Intel 460GX Table 4-1.Address Disposition (Cont’d)

System Address Map

Table 4-1. Address Disposition (Cont’d)

Address Range	Outbound	Inbound	Dest. Decision
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

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.

Intel® 460GX Chipset Software Developer’s Manual 4-9