Intel SDS2 manual O Subsystem, 1 32-bit, 33-MHz PCI Subsystem, Device IDs Idsel

Intel® Server Board SDS2 I/O Subsystem

4.I/O Subsystem

4.1PCI Subsystem

The primary I/O bus for SDS2 DP Server Board is PCI, with three PCI bus segments. The PCI buses comply with the PCI Local Bus Specification, Rev 2.2. The P32-A bus segment is directed through the HE-SL North Bridge while the two 64bit segments, P64-B and P64-C, are directed through the CIOB20 I/O Bridge. The table below lists the characteristics of the three PCI bus segments.

Table 4. PCI Bus Segment Characteristics

PCI Bus Segment	Voltage	Width	Speed	Type	PCI Slots
P32-A	5 V	32-bits	33-MHz	Peer Bus	Slots 3 and 4 – Full Length
P64-B	3.3 V	64-bits	66-MHz	Peer Bus	Slots 1 and 2 – Full Length
P64-C	3.3 V	64-bits	66-MHz	Peer Bus	Slots 5 and 6 – Full Length

Note: When an add-in 33-MHz PCI card is plugged into a P64 bus segment, such as in the P64- C slot 5, this reduces the bus speed for all devices attached to that bus segment, including the on-board SCSI controller.

4.1.132-bit, 33-MHz PCI Subsystem

All 32-bit, 33-MHz PCI I/O for the SDS2 Server Board is directed through the HE-SL North Bridge. The 32-bit, 33-MHz PCI segment created by the HE-SL is called the P32-A segment. The P32-A segment supports full-length, full-height PCI cards and contains the following embedded devices and connectors:

∙2D/3D Graphics Accelerator: ATI RAGE XL Video Controller

∙Two Network Interface Controller: Intel 82550 Fast Ethernet Controller

∙PCI Slots 3 and 4

∙CSB5 South Bridge (PCI-to-LPC bridge)

Each of the embedded devices above, except for the CSB5 South Bridge, is allocated a GPIO to disable the device.

4.1.1.1Device IDs (IDSEL)

Each device under the PCI hub bridge has its IDSEL signal connected to one bit of AD [31:16], which acts as a chip select on the PCI bus segment in configuration cycles. This determines a unique PCI device ID value for use in configuration cycles. The following table shows the bit to which each IDSEL signal is attached for P32-A devices, and corresponding device description.

Revision 1.2	11
Order Number:	A85874-002