nf7 v2.0 hypertransport: unidirectional or bidirectional?

Discussion in 'Abit' started by pigdos, Nov 3, 2006.

  1. pigdos

    pigdos Guest

    Subject says it all. Do Nforce2 boards feature a unidirectional or
    bidirectional hypertransport interface?

    --
    Doug
     
    pigdos, Nov 3, 2006
    #1
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  2. pigdos

    Paul Guest

    pigdos wrote:
    > Subject says it all. Do Nforce2 boards feature a unidirectional or
    > bidirectional hypertransport interface?
    >


    I cannot find anything definitive. Datasheets are covered under NDA,
    which means a person holding a datasheet, cannot discuss it with
    you. The review sites only say the bus is "800MB/sec" without
    elaborating whether that number is for one direction, both
    directions, or whatever. I'd say Nvidia's secret is safe.

    If you look at the layout, there appear to be sixteen diff pairs
    on the top surface of the board. They are routed between the
    Northbridge and Southbridge, and typically snake around the end
    of the AGP connector, to get to the Southbridge.

    Some pics here
    http://www.tweak.dk/tests2.php?id=267

    (16 diff pairs, middle right of picture, leading to upper
    right hand corner, eventually leading to the Southbridge)
    http://www.tweak.dk/test252/north.JPG

    With 16 diff pairs, my *guess* would be two 8 bit busses.
    But anything is possible. Certainly other product info
    I've looked at (AMD8111), Hypertransport is two separate
    busses, one transmit and one receive, and each consists
    of diff pair signalling. Maybe if the speed dropped low
    enough, a designer could consider going single-ended, but
    then, what would be the point. Diff is so much better.

    Paul
     
    Paul, Nov 4, 2006
    #2
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  3. pigdos

    pigdos Guest

    Paul, it's interesting to note that the Nforce1 boards had a 400MB/s
    hypertransport interface (at least according to the specs I've read).

    Doesn't the hypertransport spec call for a bidirectional interface?

    --
    Doug
    "Paul" <> wrote in message
    news:eigmsj$385$...
    > pigdos wrote:
    >
    > I cannot find anything definitive. Datasheets are covered under NDA,
    > which means a person holding a datasheet, cannot discuss it with
    > you. The review sites only say the bus is "800MB/sec" without
    > elaborating whether that number is for one direction, both
    > directions, or whatever. I'd say Nvidia's secret is safe.
    >
    > If you look at the layout, there appear to be sixteen diff pairs
    > on the top surface of the board. They are routed between the
    > Northbridge and Southbridge, and typically snake around the end
    > of the AGP connector, to get to the Southbridge.
    >
    > Some pics here
    > http://www.tweak.dk/tests2.php?id=267
    >
    > (16 diff pairs, middle right of picture, leading to upper
    > right hand corner, eventually leading to the Southbridge)
    > http://www.tweak.dk/test252/north.JPG
    >
    > With 16 diff pairs, my *guess* would be two 8 bit busses.
    > But anything is possible. Certainly other product info
    > I've looked at (AMD8111), Hypertransport is two separate
    > busses, one transmit and one receive, and each consists
    > of diff pair signalling. Maybe if the speed dropped low
    > enough, a designer could consider going single-ended, but
    > then, what would be the point. Diff is so much better.
    >
    > Paul
     
    pigdos, Nov 4, 2006
    #3
  4. pigdos

    Paul Guest

    Paul, Nov 4, 2006
    #4
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