Level select: Press Up, Right, Down, Left,
Up, Right, Down, Left when the "IREM"
logo appears. Start the game, and when "Stage 1" appears,
press B to select a new starting level.
Background music test: Hold B while turning on the game, then press
Start when the introduction appears.
Sound effect test: Hold A while turning on the game, then press
Start when the introduction appears.
