Mega Man X 

Get Zero's Arm Cannon before Simga's Stage 
In the Flame Mammoth stage, part of the ceiling is made of blocks that X can 
break with his head, if he has the helmet upgrade. On the other side of these 
blocks is a small room with a capsule in which Dr. Light will give you the arm 
cannon. 
Level codes 
Level 1: 4325, 5852, 1821. Level 2: 6718, 5177, 6171. Level 3: 4561, 1718, 8546. 
Level 4: 4123, 5412, 3438. 
Chill Penguin - 1322, 8782, 7738. Storm Eagle - 5386, 8666, 2458. Spark Mandrill 
- 5386, 8662, 2438. 
All weapons, Armor and Power-ups 
8441, 2176, 4423