I built a 32-bit OS from scratch and named it after my mom

The Beginning

A few months ago I didn't know what a bootloader was.

Today I have a working 32-bit operating system called

JanOS — named after my mom who supported me through

the entire journey.

What is JanOS?

JanOS is a 32-bit x86 operating system built completely

from scratch in C and x86 Assembly. No frameworks.

No shortcuts. Every line written and understood.

What it can do

• Custom bootloader that loads the kernel via LBA


• 32-bit protected mode with GDT


• FAT12 file system (read, write, delete files)


• Persistent storage via custom ATA driver


• Shell with 10+ commands


• Memory management with paging


• Hardware cursor


• Keyboard with shift support


• History navigation with arrow keys


• Screen scrolling

The hardest part

Making files persist across reboots was the biggest

challenge. I had to write a custom ATA driver that

talks directly to the disk controller hardware through

ports. No BIOS, no shortcuts — just raw hardware

communication.

What I learned

• How the CPU actually boots


• How memory is really managed


• How files are actually stored on disk


• How keyboard input really works

Video

Screenshot

What's next

• IDT (interrupt handling)


• Multitasking


• GUI

Try it yourself

GitHub: https://github.com/Gyimah-Benjamin/JanOS

Still building. This is just the beginning 🚀