Protected mode: how your OS can protect itself

In depth explanation of what x86 protected mode is, how it works, and how to switch to this mode.

Links:

Documentation:

Chapters:
0:00 Intro
0:37 History of x86
8:17 What is protected mode
8:57 Privilege levels
10:39 Segmentation
11:36 Paging
13:24 Switching from real to protected mode
17:36 A20 gate
23:38 GDT
27:26 Finishing the switch
33:18 Printing text from protected mode
36:46 Switching back to real mode
40:02 Conclusion

[stefan-danielwagner]

This series has so much potential already, I can't wait for next episodes!!!

[TheGoodCoder]

You make it seem easy when it comes to making operating systems! Keep it up!

[richardparker]

Removing music would have made it 10/10.

[treytomes]

It surprised me in a previous video when you used 32-bit registers in 16-bit mode. I didn't know you could do that, but it assembled so I guess you can. I still remember the first time I tried writing code in protected mode back in the 90s and how frustrating it was to find that all of the BIOS video commands I had come to rely on were gone.

The history lesson on protected mode was helpful for giving some context into why this is the way it is.

[aaron]

Thank you so much, these videos are highly informative and even more underappreciated

[alexandrubossro]

Underrated channel & video
Keep it up!!👍👍👍👍

[treytomes]

After over 2 decades I still remember that 0xFFA6E contains the ASCII character patterns. It's a strange thing to hold on to.

[MidnightSt]

Am i the only one who utterly hates the fact that our technology has all the weird messy hacks on literally every level of abstraction, just for the sake of backwards compatibility? The more I learn, the more I feel like we need a complete restart, greenfield redesign to get rid of all that mess and make a system that is clean and sane., without all that "because backwards compatibility" arcane nonsense...

[Trixz-the]

You're series are 🔥🔥🔥. But unfortunately I'm still a newbie 😔

[IamAFK]

Why don't you use jmp $ for infinite loop?

[mynameisjeff]

These videos show just how much legacy garbage there is still implemented on our modern day CPUs.

[twobob]

I REALLY want to watch this but the background muic is doing my head in. cant manage more than 5 minutes at a time.... What has bad backing music got to do with Protexted Mode? NOTHING. if people really want to listen to music while they learn pretty sure they would own some. Sigh :(

[maxmuster]

The protected mode is a virtual concentration camp full of handcuffs and stranglehold prisoner called the user. All around are electric barbewires and watch towers and some of the pig brothers are watching you every second.