On Tue, 9 Aug 2005 00:02:30 +0100, "Alex Fraser"
<me@privacy.net> wrote:
>
>I would have thought sound support integrated into the southbridge still
>appears like a device on the PCI bus. How else would it work?
>
The PCI bus on a (southbridge-equipped) chipset merely
connected the PCI devices TO the southbridge. The
southbridge can (and does now) have integral features that
have no need to connect to an external (PCI) bus but rather
more directly connect to the northbridge.
PCI bus connects two (or more) chips. If sound is integral
to the southbridge, what on the PCI bus would it then need
to connect to? The digitized audio leaves the southbridge
on separate traces to go to the codec, it is a serial bus
with no other functionality nor data bandwidth issues to
resolve.