1. A microprocessor system, comprising: a volatile memory for storing a first executable program; a register for holding a pre-determined checksum based on the contents of said first executable program; a communications interface; and a microprocessor for calculating a calculated checksum based on the contents of said first executable program stored in said volatile memory in response to a system reset, for comparing said calculated checksum with said pre-determined checksum, and for receiving a second executable program through said communications interface if said calculated checksum is not equal to said predetermined checksum.