82801DB Datasheet, PDF (389/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

IDE Controller Registers (D31:F1)
10.1.15 EXBAR — Expansion Base Address Register (IDE—D31:F1)
Address Offset: 24h–27h
Default Value: 00h
Attribute: R/W
Size:
32 bits
Note: This is a memory mapped BAR that requires 1 KB of DWord-aligned memory that is Intel reserved
for future functionality. BIOS needs to program the base address for a 1-KB memory space.
Bit
Description
31:0 Intel Reserved for Future Functionality.
10.1.16
IDE_SVID — Subsystem Vendor ID Register (IDE—D31:F1)
Address Offset:
Default Value:
Lockable:
2Ch–2Dh
00h
No
Attribute: R/WO
Size:
16 bits
Power Well: Core
Bit
Description
Subsystem Vendor ID (SVID) — R/Write-Once. The SVID register, in combination with the
Subsystem ID (SID) register, enables the operating system (OS) to distinguish subsystems from
15:0
each other. Software (BIOS) sets the value in this register. After that, the value can be read, but
subsequent writes to this register have no effect. The value written to this register will also be
readable via the corresponding SVID registers for the USB UHCI #1, USB UHCI #2, USB UHCI #3,
and SMBus functions.
10.1.17 IDE_SID — Subsystem ID Register (IDE—D31:F1)
Address Offset:
Default Value:
Lockable:
2Eh–2Fh
00h
No
Attribute: R/WO
Size:
16 bits
Power Well: Core
Bit
Description
Subsystem ID (SID) — R/Write-Once. The SID register, in combination with the SVID register,
enables the operating system (OS) to distinguish subsystems from each other. Software (BIOS)
15:0 sets the value in this register. After that, the value can be read, but subsequent writes to this register
have no effect. The value written to this register will also be readable via the corresponding SID
registers for the USB UHCI #1, USB UHCI #2, USB UHCI #3, and SMBus functions.
Intel^® 82801DB ICH4 Datasheet
389