System memory and a microcomputer comprising the same

摘要

A system memory which includes a plurality of memory cells capable of functioning as ROMS or RAMs and being arranged in an arbitrary minimum unit. The read only area includes the memory cells functioning as the ROMS, and the write and read area includes the memory cells functioning as the RAMs. The read only areas and the write and read areas can be mixed and arranged in a memory space of the system memory without discontinuity nor a overlap. In a microcomputer including the system memory, a program is stored in the read only area, and data is stored in the write and read area.