# Operating System Development Roadmap (Beginner Path)
## How to Follow?
[![](https://mermaid.ink/img/pako: ?type=png)](https://mermaid.live/edit#pako: )

## Phase 1: Programming Fundamentals
### 1.1 C Programming Basics
- Introduction to Programming
  - [CS50's Introduction to Programming](https://www.edx.org/course/introduction-computer-science-harvardx-cs50x)
  - [Learn C - Interactive Tutorial](https://www.learn-c.org/)
  - [C Programming at LearnCpp](https://www.learncpp.com/)

- Basic Syntax and Control Structures
  - [C Programming Language Tutorial](https://www.tutorialspoint.com/cprogramming/)
  - [W3Schools C Tutorial](https://www.w3schools.com/c/)
  - [C Language Cheat Sheet](https://cheatography.com/ashlyn-black/cheat-sheets/c/)

- Variables and Data Types
  - [C Data Types Guide](https://en.cppreference.com/w/c/language/type)
  - [Variables in C Programming](https://www.programiz.com/c-programming/c-variables-constants)
  - Practice: Create programs using different data types

### 1.2 Intermediate C Programming
- Functions and Program Structure
  - [Functions in C](https://www.geeksforgeeks.org/functions-in-c/)
  - [Program Structure Tutorial](https://www.tutorialspoint.com/cprogramming/c_functions.htm)
  - Practice: Create modular programs

- Arrays and Strings
  - [Array Operations in C](https://www.programiz.com/c-programming/c-arrays)
  - [String Handling](https://www.tutorialspoint.com/c_standard_library/string_h.htm)
  - Practice: String manipulation programs

- Pointers Basics
  - [Understanding Pointers](https://www.learn-c.org/en/Pointers)
  - [Pointer Tutorial](https://www.programiz.com/c-programming/c-pointers)
  - Practice: Basic pointer operations

### 1.3 Advanced C Programming
- Advanced Pointer Concepts
  - [Pointer to Pointer](https://www.geeksforgeeks.org/double-pointer-pointer-pointer-c/)
  - [Function Pointers](https://www.geeksforgeeks.org/function-pointer-in-c/)
  - Practice: Complex pointer programs

- Memory Management
  - [Dynamic Memory Allocation](https://www.geeksforgeeks.org/dynamic-memory-allocation-in-c-using-malloc-calloc-free-and-realloc/)
  - [Memory Layout](https://www.geeksforgeeks.org/memory-layout-of-c-program/)
  - Practice: Memory allocation programs

- File Operations
  - [File Handling in C](https://www.programiz.com/c-programming/c-file-input-output)
  - [Binary File Operations](https://www.tutorialspoint.com/c_standard_library/c_function_fread.htm)
  - Practice: File handling programs

### 1.4 Data Structures
- Basic Data Structures
  - [Arrays and Linked Lists](https://www.geeksforgeeks.org/data-structures/)
  - [Stack and Queue](https://www.programiz.com/dsa/stack)
  - Practice: Implement basic data structures

- Advanced Data Structures
  - [Trees and Graphs](https://www.geeksforgeeks.org/binary-tree-data-structure/)
  - [Hash Tables](https://www.hackerearth.com/practice/data-structures/hash-tables/basics-of-hash-tables/tutorial/)
  - Practice: Implement complex data structures

### 1.5 Assembly Language Basics
- Introduction to Assembly
  - [NASM Tutorial](https://cs.lmu.edu/~ray/notes/nasmtutorial/)
  - [x86 Assembly Guide](https://www.cs.virginia.edu/~evans/cs216/guides/x86.html)
  - Practice: Basic assembly programs

- CPU Architecture
  - [CPU Registers](https://wiki.osdev.org/CPU_Registers_x86)
  - [Instruction Set Reference](https://www.felixcloutier.com/x86/)
  - Practice: Register manipulation

- Memory Addressing
  - [Memory Addressing Modes](https://wiki.osdev.org/X86-64_Instruction_Encoding)
  - [Segmentation](https://wiki.osdev.org/Segmentation)
  - Practice: Memory access programs

## Phase 2: Computer Architecture
### 2.1 Basic Computer Organization
- CPU Components
  - [CPU Architecture](https://www.cs.cornell.edu/courses/cs3410/2019sp/)
  - [Instruction Pipeline](https://en.wikibooks.org/wiki/Microprocessor_Design/Pipeline)

- Memory System
  - [Memory Hierarchy](https://www.cs.cornell.edu/courses/cs3410/2016fa/schedule.html)
  - [Cache Memory](https://www.computer.org/csdl/magazine/mi/2001/03/m3062/13rRUxBJhBm)

### 2.2 I/O Systems
- Basic I/O Concepts
  - [I/O Architecture](https://www.sciencedirect.com/topics/computer-science/io-architecture)
  - [Device Controllers](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/13_IOSystems.html)

- Interrupt Handling
  - [Interrupt Basics](https://wiki.osdev.org/Interrupts)
  - [PIC Programming](https://wiki.osdev.org/PIC)

## Phase 3: Operating System Concepts
### 3.1 OS Basics
- OS Structure
  - [OS Components](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/2_Structures.html)
  - [System Calls](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/2_Structures.html#2_3)

- Process Management
  - [Process Concepts](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/3_Processes.html)
  - [Thread Management](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/4_Threads.html)

### 3.2 Memory Management
- Virtual Memory
  - [Virtual Memory Concepts](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/8_MainMemory.html)
  - [Page Tables](https://wiki.osdev.org/Page_Tables)

- Memory Allocation
  - [Memory Allocation Algorithms](https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/9_VirtualMemory.html)
  - [Paging Implementation](https://wiki.osdev.org/Paging)

## Phase 4: OS Development Basics
### 4.1 Development Environment
- Tool Setup
  - [Cross Compiler Setup](https://wiki.osdev.org/GCC_Cross-Compiler)
  - [QEMU Installation](https://www.qemu.org/download/)

- Debugging Tools
  - [GDB Basics](https://sourceware.org/gdb/current/onlinedocs/gdb/)
  - [OS Debugging Tips](https://wiki.osdev.org/How_Do_I_Use_A_Debugger)

### 4.2 Bootloader Development
- BIOS Programming
  - [BIOS Interrupts](https://wiki.osdev.org/BIOS)
  - [Real Mode](https://wiki.osdev.org/Real_Mode)

- Protected Mode
  - [Protected Mode](https://wiki.osdev.org/Protected_Mode)
  - [GDT Setup](https://wiki.osdev.org/GDT_Tutorial)

### 4.3 Basic Kernel Development
- Kernel Entry
  - [Kernel Basics](https://wiki.osdev.org/Kernels)
  - [Linking Script](https://wiki.osdev.org/Linker_Scripts)

- Basic Drivers
  - [VGA Text Mode](https://wiki.osdev.org/Text_Mode_Cursor)
  - [Keyboard Driver](https://wiki.osdev.org/PS2_Keyboard)

## Beginner Projects (In Order)
1. Hello World in Assembly
   - [Assembly Hello World](https://wiki.osdev.org/Assembly_Hello_World)
   
2. Basic Bootloader
   - [Bootloader Tutorial](https://wiki.osdev.org/Rolling_Your_Own_Bootloader)

3. Simple Kernel
   - [Bare Bones](https://wiki.osdev.org/Bare_Bones)

4. Memory Management
   - [Writing a PMM](https://wiki.osdev.org/Writing_A_PMM)

5. Basic Shell
   - [Writing a Shell](https://brennan.io/2015/01/16/write-a-shell-in-c/)

## Online Courses
1. [CS50: Introduction to Computer Science](https://www.edx.org/course/cs50s-introduction-to-computer-science)
2. [Nand2Tetris](https://www.coursera.org/learn/build-a-computer)
3. [Introduction to Operating Systems by Georgia Tech](https://www.udacity.com/course/introduction-to-operating-systems--ud923)
4. [MIT OCW 6.828: Operating System Engineering](https://ocw.mit.edu/courses/6-828-operating-system-engineering-fall-2012/)

## Books
1. "C Programming Language" by Kernighan and Ritchie
2. "Modern Operating Systems" by Andrew S. Tanenbaum
3. "Operating Systems: Three Easy Pieces" by Remzi H. Arpaci-Dusseau
4. "Computer Organization and Design" by Patterson and Hennessy
5. "Operating System Concepts" by Silberschatz, Galvin, and Gagne

## Research Papers
1. ["The Evolution of Operating Systems"](https://www.cs.princeton.edu/courses/archive/fall11/cos318/readings/evo-history.pdf)
2. ["Understanding the Linux Virtual Memory Manager"](https://www.kernel.org/doc/gorman/pdf/understand.pdf)
3. ["The Design of the Unix Operating System"](https://courses.cs.washington.edu/courses/cse451/04wi/papers/ritchie84evolution.pdf)
4. ["An Overview of the Singularity Project"](https://research.microsoft.com/pubs/52716/osr2007_rethinkingsoftwarestack.pdf)
5. ["Interrupts and Interrupt Handling"](https://www.cs.utah.edu/~regehr/papers/interference06.pdf)

## Additional Resources
- [OSDev Wiki](https://wiki.osdev.org/)
- [Linux From Scratch](http://www.linuxfromscratch.org/)
- [xv6 Teaching Operating System](https://pdos.csail.mit.edu/6.828/2019/xv6.html)
- [OS Development Series](http://www.brokenthorn.com/Resources/OSDevIndex.html)

## Community Resources
- [OSDev Forums](https://forum.osdev.org/)
- [Stack Overflow OS Development Tag](https://stackoverflow.com/questions/tagged/operating-system)
- [Reddit r/osdev](https://www.reddit.com/r/osdev/)
- [OS Development Discord](https://discord.gg/osdev)

## Development Tools
1. Text Editors/IDEs
   - Visual Studio Code with C/C++ extension
   - Eclipse CDT
   - CLion

2. Debugging Tools
   - GDB
   - BOCHS Debugger
   - QEMU Monitor

3. Build Tools
   - Make
   - CMake
   - NASM/YASM

4. Testing Tools
   - Unit Testing Frameworks
   - QEMU for OS Testing
   - VirtualBox for Testing

## Next Steps After Completion
1. Study existing OS codebases
2. Contribute to open-source OS projects
3. Explore advanced topics:
   - Real-time operating systems
   - Embedded systems
   - Distributed systems
