Passwords (Pass Word (sic) in game) are pretty straight forward; you'll find them laid out in a matrix of 3x4. Although you may find many different passwords throughout the game, you'll find that many of them give the same result. Your hard earned extra lives and sub tank energy don't get saved with the passwords, only the bosses you've beaten, how many Sub Tanks and Heart Tanks you acquired, and the upgrades you've gotten (excluding the Hadouken) will be saved.
