[mythtv-users] EPIA fan noise ?

[Tim Tait]

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