a programmable controller includes for controlling a system including a program memory unit for storing a group of sequence instructions including an instruction part and operand part , a data memory unit for storing a plurality of system data , a sequence execution control unit for executing sequence computations based on instructions fetched from the program memory unit and the system data from the data memory unit , and a holding register unit for holding the operand part as address part of the system data when the sequence execution control unit fetches the instruction from the program memory .