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2.9.1 Digital Video Interface (DVI)
The VMIVME-7805/VME-7805RC have a Digital Visual Interface that provides a
high-speed digital connection for visual data types that are display technology
independent. DVI is a display interface developed in response to the proliferation
of digital flat panel displays. For the most part, these displays are currently
connected to an analog Video Graphics Array (VGA) interface and, thus, require a
double conversion.
The digital signal from the computer must be converted to an analog signal for
the analog VGA interface, then converted back to a digital signal for processing
by the flat panel display. This inherently inefficient process takes a toll on
performance and video quality and adds cost. In contrast, when a flat panel
display is connected to a digital interface, no digital-to-analog conversion is
required.
DVI uses Silicon Image's PanelLink, a high-speed serial interface that uses
Transition Minimized Differential Signaling (TMDS) to send data to the monitor.
The DFP and VESA Plug and Display interfaces also use PanelLink. For this
reason, DVI can work with these previous interfaces by using adapter cables
(depending on the signal quality of the adapter.)
DVI also supports the VESA Display Data Channel (DDC) and the Extended
Display Identification Data (EDID) specifications. DDC is a standard
communications channel between the display adapter and monitor. EDID is a
standard data format containing monitor information such as vendor
information, monitor timing, maximum image size, and color characteristics.
EDID information is stored in the display and is communicated over the DDC.
EDID and DDC enable the system, display and graphics adapter to communicate
so that the system can be configured to support specific features available in the
display.
2.9.2 DVI Connectors
The DVI connector has 24 pins that can accommodate up to two TMDS links and
the VESA DDC and EDID services. The DVI specification defines two types of
connectors (see Figure 1):
• DVI-Digital (DVI-D) supports digital displays only (not supported)
• DVI-Integrated (DVI-I) supports digital displays and is backward compati-
ble with analog displays (used on the VMIVME-7805/VME-7805RC)
The VMIVME-7805/VME-7805RC use the DVI-I connector with a single TMDS
link. The DVI-I interface accommodates a 12- or 24-pin DVI plug connector or a
new type of analog plug connector that uses four additional pins, plus a ground
plane plug to maintain a constant impedance for the analog RGB signals. The
DVI-I adapter is supplied by GE.
Standard Features 37
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