First you need to port x86(or any other) instruction set. This can also be done by compiling (part of)Bochs/PCE using emscripten. Then you need to port IO (flop

First you need to port x86(or any other) instruction set. This can also be done by compiling (part of)Bochs/PCE using emscripten. Then you need to port IO (floppy,HD etc.). Then monitor and graphics card. And if you really want to be cool there are hosts of other things to port like touchscreen, networking, USB etc.