Learning About Computer Memory
People say "memory" about computers as though it is one thing. It is two, and they behave in opposite ways. Getting them mixed up is why "my computer is slow" and "my computer is full" sound like the same complaint when they are completely different problems.
RAM Is the Desk
RAM is where the computer keeps whatever it is working on right now. Open a game and the game is loaded into RAM. Open a browser tab and that goes in RAM too.
RAM is fast, and it is small, and it is temporary. Switch the power off and everything in it vanishes — which is why an unsaved drawing is gone for good if the machine dies, and a saved one is not.
Run out of RAM and the computer does not stop. It starts shuffling things back and forth to make room, and that shuffling is what "slowing down" feels like.
Storage Is the Filing Cabinet
Storage is where things stay when you are not using them: photos, videos, homework, the game itself. It is much bigger and much slower than RAM, and it keeps everything when the power goes off.
Run out of storage and you cannot save anything new — a different problem with a different fix.
Sort These
Every line below describes one of the two. Put each where it goes.
- Empties completely when the power goes off
- Holds only what you are using at this moment
- The faster of the two
- Keeps your files while the computer is switched off
- Where a photo lives until you open it
- Usually far larger, measured in terabytes
Measuring It
- A bit is the smallest piece of memory there is. It is a 0 or a 1, and nothing else.
- 8 bits make a byte — roughly one letter of text.
- 1,024 bytes make a kilobyte (KB).
- 1,024 kilobytes make a megabyte (MB).
- 1,024 megabytes make a gigabyte (GB). RAM is usually counted in these.
- 1,024 gigabytes make a terabyte (TB). Storage is usually counted in these.
Each step up is 1,024 of the one below, not 1,000. That looks like an odd number to choose until you notice that computers count in twos rather than tens, and 1,024 is what you get from doubling 1 ten times over.
The Kitchen Version
If it helps, picture baking a cake.
The counter is RAM — the mixing bowl, the eggs you have cracked, the bag of flour standing open. Everything you are using this minute, all within reach. Clear the counter and it is empty.
The cupboard is storage. Everything you own but are not using is in there, and it stays there whether you are baking or not.
A tiny counter does not stop you baking. It just means constant trips to the cupboard — which is exactly what a computer with too little RAM spends its day doing.