Hi Drew,
With initial help from Deomsh over at the 'Audio driver for Realtek HD Audio' thread, I have been using Watler's driver to get HD Audio working on Windows 98 laptops for a while, and came across one that I had some trouble with. Currently I have managed to get SoundMax AD1981HD working on a HP6710b laptop, IDT 92HD75B3X5 working on a HP 6550b laptop, and Realtek ALC272 working on a Lenovo S10-3 laptop with Watler's.
Attempting a Lenovo S20-30 proved difficult as the codec was identified as 10EC 0280 of which I could not locate a datasheet for. I used HDAICIN responses to identify all NID's/CAPS and found the connection path to be the same as ALC 272 (and most other Realtek codecs from the looks of things) with $01 = AFG, $02 = DAC, $0C = Audio Out connected to NID $14, and NID $14 = Line Out. I managed to create a working HDAICOUT.HDA file but no sound.
I had stumbled across your driver (great work I can see this being invaluable in the future!) and trialed v16, but sadly no sound to start with. So I re-installed Watler's to try some other options. What I notice is that your driver, although removed from device manager and 're-installed' to Watler's, is maybe still using the registry entries, so when I go to multimedia settings I can see the WDM driver still listed as an option, along with the midi/volume control, however Watler's is selected and installed. The HDA.SYS driver file still exists in windows\system32.
The veeeery interesting thing here is that this combination has helped me to get sound working (although buggy) on the S20-30 laptop! I have no idea how or why this works but hoping you could shed some light on it, or I can provide you some more info that may be able to help you with development? I did try to rename HDA.SYS to HDA.BAK and rebooted but got no sound at reboot which indicates to me that although Watler's driver is installed it is still somehow using HDA.SYS in combination with HDA2.DLL to route the sound to the speaker - I am good with verbs but not with codec initialization, CORB, RIRB etc.
To note: HDAcfg.ini from Watler's driver shows codec index $2 is active, which is incorrect (this is the HDMI audio out, whereas the 10EC 0280 codec is on index $0) so how I am getting any sound at all is a mystery..
At boot I get a high pitched squeal through the speakers until the initial windows start sound finishes, then I can go to sounds and play the sound samples. DirectX 9C is installed and runs the tests all okay.
Happy to assist here with any information I can provide to get you further and help me understand why sound works with this combination, just let me know if anything is required. All the best and I will be following your progress. Cheers!