Datasheet

64 Datasheet

4.8.8 HDR – Header Type Register

Address Offset: 0Eh

Default Value: 80h

Access: Read Only

Size: 8 bits

This register identifies the header layout of the configuration space. No physical register exists at

this location.

Bit Description

7:0 PCI Header (HDR): This field always returns 80 to indicate that Device #0 is a multifunction device. If

Functions other than 0 are disabled, this field returns a 00 to indicate that the GMCH is a single function

device with standard header layout. Writes to this location have no effect.

4.8.9 SVID – Subsystem Vendor Identification Register

Address Offset: 2C-2Dh

Default Value: 0000h

Access: Read/Write Once

Size: 16 bits

This value is used to identify the vendor of the subsystem.

Bit Description

15:0 Subsystem Vendor ID (SUBVID): This field should be programmed during boot-up to indicate the

vendor of the system board. After it has been written once, it becomes Read Only.

4.8.10 SID – Subsystem Identification Register

Address Offset: 2E-2Fh

Default Value: 0000h

Access: Read/Write Once

Size: 16 bits

This value is used to identify a particular subsystem.

Bit Description

15:0 Subsystem ID (SUBID): This field should be programmed during BIOS initialization. After it has been

written once, it becomes Read Only.