
82815 GMCH
R
Datasheet
111
3.6.16.
SID—Subsystem Identification Register (Device 2)
Address Offset:
2E
2Fh
Default Value:
0000h
Access:
Read/Write-Once
Size:
16 bits
Bit
Description
15:0
Subsystem ID—R/WO.
This value is used to identify a particular subsystem. The default value is
0000h. This field should be programmed by BIOS during boot-up. Once written, this register becomes
Read only. This Register can only be cleared by a Reset.
3.6.17.
ROMADR—Video BIOS ROM Base Address Register (Device 2)
Address Offset:
30
33h
Default Value:
00000000h
Access:
Read Only
Size:
32 bits
The GMCH does not use a separate BIOS ROM; therefore, this is hardwired to 0s.
31
18
17
16
ROM Base Address
(addr bits [31:18])
Address Mask (HW=0;
256 KB addr range)
15
11
10
1
0
Address Mask (cont)
(HW=0; 256 KB addr range)
Reserved
ROM
BIOS En
(HW=0)
Bit
Description
31:18
ROM Base Address
RO.
Hardwired to 0s.
17:11
Address Mask
RO.
Hardwired to 0s to indicate 256 KB address range.
10:1
Reserved. Hardwired to 0s.
0
ROM BIOS Enable
RO.
0 = ROM not accessible.
3.6.18.
CAPPOINT—Capabilities Pointer Register (Device 2)
Address Offset:
34h
Default Value:
DCh
Access:
Read Only
Size:
8 bits
Bit
Description
7:0
Pointer to the start of AGP standard register block.
Since there is no AGP bus on the GMCH , the
value of this field is DCh.
DCh = Points to the Power Management Capabilities ID Register