bios-OS/doc/build.md

Build & Run

Compilation

From the project root:

cd src
nasm -f bin boot.asm -o ..\build\bios.bin

This produces a raw BIOS ROM image (bios.bin) suitable for direct execution by QEMU.

QEMU Execution

The QEMU VGA BIOS must be copied into a local rom/ directory.

Default locations of vgabios.bin:

Windows C:\Program Files\qemu\share\vgabios.bin

Linux /usr/share/qemu/vgabios.bin

You can use an video bios from the 86box's project:

https://github.com/86Box/roms

Copy it to: roms/vgabios.bin

Then run QEMU with:

qemu-system-i386 \
  -bios build/bios.bin \
  -device loader,file=roms/vgabios.bin,addr=0xC0000,force-raw=on \
  -device isa-debugcon,chardev=myconsole \
  -chardev stdio,id=myconsole \
  -k be \
  -display sdl

This command:

• Loads the custom BIOS as the system ROM
• Injects the VGA BIOS at 0xC0000
• Redirects debug output to the console
• Displays graphics using SDL

86Box Execution

This is a bit tricky since 86box doesn't allow to pick custom BIOS file. You'll have to choose an existing computer and replace the original BIOS file with the compliled one.

create a new configuration:

• save the configuration
• go to the 86Box's roms\machines\vli486sv2g\ folder
• rename the 0402.001 file (it's the original machine's BIOS);
• copy the build\bios.bin into the 86Bos's roms\machines\vli486sv2g\ folder and rename as 0402.001