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AC’97 Audio Controller Registers (D31:F5)
12-6
82801AA and 82801AB Datasheet
12.1.12
SVID—Subsystem Vendor ID Register (Audio—D31:F5)
Address Offset:
Default Value:
Lockable:
2Dh
–
2Ch
0000h
No
Attribute:
Size:
Power Well:
Write-Once
16 bits
Core
This register should be implemented for any function that could be instantiated more than once in a
given system. For example, a system with 2 audio subsystems (one down on the motherboard and
the other plugged into a PCI expansion slot) should have the SVID register implemented. The
SVID register, in combination with the Subsystem ID register, enable the operating environment to
distinguish one audio subsystem from the other(s).
This register is implemented as write-once register. Once a value is written to it, the value can be
read back. Any subsequent writes will have no effect.
12.1.13
SID—Subsystem ID Register (Audio—D31:F5)
Address Offset:
Default Value:
Lockable:
2Fh
–
2Eh
0000h
No
Attribute:
Size:
Power Well:
RO
16 bits
Core
This register should be implemented for any function that could be instantiated more than once in a
given system (for example, a system with 2 audio subsystems, one down on the motherboard and
the other plugged into a PCI expansion slot). The SID register, in combination with the Subsystem
Vendor ID register make it possible for the operating environment to distinguish one audio
subsystem from the other(s).
This register is implemented as write-once register. Once a value is written to it, the value can be
read back. Any subsequent writes will have no effect.
12.1.14
INTR_LN—Interrupt Line Register (Audio—D31:F5)
Address Offset:
Default Value:
Lockable:
3Ch
00h
No
Attribute:
Size:
Power Well:
R/W
8 bits
Core
This register indicates which PCI interrupt line is used for the AC’97 module interrupt.
Bit
Description
15:0
Subsystem Vendor ID Value.
Bit
Description
15:0
Subsystem ID Value.
Bit
Description
7:0
Interrupt Line:
This data is not used by the ICH. It is used to communicate to software the interrupt
line that the interrupt pin is connected to.