The Konami Code
Select Gradius from the main menu, and then enter the following code at the title screen:
[Up], [Up], [Down], [Down], [Left], [Right], [Left], [Right], [B], [A]
You should hear a noise confirming that it has been entered. Then start a game as normal, however upon starting your game press the [Start] button to Max-out your ship with every power-up, except for Speed. You can only do this once!