The central unit of a computer equipment has a processor and a memory as well as redundant units as backup units for the processor and/or the memory. Further, there are members for changeover from an active unit to a corresponding backup unit in the event of a fault in the active unit. The central unit...http://www.google.ca/patents/US4941087?utm_source=gb-gplus-sharePatent US4941087 - System for bumpless changeover between active units and backup units by establishing rollback points and logging write and read operations
