T13/2132-D Revision 3

June 23, 2010

8.20.2 Interface Path

The Interface Path field at offset 48 allows software external to a system BIOS to locate mass storage device interface chips. The format of this field shall be dependent on the Host Bus type, offsets 36 through 39 of the result buffer.

Table 23 — Interface Path Definitions (part 1 of 2)

Host Bus Type

Offset

Type

Definition

ISA

48

Word

16-bit base address

 

 

 

 

 

50

Word

Reserved

 

 

 

 

 

52

DWord

Reserved

 

 

 

 

PCI

48

Byte

PCI bus number. Values 00h through FEh shall represent a valid PCI bus.

 

 

 

Value FFh shall indicate that this field is not used.

 

 

 

 

 

49

Byte

PCI slot number. Values 00h through FEh shall represent a valid PCI slot.

 

 

 

Value FFh shall indicate that this field is not used.

 

 

 

 

 

50

Byte

PCI function number. Values 00h through FEh shall represent a valid PCI

 

 

 

function.

 

 

 

Value FFh shall indicate that this field is not used.

 

 

 

 

 

51

Byte

Channel number. If more than one interface of the same type is accessed

 

 

 

through a single Bus, Slot, Function, then the channel number shall identify

 

 

 

each interface. If there is only one interface, the content of this field shall be

 

 

 

cleared to zero. If there are two interfaces, such as an ATA Primary and

 

 

 

Secondary interface, the primary interface shall be zero, and the secondary

 

 

 

interface shall be one.

 

 

 

Values 00h through FEh shall represent a valid Channel Number.

 

 

 

FFh shall indicate that this field is not used.

 

 

 

If the device is connected to a SATA controller functioning in non-PATA

 

 

 

emulation mode, this byte shall be FFh.

 

 

 

 

 

52

DWord

Reserved

 

 

 

 

50

Working Draft Enhanced Disk Drive - 4 (EDD-4)

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Western Digital T13/2132-D Revision June 23 Interface Path, Interface Path Definitions part 1 Host Bus Type Offset