This is an Arduino compatible microcontroller I made on a perfboard. I call it a Perfduino.
Full build instructions and details are available at revoltlab.com
Here is a video of it running a servo and the arduino Blink example sketch:

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The reason I ask, if it helps clarify, is I would like to use one of these with Grbl to operate a CNC machine. I'm just not sure how the computer would deliver the Gcode information to this board.
Please excuse my ignorance.
Thanks!
Are you making your own cnc machine? That sounds awesome. Please let me know when you start building it. I'd love to see how you go about the project!