| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a microcomputer equipped with an on-chip memory and a system using this microcomputer with which the increase of chip area and cost is prevented by unnecessitating the increase of memory capacity, memory contents can be freely exchanged even after integration into the system, and contents are prevented from being destroyed by unexpected operation. SOLUTION: This microcomputer is provided with a CPU, an address bus AB, and writable and readable 1st and 2nd on-chip memories MEM 1 and MEM 2, the 1st on-chip memory MEM 1 is controlled so as to always enable write operation corresponding to a data write instruction, the 2nd on-chip memory MEM 2 is controlled so as to enable write operation only at the time of specified operation state (specified interruption) corresponding to the data write instruction, and a means PP is provided for fetching data from an external MEM 3.</p> |
