Boot UnoDOS in your browser

This is the OS under full CPU emulation in your browser tab; on real hardware it is instant.

Every instruction is being translated to WebAssembly and run by your browser, so it is slower here than anywhere else it runs. A window drags at about 35 frames per second on a current desktop and a good deal less on an old laptop.
Nothing is saved. Reloading the page boots a clean machine.
The guest has no network. Nothing it does reaches the internet, and nothing you do here leaves your machine.
Click the screen to give it the keyboard; Ctrl+Esc opens the Start menu. Move the mouse off the screen to leave, and click anywhere on the page to take the keyboard back.

Want it at full speed? Download the image and write it to a USB stick, or load it in an emulator on your own machine. The manual covers what is in it.

How this works

There is no plugin and no server doing the work. The whole machine is running in this tab.

QEMU compiled to WebAssembly emulates a PC: an x86-64 CPU, a VGA card, an IDE disk and a PS/2 keyboard and mouse. Every instruction UnoDOS executes is translated to WebAssembly and run by your browser, on worker threads. That is why it needs a recent desktop browser: threaded WebAssembly needs SharedArrayBuffer, which a page only gets when it is served cross-origin isolated.

The disk is a 96 MiB image of the real release, shipped compressed at about 19 MB and expanded here in the browser. About half of that is Freedoom: the image carries Duum, the Doom engine written in Python, and its 28 MB of game data. Duum runs here at well under one frame a second and takes minutes to reach its first frame - it is worth seeing rather than playing, and the browser port of Duum is the one to actually play. It is a RAM disk once it arrives, so the machine can write to it and nothing survives a reload. The screen you are looking at is the guest's framebuffer, converted and copied into a canvas each time the machine redraws.

Written up in full, including what it costs and what it cannot do, in BROWSER-WIDGET.md.

Diagnostics

not booted