obio —
introduction to Macintosh On-Board IO bus support and
  drivers
obio0 at pci? dev ? function ?
The obio interface serves as an abstraction used by the
  autoconfiguration system to help find and attach devices (e.g. the Ethernet or
  disk controllers) connected to the Macintosh onboard I/O bus.
NetBSD includes machine-dependent On-Board drivers,
  sorted by device type and driver name:
  - esp
- NCR 53C9x SCSI interfaces.
- mesh
- Apple Macintosh Enhanced SCSI Hardware SCSI interfaces.
 
  - wdc
- Standard IDE/ATAPI type hard drive controllers.
- mediabay
- Standard IDE/ATAPI type CD-ROM drive controllers in PowerBooks.
 
  - bm
- Apple BMac ethernet interface.
- mc
- Apple MACE ethernet interface.
- gem
- GMAC ethernet interface.
- wi
- WaveLAN/IEEE and PRISM-II 802.11 wireless interfaces.
 
  - zsc
- Zilog 8530 serial communications interfaces.
 
  - awacs
- Apple's ‘audio waveform amplifier and converter for sound’
      audio device found on most macppc models.
 
  - adb
- Apple Desktop Bus for keyboards, mice, and other input devices.
- nvram
- Placeholder device for the persistent system settings.
 
adb(4),
  esp(4),
  gem(4),
  macppc/autoconf(4),
  macppc/awacs(4),
  macppc/bm(4),
  macppc/intro(4),
  macppc/mesh(4),
  mc(4),
  wdc(4),
  wi(4),
  zsc(4)
obio first appeared in NetBSD
  1.2.