5D69-6D0F Slower timer
FE69-6D0F Faster timer
DDC7-A7A4 Infinite ammo (except flame thrower)
4A6E-6FDD Infinite lives
DD62-D7DD Start with 1 life
D962-D7DD Start with 6 lives
DF37-64A4 Start on stage 2
D437-64A4 Start on stage 3
D737-64A4 Start on stage 4
D037-64A4 Start on stage 5
D4C7-64DD + E3C9-6DAD Faster Robocop, except on stages 3 and 5 
DFEC-DD67 + D4EC-DFD7 Ammo pick-ups worth more 
7DEC-DD07 + DDEC-DFD7 + 7DEC-DDA7 Ammo pick-ups worth less