I'm writing TMC driver for i8000. I were doing the same as you I think, so I can read/write the Si4709 registers, call all IOCTL from fmradio.dll, etc. At the moment I have a program showing RDS/TMC information and a virtual com driver to transfer the TMC data to outside. In progress the GFMAPI interface. My question is: are you willing to share some information with me? I'm asking this because the structure of fmradio.dll I thin the same as in the i900... Thank you.