PURPOSE: To prevent the destruction of content of information due to electrical shock or the like by locking a case containing a programmable read only memory to a holder, connecting the memory to a power supply and a computer so as to transfer the stored content of the memory to the internal memory of the computer and releasing the lock means when the transfer is finished.

CONSTITUTION: The transfer means 5 held to a holder 2 inserted to the case 1 allows the sequence circuit 21 to connect a PROM 22 to a power supply at first. Then a switch device 25 is closed to connect a data bus or the like 23 of the PROM 22 to a data bus 24 or the like of the computer and starts an interruption device 26. Thus, a CPU 27 conducts the interruption initial processing as shown in Fig. and the transfer to an RAM being the internal memory 4 of the stored content of the PROM 22 according to the interruption program written in advance in the internal memory 45 of the computer, the transfer program and the disconnecting program of an external memory. Moreover, a reset means 6 is activated by outputting a transfer end signal from an I/O and then the interruption end processing is conducted.