CadenOS Bootloader

A custom x86 bootloader and mini-kernel built from scratch.

Project Description

A minimalist 16-bit x86 bootloader written in NASM Assembly that transitions into a 32-bit Protected Mode C kernel. The project currently boots from a simulated floppy disk, loads the kernel from disk to memory, sets up the Global Descriptor Table (GDT), and executes C code capable of direct VGA memory manipulation.

Current Status

• Bootloader: Functional. Boots from MBR, loads kernel from disk, switches to 32-bit Protected Mode.
• Kernel: Minimal C kernel entry point established.
• Build System: Automated Make pipeline with QEMU emulation and GDB debugging support.

To-do

Completed

• Boot from disk, raise from 16-bit to 32-bit mode
• Load C Kernel into memory
• Basic screen printing, scrolling
• Basic kernel utils (memcpy, memset, etc)

In Progress / Next Steps

• VGA Driver:
  • Full printf style support for the kernel
• Input Driver:
  • Write PS/2 Keyboard driver (scancode handling)
  • Create a keyboard buffer/queue
• Interrupts:
  • Set up the Interrupt Descriptor Table (IDT)
  • Remap the PIC (Programmable Interrupt Controller)

Goals

• Proficiency with Assembly and Low-level Architecture
• Simple text editor + filesystem

Stretch Goals

• Number 1 most used kernel in the world
• Solve world hunger
• Found intergalatic empire focusing on human supremacy

Resources

Books

• Writing a Simple Operating System from Scratch
• Operating Systems: From 0 to 1

Helpful Code

• https://github.com/lukearend/x86-bootloader
• https://github.com/aayush598/basic-bootloader-assembly
• https://mikeos.sourceforge.net/write-your-own-os.html

Guides

• https://wiki.osdev.org/Babystep1
• https://wiki.osdev.org/Creating_A_Shell

x86 Material

• https://www.ctyme.com/intr/int.htm
• https://pastraiser.com/cpu/i8086/i8086_opcodes.html