🖥️ NexxoN OS

A complete, graphical, networked desktop operating system - written entirely from scratch.
No Linux. No libc. No borrowed binaries. Every byte, from the boot sector to the web browser, is hand-written.

What is this?

Most hobby operating systems stop at "hello world on a VGA text screen." NexxoN OS is a real desktop OS - it boots on bare metal, brings up a 1024×768 true-colour framebuffer, and drops you into a compositing window manager with a taskbar, start menu, login screen, and a full suite of GUI apps. It talks to the network, plays audio through real hardware codecs, mounts USB sticks, and stores your files in a journaling filesystem that survives power cuts.

110+ source files · 50 000+ lines of C and x86 assembly · one ~8 MB bootable image.


_{🔐 Graphical login (salted SHA-256 auth)}	_{🪟 Compositing WM with Aero chrome - multiple windows}

_{📊 NexSheet - Excel-style spreadsheet (formulas, XLSX)}	_{📁 Explorer - browse NXFS & USB drives}

_{⚙️ Settings - system, language, audio, network, security}	_{🗄️ NXFS v3 - a 20 MiB file written & verified, fsck-clean}

What the system CAN do

Boot & core kernel

✅ Boots from GRUB (CD/USB live) and from an installed SATA disk via its own hand-written 2-stage bootloader (installsys writes the MBR + stage1/stage2 + kernel).
✅ 64-bit x86_64 long mode (4-level paging, 64-bit GDT/IDT/TSS, ring-3 syscalls, runtime VBE resolution switching). PIC/PIT/RTC, ACPI shutdown.
✅ Preemptive round-robin scheduler with kernel tasks (background workers).
✅ SMP detection, ASLR (per-boot randomized offset), NX-bit when the CPU supports it.
✅ Ring 3 ↔ Ring 0 split with an int 0x80 syscall gate.
✅ Recoverable panics - a faulting Ring-3 app's window is torn down and you return to the desktop instead of rebooting; unrecoverable faults paint a full 64-bit RSOD (all 16 GP registers + RIP/RSP/CR2, a stack trace, and a crash dump to /sys/crash.log).

Graphical desktop - "Liquid Glass" (Modernised Aero)

✅ Frosted-glass compositing window manager - real backdrop blur under glass panels, 3-D glass bevels (light top/left, dark bottom/right), rounded corners on an 8 px grid, drag, resize, minimize, focus, z-order, anti-aliased text.
✅ Liquid animations - window open/close, Start-menu slide, context-menu expand and toast slide-in all run on a unified PIT-driven ease-out cubic.
✅ Dirty-rectangle compositor - recomposes + presents only the damaged region (idle ~28 ms → ~1.2 ms/frame), with MTRR write-combining on the framebuffer; frame budget is logged to COM1 ([wm/perf]).
✅ Frosted taskbar (start orb, running-window tiles, glass system tray, aero volume slider, two-line live clock) + frosted popups (calendar, network, toasts) and a soft Aero shadow.
✅ Two-pane glass Start menu with app launcher, glossy glass avatar, shutdown/restart, search box, and the shared Aero button/tab/slider controls.
✅ Persistent desktop icons + right-click context menus, screensaver.

Built-in applications

✅ Shell (60+ commands, line editing, tab, Ctrl+C) · Text Editor (find, clipboard)
✅ NexSheet spreadsheet - formulas (SUM/AVG/IF/…), formatting, cell merge, CSV + XLSX I/O
✅ Web Browser - renders live, real websites via a Puppeteer proxy (see below)
✅ File Explorer, Image Viewer (BMP/PNG/JPEG, zoom), Music Player (WAV)
✅ Task Manager (live CPU / RAM / network graphs), Settings, User Manager, Device Manager
✅ Recycle Bin, NexxStore package browser, Pong

Networking (a from-scratch TCP/IP stack)

✅ NIC drivers: Intel E1000, AMD PCnet, Realtek RTL8169.
✅ IPv4, ARP, ICMP (ping), TCP (full state machine, RTO retransmit, 256 KiB ring), UDP.
✅ DHCP client, DNS resolver, NTP time sync, HTTP/HTTPS downloads.
✅ Crypto: SHA-256, HMAC, AES-128-GCM, TLS 1.2 client handshake.
✅ Browser proxy auto-discovery - the proxy advertises itself via a UDP LAN beacon; NexxoN finds it automatically (manual IP stays as a fallback). 📡

Audio

✅ Native Intel HDA driver (CORB/RIRB, codec walk, BDL streaming) - real sound on modern boards (Realtek codecs).
✅ Legacy AC'97 path + PC-speaker fallback. System tones, music, and browser audio all route through a shared mixer (volume/mute).

Storage & filesystems

✅ NXFS v3 - our own journaling filesystem:
- ✅ No file-size limit - 12 direct + single/double/triple indirect blocks (4 KiB blocks → multi-GiB files; design ceiling 4 TiB/file).
- ✅ Write-ahead metadata journal with CRC32 + crash replay → survives power loss.
- ✅ Streaming read/write API (64-bit offsets), nxfsck consistency checker/repair.
- ✅ installsys formats the target disk at its real size and copies the live tree.
✅ AHCI/SATA with automatic legacy IDE/ATA PIO fallback.
✅ USB mass storage (xHCI) - hot-plug/hot-swap auto-mount under /usbN:
- ✅ FAT16/32 read and write (create/delete/mkdir/rename) with long filename (LFN) support
- ✅ exFAT read and write (verified fsck.exfat-clean), NTFS read-only
- ✅ Streamed, un-capped file copy between volumes (no more 2 MiB limit)
✅ USB HID keyboard + mouse (boot protocol, hot-swap, system-wide key repeat).

Security & i18n

✅ Graphical login, salted SHA-256 passwords, Admin/User roles, up to 8 accounts.
✅ Full English + Hungarian localization, switchable at runtime - zero hardcoded UI strings - with automatic US-QWERTY ↔ HU-QWERTZ keyboard layout switching.

What the system CANNOT do (yet)

Honest limitations - these are the next things on the roadmap, not hidden bugs:

❌ No multitasking for user apps - apps run cooperatively on one shell context; only kernel worker tasks are preempted. No process isolation between apps.
❌ The browser is a thin client - it does not parse HTML/CSS/JS locally; it streams JPEG frames from a host-side Puppeteer/Chromium proxy. No proxy ⇒ no web.
❌ NTFS and the local HTML engine are read-only / absent - write support is FAT/exFAT/NXFS only.
❌ Directories cap at 64 entries in NXFS v3 (file size is unbounded; dirent scaling is future work).
❌ No real GPU acceleration - software rendering into a VBE/BGA linear framebuffer only. (NOTE: the OS now boots in 64-bit x86_64 long mode by default - see below.)
❌ No Wi-Fi data path - the Wi-Fi app enumerates/associates but bulk traffic goes over wired NICs.
❌ No virtual memory paging to disk for apps, no dynamic-library loading for third-party binaries (there is an internal nxl loader for built-ins only).
❌ TCP uplink window is single-segment - fine for the browser's command channel, not for bulk uploads.

Quick Start

Prerequisites

# Ubuntu / Debian
sudo apt install build-essential nasm \
                 grub-pc-bin grub-common xorriso mtools \
                 qemu-system-x86 dosfstools netpbm

Build & run

git clone https://github.com/SubCoderHUN/NexxoN-OS.git
cd NexxoN-OS
make          # build the 64-bit kernel + bootable nexxon-os.img (x86_64)
make run      # launch in qemu-system-x86_64 (audio + networking + AHCI disk)

GRUB loads, the splash clears, and you land at the login screen.

Default login: admin / admin

Target	What it does
`make`	Build the 64-bit `nexxon-os.img` (bootable hybrid ISO/USB image)
`make run`	Boot in `qemu-system-x86_64`; creates a persistent `nxfs-disk.img` on demand
`make run-debug`	Boot with serial → terminal (watch COM1 / CPU exceptions)
`make clean`	Remove all build artifacts
`make proxy`	Install Node deps for the web-browser proxy

Install to a real disk

Boot the live image, then from the shell:

installsys        # writes MBR + bootloader + kernel + a fresh NXFS v3 partition

Reboot without the USB/CD and the machine boots NexxoN straight from SATA. The prompt switches from …[EN:LIVE] to …[EN:HDD]. 💾

Enable the web browser

cd proxy && npm install     # one-time
node server.js              # starts the proxy + LAN discovery beacon (UDP :9099)

Then launch Browser inside NexxoN - it auto-discovers the proxy on the LAN (or set the IP manually in the toolbar).

##️ Architecture

  ┌──────────────────────────────────────────────────────────────────┐
  │  Ring 3   Shell · Editor · Browser · Explorer · NexSheet · Pong   │
  ├──────────────────────────────────────────────────────────────────┤
  │                      int 0x80  syscall gate                       │
  ├──────────────────────────────────────────────────────────────────┤
  │  Ring 0   Window Manager · Compositor · Scheduler · IPC · Audio   │
  │           NXFS v3 (journal) · VFS · USB(xHCI) · AHCI/IDE · DMA     │
  │           TCP/IP · DHCP · DNS · NTP · TLS · Crypto · Downloads     │
  │           SMP · ASLR · NX · GDT/IDT/PIC/PIT/RTC · Panic/Recovery   │
  ├──────────────────────────────────────────────────────────────────┤
  │  HW   PCI · E1000/PCnet/RTL8169 · Intel HDA/AC'97 · USB · VBE      │
  └──────────────────────────────────────────────────────────────────┘

The boot chain on an installed disk is fully hand-written: stage1 (MBR, 512 B) → stage2 (unreal-mode ELF loader: reads the kernel in real mode, copies it above 1 MiB) → kernel (Multiboot-v1 ELF).

NXFS v3 - the in-house filesystem

Property	Detail
Block size	4 KiB (8 sectors)
Max file size	Effectively unlimited - 12 direct + 1×/2×/3× indirect (≈4 TiB ceiling)
Random access	Any byte offset reached in ≤ 3 indirect reads (no scanning)
Crash safety	Write-ahead metadata journal (header + payload + CRC32 commit), replayed on mount
Data ordering	Data written before the referencing transaction → crash can leak blocks, never corrupt structure
Repair	`nxfsck [repair]` rebuilds bitmaps from the reachable tree, reclaims leaks
Modes	RAMFS in LIVE mode (lost on reboot) · persistent on an installed SATA disk

Verified in QEMU: a 20 MiB file written through the double-indirect path, byte-pattern verified, nxfsck clean; a kill -9 during a 100 MiB write leaves a consistent shorter file on remount (0 problems, 0 leaks) - journaling works. ✅

Web browser (thin client)

  NexxoN OS (guest)                        Host machine
  ┌──────────────┐    TCP :9090       ┌─────────────────────┐
  │ Browser      │ ─── clicks/keys ─► │ Puppeteer proxy      │
  │ (JPEG viewer)│ ◄── IMG/TILE/AUD ─ │ (headless Chromium)  │
  └──────────────┘    frames          └─────────────────────┘
        ▲   UDP :9099 discovery beacon ◄──────────┘

The proxy renders real pages in headless Chrome, streams JPEG frames + MP3 audio over TCP, and broadcasts a discovery beacon so the OS finds it with zero config. JPEG decoding runs in a background worker task, so heavy pages never freeze the UI.

Tested on

QEMU (qemu-system-x86_64) · target hardware: ASUS P8Z77 (Ivy Bridge, Intel 82579V NIC, Realtek HDA, xHCI USB). The 64-bit build is QEMU-verified end to end (boot, desktop, ring-3 GUI apps, NXFS install + installed-disk boot, resolution switching, networking, audio) and awaits its first real-hardware pass - boot make run-debug and watch the COM1 log ([BOOT]/[vga]/[xhci]/[hda] markers) on the P8Z77.

_{NexxoN OS - built byte by byte. 🧱 Bootloader, kernel, drivers, filesystem, network stack,
window manager and apps: all from scratch.}

Name		Name	Last commit message	Last commit date
assets		assets
docs/screenshots		docs/screenshots
iso/boot/grub		iso/boot/grub
proxy		proxy
scripts		scripts
src		src
tools		tools
userland		userland
.gitignore		.gitignore
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
linker.ld		linker.ld
linux-subsystem-test.ppm		linux-subsystem-test.ppm
run-qemu.sh		run-qemu.sh

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🖥️ NexxoN OS

What is this?

What the system CAN do

Boot & core kernel

Graphical desktop - "Liquid Glass" (Modernised Aero)

Built-in applications

Networking (a from-scratch TCP/IP stack)

Audio

Storage & filesystems

Security & i18n

What the system CANNOT do (yet)

Quick Start

Prerequisites

Build & run

Install to a real disk

Enable the web browser

NXFS v3 - the in-house filesystem

Web browser (thin client)

Tested on

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🖥️ NexxoN OS

What is this?

What the system CAN do

Boot & core kernel

Graphical desktop - "Liquid Glass" (Modernised Aero)

Built-in applications

Networking (a from-scratch TCP/IP stack)

Audio

Storage & filesystems

Security & i18n

What the system CANNOT do (yet)

Quick Start

Prerequisites

Build & run

Install to a real disk

Enable the web browser

NXFS v3 - the in-house filesystem

Web browser (thin client)

Tested on

About

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