Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
443
Messaging Unit—Intel
®
81341 and 81342
4.9.22
Index Address Register - IAR
The Index Address Register (IAR) contains the offset of the least recently accessed
Index Register. It is written by the MU when the Index Registers are written by a Host
I/O Interface agent. The register is not updated until the Index Interrupt bit in the
Inbound Interrupt Status Register is cleared.
The local memory address of the Index Register least recently accessed is computed by
adding the Index Address Register to the Inbound ATU Translate Value Register.
Table 286. Index Address Register - IAR
Bit
Default
Description
31:12
000000H Reserved
11:02
00H 00
2
Index Address - is the local memory offset of the Index Register written (050H to FFCH)
01:00
00
2
Reserved
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rv rv rv rv rv rv rv rv rv rv rv rv rv rv rv rv rv rv rv rv ro ro ro ro ro ro ro ro ro ro rv rv
na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
IAR
internal bus address offset
4080H