How does RAM work in modern OS?

[phl92]

I've always thought that RAM memory is temporary storage that only stores data as long as it has power. In short, when you turn off the PC, the RAM is empty again.
I used Windows 8.1 until 2 days ago on my desktop PC, and for the last 1-2 years I've noticed that, for example, Google Chrome still has the same tabs open in the browser even after switching it off and restarting it. I think it's a setting in Chrome that saves the tabs like bookmarks and then calls them up again.
Now I have Windows 11 and this "memory effect" is not only noticeable in Google Chrome, but in almost all programs. In principle, after booting, everything is the same as it was before shutting down.

I wonder how that works? And whether the RAM memory is actually almost never emptied? I have to say that shutting down is not actually what a power cut corresponds to, strictly speaking the PC components are probably only completely without power if you disconnect the power cable and wait for a few minutes. (I haven't tested whether that should make a difference when booting.)

So it's more of a question of interest, because of course it's more of a positive effect when you know that everything is actually always saved at all times (even if you write something offline in a simple editor and suddenly have a crash)

 

[Lihp8270]

2 main ways of doing this.

1) Keep ram powered during sleep.
2) Write ram to disk then recall on reboot

 

[Basic75]

Shutting down the computer will indeed clear the RAM. Applications frequently save their state including window positions and open files or web pages to persistent storage so that they can resume from the exact place they left off even after being shut down.

 

[Basic75]

2) Write ram to disk then recall on reboot

That's suspend-to-disk, not reboot.

 

[velocityg4]

By default Windows 11 saves the state of apps and relaunches them on restart.

https://allthings.how/how-to-stop-windows-11-from-reopening-apps-on-sign-in-or-restart/

Also in Windows. Restart is by default a more complete refresh than shutdown. It's been this way for a while. Disable Fast Startup.

How to Turn Fast Startup On or Off in Windows 11

Turning off Fast Startup does have its benefits, but how do you do it on Windows 11? Here's how.

www.makeuseof.com

I couldn't say if this takes care of everything. I still haven't made the move to 11.

I think a lot of this is similar to what macOS has had available for quite a few years. Except macOS asks you if this is what you want. Instead of just doing it.

 

[Boyd01]

MacOS has this setting to re-open windows after a shutdown/restart. I always leave it un-checked, but frequently they seem to re-open anyway which is somewhat annoying. It has been this way for quite some time on MacOS, however I'm not sure that it's happened since I updated to Monterey. It definitely happened all the time with Cataliina, even though I always make it a point to quit from all programs and close all windows before a shutdown/restart. But some apps just seemed to randomly open up on a re-boot.

 

[Yebubbleman]

I've always thought that RAM memory is temporary storage that only stores data as long as it has power. In short, when you turn off the PC, the RAM is empty again.
I used Windows 8.1 until 2 days ago on my desktop PC, and for the last 1-2 years I've noticed that, for example, Google Chrome still has the same tabs open in the browser even after switching it off and restarting it. I think it's a setting in Chrome that saves the tabs like bookmarks and then calls them up again.
Now I have Windows 11 and this "memory effect" is not only noticeable in Google Chrome, but in almost all programs. In principle, after booting, everything is the same as it was before shutting down.

I wonder how that works? And whether the RAM memory is actually almost never emptied? I have to say that shutting down is not actually what a power cut corresponds to, strictly speaking the PC components are probably only completely without power if you disconnect the power cable and wait for a few minutes. (I haven't tested whether that should make a difference when booting.)

So it's more of a question of interest, because of course it's more of a positive effect when you know that everything is actually always saved at all times (even if you write something offline in a simple editor and suddenly have a crash)

You are correct that RAM is "temporary storage". Though, it's a little bit more complicated than that. When I am teaching/tutoring folks about computers, I use the following analogy:

Your computer is like a kitchen. You have the chef (CPU), ingredients (data), storage location for said ingredients [cupboards, fridge, etc. (disks/drives)], and the counter-top in which you're going to work with the food (RAM). Whenever you go to make yourself food, you go and grab food from wherever it is stored, assemble/cook it on your counter-top, and then, when you're done, you put it all away.

In the same respect, when your computer boots up or opens pretty much any program or file, it loads data into RAM from disk. Then you do whatever you're going to do with it and then, when you're done, it gets put away and isn't in RAM anymore.

That all having been said; very long-winded explanation short, what you are seeing in Chrome and probably other apps too is a form of application state saving. Chrome does this on all platforms. macOS does it in a lot of cases too. It's similar to hibernation. Basically, the computer (or application, if it's only one app) saves its state to disk and then when it is relaunched, the state is loaded and resumed. It's a cheap parlor trick that FEELS like it was stored in RAM, but it wasn't.

Hope that helps.