One-chip microcomputer capable of executing correction program and microcomputer capable of correcting ROM

摘要

An instruction for returning to a ROM is written to a position where data is not broken even if a next correction is executed in order not to the content of a register even if an interruption processing for correction and a processing for returning a ROM program are executed. A microcomputer connected through a serial i/O bus, an EEROM, and a correction data writing device comprises a CPU, a RAM, a ROM, a PC comparison register section, a ROM correction processing circuit having a PC value latch section, and a serial i/O section. The CPU sequentially executes an internal sequence control of the microcomputer and a logical operation in accordance with instructions written in the ROM as a program in advance. The RAM temporarily saves intermediate processing data of, e.g. calculation, or saves an adjustment value transferred from the EEPROM when the program is actually executed.