Press the 'LEFT SHIFT' and slowly type "NEM YDID EHT" and press 'RETURN'.
You'll hear a sound. Now 'C' will complete your mission.

Push the joystick down and to the right and press 'ENTER' for full shields
and weapons.

LEVEL CODES

1--"AURIGA" | 4---"MUSCA" | 7--"FORNAX"
2-"CEPHEUS" | 5---"PYXIS" | 8--"CAELUM"
3----"APUS" | 6---"CETUS" | 9--"CORVUS"