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os-tutorial
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===========
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How to create an OS from scratch!
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**New lessons will be added about every week, at the same pace that I learn each concept**
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I have always wanted to learn how to make an OS from scratch. In college I was taught
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how to implement advanced features (pagination, semaphores, memory management, etc)
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but:
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- I never got to start from my own boot sector
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- College is hard so I don't remember most of it.
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- I'm fed up with people who think that reading an already existing kernel, even if small, is
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a good idea to learn operating systems.
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Inspired by [this document](http://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf)
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and the [OSDev wiki](http://wiki.osdev.org/), I'll try to make short step-by-step READMEs and
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code samples for anybody to follow. Honestly, this tutorial is basically the first document but
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split into smaller pieces and without the theory.
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Features
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--------
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- This course is a code tutorial aimed at people who are comfortable with low level computing. For example,
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programmers who have curiosity on how an OS works but don't have the time or willpower to start reading the Linux kernel
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top to bottom.
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- There is little theory. Yes, this is a feature. Google is your theory lecturer. Once you pass college,
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excessive theory is worse than no theory because it makes things seem more difficult than they really are.
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- The lessons are tiny and may take 5-15 minutes to complete. Trust me and trust yourself. You can do it!
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How to use this tutorial
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------------------------
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1. Start with the first folder and go down in order. They build on previous code, so if
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you jump right to folder 05 and don't know why there is a `mov ah, 0x0e`, it's because you missed lecture 02.
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Really, just go in order. You can always skip stuff you already know.
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2. Open the README and read the first line, which details the concepts you should be familiar with
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before reading the code. Google concepts you are not familiar with. The second line states the goals for each lesson.
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Read them, because they explain why we do what we do. The "why" is as important as the "how".
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3. Read the rest of the README. It is **very concise**.
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4. (Optional) Try to write the code files by yourself after reading the README.
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5. Look at the code examples. They are extremely well commented.
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6. (Optional) Experiment with them and try to break things. The only way to make sure you understood something is
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trying to break it or replicate it with different commands.
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TL;DR: First read the README on each folder, then the code files. If you're brave, try to code them yourself.
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Contributing
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------------
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I'm still learning this. For the moment, please restrict your contributions to fixing possible bugs
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or improving existing documents. I'm not yet ready to accept enhancements.
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