RE: what's a pci expansion card for?

["Ingraham, Andrew" <Andrew.Ingraham@hp.com>]

> what is a pci expansion card meant for?
 
Unfortunately, "expansion card" means different things.

An "expansion board" can mean any regular PCI card.  The PCI
Specification (revision 2.2) uses this definition.  It also calls them
"add-in cards."

An "expansion card," "expander card," or "extender card" can also mean a
device to extend the space between the PCI connector and the bottom of a
regular PCI card.  When you plug the regular PCI card into the top of
the extender card, the regular PCI card is physically up above the other
cards where you can easily reach all of it.  This lets you attach 'scope
probes.  This kind of expander card just has etch traces on it, from to
top to bottom.  Using it technically violates the PCI Spec (because all
the traces are too long), but it can be real handy for debugging.

An "expansion card" might also be a plug-in card that has three or four
PCI connectors on it, which lets you add three or four regular PCI cards
into a PC that has only one PCI connector left.  These expansion cards
use a PCI-PCI bridge to create a subordinate bus segment.  There are
also fancier systems to do the same thing (i.e., expand the PCI bus to
more devices), that don't require you to leave the cover off the PC.

>  is it like a
> general purpose PCB for pci provided i have some
> method for the PCI interface signal handling... 
 
What you describe, and what I see in the links you provided, is
different from any of the above.  I would call this a "breadboarding" or
"prototyping" card (even though one of them also calls it an "expansion"
card).  It lets you add circuitry (or "breadboard") and experiment with
it, on a standard PCI-size card.

Regards,
Andy