A method is described for operating a bistable resistance random access
memory having two memory layer stacks that are aligned in series is
disclosed. The bistable resistance random access memory comprises two
memory layer stacks per memory cell, the bistable resistance random
access memory operates in four logic states, a logic "00" state, a logic
"01" state, a logic "10" state and a logic "11" state. The relationship
between the four different logic states can be represented mathematically
by the two variables n and f and a resistance R. The logic "0" state is
represented by a mathematical expression (1+f)R. The logic "1" state is
represented by a mathematical expression (n+f)R. The logic "2" state is
represented by a mathematical expression (1+nf)R. The logic "3" state is
represented by a mathematical expression n(1+f)R.