Register Descriptions

subordinate bus number is in that range. For a type 1 cycle, the Bus Number is mapped to AD[23:16] during the address phase.

15:11 Device Number.

This field selects one agent on the PCI bus selected by the Bus Number. Device 16 (10h) on Bus #0 is always reserved for programming the CBN. On the bus that the chipset is mapped into (determined by the CBN register), Device Numbers 0-31 are reserved for the 460GX chipset components as shown in Table 2-1. All other devices numbers are forwarded to the selected bus.

1 0:8 Function Number.

This field is mapped to AD[10:8] during PCI configuration cycles. This allows the configuration registers of a particular function in a multi-function device to be accessed.

7:2 Register Number.

This field selects one register within a particular Bus, Device, and Function as specified by the other fields in the Configuration Address Register. This field is mapped to AD[7:2] during PCI configuration cycles.

1:0 reserved (0)

2.3.2CONFIG_DATA: Configuration Data Register

I/O Address:

CFCh

Size:

32 bits

Default Value:

00000000h

Attribute:

Read/Write

Sticky:

No

Locked:

No

CONFIG_DATA is a 32 bit read/write window into configuration space. The portion of configuration space that is referenced by CONFIG_DATA is determined by the contents of

CONFIG_ADDRESS.

Bits Description

31:0 Configuration Data Window (CDW).

If bit 31 of CONFIG_ADDRESS is 1 any I/O reference that falls in the CONFIG_DATA I/O space will be mapped to configuration space using the contents of

CONFIG_ADDRESS.

2.4Error Handling Registers

2.4.1SAC

2.4.1.1

SECTID: SEC ITID

 

 

 

 

Bus CBN, Device Number:

00h

Function:

0

 

Address Offset:

80h

Size:

8 bits

 

Default Value:

00h

Attribute:

Read Only/Write

 

 

 

 

Clear, Read/Write

 

Sticky:

Yes

Locked:

No

This register is used to capture the ITID for a single bit memory ECC error. The ITID can then be used to determine the address of the failure. To force the ITID to be cleared and re-used, write a 1 to bit 6. This register is set anytime that the SEC bit is sent from the SDC to the SAC on a ’Retire ITID’ command.

Intel® 460GX Chipset Software Developer’s Manual

2-5