Writing an emulator for a simple processor isn't particularly complicated. You only need a reference manual of the processor (which I assume he had). The emulat

Writing an emulator for a simple processor isn't particularly complicated. You only need a reference manual of the processor (which I assume he had). The emulator itself can be as simple as a while loop with a switch statement inside and some simple variable manipulation. Nowhere near "feat of computer programming" or "major legend". Source: I've written Z80 and x86 emulators for fun.