From a technical perspective, I remember VIA 686B southbridge supports special logics for trapping legacy SoundBlaster compatible I/O, so the driver actually uses that to emulate SBPro compatibility in DOS with AC97 audio. This was something that Intel had never bothered to support, but unfortunately VIA unique proposition wasn't very successful and not many people would buy into it. In fact, with PCI bus as the north-south interconnect in this generation of VIA chipsets, any PCI addon sound could trap SB I/O flowing downstream and implement their own SBPro emulation, making AC97 solution an even harder sell in general.
--------------------------------------------------------------------------------6.0 Legacy Audio Support-------------------------------------------------------------------------------- Legacy audio (Sound Blaster* and Sound Blaster Pro*) is hardware accelerated by default. However, if you are installing this driver on a CS4232 or CS4236, it is recommended that you use Microsoft Sound Blaster emulation.
C-media Onboard Ac97 Audio Driver For Mac
What I discussed earlier was a generic SoundBlaster Pro and SWMIDI solution for *ANY* AC97 audio controller with WDM audio driver. You are right that VIA chipsets has special logic that works with their software for pure DOS support. However, Microsft WDM audio specification already includes SoundBlaster Pro and SWMIDI emulation through the OS if one plays the DOS games from Win9x DOS box, without the needs of any real-mode drivers from CONFIG.SYS or AUTOEXEC.BAT. I confirmed that SoundBlaster Pro wave/pcm playback indeed worked very well, but not the SWMIDI. The WDM audio driver even provides a correct BLASTER env (BLASTER=A220 I5 D1 P330 T4) a SoundBlaster Pro and MIDI port at 330h. I expected the MIDI support would have been routed to DirectMusic Roland GS synthesizer licensed by Microsoft for games supporting General MIDI, but that was not the case, which was a let-down. 2ff7e9595c
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