Show HN: A DOS-like hobby OS written in Rust and x86 assembly

116 krustowski 19 6/19/2025, 1:38:57 PM github.com ↗
To try it out, simply build the project yourself from source, or use attached bootable ISO image of the system (in Releases on Github) and run it in QEMU.

https://blog.vxn.dev/rou2exos-rusted-edition

Comments (19)

rollcat · 6h ago
Memory-safe language. x86_64, with Arm on the roadmap. Networking stack. Boots from a CD and via multiboot. Your hobby project wipes the floor with DOS.
pvg · 5h ago
Whoa there. Gotta run Doom and BASIC to compete with DOS. That is the officially recognized DOS-Kármán line.
krustowski · 5h ago
What a challenge! Need to implement some interrupts it seems then, to provide an API for filesystem and so... Thank you for such idea
rzzzt · 22m ago
Doomgeneric has a very thin platform-specific layer: https://github.com/ozkl/doomgeneric?tab=readme-ov-file#porti...
jmspring · 19m ago
I want some TSRs and print spoolers...
rollcat · 2h ago
DOOM required DOS 5.0. rou2exOS is only the second take. Watch this area ;)
mycall · 36m ago
also, can't be a dos with the 'dir' command.
krustowski · 29m ago
Afaik there is a 'DIR' command in MS-DOS. Anyway, what would be a better command to list a directory? I could think of 'ls' maybe
jdsully · 51m ago
Nobody cares about Lotus 1-2-3 support any longer :)
mixmastamyk · 27m ago
I would have preferred something like this to the current UEFI environment and shell, a FLOSS 64-bit DOS. A cool retro boot manager and diagnostic env perhaps.

Could this run from an efi system partition? Seems to support fat12, what about gpt?

Does it poke video hardware like DOS, or have a terminal like output?

krustowski · 2m ago
Booting from an EFI system partition has not been tested yet. FAT12 is the only filesystem (ok, there is a memdisk implementation, but it won't work now) supported, so GPT is not supported at the moment too (yet). Kinda aiming for FAT32 implementation to be the very next implemented (flash disks are usually FAT32 iirc). Not sure about the last question: the OS utilizes/directly writes to the VGA buffer in memory, the provided resolution is 80x25 by GRUB.
DrNosferatu · 5h ago
DOS-like but not DOS-compatible, correct?
krustowski · 5h ago
You are right. The first iteration however is 16bit and is very close to MS-DOS in terms of compatibility. Moreover, any OS that can handle simple disk I/O ops could be considered a DOS system too, innit?
leeter · 4h ago
Correct, there is a difference between MS-DOS and IBM-PC compatible and a DOS (ex: all the DOSes that existed for Amiga/Apple II/Commodore etc). There are many DOSes (and even MSDOSes, because yay early PC era incompatibilities!), but there is a very dubious list of things needed to be MS-DOS and IBM-PC compatible. You can probably do it if you're willing to setup a hypervisor and emulate some hardware.

NGL one of my long term projects was/is something exactly like this but UEFI and secure boot. The idea being to use the VM extensions to create IBM-PC and DOS compatible environments. For anything using DPMI[1] I'd probably do the same trick as Win95 did and just replace it with my own implementation so it's not too overburdened with layers.

[1] https://en.wikipedia.org/wiki/DOS_Protected_Mode_Interface

JdeBP · 2h ago
A version of (say) FreeDOS that was layered on top of the EFI API instead of PC98 firmware interrupts would be quite interesting. That would be a major architectural change to most of the programs, of course. But one would have provided the EFI Shell with essentially a complete suite of MS-DOS (albeit not PC-DOS or DR-DOS) commands. That could probably be quite easily ported to (say) ARM whereas the original still has x86isms.

On the other hand, did you see https://github.com/FlyGoat/csmwrap when it came up a few weeks ago?

* https://news.ycombinator.com/item?id=44101828

There are already projects to provide replacements for the vanished Compatibility Support Module.

leeter · 51m ago
I did see that and for people that need that specific functionality it seemed like a good solution.

My goal was more "What if DOS hadn't ended and but kept up support for modern hardware" along with emulation of common things in DOS gaming. So for example you would be able to set up a PIV that mapped certain resources directly or emulated them depending on the need.

Could I use DOSBox for this... yes, but this is a "why not" sort of thing. I figured it would be a good excuse to learn OS dev. But life has kept me busy for now.

DrNosferatu · 2h ago
...meaning MS-DOS compatible :)

I.e.: runs Alley Cat and Dune 2 - and Doom.

JdeBP · 2h ago
And prevents Lotus 1-2-3 from running? (-:
vardump · 1h ago
That's the litmus test. No version of DOS is complete until Lotus 1-2-3 no longer runs.