A system efficiently expands program memory without extensively modifying the remaining microcontroller architecture. Since a flag standalone is not set in a script NCL Script 133, the script NCL Script 133 is executed from time t13 till time t15, simultaneously with a script NCL Script 132 and a script NCL Script 134. A plurality of subassemblies may stacked together with an end plate to form a complete stack, the edges of each subassembly being attached together to form a complete unit.