On the map screen type "DONTPANIC" and use the following keys while
on the map screen:

          'A'______________________Gives you all power ups.
          'Q'____________________________Adds stars to you.
          'W'_____________________Subtracts stars from you.
          'F5'____________________Adds lives to your stock.
          'F6'_____________Subtracts lives from your stock.
          'F7'______________________Add gems to your stock.
          'F8'_______________Subtract gems from your stock.
          'F9'_____________________Add bombs to your stock.
          'F10'_____________Subtract bombs from your stock.
          'F1-F4'______________Jump to corresponding level.
          '1-7'______________Warp around the current world.

Use the following keys during the platform sections:

          'F1'_______________Turns you in to the fire ball.
          'F2'__________________________Gives you a shield.
          'F3'__________________________Gives you a shield.

                               (HINTS)

On level one, when you come to the first teleporter, keep going
right, until you find the the first ladder.  Go up to it and get a
blue flag - it has loads of gems, lives and hit points, so you can
keep going until you have thousands of stars and 99 lives.

The following didn't work on my version:

Pause the game and slowly type any of the following:

        "COOL JUMP NUT"_____________________For infinite lives
        "SORCERER"___________________________For invincibility
        "OCEANSOFT"____________To activate the following keys:

        'F9'_________________________________________For bombs
        'F10'_____________________________________For diamonds
        'SPACE'_________________________________To skip levels