HDCP is a copyright protection system (High bandwidth Digital Copy Protection). Therefore its primary aim is to prevent protected material (usually High Definition video) from being copied.
It does this by encrypting the video signal between the source (e.g. DVD player) and sink (e.g. display). To do this, each source and sink must be HDCP compatible and negotiate with each other to create a secure link. They do this by exchanging 'keys' and working out a secret encryption 'password'.
Thus units that support HDCP in the CORIO range (Which CORIO products support HDCP?) are required (by the HDCP license) to ensure that encrypted data from a source stays encrypted on its outputs.
This requirement then forces an HDCP-compliant unit to shut-down any non-encrypted outputs such as analog RGB, SDI or composite video.
This is not a fault with the CORIO unit, but a requirement by the HDCP license granted to TV One - and thus all HDCP compliant units should work in the same way.
The HDCP implementation is version 1.2, with full repeater support of up to 10 down-stream devices.
Summary: a HDCP-encrypted DVI/HDMI source entering a unit *must* leave by a HDCP-encrypted DVI/HDMI output. No other outputs are allowed to work under the terms of the HDCP license.
Also see: HDCP not working on CORIO2 unit