Abstract: When a rewriting instruction, which designates a specified rewriting bank is received, a rewrite processing unit copies data of the rewriting bank into a backup bank and, thereafter, writes new data prepared in a work memory such as an RAM or the like and clears the backup bank after completion of the writing operation. In this instance, flag information indicating whether data is valid or invalid is set into a plurality of banks of a flash memory. A restarting process after the writing process was interrupted is recovered by checking the flag information in all of the banks before the start of the rewriting operation and by executing the rewriting process from the beginning or in the middle of the process.

Abstract: A data transfer process for transferring data from a first system to a second system while carrying out loop checking, including: a first step for sending out a part of the above data from the first system to the second system; a second step for sending first information that the part of the data has been sent out from the first system to the second system; a third step for receiving the above part of the data in the second system; a fourth step for sending out the part of the data, which has been received in the third step from the second system to the first system; a fifth step for sending second information that the part of the data has been sent out from the second system in the fourth step, a sixth step for receiving the part of the data, which has been sent from the second system, in the first system; a seventh step for determining whether or not the data which has been sent out from the first system in the first step and the data which has been received in the second system in the sixth step are equal;