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User Guide XB1 COM Express Module
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Graphics Subsystem
The graphics subsystem is part of the versatile Intel i915GM Graphics/Memory Controller Hub
(GMCH), and is also known as Intel Graphics Media Accelerator (GMA) 900. As an alternative, PCI
Express based graphics is supported (requires discrete PEG controller present on the carrier board).
The main features of the GMA900 are:
< Dual Serial Digital Video Output (SDVO) - allows for two independent DVI connectors
< RGB output - suitable for a VGA style connector
< TV out (HDTV resolution)
< LVDS wide panel support
For legacy CRT style monitors, the XB1 COM Express Module is provided with RGB signals on the
J-COM A-B connector, suitable for a VGA D-Sub accommodated on the carrier board. Also the TV out
and the LCD panel signals (LVDS port) are routed to the J-COM A-B connector.
The GMCH multiplexes a PCI Express Graphics interface with two Intel SDVO ports. The SDVO ports
can each support a single-channel SDVO device. If both ports are active in single-channel mode, they
can have different display timing and data. Alternatively the SDVO ports can be combined to support
dual channel devices, enabling higher resolutions and refresh rates. On the XB1 COM Express Module,
the SDVO/PEG signals are routed to the connector J-COM C-D. Typically, one or two discrete display
transmitter chips located on the carrier board are used to convert Intels proprietary, PCI express based
SDVO interfaces to the differential DVI signals required for attachment of modern flat panel monitors.
E.g., the SiI1362 (Silicon Image) transmitter uses PanelLink® Digital technology to support displays
ranging from VGA to UXGA resolutions (25 - 165Mpps) in a single link interface. With two DVI
connectors on the carrier board, independent dual screen operation is available (this also applies for
one DVI and one D-Sub connector).
The GMCH supports several video resolutions and refresh rates. A partial list is contained in the table
below. Please note, that flat-panel displays should be operated with their native (maximum) resolution
at 60Hz refresh rate (some models also accept 75Hz). 16-bit high colour mode is recommended.
Partial List of i915GM GMCH Video Modes (analog / digital)
Resolution 60Hz 70Hz 72Hz 75Hz 85Hz
640x480 T / TT / TT / TT / TT / T
800x600 T / TT / TT / TT / TT / T
1024x768 T / T
1)
T / TT / TT / TT / T
1280x1024 T / T
1)
T / TT / TT / TT / T
1600x1200 T / T
1)
2)
T / - T / - T / - T / -
2048x1536 T / - T / - T / - T / - - / -
1)
This video mode is suitable for popular flat-panel displays
2)
In dual screen mode 2 x 1600x1200, 32-bit true colours are not available for both outputs simultaneously
Graphics drivers for the i915GM can be downloaded from the Intel website.