I can only talk about the VDIP1 as that is the only one I have used so far.

The VDIP1 comes with firmware burned in from the factory. The firmware can be modified / customized somewhat.

Here is a good page to start
http://www.vinculum.com/

This page has the different firmwares available
http://www.vinculum.com/downloads.html#vfirmware

Near the bottom of that page in applications and utilities. there is a program called
Vinculum Firmware Customiser (V1.1b)

This allows to modify some of the main settings of the firmware. Once the firmware has been modified, if using the VDIP1, copy the firmware to the root of a USB "thumb drive". Placs the drive into the VDIP1, at power up the VDIP1 will load the new firmware from the "thumb drive". This all can also be accomplished via serial port connected to the VDIP1 but the flash/thumb drive is so easy.