Well, i object to the name for a start. It's not
Universal (in that of
the 200 or so computers I own, not one of them has a USB port or can have
a USB port). It is serial. It's not a bus , at least not electrically. I
guess one aout of 3 is not too bad :-(
It is universal since you can create a usb host interface for anything
you have :)
For suitable values of 'small'. It's a lot
harder to send/.recive data on
a USB port (both in terms of hardware and software) than to use any of
the 'classic interfaces' like RS232, Centronics, GPIO, HPIB, etc.
It depends of what you are using. I have a FT-232 here and it is
transparent to me as a serial port. Electricaly it is a bit complicated, but
clearly possible to do bitbanging and creating a usb slave. Look for
igorplug on the net, and see a totally software solution for that.
:o)
Alexandre