C²L (Cascading Communication Logic)

Portrait Displays' proprietary C²L takes advantage of many different methods of DDC/CI communication. The C²L enables I²C communication by going directly to the graphics processing unit's (GPU's) registers. This technique has proven reliable but needs to be updated to support new GPUs as they are released in the market. In some cases, access to the GPU registers is hidden or not available. In this case, the C²L relies on the graphic driver’s API to establish communication. In addition, Vista has its own documented API that software can access. The C²L also supports USB on select displays. The advantage of using the APIs or USB is that the communication is based on standard drivers. When new cards/GPUs are introduced, the user simply updates the graphic driver for DDC/CI support.

With all these methods, the C²L has a sophisticated method of querying the OS and the display to identify the best method of communication. The C²L polls the display and selects the best driver based on the computer configuration. Changes to the graphic driver, graphic subsystem, OS, or failure to communicate after a successful selection, initiates the C²L to verify the best method of communication.

With C²L, Display Tune has the industry's most reliable DDC/CI communication for any computer display.