Specifications

17 January 1997 – Subject to Change
System Address Mapping A–41
PCI-to-Physical Memory Addressing
A.4.4 Suggested Use of a PCI Window
Figure A–20 shows a power-up PCI window assignment (as configured by firmware)
and Table A–13 lists the details. PCI window 0 was chosen for the 8MB-to-16MB
ISA region because this window incorporates the mem_cs_l logic. PCI window 3
was not used as it incorporates the DAC cycle logic. PCI window 1 was chosen
arbitrarily for the 1GB direct-mapped region, and PCI window 2 is not assigned.
Figure A–20 Default PCI Window Allocation
21164
Memory Space
PCI
Memory Space
4GB
4GB
2GB
1GB
1GB
Scatter-Gather
Window 0
Direct-Mapped
Window 1
16MB
8MB
0MB
0
1GB
1GB
8MB
LJ-04278.AI