Intel
82801BA ICH2 Datasheet
6-3
Register and Memory Mapping
6.3.1
Fixed I/O Address Ranges
Table 6-2
shows the fixed I/O decode ranges from the processor perspective. Note that for each I/O
range, there may be a separate behavior for reads and writes. The hub interface cycles that go to
target ranges that are marked as “Reserved” are not decoded by the ICH2; they are passed to PCI. If
a PCI master targets one of the fixed I/O target ranges, it will be positively decoded by the ICH2 in
Medium speed.
Refer to
Table A-1
for a complete list of all fixed I/O registers. Address ranges that are not listed or
marked “Reserved” are NOT decoded by the ICH2 (unless assigned to one of the variable ranges).
Table 6-2. Fixed I/O Ranges Decoded by ICH2
I/O Address
Read Target
Write Target
Internal Unit
00h–08h
DMA Controller
DMA Controller
DMA
09h–0Eh
RESERVED
DMA Controller
DMA
0Fh
DMA Controller
DMA Controller
DMA
10h–18h
DMA Controller
DMA Controller
DMA
19h–1Eh
RESERVED
DMA Controller
DMA
1Fh
DMA Controller
DMA Controller
DMA
20h–21h
Interrupt Controller
Interrupt Controller
Interrupt
24h–25h
Interrupt Controller
Interrupt Controller
Interrupt
28h–29h
Interrupt Controller
Interrupt Controller
Interrupt
2Ch–2Dh
Interrupt Controller
Interrupt Controller
Interrupt
2Eh–2Fh
LPC SIO
LPC SIO
Forwarded to LPC
30h–31h
Interrupt Controller
Interrupt Controller
Interrupt
34h–35h
Interrupt Controller
Interrupt Controller
Interrupt
38h–39h
Interrupt Controller
Interrupt Controller
Interrupt
3Ch–3Dh
Interrupt Controller
Interrupt Controller
Interrupt
40h–42h
Timer/Counter
Timer/Counter
PIT (8254)
43h
RESERVED
Timer/Counter
PIT
4E–4F
LPC SIO
LPC SIO
Forwarded to LPC
50h–52h
Timer/Counter
Timer/Counter
PIT
53h
RESERVED
Timer/Counter
PIT
60h
Microcontroller
Microcontroller
Forwarded to LPC
61h
NMI Controller
NMI Controller
processor I/F
62h
Microcontroller
Microcontroller
Forwarded to LPC
63h
NMI Controller
NMI Controller
processor I/F
64h
Microcontroller
Microcontroller
Forwarded to LPC
65h
NMI Controller
NMI Controller
processor I/F
66h
Microcontroller
Microcontroller
Forwarded to LPC
67h
NMI Controller
RESERVED
5
NMI Controller
processor I/F
70h
NMI and RTC Controller
RTC
71h
RTC Controller
RTC Controller
RTC
72h
RTC Controller
NMI and RTC Controller
RTC
73h
RTC Controller
RTC Controller
RTC
74h
RTC Controller
NMI and RTC Controller
RTC
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