I was looking at the Linux From Scratch project awhile ago and was sort of disapointed that you needed an existing copy of Linux on your machine to build it. I know that Linux is very easy to obtain, install, etc. but I was hoping to build the LFS project outside of the modern operating systems (Unix/Linux/OS-X/Windows/Etc.) and in something like DOS.
My question is, how might I build a project whether it be C, C++ or some other language with a C compiler, without building that project within another operating system. By operating system I mean Unix, Linux, OS-X, Windows, and every other GUI capable 'modern-ish' OS.
So specifically I'm looking for something that works much like DOS. I'm not above using DOS if thats all that is available, however I'm thinking something that has the ability to use all available memory, processing power, etc. I want to start my computer and be welcomed by a "prompt" from which I can build or execute a program (like another Operating System).