The Data Cell has one input side, two input/output sides and one output side (shown in the picture) for Red Alloy Wire, Redstone, an adjacent circuit, machine, lamp or anything that can be controlled with redstone signals.
Using the screwdriver from Project Red, the orientation of the gate can be changed freely in all four directions.
The side inputs/outputs control, whether the gate is in read only mode (off) or read/write mode (on), the lower side is an input, and the upper side is the output.
If the side inputs/outputs are off (read only mode ) then the upper output state is frozen, and toggling the lower input will do nothing. If the side inputs/outputs are on (read/write mode) then the upper output will change to mach that of the lower input. Turning the side inputs/outputs off after changing the value will freeze the new value on the output, until the side inputs/outputs are turned on again.
Because the sides are both inputs and outputs, this gate can be chained to form re-writeable data storage cells.