How to Build an Emulator for a Fantasy CPU in JavaScript

How to Build an Emulator for a Fantasy CPU in JavaScript? How to build a simple machine that will run programs written for a fantasy CPU. Emulators are cool pieces of technology that allow users to run a totally different system on top of another one. Here, we'll explore how a CPU works and how its software can emulate one. We need to know the CPU instructions if we want to emulate that CPU into software. The CPU doesn't execute virtual instructions and assumes that an instruction is an address and assumes to jump to an address.