my-OS

my-OS is a custom 32-bit operating system kernel written from scratch in C and Assembly. It boots via a Multiboot-compliant bootloader and runs in Protected Mode.

🚀 Features

• Custom Bootloader Stub: Written in NASM Assembly to set up the stack and handle Multiboot headers.
• Kernel in C: A freestanding C kernel running on bare metal.
• VGA Video Driver: Direct memory manipulation of the VGA buffer (0xB8000) to display text and colors.
• Cross-Compiler: Built using a custom GCC toolchain for i686-elf.

🛠️ Build Dependencies

To build and run this OS, you need the following tools:

• NASM (Assembler)
• GCC Cross-Compiler (i686-elf-gcc)
• QEMU (Emulator for testing)

⚡ How to Build & Run

1. Compile the Bootloader

nasm -f elf32 entry.asm -o entry.o

2. Compile the kernel

i686-elf-gcc -c kernel.c -o kernel.o -std=gnu99 -ffreestanding -O2 -Wall -Wextra

3. Link the OS

i686-elf-gcc -T linker.ld -o myos.bin -ffreestanding -O2 -nostdlib entry.o kernel.o -lgcc

4. Run in QEMU

qemu-system-i386 -kernel myos.bin

🗺️ Development Roadmap

• I am building this OS stage-by-stage to understand low-level computing.

• Phase 1: The Foundation (Current Stage)

• [x] Bootloader: Get into Protected Mode (32-bit).

• [x] Kernel Entry: Jump from Assembly to C.

• [x] VGA Output: Print raw characters to video memory (0xB8000).

[ ] Terminal Driver:

Support Newlines (\n)

Implement Scrolling (when screen fills up)

Support standard colors

• Phase 2: The Standard Library (libc) Since there is no Linux/Windows underneath, I cannot use <stdio.h>. I must write my own:

[ ] Implement strlen (String Length)

[ ] Implement memcpy & memset (Memory operations)

[ ] Implement itoa (Integer to ASCII for printing numbers)

• Phase 3: Hardware Integration

• [ ] GDT (Global Descriptor Table): Configure memory segments for security.

• [ ] IDT (Interrupt Descriptor Table): Handle CPU interrupts.

• [ ] Keyboard Driver: Read scancodes from port 0x60 and convert to text.