What to do without Windows 7 or above?

[retoa]

Same problem on Linux, KK works with wine but without support for USB, so it's quite useless.
I always have to reboot in win 7 :-(

I don't think we will receive support from HP, their target is windows, not iOS nor Linux.

There is a third party software named PrimeComm that works with dot.net, I can start it in linux but there is still no support for USB, so it does not work.
You can try it on iOS.

Reto