I'm really curious right now. I'm a Python programmer, and this question just boggled me: You write an OS. How do you run it? It has to be run somehow, and that way is within another OS?
How can an application run without being in an OS? How do you tell the computer to run, say, C, and execute these commands to the screen, if it doesn't have an OS to run in?
Does it have to do with a UNIX kernel? If so, what is a Unix kernel, or a kernel in general?
I'm sure OSes are more complicated than that, but how does it work?
Best Answer
There are plenty of websites that go through the boot process (such as How Computers Boot Up). In a nutshell, its a multi-stage process that keeps building up the system a little bit at a time until it can finally start the OS processes.
It starts with the firmware on the motherboard which tries to get the CPU up and running. It then loads up the BIOS which is like a mini operating system that gets the other hardware up and running. Once that is done it looks for a boot device (disk, CD, etc) and, once found, it locates the MBR (master boot record) and loads it into memory and executes it. It's this little piece of code that then knows how to initialize and start the operating system (or other boot loaders as things have gotten more complicated). It's at this point that things like the kernel would be loaded and start running.
It's pretty incredible that it works at all!