What's up guys,
I hope you're all doing well.
Introduction
The basic intro for this article is that a computer system has a lot of different types of memory besides RAM. I'm going to try to introduce those other types of memory and give you a basic understanding of how they work and how they might be utilized in the computer system.
The basic foundation of computer memory is something called the “Memory Hierarchy”
800px-ComputerMemoryHierarchy.png
This is a picture of the Memory Hierarchy. [Image source: -Wikipedia]
First check out the bottom of the Memory Hierarchy, these include memories that are really slow but really big. Examples include your Hard Drives, flash drives, they can hold terabytes of data and have your music, games, movies, etc.
Bottom of the hierarchy is for slow and big memories. At the very top of the memory Hierarchy, that's where the fastest and smallest memories exist. The fastest and smallest memory is a register and I'll go over that later.
“A brief recap”
The bottom of the Hierarchy is for slow and big memories, the top of the Hierarchy is for fast but really small memories. Just keep that in mind and everything will be a lot easier to understand. The slowest and biggest memories you already know, those are your Hard Drives and they keep all your data when there's no electricity in them. They also hold terabytes of data and you can carry them around.
The next level of memory above Hard Drives is “RAM”. You can never really have terabytes of RAM, just gigabytes of it. It's much smaller than your Hard Drive but it's much faster to access. Remember, any type of program run your computer has to exist in RAM first for the processor to execute it.
Let's go one level above RAM to a memory that's called “L2 cache”. L2 cache memory sounds really cool and it is really cool, so let’s check it out.
L2 cache
An L2 cache is smaller than RAM and it’s also much faster. While you have 8 or 16 gigabytes of RAM, your L2 cache is on the order of megabytes, maybe 256 megabytes. The concept of an L2 cache is more or less simple, important data that access it frequently is kept in the L2 cache, so the processor can get to it much faster without going back into RAM.
If your closet was RAM, then the L2 cache would be your bedroom floor where you keep your favorite boxers all the time that you wear every day. All the memory that I've explained up into this point is called “off-chip memory”
What’s off-chip memory?
If you ever open up your computer, you see a processor which is that cool little square thing that has cooling system on it to keep it cold, that’s the processor also known as the chip. Whenever someone says something is off-chip, it's not included on the little cool square processor.