what purpose do the usb ports serve on a colour touch screen ?
None, really. They are there for future expansion, should they be needed. A firmware update is required if they are used.
the operating system on calour touch screen are embedded windows XP.. if you now the programing language, or you are expect in software engineering, the usb, will be very usefull..
Data and power inputs, data outputs, updates and memory expansion. Every time I see a USB port I think IPOD !