The LX, SS10, and SS20, as well as the Tadpole Sparcbook 3 and the Sun SparcStation Voyager portables use dbri for audio. Most DBRI-equipped systems have an interface for the Sun SpeakerBox. It provides a speaker, and stereo line out, stereo line in, stereo headphone, and monaural microphone connections. The onboard interface lacks line in and line out support. LX machines and Sun SpeakerBoxes have Crystal Semiconductor 4215 codecs.
Machines provide connectors for microphone and headphone.
As I already mentioned, the 79C30 is actually an isdn controller that Sun used for audio on these machines. If you didn't get it above, here's the info in table form. For some reason Lynx hates these tables. The OSS mixer ioctl support was heavily reworked in August 1999 to behave more like a PC, and to simply behave better. Control of each input and output is now possible using e.g. aumix.