One-chip microcomputer system having function for substantially correcting contents of program

摘要

A one-chip microcomputer system (4) includes a one-chip microcomputer (1), a nonvolatile memory (2) which can electrically rewritably store changing data of a program stored in a mask ROM (1a) of the one-chip microcomputer (1), an input unit (connection unit) (3) for receiving data to be written in the nonvolatile memory from an external device (6), and an object (5) to be controlled by the one-chip microcomputer (1). In one aspect, the mask ROM (1a) stores ROM version data, and the nonvolatile memory (2) stores board version data. Upon writing of the data via the input unit (3), bug correction data is selected based on the ROM version data and the board version data, and the selected data is written in the nonvolatile memory (2).