You are looking at a computer running inside a browser tab, running on a real computer of yours, talking to a real computer of mine. A doll inside a doll inside a doll. Open CrabWeb and load this page inside itself — go one doll deeper.
None of this is emulated hardware. It is just text — angle brackets your machine agreed to render — pretending to be a machine. That pretending is the whole point.
Why it exists: You Can Put a Song in a Game · The Magic of HTML