| abstract |
(57) [Summary] [Object] To provide a microcomputer with built-in flash memory that is easy to use. [Structure] Central processing unit, flash memory, mask R A microcomputer having an OM, a serial communication interface, and an I / O port, a first function of writing a program to the flash memory by a PROM writer before the microcomputer sealed with resin is mounted on a system; A second function of rewriting a program area of the flash memory by the central processing unit executing a rewrite control program stored in the mask ROM while the microcomputer is mounted on the system. Second Function, the program area of the flash memory is rewritten with information input from the outside via the serial communication interface or the I / O port. |