Sound test:
Hold Select and press A + B at the title screen. Use the D-pad to select a song and press A to play the current selection.

Cheat mode:
Press Select + A, release both buttons, then press Select + B at the title screen. Repeat these entries until a sound is played to confirm correct code entry. Begin game play and enter one of the following codes to activate the corresponding cheat function.

Temporary invincibility
Hold Select and press Right.

More gold
Hold Select and press Left.

Jumping Shoes
Hold Select and press Up.

Full life
Hold Select and press Down.

More lives (up to 99)
Hold Select and press Up/Right.

Power-up weapon
Hold Select and press Down/Left.

Moon Mirror
Hold Select and press Up/Left.

Zap energy
Hold Select and press Down/Right.