Re: PCI riser cards and PCI irq routing, etc

From: Udo van den Heuvel
Date: Fri Feb 23 2007 - 13:17:27 EST

Krzysztof Halasa wrote:
> Udo van den Heuvel <udovdh@xxxxxxxxx> writes:
>> I will try a different case with a different dual PCI riser card soon.
>> This Morex riser has DN20-31 or so, so more options.
>> Could this help solve my irq issue? (try 4 consecutive DNs until I have
>> the right mapping?)
> I don't think so. Unless you can configure INT connections on the riser
> card, of course.
> You need DN19 for the second slot (and perhaps 10 would work with
> double INTx rotation), that's fixed in the BIOS.

I have DN19 and DN20 now and it doesn't work.
Only because the INT mapping on the riser is not right? shows some IDSEL
jumper with ADxx numbers. What could these be?
Photo at

Still DN's?

>> This Morex riser has DN20-31 or so, so more options.
> OTOH I wonder how do they use DN 21-31? The board uses lines AD11 to AD31
> (21 lines) for selecting devices #0 - #20. 32-bit PCI bus has only 32
> address/data lines :-)
> Perhaps they mean AD20-AD31 lines = device #9 - #0x14=20? If that is
> the case, you can try:
> - their "DN30" = device 0x13 = 19, which is apparently what the VIA riser
> card does,
> - their "DN21" = device 0xA = 10, which could work as well.
> I'm afraid both would require (different) soldering.

So at least try the different jumper settings (without additional info,
I hope Morex responds to my emails).
Else do a little soldering.

> It's possible that the riser card includes a bridge, though. A bridge
> chip can select devices differently and thus it can handle 32 devices.

Looking at the photo I don't think I see a bridge...

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