57 ABSTRACT A device which switches data processing from an active processor, about to
fail, to a back-up processor includes a memory change detector which captures memory
changes in the memory of the active processor and a mirroring control circuit which causes
the memory changes when committed by establishing recovery point signals generated by
the active processor to be dumped into the memory of the back-up processor so that the
back-up processor resumes operation of the active processor from the last established …