[mythtv-users] EPIA fan noise ?

Adam Wood AdamWood at XePhi.co.uk
Tue Aug 3 03:29:18 EDT 2004


> Maarten wrote:
> 
> >On Monday 02 August 2004 23:59, Gert van der Knokke wrote:
> >
> >
> >>Maarten wrote:
> >>
> >>
> >>>On Monday 02 August 2004 18:59, Stephen Tait wrote:
> >>>
> >>>
> >>>>At 17:47 02/08/2004 +0100, you wrote:
> >>>>
> >>>>
> >
> >
> >
> >
> >>>In any case, a PCI riser card 'rises' only one PCI slot.  You cannot
> put a
> >>>two-slot risercard in one slot and expect both slots to work then. PCI
> >>>isn't designed that way.
> >>>
> >>>
> >>Erm, yes it is, all PCI slots share the same data and address lines,
> >>it's a bus remember.
> >>
> >>
> >
> >Sorry but you're wrong.  Read the PCI-SIG specifications.
> >"It's a bus remember".  Sigh. Not all buses are alike, and not all slots
> on a
> >bus automatically have the same connections.
> >
> >http://www.techfest.com/hardware/bus/pci.htm
> >
> >I'll quote you some excerpts:
> >
> >"Initiators arbitrate for ownership of the bus by asserting a REQ# signal
> to a
> >central arbiter. The arbiter grants ownership of the bus by asserting the
> >GNT# signal. REQ# and GNT# are unique on a per slot basis allowing the
> >arbiter to implement a bus fairness algorithm."
> >
> >and
> >
> >REQ#	    Request is used by a PCI device to request use of the bus. Each
> PCI
> >device has its own unique REQ# signal.
> >
> >GNT#	    Grant indicates that a PCI device's request to use the bus has
> been
> >granted. Each PCI device has its own unique GNT# signal from the PCI
> system
> >arbiter.
> >
> >
> >
> >>The IRQ's are usually connected in a round robin way, IRQ A is IRQ B on
> >>the second slot and IRQ C on the third etc. A PCI card normally takes up
> >>the first IRQ but can take second, third or fourth. All PCI cards should
> >>be able to share IRQ's but some are more well behaved than others...
> >>
> >>
> >
> >The fact that there are 4 separate IRQ lines (INTA#, INTB#, INTC#, INTD#)
> does
> >nothing to permit more than one card per slot, as the INT lines have
> nothing
> >to do with the bus arbitration.
> >
> >
> >
> >>There are lots of proprietary motherboards around which have only one
> >>PCI slot with a riser to create 2, 3 or 4 horizontal PCI slots. (Low
> >>profile Compaqs, HPs etc.)
> >>
> >>
> >
> >Yes. And those invariably have a proprietary slot onboard where the
> risercard
> >fits in. NOT a PCI slot.
> >
> >Maarten
> >
> It is true that Request/Grant is unique per device. Though not all
> devices need Request/Grant, it is only needed for "Bus Mastering"
> peripherals. Of course, most high performance devices  (ethernet, IDE,
> VGA, and I am going to assume Video capture cards) do need it to achieve
> decent performance. The 2nd slot should be perfectly useable for a UART
> or Parallel port card:)
> 
> Tim

I'm certainly no PCI expert but I have a generic 2 slot PCI riser, at least
that's how it was sold to me, and it runs my PVR-250 and Nova-t cards fine
on an EPIA-M 10000. I'm just wondering if anyone who thinks it doesn't work
has tried it. It sounds like I'm not the only one with success.

Adam




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