Hi,
just a note to help avoid confusion:
A parallel port is a motion controller, Machs Parallel Port Driver takes numerical data from Machs trajectory planner
and produces pulse streams which are communicated using the parallel port of the PC. The smart bit is the software
driver. The parallel port on its own is vunerable to abuse so a breakout board (BoB) is used, its really only an amplifier/buffer,
it doesn't do anything smart. Reasonable BoBs can be had for as little as $10 but better made ones maybe $50.
An external motion controller takes numerical data from Mach via USB or Ethernet and it generates the pulse streams.
They commonly need a BoB to buffer them to the external environment. These controllers have either microcontrollers,
FPGAs or DSP chips, ie they are smart. There are some cheap but crappy ones but good ones start around $120.
External controllers mean that you are not restricted to desktop 32bit machines as you would be with a parallel port solution.
They are also subject to very much less disruption by background software running on the machine which can limit parallel
port machines.
The 4 axis G540 combines a BoB and four stepper drivers in the same device. You would only need to use three.
Gecko have a very good reputation for reliability and backup.
Craig