[LAU] irq sharing

Mark Knecht markknecht at gmail.com
Wed Aug 25 15:45:41 UTC 2010

On Wed, Aug 25, 2010 at 5:27 AM, David Santamauro
<david.santamauro at gmail.com> wrote:
> On Wed, 25 Aug 2010 14:15:35 +0200
> Arnold Krille <arnold at arnoldarts.de> wrote:
>> On Tuesday 24 August 2010 21:42:53 Mark Knecht wrote:
>> > There are two kinds of PCI cards - those with a single indentation
>> > in the gold connector area on the card and those with two
>> > indentations. Cards with a single indentation required 5 volts
>> > (IIRC) and those with 2 indentations did not. A PCI card with two
>> > indentations only used 3.3 volts <snip>
>> Nope, the cards with two indentations run with both 5V or 3.3V. The
>> ones with one indentation have the voltage hard-coded by the position
>> (back or front) and don't run with the other voltage at all. Even if
>> you break out the saw to make them fit...
> both the delta and the 2496 have two indentations. I *may* just try and
> stick it in my 64-bit box alongside the delta, although frying it
> wouldn't be a good thing... needs more thought and research first.
> David

   Arnold is probably right about me having the description backward.
I know from serving on some of the committee that wrote these bus
specs (PCI-X, 1394a, 1394b, etc.) that the intention was ALWAYS to be
user-friendly and safe to hardware. My intention earlier was simply to
help you see how you might possibly be able to do more with your
hardware than you previously realized was possible.

   Still, as I said early in this thread, I don't believe that the
noise you are experiencing is interrupt-based, nor do I believe that
changing slots is likely to help. The root cause almost certainly lies
elsewhere and we just don't understand it yet.

   Should you be interested in using your empty PCI-X slots for
something else then look around for something you don't mind killing
should that happen. An old NIC card or possibly an old PCI-based VGA
card sleeping in a dusty box in the dark garage somewhere and try that
first. No reason to subject your most important audio cards to this
sort of a experiment before you know it works with other things less

   Post back more info and we can try to guess what is really going on here.

- Mark

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