INFORMATION PROCESSOR

PROBLEM TO BE SOLVED: To prevent the operation of a processor from completely stopping due to the run away of the processor by providing a selecting means which switches the internal connection destination of a ready signal terminal among plural internal devices and a change preventing means which inhibits the change to the setting in which the internal connection destination becomes an operation processing means. SOLUTION: A function selection circuit 14 outputs a prescribed function selection signal that corresponds to setting performed by a processor 8 to a function selection signal line 15, and according to the function selection signal an input-output control circuit 16 switches an internal connection destination of a ready signal terminal 17. A selection circuit of the circuit 14 maintains the setting performed by the processor 8 and also outputs a function selection signal 15 that corresponds to the setting. Also, a monitor circuit of the circuit 14 supervises the signal 15, outputs a ready release signal onto a ready release signal line to the selection circuit and inhibits subsequent setting change when the signal 15 is changed from the ready input setting of initialization to a general port input setting and is further changed to the ready input setting again.