Fascinating.
A lot of my design work is done on the PC running the CNC machine while I sit there monitoring the CNC, as the CNC only uses about 5% of the CPU. But that computer is NOT on the net and never will be. Stability, NDAs and security are factors.
Fortunately, I run Mach3 0.062, an ESS fully updated (by USB key), and AutoSketch V10. CNC programming is done in Notepad. This includes 4-axis simultaneous work.
Curiously, this all works very well.
Cheers
Roger