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Intel® 460GX Chipset Software Developer’s Manual 4-9
System Address Map
Note: Accesses listed as “unclaimed” in the table for inbound transactions assume the PXB is
programmed correctly. If an access were received up the Expander bus that hits in the listed address
range, then its behavior is the same as outbound transactions to the same range.
Note: The PXB will never respond to an access that it is the master for. This means that an OB access will
not be claimed by the PXB, even if that access hits a range to which the PXB would normally
respond with DEVSEL#.
Note: The only ranges the PXB doesn’t claim are MMBASE to MMT, FEF0_0000h to FEFF_FFFFh, and
4G-16M to 4G. If the PCI card initiates a request to any other address, it will be sent up as TPA or
memory.
FEF0_0000h to FEFF_FFFFh PCI0a unclaimed Reads are sent to PCI-0a for master
abort. Writes get No-Data response
and are dropped. PXB never claims
this range
FF00_0000h to FFFF_FFFFh PCI0a unclaimed Firmware region always enabled
1_0000_0000h to TOM DRAM DRAM main memory (if present) above 4 GB
Above TOM na na BINIT
Table 4-1. Address Disposition (Cont’d)
Address Range Outbound Inbound Dest. Decision