VDPS (Vinculum Disk, PC monitor and Slave port) firmware is used if a microcontroller needs both USB Host functionality and will connect to a host port on a PC. The VNC1L will enumerate as an FTDI FT232 device and cause the PC to load the same FTDI VCP and/or D2XX device drivers used for the FTDI device chips.  Data from the PC is then transferred to the VNC1L monitor port. The PC USB Host port can only be connected through the VNC1L Port 1.