PURPOSE: To enable retry even though an instruction in execution is in a retry disabling area when a fault is generated in a conversion memory section.

CONSTITUTION: When the fault of a conversion memory section 2 is detected by a fault detection mechanism 12, a reading register 3 and an instruction reading register 4 are held and a selector 11 selects a conversion memory fault processing microprogram start address 13 to start the microprogram. The microprogram notifies the fault processing processor (not shown in the illustration) of the fault. The fault processing processor reads the correct value of the conversion memory section 2 by the instruction reading register 4 from the fault processing processor storage device, performs re-load to the section 2, arranging the environment capable of retrying the instruction. As the all instructions supplied before the instruction with the fault generated are completed, the retry of the instruction can be performed without fail.