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CHAPTER 3 CPU
3.1 Memory Space
The microcontrollers of the MB89950/950A series offer a memory space of 64 Kbytes.
The memory space contains the I/O area, RAM area, ROM area, and external area. The
memory space contains areas used for special purposes such as the general-purpose
registers and vector table.
■ Memory space structure
●
I/O area (addresses: 0000
H
to 007F
H
)
• Control registers and data registers for the internal peripheral functions are located in this area.
• As the I/O area is allocated within the memory space, I/O can be accessed in the same way as memory.
High-speed access using direct addressing is available.
●
RAM area
• Internal static RAM is provided as an internal data area.
• The internal RAM size differs from product to product.
• Addresses between 0080
H
and 00FF
H
support high-speed access using direct addressing.
• Addresses between 0100
H
and 01FF
H
can be used as the general-purpose register area (restrictions
apply for some products).
• The contents of RAM is indeterminate after a reset.
●
ROM area
• Internal ROM is provided as an internal program area.
• The internal ROM size differs from product to product.
• Addresses between FFC0
H
and FFFF
H
are used for the vector table, etc.