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attaching to pci cards to same pci slot?

Discussion in 'Electronic Design' started by Michael, Dec 24, 2003.

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  1. Michael

    Michael Guest

    Hi - I'd like to attach two mini-pci cards to one mimi-pci slot. I've heard
    that there are "pci risiers" that allow you to connect more than one pci
    card to the same pci slot. I'd assume you could do the same thing with a
    mini pci card since they're essentially the same as a pci card. Is this
    super complicated? Or can the cards just be wired in parallel? (ok I'm
    guessing it's not that easy)


  2. Mac

    Mac Guest

    I don't think wiring cards in parallel will work at all.

    At bootup, or potentially at other times, too, the host in charge of the
    PCI bus can enumerate devices. My recollection of the details is a little
    fuzzy, but I'm pretty sure this process would fail if you had two devices
    connected to one slot. Then there is the issue of interrupts. It is
    possible that the devices would share the same interrupt, and while PCI
    does support interrupt sharing, the setup might not work properly in this
    unforseen case. Of course if one of the cards doesn't generate interrupts,
    then there is no problem as far as that goes.

    Futhermore, the PCI specification explicitly forbits placing two loads on
    the PCI clock signal going to one slot. By itself this doesn't gaurantee
    that it won't work in practice, but it does mean that you can't complain
    to the vendor if it doesn't work, since you are violating the

    Now, there may be riser cards with a PCI bridge chip on board. This type
    of design can be made to work without violating the PCI specification at

  3. Michael

    Michael Guest

    The two cards are a Ethernet/Modem card and a 802.11b card. Do you know of
    any example PCI bridge chips? Or how complicated this would be? (my
    electronics knowledge is pretty limited to the work I do with AVRs [8 bit
    microcontrollers]. Thanks alot!

  4. Ian Stirling

    Ian Stirling Guest

    IIRC, you can buy 802.11b/ethernet combo cards.

    Or plug a wireless access point into the ethernet port, with a
  5. Michael

    Michael Guest

    I've never seen a combo card like that. I'd be quite surprised if they
    could fit all of that into a mini-pci card. Space is extremely limited - so
    I don't think there's anyway I could fit a hub and an ethernet 802.11b
  6. Ian Stirling

    Ian Stirling Guest

    I'm sure I saw some on ebay, however I was looking for something else
    at the time, and can't seem to find any now.
    Space would be a problem, but I think it's possible with some
    of the newer chipsets with lower parts counts.

    Some more information might be handy.

    I assume this isn't for a laptop.
  7. Michael

    Michael Guest

    Well essentially it is - it's for an Internet appliance. A Virgin Webplayer
    to be exact (more info here:
  8. Michael

    Michael Guest

    BTW I found what I'm looking for - only in the wrong form factor (pci not

    If only I couldget my hands on one of those bad boys to figure out what
    chip they're using.
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