On Thu, 2007-07-19 at 18:12 +0100, David Webb wrote:
(2.2a Where can an AD'97 manual be found? - I could not find one on the intel site)
The AC'97 PRM is here: http://download.intel.com/design/chipsets/manuals/30701701.pdf The Intel HD Audio PRM is here: http://download.intel.com/design/chipsets/manuals/30234903.pdf
Both are specs for onboard codec buses. More recent chipsets utilize the HD Audio bus specification, as it gives superior output capabilities and supports more devices (like modems and other vendor defined codecs). One of the main improvements over the AC'97 spec is the uniform programming interface (which is one of the problems you seem to be running into).
Beyond that, others will need to interject more answers to your questions.