In the first part of this series of articles on computer memory and it works, we talked about your computer system's RAM and what it does. We also mentioned some of the other types of computer memory are available and some of the other devices that you likely use on a daily basis that also use their own forms of computer memory, like your cell phones or your video game consoles. To recap quickly, the following are some of the more common types of computer memory that you may encounter at some point, often without even realizing it.
- RAM
- ROM
We already talked about how the RAM in your computer system works and what it does, but the RAM is not the only type of computer memory that a typical computer system comes with. A typical computer system also has Level 1 and Level 2 caches, virtual memory and a hard drive (sometimes also called a hard disk) in addition to that regular system RAM we already discussed. You may wonder, though, why your computer system has to have so much memory in so many different forms.
The answer to that question is rather simple. You are already likely aware that a fast central processing unit (or CPU) is always desirable. The faster your CPU is, the faster your computer is capable of running – though it can't do that without enough memory to use in the process. For your central processing unit to perform to its highest potential, it needs to have extremely fast and extremely easy access to very large amounts of data. If your central processing unit is not able to get to the information or data that it needs for a particular task or function, then it will literally grind to a halt and wait for it to materialize before it can go back about its business.
Modern CPUs run at speeds of about 1 gigahertz or more, and a CPU that runs that quickly can consume huge amounts of data in no time flat – we are talking, literally, billions of bytes per second. But to build memory that can actually keep up with a CPU that runs at that speed ends up being extremely expensive, so computer designers have had to come up with ways to use the expensive type of memory in small quantities and then back that expensive stuff up with other types of less expensive memory. This is called “tiering memory.”
The cheapest form of memory that is in common use today is the hard drive or hard disk. They provide a large amount of memory for permanent data storage for a relatively small amount of money. Hard drive space costs only pennies per megabyte when you do the math, but hard drives are slow – it can take seconds to read just one megabyte of information off of a hard drive. Because it is so cheap, though, hard drives make up the lowest tier of computer memory, and it is called virtual memory.
Up one level from that is your RAM, which we already talked about, but you can find a more in depth overview of system RAM in a later installment in this Be Your Own IT series called “System RAM.” System RAM is middle of the road when it comes to pricing, falling between the price of memory that can keep up with your speedy CPU and the price range you will find on the market today for hard drives or hard disks.
Stay tuned for the next installment in this series about computer memory and how it all works!
