How do I get into Source Code for EMC2 and Axis?

I think I have looked at the blog or similar related information before mentioned at: axis.unpy.net/01198594294

From what I can see it is only i/o connections over serial.

The code I am using from Simen Grbl has all of the control on the Arduino Board. Motion code control and timing etc.
github.com/simen/grbl/

Python interface I am building does 3D drawing and user friendly functions that basically sends gcodes to Simen Grbl code on arduino and the Simen code on Arduino runs it.

I tried modifying EMC/Axis as a starting/learning point but got lost. It was easier to start from scratch and create a new interface.

Status Update: I have finished my first basic version of a USB CNC Python HMI/GUI Program that works with a slightly modified version of Simen Grbl Arduino code at github.
- USB Handshaking has been added between Python and Arduino to make sure complete gcode lines get sent back and forth.
- Python program also uses OpenGL to graphically display gcode file image.
- Testing so far, the program has ran a gear tooth file with 3200 lines of code successfully, no hang ups etc.

Code is located at: github.com/Highlander01/Highlander01HMI

I am interested in RTOS (real time operating system) aspect of EMC2/Axis code. For EMC2/Axis I believe RTLinux is being used as the RTAI. Is RTAI the same thing as a RTOS? Ex Pulsing for stepper motor timing. Where is this code, which files and programs in EMC2/Axis do the work? Is it Python code or something else?

I am interested in latency aspects etc... I would like to think I could take a newer faster multi core computer and get some great performance.

wiki.linuxcnc.org/emcinfo.pl?RealTime

(I did some looking to see what else is out there and I found INTime By TenAsys as an RTOS that takes adavantage of multi core processing. Any comments?)

I was looking at the atoms also. I am thinking I will get a Intel atom D525MW. I am guessing that will perform the same as a 510.

(Is there any specific files in the source to look at regarding Real Time, RTLinux, and stepper pulsing.)