I received my NVME SSD drive a day early (yay Amazon!), got it installed, and then installed Ubuntu 18.04. That OS really makes this board perform well–very pleasant experience for this old Linux user! I’m sure Windows would be fine as well, but I prefer Linux.
That being said, I’ll continue trying to figure out this 4-pin header serial interface this week. @Baozhu, do you have any additional documentation you could give us on this little 4-pin header next to the Arduino header? My ultimate intention is to install i2c-tools and use the 40-pin RPi-compatible header to do some embedded projects, but it would sure be nice to have a UART to the main Linux OS. So maybe that’s what the 4-pin header is for, I’m thinking?
TB