Re: CPU <> Memory chip communication interface

Discussion in 'VHDL' started by Skybuck Flying, Aug 5, 2005.

  1. Nice introduction to signals across a wire.

    http://penguin.dcs.bbk.ac.uk/academic/technology/physical-layer/asynchronous/index.php

    I never understood the difference between voltage and ampere... to bad this
    page doesn't discuss how ampere is related to voltage. (voltage<->ampere
    very confusing )

    One thing I do understand now. The higher the voltage the higher the one ;)
    (or maybe is ampere at work here as well ? )

    Another surprising things is ;) +voltage is zero and -voltage is one. I
    would have done it the other way around... 1 is closer to positive so
    +voltage is 1 and -voltage is closer to zero so -voltage is 0.

    Bye,
    Skybuck.
    Skybuck Flying, Aug 5, 2005
    #1
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  2. Skybuck Flying

    Pooh Bear Guest

    Skybuck Flying wrote:

    > Nice introduction to signals across a wire.
    >
    > http://penguin.dcs.bbk.ac.uk/academic/technology/physical-layer/asynchronous/index.php
    >
    > I never understood the difference between voltage and ampere... to bad this
    > page doesn't discuss how ampere is related to voltage. (voltage<->ampere
    > very confusing )


    That's pretty fundamental. The classic example is to compare electricity to water.

    Voltage is like water pressure - current is like water flow. With no pressure no water
    flows. The larger the pipe ( less resistance to flow ) the more water flows. In a similar
    way, the less electrical resistance, the more Amps flow in a circuit for a given voltage.

    Reduce the pressure ( Volts ) and the flow ( current ) will reduce likewise.

    You sound interested in electronics. An admirable interest.

    Why not do what I did when young and simply do some self-study ? Books can be good you
    know ! Maybe today's way of living tends to overlook this obvious source of excellent
    info ?

    Now - please stop trolling here.

    http://en.wikipedia.org/wiki/Usenet_troll


    Graham
    Pooh Bear, Aug 5, 2005
    #2
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  3. "Pooh Bear" <> wrote in message
    news:...
    >
    > Skybuck Flying wrote:
    >
    > > Nice introduction to signals across a wire.
    > >
    > >

    http://penguin.dcs.bbk.ac.uk/academic/technology/physical-layer/asynchronous/index.php
    > >
    > > I never understood the difference between voltage and ampere... to bad

    this
    > > page doesn't discuss how ampere is related to voltage. (voltage<->ampere
    > > very confusing )

    >
    > That's pretty fundamental. The classic example is to compare electricity

    to water.
    >
    > Voltage is like water pressure - current is like water flow. With no

    pressure no water
    > flows. The larger the pipe ( less resistance to flow ) the more water

    flows. In a similar
    > way, the less electrical resistance, the more Amps flow in a circuit for a

    given voltage.

    Does this mean a pipe diameter (of a certain material) always allows a
    certain maximum voltage ?

    So if the source of the voltage becomes to high the pipe blows ? :)

    Probably yes, ok that's easy.

    Now what about two different pipes:

    Pipe A has a large diameter with a maximum of 100 volts to flow through it.

    Pipe B has a small diameter with a maximum of 15 volts to flow through it.

    Source A has a pressure of 14 volts and is connected to pipe A.

    Source B has a pressure of 14 volts and is connected to pipe B.

    I have two meters.

    I stick a voltmeter A in pipe A.... what would it measure ?

    I stick a voltmeter B in pipe B... what would it measure ?

    Both would probably measure 14 volts.

    The difference would be the ampere.

    The flow through pipe B would have to be faster, since it's smaller.

    The flow through pipe A could be slower, since it's wider.

    According to your explanation:

    Sticking an ampere meter in pipe A should show a lower ampere.

    Sticking an ampere meter in pipe B should show a higher ampere.

    If this is how it works I think I understand it a little bit :)

    However microelectronics are very very very small.

    So for me it's hard to see the diameter and the resistance... (resistance is
    related to the material ;)) :)

    Ok I think I am starting to get it.

    Let's see even a more complex example:

    Pipe A is split up into

    Pipe A1 with a diameter of allowing 5 volts

    Pipe A2 with a diameter of allowing 95 volts.

    Now a good question is the following:

    The voltage at pipe A1 would be 5 volts ? or would it blow up ?

    It could be possible that the remaing 9 volts would simply go into pipe
    A2...

    It probably depends on the strength of pipe A1...

    At this point I really wouldn't know what the answer is ;)

    Maybe it's related to the resistance or something... if it could resists 15
    volts it might survive...
    But I don't think this is what resistance means ? or maybe it does ?

    I thought resistance means how much voltage is lost....

    Maybe this is the correct answer after all... if Pipe A1 has a resistance of
    9 volts it could allow 5 volts to flow through it...

    But what would happen to the other 9 volts ?

    Would it go lost in Pipe A1 or would it flow through Pipe A2 without loss ?

    I dont think the voltage would be simply halfed... since that's not how
    water behaves ;)

    So the point is: The concepts pressure, flow, maybe even resistance are easy
    to understand... but how it behaves in reality especially in electronics is
    a little bit more difficult to understand ;)

    Unless the answers are really simple... so I am curious what the answer(s)
    would be :) Especially the splitting up of the pipe question ;)

    Bye,
    Skybuck.
    Skybuck Flying, Aug 5, 2005
    #3
  4. Skybuck Flying

    Pooh Bear Guest

    Skybuck Flying wrote:

    > "Pooh Bear" <> wrote in message
    > news:...
    > >
    > > Skybuck Flying wrote:
    > >
    > > > Nice introduction to signals across a wire.
    > > >
    > > >

    > http://penguin.dcs.bbk.ac.uk/academic/technology/physical-layer/asynchronous/index.php
    > > >
    > > > I never understood the difference between voltage and ampere... to bad

    > this
    > > > page doesn't discuss how ampere is related to voltage. (voltage<->ampere
    > > > very confusing )

    > >
    > > That's pretty fundamental. The classic example is to compare electricity

    > to water.
    > >
    > > Voltage is like water pressure - current is like water flow. With no

    > pressure no water
    > > flows. The larger the pipe ( less resistance to flow ) the more water

    > flows. In a similar
    > > way, the less electrical resistance, the more Amps flow in a circuit for a

    > given voltage.
    >
    > Does this mean a pipe diameter (of a certain material) always allows a
    > certain maximum voltage ?
    >
    > So if the source of the voltage becomes to high the pipe blows ? :)


    That would be exceptional and irrelevant to any sensible understanding.

    I'm getting bored of your trolling now.....

    Graham
    Pooh Bear, Aug 5, 2005
    #4
  5. "Pooh Bear" <> wrote in message
    news:...
    >
    > Skybuck Flying wrote:
    >
    > > "Pooh Bear" <> wrote in message
    > > news:...
    > > >
    > > > Skybuck Flying wrote:
    > > >
    > > > > Nice introduction to signals across a wire.
    > > > >
    > > > >

    > >

    http://penguin.dcs.bbk.ac.uk/academic/technology/physical-layer/asynchronous/index.php
    > > > >
    > > > > I never understood the difference between voltage and ampere... to

    bad
    > > this
    > > > > page doesn't discuss how ampere is related to voltage.

    (voltage<->ampere
    > > > > very confusing )
    > > >
    > > > That's pretty fundamental. The classic example is to compare

    electricity
    > > to water.
    > > >
    > > > Voltage is like water pressure - current is like water flow. With no

    > > pressure no water
    > > > flows. The larger the pipe ( less resistance to flow ) the more water

    > > flows. In a similar
    > > > way, the less electrical resistance, the more Amps flow in a circuit

    for a
    > > given voltage.
    > >
    > > Does this mean a pipe diameter (of a certain material) always allows a
    > > certain maximum voltage ?
    > >
    > > So if the source of the voltage becomes to high the pipe blows ? :)

    >
    > That would be exceptional and irrelevant to any sensible understanding.
    >
    > I'm getting bored of your trolling now.....


    I am not trolling I am trying to understand it. But ok I can see how a dirty
    mind might think that's funny.

    And in case you didn't understand that sentence here it is again:

    So if the pressure of source of the voltage becomes to high the pipe blows ?

    Without the smiley :D :p :D

    Bye,
    Skybuck.
    Skybuck Flying, Aug 5, 2005
    #5
  6. Skybuck Flying

    Pooh Bear Guest

    Skybuck Flying wrote:

    > "Pooh Bear" <> wrote in message
    > news:...
    > >
    > > I'm getting bored of your trolling now.....

    >
    > I am not trolling I am trying to understand it. But ok I can see how a dirty
    > mind might think that's funny.


    Your amusement factor is declining fast.

    I suggest ( if you're serious ) that you start reading a few decent books on electronic
    theory and practice. It'll come in handy !

    Ohhh... hobby magazines such as Elektor ( if it still exists ) are a good source of info
    about practical circuits that can be easily built on a hobbyist basis. They are good
    foundations upon which to learn.

    Graham
    Pooh Bear, Aug 5, 2005
    #6
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