Redstone Card
The redstone card allows computers to read and emit analog redstone signal in adjacent blocks. When an incoming signal strength changes, a signal is injected into the computer.
If there are any supported mods present that provide bundled redstone facilities, such as RedLogic, Project Red or MineFactory Reloaded; or mods that provide wireless redstone facilities such as WR-CBE and Slimevoid's Wireless mod, a second tier card is available that allows interacting with these systems.
The side provided to the several methods are relative to the orientation of the computer case / robot / rack. That means when looking at the front of the computer, sides.right is at your left and vice versa.