In order to provide reliable backup memory for the operational memory (RAM) of a control unit, two segments of a memory with write protect facility are used. Only one of these segments contains the backup memory at any one time, but the other segment may be updated with a new release. Write ...http://www.google.fr/patents/US5829047?utm_source=gb-gplus-shareBrevet US5829047 - Backup memory for reliable operation
