I Built a 64‑Bit OS from Scratch: BIOS/UEFI, GUI, Networking, a Browser, and DOOM

Description and use

BoltOS is a fully custom 64‑bit OS built from scratch, supporting BIOS/UEFI, a GUI, networking, a browser engine, and a DOOM port.

Problem

Developing a fully functional 64‑bit operating system from scratch without relying on existing kernels, bootloaders, or external libraries.

Outcome

BoltOS demonstrates that a complete 64‑bit OS can be built from scratch, supporting modern hardware, networking, a GUI, and applications like a DOOM port, all without external bootloaders or libraries.

Workflow

• 1. Implement custom BIOS MBR and UEFI boot chain to load a 64‑bit higher‑half kernel
• 2. Build kernel core with ACPI, APIC, SMP, preemptive scheduling, ring‑3 userland, ELF loading, and syscalls
• 3. Add memory management (physical/virtual, ASLR, SMAP/SMEP, swap, stack canaries)
• 4. Develop graphical desktop: compositor, window manager, TrueType rendering, clipboard, file manager, IDE, task manager, and 24 apps
• 5. Implement persistent storage via VFS and block layer (ATA, AHCI SATA, NVMe, EXT2, FAT32)
• 6. Create in‑kernel network stack (DHCP, TCP/UDP, DNS, HTTP, TLS 1.2/1.3, X.509)
• 7. Build browser engine (DOM, CSS cascade, layout) and JavaScript interpreter
• 8. Add DOOM port, audio, USB HID, and PE32+ loader for Windows executables
• 9. Provide build scripts (build.sh, run.sh, run-uefi.sh) and QEMU launchers
• 10. Release source on GitHub and invite community feedback

Evidence

I built BoltOS as a 64‑bit operating system in C and x86‑64 assembly, starting with the boot chain rather than an existing kernel or bootloader.

Source

The first source release is available at BoltOS v0.1.0 — Initial Public Preview.

Source