I wouldn't pick Unix for a first self-study of internals. I'd point somebody as OS-8, RT-11, or IAS for an OS that is closer to full-blown timesharing. I have no idea which IBM software products would be useful. Note that I said self-study and starting out small. If a person can think, I'd point them at TOPS-20 with its automatic loading of the debugger for any usermode program.
No, I don't suppose you would. I picked Mini Unix as an example because it seems to me to...
Sigh! That is what an OS does. This memory Debt Management is the reason to have an OS. Note that I-O devices have to have reasonalbe memory managing done by the OS. The OS tells the device "put it there" and then hands the user the address of the bits for his consumption.
I didn't say that it wasn't an OS. I said that it is an example of what not to do.
You need to look at the DOSes that did do things well. You also should look at other OSes that ran on small machines and delivered computing services without daily needs for toilet paper.
A FAT is a spec of how a file system is arranged. I don't these specs but there are ways to implement any spec without cuasing grief to the owner of the data.
Choosing any timesharing OS would probably be a bad idea for first exposure. Things get...