JPH05233844

PURPOSE:To provide the one-chip microcomputer which can change a user logic circuit in a chip even after the chip is completed or integrated into an electronic equipment. CONSTITUTION:An FPGA (programmable logic circuit) 6 and a PROM 7 to store circuit data corresponding to the FPGA 6 are provided in a one-chip microcomputer 17. Therefore, the circuit data are written from the outside to the PROM 7 or a CPU 1 reads the circuit data from the outside, writes them in the PROM 7 and writes the data in the PROM 7 into the FPGA 6 so as to constitute the arbitrary user logic circuit in the FPGA 6.