Disk operating system

So when you start up a program, you go back to the days before you had what we would think of now as an operating system.

And even honestly, like on DOS, you could still do what I'm about to say, where you go in and your program has full access to the entire range of memory from All of it, right? They can say, I want to read and write this piece of memory, and it would reference its hardware address.

And nothing in the system would stop it from doing that, which for the most part, it's like, well, if you're in the program and you want to blow your computer up, well, who are we to stop you? Right? Because again, it's not multi-user, it's not a shared experience, it's just you.

But of course, then again, if you're just an end user and you just bought a floppy disk and you throw this program in there and it gets in there and starts writing over the DOS kernel with whatever program you got, that's a problem, right? So with the Windows era, they're like, well, we got to stop that from happening.

So now every process gets its own thing.

So when it says I want to talk to memory address zero, It's not the physical memory address zero.