Developer unartic has unveiled a working prototype of his X16 DOS BIOS, a fully custom ROM and disk-based operating system designed to bring the Commander X16 closer to the MS-DOS era of computing. Unlike the official KERNAL, this BIOS skips BASIC entirely and boots straight into a command-line interface that echoes the feel of vintage IBM PC XT/AT machines.
Built entirely from scratch, the X16 DOS BIOS communicates directly with hardware, bypassing the stock ROMs and embracing a minimal but powerful setup. The BIOS currently occupies just 7KB of space and already supports essential functionality including SD card I/O, FAT32 read/write, ISO-compatible text mode video, and full keyboard and RTC access over the I2C bus.
Built-In Command-Line Features
The custom shell comes with a growing list of familiar tools:
- Directory navigation without needing
cd - Simple program launching
- Commands like
cls,ver,path,reset, and file operations (md,mf,open,write,close) - MS-DOS-like PATH behavior, allowing
/binutilities to be run from anywhere
Included Utilities
Stored in /bin, these utilities demonstrate the flexibility of the system:
- A hex viewer
- Text viewer
- Character set browser
- Wozmon monitor
Launching programs is intuitive. Type a directory name to enter it. Hit Enter for a dir-like listing. Type an executable name to run it. It’s a minimal interface with maximum nostalgia.
What’s Next?
Unartic has ambitious plans for this retro-modern BIOS:
- A built-in audio and graphics library that taps into the full power of VERA and VERA FX
- A ROM-based nxtBasic runtime, enabling smaller compiled programs with room for richer games and apps
- A powerful debugger/monitor baked right in
- Full documentation and open-source release on GitHub
A demonstration video is already online, showcasing these features in action. Contributors and testers are welcome—reach out via the Commander X16 forum post or Discord.
