An electronic apparatus includes a master chip for writing correction data, which is input from an external communication controller via an external bus, to an EEPROM. After a system reset, the master chip reads the correction data written to the EEPROM. If it is determined that the data read from the EEPROM is the correction data, the master chip replaces a portion to be corrected in an existing program with the read correction data and downloads (uploads) a corrected program into a slave chip.