Abstract: In the refreshing of the memory contents of the non-volatile memory device, a refreshing buffer memory is provided for temporarily storing a data signal of an address to be refreshed. Not only this data signal is stored in the refreshing buffer memory, but also the address of this data signal and the status of the refreshing processes, that is, up to which step of the refreshing routine the refreshing operation has proceeds, is stored in this refreshing buffer memory. Then, even when the power supply is shut off during the course of the refreshing action, at the next chance of the resumption of the power supply, the refreshing routine can correctly be started from the step at which the refreshing routine was previously terminated, thereby the refreshing operation can always be completed correctly.

Abstract: A non-volatile memory control circuit for reprogramming non-volatile memory devices before their natural decay causes their "1" and "0" levels to become indistinguishable. Signals representing the memory states of the non-volatile memory devices are temporarily stored while the non-volatile memory devices are erased. After erasure the memory states are rewritten into the non-volatile memory devices. After rewriting, the control circuit is automatically reset. The erase/write operation is triggered by interrogating a second set of "parallel" non-volatile memory devices containing a predetermined data pattern, the interrogation occurring with a threshold detection level greater than that at which the memory levels of the primary non-volatile devices become indistinguishable.