Yeah, I also have to push back a little bit of the discussion of the first game. A lot of the old Nintendo games had cheat codes, character names, or special passwords that let you access abilities, weapons, or the end game: Mike Tyson's Punch Out, Metroid, and the original Zelda come to mind. If the original Super Mario Brothers had needed or implemented a password system, it probably would have had a similar code.
Just out of curiosity, has anyone ever played the Kid Icarus gameboy game? Was it largely the same as the NES game?