For cheats in this game, use the DOS utility DEBUG. First
backup your game to be edited, then type the following from
the dos prompt:
ren e:\dr.exe cheater.cht
debug e:\cheater.cht
For infinate missiles, type: e37a3 90 90 90 90
e3e71 90 90 90 90
For invulnerability, type: e2dbc 90
e 34ca 90 90 90 90
e 344b 90 90 90 90
w
q
Then rename CHEATER.CHT back to its previous name.