On the title screen, type "SERIALINTERFACE". Pressing 'F9' will replenish your energy and 'F10' will skip levels.
Try this one as well, once loaded press 'F3' to access the high score table and type in "BAMBOOZULEM", then press 'HELP'. You should have infinite energy. When you're in the shooting gallery don't move the joystick and you will have 1186 targets.