Hi,
I have used Mach4 and an Ethernet Smoothstepper for about nine years and Mach3 prior to that.

Mach3 is obsolete to my way of thinking......NFS (the manufacturer of Mach) has ceased all development work on Mach3 nine years ago.

It still works and has a large and loyal fanbase but whatever faults it has it is stuck with.

Development on Mach4 is on-going. Mach4 all but requires a standalone motion controller, there is a parallel port called 'Darwin' for which a $25.00 license fee applies, but it is not nor ever will
be a complete motion controller. With the exception of XHC (avoid like the plague.....buggy as hell) NO Chinese manufacturers have bothered with Mach4, they'd rather pirate Mach3....and that is
why there is still so much cheap Chinese hardware for Mach3 but none for Mach4. There are however six credible US and European Motion control manufacturers whom make Mach4 ready
controllers.

Craig