RG82855GMESL72L Datasheet, PDF (150/213 Pages) Intel Corporation – Intel® 855GM/855GME Chipset Graphics and Memory Controller Hub (GMCH)

Functional Description
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6.4.4.2
Alpha Stretch BLT
The stretch BLT function can stretch source data in the X and Y directions to a destination larger
or smaller than the source. Stretch BLT functionality expands a region of system memory into a
larger or smaller region using replication and interpolation. The stretch BLT function also
provides format conversion and data alignment.
6.4.5 Planes and Engines
The GMCH display can be functionally delineated into planes and engines (pipes and ports). A
plane consists of rectangular shaped image that has characteristics such as source, size, position,
method, and format. These planes get attached to source surfaces, which are rectangular system
memory surfaces with a similar set of characteristics. They are also associated with a particular
destination pipe.
A pipe consists of a set of planes that will be combined with a timing generator. A port is the
destination for the result of the pipe. The GMCH supports one Analog Output Port, one LVDS
LCD Flat Panel Port, and two DVO ports. In conclusion, planes are associated with pipes and
pipes are associated with ports.
6.4.5.1 Dual Pipe Independent Display Functionality
The display consists of two display pipes, A and B. Pipes have a set of planes that are assigned to
them as sources. The analog display port may only use Pipe A or Pipe B, the DVO B or C ports
may use either Pipe A or Pipe B, and the Internal LVDS interface may only use Pipe B. This
limits the resolutions available on a digital display when an analog CRT is active.
Table 37. Dual Display Usage Model (Intel^® 852GM GMCH)
Display Pipe A
CRT
DVO B or C or Both
CRT
DVO B or C or Both
CRT/DVO B or C or Both (No TV Support)
Display Pipe B
Internal LVDS
CRT
DVO B or C or Both
Internal LVDS
Internal LVDS
6.4.6
Hardware Cursor Plane
The GMCH supports two hardware cursors. The cursor plane is one of the simplest display
planes. With a few exceptions, has a fixed size of 64 x 64 and a fixed Z-order (top). In legacy
modes, cursor can cause the display data below it to be inverted. In the alpha blend mode, true
color cursor data can be alpha blended into the display stream. It can be assigned to either display
pipe A or display pipe B and dynamically flipped from one to the other when both are running.
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