operates in a comparatively long access cycle read write cycle a nonvolatile memory such as a flash memory whose storage data are not lost even if power supply from primary and secondary cells is disconnected is used for the rom section 1 in order to rewrite the rom section 1 it must be placed into a special mode called ipl mode the ram section 2 is a program execution area of the portable telephone set and has a small storage area but operates in a comparatively short access cycle a volatile memory flash rom whose storage data are not lost even if the primary cell is disconnected but are lost if the secondary cell is disconnected is used for the ram section 2 the ram section 2 thus requires continual rewriting from a cpu the portable telephone set is shipped after a program is written into the memory space of the rom section 1 upon execution of the program it is partly copied from the rom section 1 into the ram section 2 this is because it is intended to execute the program as fast as possible it is to be noted here that since the area of the ram section 2 in the portable telephone set is usually smaller than the area of the rom section 1 all data of the rom section 1 cannot be placed into the ram.