Specifications

17 January 1997 – Subject to Change
System Address Mapping A–33
PCI-to-Physical Memory Addressing
Figure A–15 PCI Target Window Compare
The comparison logic associated with ad<63:32> is used only for DAC with
window 3. The other windows recognize only 32-bit PCI addresses (SAC).
For a hit to occur on a DAC address, address bits <63:40> must be zero and
ad<39:32> must match the W_DAC[DAC_BASE<7:0>]. The low-order address
bits ad<31:20> must also hit. This scheme allows a NATURALLY ALIGNED
1MB-to-4GB PCI window to be placed anywhere in the first 1TB of a 64-bit PCI
address space.
When an address match occurs with a PCI target window, the CIA translates the
32-bit PCI address ad<31:0> to a memory address <33:0>. The translated address is
generated in one of two ways as determined by Wn_BASE[Wn_BASE_SG].
Zero
Detect
Hit (Window 3 Only)
W_DAC
63
40 39
32
31
02
n n-1
20 19
PCI Address
Target
Window
Hit Logic
Wn_MASK
Wn_BASE
Compare &
Hit Logic
LJ04273A.AI5
31 n
n-1
20
00000000
11111
DAC
XXXXX
31 n
n-1
20
Hit Window 3
Hit Window 2
Hit Window 1
Hit Window 0
Window 3 SG Bit
Window Enable (WENB)
Window 2 SG Bit
Window 1 SG Bit
Window 0 SG Bit