82845PE Datasheet, PDF (111/176 Pages) Intel Corporation – 82845GE Graphics and Memory Controller Hub (GMCH) and 82845PE Memory Controller Hub (MCH)

Functional Description
5.2
System Memory Controller
The (G)MCH supports DDR SDRAM memory only.
5.2.1
DDR SDRAM Interface Overview
The (G)MCH can support DDR333 and DDR266 SDRAM mode with SSTL_2 signaling. The
(G)MCH includes support for:
• Up to 2 GB of 333 MHz or 266 MHz DDR SDRAM
• DDR266/DDR333 unbuffered 184-pin non-ECC DDR SDRAM DIMMs
• Maximum of two DIMMs, single-sided and/or double-sided
• Byte masking on writes through data masking
The bank address lines and the address lines allow the (G)MCH to support 64-bit wide DIMMs
using 64-Mb, 128-Mb, 256-Mb, and 512-Mb SDRAM technology. The four chip select lines
support up to four rows of double-sided SDRAM DIMMs. For write operations of less than a
QWord, the (G)MCH performs a byte-wise write. The (G)MCH does not support ECC DIMMs,
registered DIMMs, or double-sided x16 DIMMs.
5.2.2 Memory Organization and Configuration
In the following discussion the term “row” refers to a set of memory devices that are
simultaneously selected by a chip select signal. The (G)MCH supports a maximum of 4 rows of
memory. For the purposes of this discussion, a “side” of a DIMM is equivalent to a “row” of
SDRAM devices.
The memory bank address lines and the address lines allow the (G)MCH to support 64-bit wide x8
and x16 DIMMs using 64-Mb, 128-Mb, 256-Mb, and 512-Mb SDRAM technology.
For the DDR SDRAM interface, Table 5-2 lists the supported DDR DIMM configurations. Note
that the (G)MCH supports configurations defined in the JEDEC DDR DIMM specification only
(A,B,C). Non-JEDEC standard DIMMs (e.g., double-sided x16 DDR SDRAM DIMMs) are not
supported. For more information on DIMM configurations, refer to the JEDEC DDR DIMM
specification.
Table 5-2. Supported DDR DIMM Configurations
Density
Device
Width
Single /
Double
184 pin
DDR
DIMMs
64 Mbit
X8
X16
128 Mbit
X8
X16
SS/DS SS/DS
SS/DS
SS/DS
64 MB / 32 MB / 128 MB / 64 MB /
128 MB
NA
256 MB
NA
256 Mbit
X8
X16
512 Mbit
X8
X16
SS/DS
SS/DS
SS/DS
SS/DS
256 MB / 128 MB / 512 MB / 256 MB/
512 MB
NA
1024 MB
NA
Intel^® 82845GE/82845PE Datasheet
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