I recently posted about emulating the NES with JavaScript.

http://blog.alexanderdickson.com/javascript-nes-emulator-par...

Part 2 will be posted when it's done. :)

If you want to get something done much quicker, have a go at emulating the Chip-8 VM.

I also have a post, but it's less hand-holding than the first.

http://blog.alexanderdickson.com/javascript-chip-8-emulator

Good luck!

You want to write an emulator, but you probably don't want to write one for x86. A nice architecture would be 8 bit AVR microprocessors, for example.

There are two sensible approaches: interpretation or dynamic translation.

If you want to write one as a learning experience for how the platform you're emulating works and how an emulator could work in principle, you probably want to write an interpreter: find out how the platform boots, build something to start reading and interpreting instructions, start adding emulated hardware devices, and you'll get an increasingly functional interpreter.

For a start, you could ignore emulation of devices, and just write a CPU core that interprets instructions.

If you want to learn how modern (but still non-hardware-assisted) emulation works, read about how qemu's dynamic code translator and other JIT compilers work, and build a CPU emulator based on that.

I'm not the OP but check out the book: "The Elements of Computing Systems: Building a Modern Computer from First Principles" It's quite comprehensive, not exactly about writing an emulator, but it should give you what you need.

Canonical place to start: http://stackoverflow.com/questions/448673/how-do-emulators-w...