd better have a code of ethics how to treat the new guys on the block, as they will have their own agendas, eventually.

    I use synthetic because artificial implies it is not real somehow, while synthetic only deals with how it was made. I am very into science fiction. There have been some good stories that have come out over the years, such as James P. Hogan's "The Two Faces of Janus".
     
  18. rbaulbin

    Thread Starter New Member

    Jan 4, 2011
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    I wouldn't say logic IC's are sentient in and of themselves, but play a role...

    I would say on the order of probing differences and intersections between human and machine reasoning. The term compare sends up flags of volition and decision-making capacity -- yet a machine can "emulate" this using only logic and makes decisions, but the term doesn't mean the same as "human decisions". Or does it...
     
  19. thatoneguy

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    Feb 19, 2009
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    The magnitude comparator I posted the datasheet for can only do what the humans intended it to do.

    There's no rule that the LSB is rightmost, etc. Unless wired to interpret what humans consider "magnitude", then fed numbers in a human format that is machine usable (binary), it cannot compare anything.
     
  20. Wendy

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    Mar 24, 2008
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    At the moment, I don't think so. Like I said, we lack the basic theories.

    Something to think about, all the current experiments with neural nets are being done with high power computers simulating them.

    Look at the current state of robotics, it is a pretty good clue where we are at. At the moment we are working on basic perceptions, balance (and walking), vision (and facial recognition), hearing (and speech recognition). The basics are still being working on, not the higher centers like problem solving (or at least not as much).
     
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