Intel
82801BA ICH2 Datasheet
6-5
Register and Memory Mapping
6.3.2
Variable I/O Decode Ranges
Table 6-3
shows the Variable I/O Decode Ranges. They are set using Base Address Registers
(BARs) or other configuration bits in the various PCI configuration spaces. The PNP software (PCI
or ACPI) can use their configuration mechanisms to set and adjust these values.
When a cycle is detected on the hub interface, the ICH2 positively decodes the cycle. If the
response is on the behalf of an LPC device, ICH2 will forward the cycle to the LPC interface.
Refer to
Table A-2
for a complete list of all variable I/O registers.
Warning:
The Variable I/O Ranges should not be set to conflict with the Fixed I/O Ranges. Unpredictable
results if the configuration software allows conflicts to occur. The ICH2 does not perform any
checks for conflicts.
Table 6-3. Variable I/O Decode Ranges
Range Name
Mappable
Size (Bytes)
Target
ACPI
Anywhere in 64 KB I/O Space
64
Power Management
IDE
Anywhere in 64 KB I/O Space
16
IDE Unit
USB #1
Anywhere in 64 KB I/O Space
32
USB Unit 1
SMBus
Anywhere in 64 KB I/O Space
16
SMB Unit
AC’97 Audio Mixer
Anywhere in 64 KB I/O Space
256
AC’97 Unit
AC’97 Bus Master
Anywhere in 64 KB I/O Space
64
AC’97 Unit
AC’97 Modem Mixer
Anywhere in 64 KB I/O Space
256
AC’97 Unit
TCO
96 Bytes above ACPI Base
32
TCO Unit
GPIO
Anywhere in 64 KB I/O Space
64
GPIO Unit
Parallel Port
3 ranges in 64 KB I/O Space
8
LPC Peripheral
Serial Port 1
8 Ranges in 64 KB I/O Space
8
LPC Peripheral
Serial Port 2
8 Ranges in 64 KB I/O Space
8
LPC Peripheral
Floppy Disk Controller
2 Ranges in 64 KB I/O Space
8
LPC Peripheral
MIDI
4 Ranges in 64 KB I/O Space
2
LPC Peripheral
MSS
4 Ranges in 64 KB I/O Space
8
LPC Peripheral
SoundBlaster
2 Ranges in 64 KB I/O Space
32
LPC Peripheral
LAN
Anywhere in 64 KB I/O Space
64
LAN Unit
USB #2
Anywhere in 64 KB I/O Space
32
USB Unit 2
LPC Generic 1
Anywhere in 64 KB I/O Space
128
LPC Peripheral
LPC Generic 2
Anywhere in 64 KB I/O Space
16
LPC Peripheral
Monitors 4:7
Anywhere in 64 KB I/O Space
16
LPC Peripheral or Trap on
PCI
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