| 摘要 |
<p>PURPOSE:To unnecessitate making a mask for exposure at the time of changing a program of a mask ROM and to enable substantially neglecting a time for changing a program of microcomputer. CONSTITUTION:Data is written in an EPROM region of a memory element, when necessary, using a memory mat 40 consisting of memory element having a mask ROM region and an EPROM region, data from the memory element is read out with an EPROM mode by a mode switching circuit 2. Thereby, a user of a microcomputer can neglects difference between the mask ROM and the EPROM, can effectively utilize a storage device, and can cope with change of software. Since the mask ROM mode and the EPROM mode are automatically switched over, they can be used without being conscious of difference.</p> |
