My guess is that you have a late sixties or early seventies Bianchi "Sprint". This was their entry level model. I cannot boast to know too much more about the bicycle except that pre-eighties Bianchi bicycles are not all that common in North America. You will find great pleasure in resurrecting your old Italian steed and even more fun riding it.

197? Bianchi "Sprite"

Hope this is a help.