VT82C686B
PCI Configuration Space I/O
PCI configuration space accesses for functions 0-6 use PCI
configuration mechanism 1 (see PCI specification revision 2.2
for more details). The ports respond only to double-word
accesses. Byte or word accesses will be passed on unchanged.
There are 7 “functions” implemented in the VT82C686B:
Function # Function
0
1
2
3
4
PCI to ISA Bridge
IDE Controller
Port CFB-CF8 - Configuration Address .........................RW
31 Configuration Space Enable
USB Controller Ports 0-1
USB Controller Ports 2-3
0
1
Disable ...................................................default
Convert configuration data port writes to
configuration cycles on the PCI bus
Power Management, SMBus & Hardware
Monitor
........................................ always reads 0
30-24 Reserved
5
6
AC97 Audio Codec Controller
MC97 Modem Codec Controller
23-16 PCI Bus Number
Used to choose a specific PCI bus in the system
15-11 Device Number
Used to choose a specific device in the system
10-8 Function Number
Used to choose a specific function if the selected
device supports multiple functions
7-2 Register Number
The following sections describe the registers and register bits
of these functions.
Used to select a specific DWORD in the device’s
configuration space
........................................ always reads 0
1-0 Fixed
Port CFF-CFC - Configuration Data ..............................RW
Revision 1.71 June 9, 2000
-54-
Function 0 Registers - PCI to ISA Bridge
ETC [ ETC ]
