This paper reports research into cellular automata with two binary inputs, two binary outputs, and an octal control variable. A set of control variables is chosen and it is shown that any function of three variables can be realized by a 2 x 2 array of cells, any function of four variables by a 2 x 6 array of cells. A construction based on the Shannon Decomposition Theorem is given for the realization of functions of more than four variables. The existence of a more efficient construction is conjectured. A definition of the circuit defining the cell is given as well as an implementation using NAND gates. A practical configuration of the cells is suggested and fault correction is discussed.