General CNC 40-915xm1 G-codes

I bought a General CNC 40-915xm1 used, but didn't get the software for it. No problem, I've worked with G-codes a bit. The company is out of biz, so I can't ask them questions.
My firmware is 2.003
HMI file is 2.005.fj (whatever that is?)
Serial #: 404000315

I kind of got it running, using hand written G-code. I set the machine to inch with it's pad. Wrote code for a 1 inch square. It hardly moved at all, I thought something was wrong. Seems no matter what I do it is working in MM, so I made a 1mm square and didn't see it move as I was cutting air. I didn't include g20 or g21 commands i the code and haven't tried that yet. I can now make straight cuts using metric. The machine didn't recognize G02 for an arc or G12 for a circle pocket. I know some controllers interpret codes differently and some don't have all the G codes available. So has anyone figured out what this board is capable of, what code it recognizes?

If the board is limited, then has anyone put a better board in the machine?