The source code being the code that creates all the files and wipes yours. Pretty much the code behind the install manager, that instead of loading the files, it creates and loads the files with modern libraries, also with a safety so if you compile it your files don't get wiped immediately. It's a lot to ask so I would at least like, the file creation code so i can edit it and create my own linux version.
In electronic systems and computing, firmware is the combination of persistent memory and program code and data stored in it.
-Wikipedia
you probably dont install such a firmware on your pc.
Get a linux OS like Kubuntu or linux mint and dual boot with m$-windows.Then,from inside this latest linux distribution do your tinkering and research in linux.
You probably have many misconceptions , try solving them , know more about computers ,OSes etc.
WORD OF ADVICE:
I was quickly taking a peek at your Posts\Threads and clearly you do not understand much about Kernel \ Boot level programming. You are not skilled to program such Software' s.
Operating System Programming is very hard last Time I programmed a OS it made a mess into my VMware in fact the actual VMware kept crashing as my OS was not programmed properly.
Besides that OS programming takes years if not months depending on your learning capabilities, Apart from that there is building Ring0 till Ring3 while creating a completely new Standard API. Then there is Memory Management and Allocation and GUI which will take a long time that's why I could not program a GUI nor a API but a simple application as a OS. Then there is creating a Security management and building a Network Layers perfectly.
Just trust me one person cannot do such a thing. Sometimes even large companies find it highly difficult. You are short of much of the knowledge if not all that requires programming OS. Interaction with Hardware and such are just to complex for one person to do.
Any intelligent person would agree with me.
Copy pasting is not the solution, first of all it would not be as fun as programming it from scratch and also it would be useless if you are learning nothing.