PURPOSE: To improve availability of an error recovery system by resetting the contents of a local memory to a state set before updating against the executing fault of an instruction that replaces the contents of the local memory and therefore increasing the recovery range to said executing fault.
CONSTITUTION: In case an instruction fault occurs before the next check point is set when the updating is through with memory contents, the contents of the head entries of the 1st and 2nd local memories 5 and 6 are read out together with TAG, M and P bits of said entries. Based on those M and P bits, an MXOR circuit 12 decides whether the data obtained before execution of the present instruction train is stored in the memory 5 or 6. A selector 13 selects the read-out data and stores it in a data register 15. Then the data stored in the register 15 is stored again in an entry address of a register corresponding to a local memory 1 via a selector 16.