1. A client processor device including: a communications receiver for receiving file fragments for said device; a microcontroller system including a microcontroller and a programmable non-volatile memory system, for building and storing application and data files from said fragments, and executing an application of said device by processing at least one application file and associated data identified by configuration instructions included in at least one of said fragments; wherein the device stores application and data files for different versions of an application, and said configuration instructions select said versions for execution by said device.