Hello i had for sometime the the atmel samd21 xplained board. I learned what the pinout is so i can program it. However one thing when i plug the usb into the Target USB it comes up arduino zero native usb. But if i plug it into the debug USB the board turns into a Mass storage device and it shows up in my computer as a drive. What I'm asking is this normal for this board. i have never saw a arduino board as a mass storage board before.