@TLapworth93: The last compiler written in machine code was an old one for Pascal, by the great Anders Hejlsberg. At least, that's what I heard. Why you'd write anything else other than a compiler in machine code, I don't know. Just for the challenge, eh? I wondered if it was possible to teach a young child to read machine code fluently ... don't know how I would teach it though. I think it's really an exercise worth trying but you'd probably give up after "Hello World!". After you get that far, everything is just a simple matter of coding ... forever.