Note that all the USB devices quoted so far are real products - so you might actually find that you already have a piece of USB equipment which is based upon one of these chips!

This can be problematic, as you don't want your USB experiments to interfere with the operation of your paid-for USB peripherals - or vice-versa!

For example, I have a D-Link multifunction hub which is based on the FTDI chip. This means that I can't try the Triscend FTDI-based Reference Design without uninstalling my D-Link hub - which I am reluctant to do!