PURPOSE: To perform a switching process of an OS without operating a console, by burying previously a reset instruction (microinstruction) into a program and then carrying out the initialization of a system with the execution of the reset instruction.

CONSTITUTION: The initialization of a system is possible with a reset instruction which is buried into a program. In this case, a reset instruction is buried into the end of a system generation program to switch an OS1 to an OS2. This reset instruction is set to an instruction register and then decoded by an instruction decoder. Thus a reset signal is turned on to execute a microprogram. Then the initialization is carried out for the system, and a new OS2 is loaded by an IPL program. In such a way, a switching process of OSs is possible without operating a console.