RG82855GMESL72L Datasheet, PDF (25/213 Pages) Intel Corporation – Intel® 855GM/855GME Chipset Graphics and Memory Controller Hub (GMCH)

Intel® 855GM/855GME Chipset GMCH Overview
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Table 1. DDR SDRAM Memory Capacity
Technology
Width
128 Mb
16
256 Mb
16
512 Mb
16
128 Mb
8
256 Mb
8
512 Mb
8
System Memory
Capacity
256 MB
512 MB
1 GB
256 MB
512 MB
1 GB
System Memory
Capacity with Stacked
Memory
-
-
-
512 MB
1 GB
2 GB
2.4
The GMCH system memory interface supports a thermal throttling scheme to selectively throttle
reads and/or writes. Throttling can be triggered either by the on-die thermal sensor, or by preset
write bandwidth limits. Read throttle can also be triggered by an external input pin. The memory
controller logic supports aggressive Dynamic Row Power Down features to help reduce power
and supports Address and Control line Tri-stating when DDR SDRAM is in an active power
down or in self refresh state.
The GMCH system memory architecture is optimized to maintain open pages (up to 16-kB page
size) across multiple rows. As a result, up to 16 pages across four rows is supported. To
complement this, the GMCH will tend to keep pages open within rows, or will only close a single
bank on a page miss. The GMCH supports only four bank memory technologies.
Graphics Features
The GMCH IGD provides a highly integrated graphics accelerator delivering high performance
2D, 3D, and video capabilities. With its interfaces to UMA using a DVMT configuration, an
analog display, a LVDS port, and two digital display ports (e.g. flat panel), the GMCH can
provide a complete graphics solution.
The GMCH also provides 2D hardware acceleration for block transfers of data (BLTs). The BLT
engine provides the ability to copy a source block of data to a destination and perform raster
operations (e.g., ROP1, ROP2, and ROP3) on the data using a pattern, and/or another destination.
Performing these common tasks in hardware reduces CPU load, and thus improves performance.
High bandwidth access to data is provided through the system memory interface. The GMCH
uses Tiling architecture to increase system memory efficiency and thus maximize effective
rendering bandwidth. The Intel 855GM/855GME GMCH improves 3D performance and quality
with 3D Zone rendering technology. The Intel 855GME GMCH also supports Video Mixer
rendering, and Bi-Cubic filtering.
Datasheet
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