To advance to upper levels, type these codes:

1: 120Z
2: 221Z or 2119
3: 322Z
4: 423Z or 433B
5: 5149
6: 6159
7: 736B
8: 8179 or 827Z

Note: Some of the secondary codes work only after you've completed the levels below it, but I have used all of the above codes as I am completing the game. What a hoot!