The demo is a whole fake computer now

There is a demo of ESP-KVM at demo.espkvm.io. It needs no hardware, no sign-up and no install: one page, about 300 KB, and you are looking at the console.

The important part is what is real and what is not. The console is the real one - the same code the firmware serves, built from the same repository. What is faked is the device underneath it: the page intercepts the calls the console makes and answers them itself, from data captured off a live device.

Behind those answers sits a machine. Not a video of a machine, an actual little state machine with stages, a clock and an 80x25 character screen laid out with the same geometry the firmware reports for a real UEFI console.

So the story runs like a call-out would. The page opens on a machine mid-POST - deliberately not a dark screen - and it lands on "No boot device found". The screen tells you to pick an image under Media. Choosing one writes the same setting that mounts a disc on a real device. Reset boots it. The prompt takes the keys you type. If you do nothing for fifteen seconds the demo loads an image and boots it by itself, and the first thing you do stops that for good.

There are four things to boot, and each falls over in its own dialect:

• HalfOS Life - a shell; type startx and the pointer constellation comes up. Type something unwise at the prompt and you get a kernel panic with a call trace.
• Sheeps XP - flat hills, walking sheep and a taskbar (that is the picture above; the flock gathers round the pointer once you have taken control, and grazes when you leave it alone). Click the black sheep and the machine stops with BLACK_SHEEP_NOT_RESPONDING, wool.sys, "contact your shepherd".
• Pear OS - a smiling computer, a progress bar that sticks at nine tenths, then a desktop with a dock. One tile in that dock tells you to restart your pear.
• memtest - a memory test that never finishes, with a pass counter that keeps climbing until it finds a one-bit failure.

Every crash screen is text on purpose. That is the whole point of the product: read the words off a machine that has stopped and put them in a report. On those screens Select and Copy light up and really work, because there really are characters there to read.

The firmware update runs end to end too. The demo serves its own manifest, offers a newer version, streams an image of the right size in chunks so both progress bars move, then fails every call for seven seconds while the "device" restarts, and comes back on the new version.

One more thing worth saying out loud: building this found two real bugs in code that ships. A refused image left the console stuck behind its own full-screen overlay with only a reload out. And the console read every keyboard report as a fresh press, so two overlapping keys - which is what fast typing is - repeated a letter. A fake device exercises paths a real one rarely reaches.