First person view
Press Square + Triangle + Start. Game play will be paused. Press Start to resume game play with the new camera angle. Substitute Select in the code instead of Start for the Japanese version of the game.
Submitted by Hideyoshi

Fixed camera view
Press Circle + X + Start. Game play will be paused. Press Start to resume game play with the camera fixed at the present location. Substitute Select in the code instead of Start for the Japanese version of the game. 
Submitted by Hideyoshi

Return to default view
To return to the default view, press Start to pause game play, then press Start to resume. Substitute Select instead of Start for the Japanese version of the game. 
Submitted by Hideyoshi

Death bonuses
Intentionally die with less than -50,000 credits. The game will restart from the first level with all items gained in the previous game. The first time this is done, the radar will become a grid system. The fourth time this is done, the rear weapon may be fired while in motion. The sixth time that this is done, 
available energy will be doubled.