An automatic film processor having control circuitry including a microprocessor and an electrically alterable programmable read-only memory (EAPROM) with a stored main program for control of the processor, has an auxiliary read-only memory (ROM) containing a bootstrap program including instructions for reprogramming the EAPROM using addresses and data from a disk drive or RS232 port. Reprogramming occurs in response to manual or automatic setting of a switch, without physically removing or replacing the EAPROM.