Secret Weapons Over Normandy

From the starting menu where "New Game" or "Continue"
can be selected (AKA main title screen):

U,R,D,L,U,R,D,L,L1,R1             - Infinite Ammo
U,D,L,R,L,L,R,R,L1,L1,R1,R1,L2,R2 - Invulnerability

where U - Up
      D - Down
      R - Right
      L - Left

 