This week I’d like to dispel a common misconception about two distinctly different pieces of standard computer hardware — that the two ways that your computer stores data are the same.

Technicians and marketers often assume the public understands when it comes to RAM and hard drives, so the terms get tossed around without much explanation. Let’s clear this up.

RAM vs. Hard Drives

When a standard computer is turned off, its memory is completely blank while its operating system and your personal files are stored safely on a hard drive.

When the computer is powered on, it begins reading information from your hard drive and storing that information temporarily in your computer’s Random Access Memory (RAM).

RAM is temporary. When your computer loses power, whether intentional or not, the current contents of your RAM are lost.

Each time you reboot your computer, the contents of RAM are erased and cleared out for fresh usage.

This is why, when things go wrong with your computer, a reboot is often all it takes to start over again.

On the other hand, information that is written to your computer’s hard drive is significantly more permanent.

Hard drives are long-term storage where information is parked until called upon.

When you create a spreadsheet and save it to your “C drive,” you’re using your hard disk.

When your computer is turned off, its memory forgets all about your spreadsheet while your hard drive does not.

Hard drives slower than RAM

Hard drives aren’t nearly as fast as memory. Computers are a bit like humans, really.

For example, if I asked you for your phone number, you could rattle it off the top of your head. That’s because your phone number is stored in your “memory.”

But what if, on the other hand, I asked you for the number of the nearest pizza delivery place? Would you have to look up the number online or in the phone book? That would be like your computer consulting its hard drive.

The time it takes you to find information that isn’t “in memory” takes longer.

Working in concert

Hard drives and RAM work together constantly. When you turn on your computer, large chunks of your computer’s operating system are read from the hard drive and stored temporarily in RAM.

When you access programs like your word processor, portions of those programs are copied into RAM while they’re in use. When you open a document, it is loaded into RAM while you’re working on it — the changes are written back to the hard drive when you click “Save.”

So, what happens when a program requests a chunk of RAM, but your memory is already full?

Your operating system is designed to “cheat” a bit by taking information stored in RAM and writing it to a special place on the hard drive. This makes room for the new application that needs memory.

Unfortunately, this process creates a bottleneck. When the portion of the program that was temporarily written to the hard drive needs to be used, it must be written back into RAM, usually necessitating something else be written temporarily to the hard drive.

This process is called “swapping” (or “paging”) because your computer is swapping information from one form of memory to another. The problem is, this process takes time.

This is why computer geeks are always telling you to upgrade your memory.

It’s not that your computer can’t store enough information. Not at all. You’ve probably got room for tons more documents, spreadsheets and MP3s. You need more memory when you want to run more programs simultaneously. If your RAM frequently gets full and your computer has to begin “swapping” to your hard drive, your computer will slow to a crawl just when you’re using it the most.

Kevin McDonald: Writer and professional computer/network administrator. He lives in Amarillo with his wife and children, and owns and operates Definition Computers. E-mail Kevin at askthegeek@definitioncomputers.com with questions you’d like to see answered in this column.

(This article was originally published in the Amarillo Independent newspaper.)