A software routine that writes downloaded updated operating system software over existing application code to flash memory of a cable modem in an inverted arrangement. If the download process is interrupted before the update can be verified, a pointer still points to the existing code to facilitate update-interruption recovery. After verifying a successful update, a new pointer is generated that points to the updated operating system. Then, updated application code can be downloaded and stored in the flash memory over the old operating system code.Thus, each time an update is performed, the location of the operating system within the flash memory with respect to the location of the application code is inverted. This allows the size of flash memory to be reduced, as only one copy of the operating system and application code must be stored, while retaining capability to recovery from an incomplete download.