22
CHAPTER 3 CPU
3.1 Memory Space

The MB89202/F202RA series has 64-KB memory space that consists of the I/O area,

RAM area, ROM area, and external area. Part of the memory space is applied for specific

use such as general-purpose registers or a vector table.

Configuration of Memory Space
I/O area (address: 0000H to 007FH)
The control registers and data registers for built-in peripheral functions are assigned.
The I/O area is assigned as part of the memory space, thus access to the I/O area can be obtained in the
same manner as access to memory. Also, direct addressing provides high-speed access.
RAM area
Static RAM is equipped as the internal data area.
The size of internal RAM depends on the model.
Direct addressing allows high-speed access to an area from 80H to FFH. (Some models restrict the usable
range of the area.)
100H to 1FFH can be used as the general-purpose register area.
If a reset occurs while data is being written into RAM, the data being written cannot be guaranteed.
ROM area
ROM is equipped as the internal program area.
The size of internal ROM depends on the model.
FFC0H to FFFFH are usable as a vector table or another feature.