
Nowadays a computer can run multiples program. Where, last time, I mentioned a computer will run everything through the CPU.
But how can a CPU take data? It will take it from Memory, or RAM. RAM basically is a stack — a common data structure.
So how can a RAM share its memory? Well, it is just like slicing a cake, we will slice a stack into multiple paths. And what we need is just a place to cut and its length. Which transform to technical terms is base and limit registers.

The CPU then checks user reference (we will talk later), ensuring its fall between base and limit registers