Simple 8-bit Assembler Simulator in Javascript

Link: Simple 8-bit Assembler Simulator in Javascript: "One of many simple CPU simulators. I'm teaching a course in Operating Systems and I've been looking for a really simple and clear visual simulator for a CPU. This one is the best one yet. But I would like a better one. This one is missing any kind of support for IO or System calls or something like that. But it's usable."