PURPOSE: To provide a computer system whose flexibility of a data processing is higher than conventional system, and which can speedily correspont to the generation of a data error or the like.

CONSTITUTION: At the time of the generation of a pattern processing on executing a processing, a pattern number is generated by a memory space 1, and at the same time an interrupt is operated to the present processing by a dispatcher 3. Then, a pattern management film 2 is read in by the generated pattern number, and the dealing method program of a dealing method storage file 4 is loaded to a dealing method program executing memory 5 based on the obtained deal number. Afterwards, the dealing method program is executed, and the control is returned to an original routine by the dispatcher 3 after the completion of the dealing method program.