 The Atmel-ICE device or AVRISP mkII (Legacy device) connects to a computer's USB port and performs in-system programming using Atmel's software.AVRDUDE (AVR Downloader/UploaDEr) runs on Linux, FreeBSD, Windows, and , and supports a variety of in-system programming hardware, including Atmel AVRISP mkII, Atmel JTAG ICE, older Atmel serial-port based programmers, and various third-party and "do-it-yourself" programmers.The Program and Debug Interface (PDI) is an Atmel proprietary interface for external programming and on-chip debugging of XMEGA devices.