Creation of a file system

[Bitwize]

There's something I've wanted to know for a while that seems pretty hard to find information on online, but in theory sounds like it should be available. I'm trying to understand what exactly goes into creating a custom file system format (like FAT), and how it can be achieved using C++.

Now I realize that, with a new file system, it'd require a new application to access/read/write the data, along with drivers to recognize the drive/partition in that format.

But the question still remains, at least for a partial, how would this be achieved?
I ask this purely for learning purposes.

[JLBorges]

This should get you started: http://thecoffeedesk.com/geocities/rkfs.html