An ATMega16u2 takes care of the USB connection, ... only requiring a connection between the ‘328 ISP header and the pins on the ’16u2 ... Arduino has never been about the maximal use of ...

Arduino AVR ISP 3 Articles . Dirt-Cheap USB Arduino Hack From The Past. March 29, 2016 by Elliot Williams 17 Comments . Mass production is a wonderful thing.