Hello i am new to diy cnc and i was thinking of using mach but i wanted to under stand how it works before i go further. I have tried to research as much as i can but im stuck on some aspects. I have programmed other machines and do allot of tech work but without physically using mach im stuck. Any help would be appreciated.

1 obviously you put a gcode file from a cam software into mach, but how is the information sent to the stepper/servo controller? (in gcode or is it decoded into machine language or something)

2. at which point in the processes are the gcodes decoded into a usable signal for the steppers/servos?

3. is it a digital signal with packets being used throughout the machine or at somepoint does the machine use electrical pulses?

4. if servos are being used does the positioning feedback get sent to the servo controller or to mach?

Thank you guys allot i figure this would be easy questions for a seasoned diy machinist.

Mach is software which provides for the control of different CNC machines. Mach is configured / setup for a machine and in that it knows how to send the appropriate information / commands to the hardware. The hardware consists of the drives or whatever which run the motors sending the proper signals to the motors which move the axes of the machine.
Gcode are instructions that Mach ( controlling software ) understands and thus sends that information in the proper way to the drive.
The closed loop of servos is done by the servo drive.  

For more information please read the different Mach manuals, watch the videos, etc.

RICH  

1) Individual step and direction signals are sent to the drives.

2) While the g-code is running.

3) The direction signal is either 0V or 5V, and the step signals are pulses.

4) Mach3 only sends step and direction signals, so the feedback goes to the drive.
There is an exception here, if you use a Mach3 compatible motion controller that supports analog servos.