Minecraft wiki entry for Logic_gates, associated text: 1 Adders
1.1 Version 1
1.2 In-Line Adder
1.3 Version 2
1.4 Version 3
1.5 Fast Adding
1.6 Piston Adders
1.7 4-bit Adder
1.8 Alternate 4-bit Adder
2 Subtracting
3 Logic units
3.1 Arithmetic logic unit