1. A process for controlling a control unit including a CPU unit for conducting program sequence control and special function units for performing special function control in accordance with commands from said CPU unit, comprising steps of: creating a program having at least one instruction step which includes a function-symbol indicating a special function unit-corresponding instruction and a type-symbol denoting a special function type, said function-symbol and said type-symbol being independent of an address of said at least one instruction step; storing said program into a program memory; and executing each instruction in said program, said executing step comprising: determining whether a current instruction from said program corresponds to one of said special function units, based on said function symbol and said type symbol of said current instruction.