MBR-Bootloader

A minimalist x86 bootloader that prints a message from the Master Boot Record (MBR). This bootloader fits within 512 bytes and demonstrates how to initialize registers, print a string via BIOS interrupts, and safely halt the CPU. This was done as a learning experience, if you notice any error, please open an issue!

Overview

This project serves as a foundational step into low-level and systems programming using 16-bit real mode x86 assembly. It provides a fully working example of:

• Writing a valid MBR boot sector
• Using BIOS interrupt 0x10 for TTY output
• Initializing segment registers manually
• Embedding null-terminated strings

For a line-by-line breakdown of the code, see here.

Requirements

To build and run this bootloader, you will need:

• nasm (Netwide Assembler)
• qemu-system-x86_64 (or any other x86 emulator for testing)

Installation

1. Clone the repository and initialize the build directory:

    git clone https://github.com/wellatleastitried/MBR-Bootloader.git
    cd MBR-Bootloader && mkdir build

2. Build the bootloader and run it with QEMU:

   make run

   OR only build the bootloader:

   make

3. To clean up the build files, run:

   make clean