Re: firewire bus/card counter

Quoting Stefan Richter <[email protected]>:

> Dan Dennedy wrote:
>> I have some true dual bus cards, but PCI only. Not seen PCMCIA.
>
> I also am only aware of dual controller PCI cards (from IOI in
> particular) and of a quad controller PCI-X card (from Indigita).
>
> It is highly unlikely that there are any commercially available dual
> controller cards for PCMCIA (CardBus actually) or ExpressCard, although
> it seems feasible, especially in case of ExpressCard with the recent
> generation of PCIe 1394 link & PHY chips with their small footprint.

There are probably several issues with making either a cardbus or  
expresscard dual controller cards:

1)  [Power] There is a limited amount of power supplied to the cardbus  
or expresscard slot which is often not enough for existing firewire  
designs (I've seen several that require an external power supply).  I  
seem to remember someone complaining that they had an opportunity to  
solve the power problem in  cardbus specs when they made the spec for  
expresscard, but it didn't get improved?  I might be mistaken here.

2)  [Space] Cramming two controllers and possibly a needed PCI-PCI  
bridge into a cardbus or expresscard form-factor is also a challenge.   
If there was a vendor that came up with an integrated solution then  
that would be a possibility but that would require custom silicon  
which would probably only be used in this application which would  
probably prove to be too costly.

3) [Interrupt Request Lines] This is an assumption on my part, but a  
cardbus slot probably only gets a single interrupt request line.   
(just like every PCI slot)  Each firewire controller would want its  
own interrupt request line.  Of course this could be designed around  
but again, this points to custom silicon which is unlikely due to what  
I mentioned in 2).

Sorry if I just wasted the bits in sending this out.  Maybe no one  
even cares...

George Morgan



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