Specifications

A–44 System Address Mapping
Subject to Change – 17 January 1997
PCI-to-Physical Memory Addressing
Figure A–22 Memory Chip Select Signal (mem_cs_l) Logic
Consequently, the window address area must be large enough to encompass the
mem_cs_l region programmed into the PCI-to-ISA bridge. The remaining window
attributes listed as follows are still applicable and/or required.
•
W0_BASE [Wn_BASE_SG] determines if scatter-gather or direct mapping is
applicable.
•
W0_MASK size information must match the mem_cs_l size for the scatter-
gather and direct-mapping algorithms to correctly use the translated base
register.
•
The mem_cs_l enable bit, W0_BASE [MEMCS_ENABLE], takes precedence
over W0_BASE [W_EN].
mem_cs_l
devsel
1
0
Window 0
Hit Detect
Logic
PCI Address
Wn_BASE
Wn_MASK
W0_BASE<mem_cs_enable>
LJ-04280.AI