4.11 Base Address Register 0
The bridge requires no additional resources. Base address register 0 is read-only and returns 0s when read.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Name
Type
Default
Bit
Base address register 0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
9
R
0
8
R
0
7
R
0
6
R
0
5
R
0
4
R
0
3
R
0
2
R
0
1
R
0
0
15
14
13
12
11
10
Name
Type
Default
Base address register 0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Register:
Type:
Base address register 0
Read-only
Offset:
Default:
10h
0000 0000h
4.12 Base Address Register 1
The bridge requires no additional resources. Base address register 1 is read-only and returns 0s when read.
Bit
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Name
Type
Default
Bit
Base address register 1
R
0
R
0
R
0
R
0
R
0
R
0
R
0
9
R
0
8
R
0
7
R
0
6
R
0
5
R
0
4
R
0
3
R
0
2
R
0
1
R
0
0
15
14
13
12
11
10
Name
Type
Default
Base address register 1
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
R
0
Register:
Type:
Base address register 1
Read-only
Offset:
Default:
14h
0000 0000h
4.13 Primary Bus Number Register
The primary bus number register indicates the primary bus number to which the bridge is connected. The bridge uses
this register, in conjunction with the secondary bus number and subordinate bus number registers, to determine when
to forward PCI configuration cycles to the secondary buses.
Bit
7
6
5
4
3
2
1
0
Name
Type
Default
Primary bus number
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Register:
Type:
Offset:
Default:
Primary bus number
Read/write
18h
00h
4–7