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Programmer’s Reference Manual 109
Intel® High Definition Audio BIOS Considerations
4 Intel
®
High Definition Audio BIOS
Considerations
The Intel
®
HD Audio controller (Bus #0, Device #27, Function #0) is an ICH7 internal PCI
Express Endpoint device. Software may access the Intel® HD Audio controller registers (including
the memory mapped registers) by byte, word, DWord quantities and on natural boundaries; DWord
accesses must be on dWord boundaries, word accesses on word boundaries, etc. This chapter
describes BIOS requirements for Intel® HD Audio controller support.
4.1 Intel
®
High Definition Audio/AC’ 97 Signal Mode
Selection
The Intel® HD Audio controller and the AC’97 controllers (audio and modem) share the same
physical signal pins to communicate with codecs as Figure 4-1 shows. The Intel® HD Audio/
AC97# Signal Mode (AZ/AC97#) bit at D27:F0:Reg40h[0] determines which one of the two
controllers is connected to the codec.
Figure 4-1. Intel
®
ICH7 High Definition Audio/AC’ 97 Share Signals to Codecs
ICH7
AC’ 97
D30:F2,F3
- ICH7 HD Audio/AC’ 97 Share Signals to Codecs -
HD Audio
D27:F0
ACZ_SDIN[2:0]
ACZ_SDOUT
ACZ_BIT_CLK
ACZ_SYNC
ACZ_RST#
Signal Names
Codecs
X
X
( D27:F0:Reg40h[0] AZ/AC97# )
- HD Audio/AC97Signal Mode Selection
=1
=0
Intel
®
ICH7