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Re: Choppy audio playback

On Mon, Mar 10, 2008 at 04:52:01PM -0400, Miles Nordin wrote:
> >>>>> "kjl" == Kurt J Lidl <lidl%pix.net@localhost> writes:
>    kjl> So, you have to plan your PCI card insertion carefully, and
>    kjl> make sure you have no more than one 3.3 volt card, if you are
>    kjl> putting multiple PCI cards into one of those machines.
> how does this work exactly?  I thought it was not about supplying
> power, but about the logic voltage, like with the varying voltages of
> AGP <?>x slots.

I don't know about AGP slots.  What I meant was there was a single
slot in the Ultra motherboard that does 3.3 volt signaling.  The other
slots do 5 volt signaling.

> Isn't a PCI slot, even on a PeeCee, either 5V or 3.3V forever,
> depending on how it's wired, and never adaptable to the card inserted?

Yes, you are quite right.

> and necessarily so, since the logic pins of a PCI slot are shared with
> other slots and thus other cards on the ``bus'' which, if slots tried
> to be dual-voltage, could be cards of the wrong voltage?  so, only
> cards can be dual-voltage, not slots?

Yes.  I was wrong in how I characterized the slots -- one is 3.3 volt
signaling, and the others are 5.0 volt.  Presumably, all the slots
actually have all the voltages (3.3, 5.0 and 12.0) present on the
power rail pins.

> And a slot signifies which kind it is by whether the keying bar is in
> the back (5V) or near the card edge (3.3V)---many cards have two
> openings for keying bars, but you'll never see a PCI slot without a
> keying bar in either one spot or the other.  I have been assuming this
> order of affairs but don't know for sure.

Yup.  The cards that can run with either 3.3 or 5.0 volt signaling are
"universal" cards.  Some (old) cards only run with 5.0 volt signaling,
and any pci-x cards will be 3.3 volt.  The PCI 2.2 spec abolishes the
5.0 volt signaling entirely.


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