Bellard's jslinux runs within a web browser and provides a 32-bit X86 CPU, an interrupt controller, interrupt timer as well as serial interface within 90 KB. According to the developer, the emulator has been tested with Firefox 4 and Chrome 11 (it does not work in Chrome 12 beta) under Windows, Mac OS X and Linux. The code runs substantially faster in Firefox than in Chrome.
Since it works with Firefox 4, it also works on Android smartphones and tablets using the browser (which we briefly tested). jslinux is not compatible with the standard Android browser.