The Memory Management Unit Keeps Track of the Memory Addresses in the Hardware

The operating system keeps track of all that whenever i want to switch over from running one process to running a different one. That's called a context switch. And again, the processes are kept track of using these process idee numbers. So every time the processer wants to flip from one process to another, there's a certain amount of delay because not only it doesn't just have to reload the register programm counters and somewhere but also has to reload all the mappings in the memory management unit. But that's ok, because this doesn't actually take that long. Because, remember, we're ticking over billions of times a second, so we've got the clock ticks to spare.