Number Man machine:
When you get far enough into the game, Mr. Higsby's shop will open up. When you enter his shop you will see a Number Man machine. Enter one of the following codes in the Number Man machine:

15789208
Air Chute 3 chip

23415891
Air Shoes

01697824
Copy Damage chip

87824510
Enemy Search sub-chip

56892168
Full Energy sub-chip

76889120
Fumikomi Cross S chip

95913876
Guts Straight S chip

86508964
Mini-Energy sub-chip

50098263
Muramasa Blade M chip

35331089
Open Lock sub-chip

03284579
Paladin Sword P chip

67918452
Quick Gauge

19878934
Set Sand

24586483
Shinobi Dash sub-chip

11002540
Spin Blue

28274283
Spin Green

72563938
Spin Red

77955025
Spin White

31549798
Spread Gun chip

05088930
Untrap sub-chip

63997824
Variable Sword F chip

41465278
Weapon Level +1

Thanks to Revolution reader vince!