In my next game, I want the player to be able to type in my predefined programming codes, and have them show up on the screen (think I.S.O.S. http://www.adventuregamestudio.co.uk/games.php?action=detail&id=931).
Is this simple, or am I in the wrong area?
It's relatively simple, depending on your scripting/AGS experience. All you need is a GUI with an INPUT BOX. You can turn this GUI on, and then react to anything the player types into that box. Parser games are (mostly) made that way.