This is a Kicad breakout board for an older Bungard CCD (ATC in this case, but it should work with manual change spindles) PCB mill. That's the version with the DB-25 and male/female DB-15's. It's intended to be used with a GRBL controller of some sort.
At the moment I'm running my machine with a custom ATMega328P GRBL controller (Uno/Nano equivalent), DM542 stepper drivers, a JYQD-V8.5E bldc motor driver, and a Meanwell LRS 350-24 PSU. The spindle maxes out around 35k RPM with that motor driver, but otherwise everything works fine.
To release the pneumatic collet, the CHUCK signal should be pulled to GND by a switch.
X,Y,Z limit switches are wired NC. The tool length switch (TOOL) is NO, and I've split that off on my machine into a connector for performing the usual auto-leveling.
I've milled my board single sided as there's only a couple of jumpers needed.