I've never heard of running a Roland with Mach3, but if your machine connects with a parallel port, I suppose it's possible. Roland products usually use the computer's print function to operate - open up the printer queue and you'll see your toolpath files ready to run. Mach3 doesn't have any CAM capabilities itself, but the same company (ArtSoft) makes a "LazyCAM" product that will generate basic 2d toolpaths from vector graphic files; if you used it, you might still need Dropout to send it to the machine, unless you managed to switch it over to Mach3 control. But there's no problem transferring the files from your laptop to the desktop that runs the machine; it would probably work better that way than trying to run it from your laptop.
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