Abstract: Embodiments described herein relate to an IMD operating in a backup mode in a manner that mitigates against adverse effects of a memory failure. The IMD includes a NVM that stores backup mode firmware, a RAM that includes multiple separate RAM blocks, a processor, and a counter. The processor executes the backup mode firmware to operate the IMD in accordance with a backup mode in response to detection of a malfunction that when detected should cause the IMD to operate in accordance with the backup mode. While the processor operates the IMD in accordance with the backup mode the processor stores and accesses variables in one of the RAM blocks. The counter is selectively incremented and used to select which one of the RAM blocks the variables are stored within while the processor executes the backup mode firmware to operate the IMD in accordance with the backup mode.