IN DEVELOPMENTBIOS / x86 / NASM
noOS

AN OPERATING SYSTEM FROM ZERO

Just
Assembly.

No Linux. No Windows. No C.

A real x86 operating system built from its first boot sector to an interactive shell. Persist files, schedule kernel workers, and execute validated static ELF32 programs in ring 3—all in NASM.

Boot noOS Explore the architecture
THE ACTUAL MACHINE01 / x86
noOSQEMU · BIOS pc
The real noOS operating system booted in QEMU, showing its Assembly kernel welcome screen and shell.
REAL RUNTIME CAPTURE NO HOST OS INSIDE

A real shell. Persistent files. Ring 3 ELF32 programs.
NASM is the runtime language. QEMU is the test machine.

512BFIRST BOOT SECTOR
32bitPROTECTED MODE
40VERIFICATION GATES
100%ASSEMBLY RUNTIME

01 / THE BOOT PATH

From reset.
To your kernel.

The BIOS hands over control. noOS takes it from there.

  1. 01

    Boot sector

    The BIOS loads the 512-byte first stage at 0x7C00. It preserves the boot drive and loads stage two.

    boot/stage1.asm
  2. 02

    Second stage

    Loads the kernel from disk, preserves the BIOS E820 memory map, checks A20, and installs a Global Descriptor Table.

    boot/stage2.asm
  3. 03

    Protected mode

    Sets the protected mode bit, performs a far jump, and establishes the kernel’s 32-bit environment.

    boot/gdt.asm
  4. 04

    Kernel entry

    Execution reaches 0x10000. The kernel initializes its terminal, interrupts, memory, and timer, then starts the shell.

    kernel/entry.asm

02 / BUILT IN THE OPEN

Proof before
percentage.

Eight milestones. Forty equal verification gates. Progress increases when an implementation is verified; completing this checklist does not imply production maturity.

—OF THE 40 DEFINED GATES

Loading verified gates…

Read the engineering roadmap

Loading the roadmap…

03 / RUN IT YOURSELF

Four commands.
A fresh boot.

Install NASM, QEMU, GNU Make, and Python 3 on your host. Then build and boot the real disk image.

Build, test, and debug
HOST TERMINAL
git clone https://github.com/OthmaneBlial/noOS.git
cd noOS
make
make run
make test checks the boot path in QEMU. make debug pauses it for GDB.
KNOW THE BOUNDARY

This is an experimental operating system for QEMU’s BIOS pc machine. Physical memory management currently covers the first 128 MiB. Physical hardware and UEFI are unvalidated; kernel workers share one address space, and user programs run one at a time. The defined roadmap records specific verification gates rather than general hardware compatibility or production maturity.