Access the computer's Bios source code [closed]

You can not access the source code, and companies will certainly not provide the software in this format. There are very few companies that work with BIOS and charge for them, including charging for customizations for specific products.

What might and should be a lot of effort is reverse engineering, looking at the contents of memory. But it seems better and less laborious to observe the functionality and make another code that replicate / emule / simulate.