910GL datasheet(226/426 Pages) INTEL

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Functional Description

226

Datasheet

12.3

System Memory Configuration Registers Overview

The configuration registers located in the PCI configuration space of the (G)MCH control the

system memory operation. Following is a brief description of configuration registers.

• DRAM Rank Boundary (CxDRBy): The x represents a channel, either A (where x = 0) or

B (where x = 1). The y represents a rank, 0 through 3. DRB registers define the upper

addresses for a rank of DRAM devices in a channel. When the (G)MCH is configured in

asymmetric mode, each register represents a single rank. When the (G)MCH is configured in

a dual interleaved mode, each register represents a pair of corresponding ranks in opposing

channels. There are 4 DRB registers for each channel.

• DRAM Rank Architecture (CxDRAy): The x represents a channel, either A (where x = 0)

or B (where x = 1). The y represents a rank, 0 through 3. DRA registers specify the

architecture features of each rank of devices in a channel. The only architecture feature

specified is page size. When the (G)MCH is configured in asymmetric mode, each DRA

represents a single rank in a single channel. When the (G)MCH is configured in a dual-

channel lock-step or interleaved mode, each DRA represents a pair of corresponding ranks in

opposing channels. There are 4 DRA registers per channel. Each requires only 3 bits, so there

are two DRAs packed into a byte.

• Clock Configuration (CLKCFG): Specifies DRAM frequency. The same clock frequency

will be driven to all DIMMs.

• DRAM Timing (CxDRTy): The x represents a channel, A (where x = 0) or B

(where x = 1). A second register for a channel is differentiated by y, A or B. The DRT

registers define the timing parameters for all devices in a channel. The BIOS programs this

DIMM in the channel.

• DRAM Control (CxDRCy): The x represents a channel, A (where x = 0) or B

(where x = 1). A second register for a channel is differentiated by y, A or B. DRAM refresh

mode, rate, and other controls are selected here.

910GL датащи(PDF) 226 Page - Intel Corporation