The firmware may contain multiple application modules, which can operate independent of each other such that upgrade of one application module does not affect the operation of the other. A compressed backup copy of a module is stored in a non-volatile memory before upgrading the module from a previous version to a newer version. If the upgrading operation fails, the backup copy is used to restore the previous version. To simplify the upgrading or restoring operations, each application module may be assigned to a pre-specified area of a non-volatile memory forming a firmware. As a result, upgrading or restoring may merely require replacing of a version in the firmware. Compression of the backup copy may be optional with status data indicating whether the backup copy is compressed.