Electronic apparatus for which program is rewritable and program rewriting method

An image forming apparatus comprising:

• (a) a memory for rewritably storing data for controlling an operation of the image forming apparatus;
• (b) a receiver for receiving a version upgrade data;
• and
• (c) a processor for performing a version upgrade process to rewrite the data in the memory with the version upgrade data in response to a version upgrade instruction signal received by the processor,
• wherein the upgrade process includes:
• (i) a plurality of writing operations for writing a unit of a predetermined amount of the version upgrade data received by the receiver,
• (ii) a plurality of first checking operations for checking whether an error exists in the unit of the predetermined amount of the version upgrade data every time the unit of the predetermined amount of the version upgrade data is written, and
• (iii) a second checking operation for, after the writing operations for writing the entire version upgrade data have been finished, checking information regarding a number of the writing operations so as to determine whether or not the entire version upgrade data has been written successfully, and
• wherein the processor determines that the entire version upgrade data has been written successfully when no error is detected by the first checking operations and the entire version upgrade data is determined to have been written successfully by the second checking operation.