Use the joystick to move the cursor to the top left corner of the cargo/energy 
screen. Press [Keypad Plus] + Fire to enable cheat mode The screen will flash 
to confirm correct code entry. Unlimited shields and lives will be available 
while cheat mode is active. 

Result             Key 
-----------------------
Disable enemies  - [F1]
Full energy      - [F6]
Various weapons  - 0 - 9