H8S2245 datasheet(64/818 Pages) RENESAS

64 / 818 page

Section 2 CPU

Rev.3.00 Mar. 26, 2007 Page 22 of 772

REJ09B0355-0300

2.2

CPU Operating Modes

The H8S/2000 CPU has two operating modes: normal and advanced. Normal mode supports a

maximum 64-kbyte address space. Advanced mode supports a maximum 16-Mbyte total address

space (architecturally a maximum 16-Mbyte program area and a maximum of 4 Gbytes for

program and data areas combined). The mode is selected by the mode pins of the microcontroller.

CPU operating modes

Normal mode

Advanced mode

Maximum 64 kbytes, program

and data areas combined

Maximum 16-Mbytes for

program and data areas

combined

Figure 2.1 CPU Operating Modes

(1) Normal Mode

The exception vector table and stack have the same structure as in the H8/300 CPU.

Address Space: A maximum address space of 64 kbytes can be accessed.

Extended Registers (En): The extended registers (E0 to E7) can be used as 16-bit registers, or as

the upper 16-bit segments of 32-bit registers. When En is used as a 16-bit register it can contain

any value, even when the corresponding general register (Rn) is used as an address register. If the

general register is referenced in the register indirect addressing mode with pre-decrement (@–Rn)

or post-increment (@Rn+) and a carry or borrow occurs, however, the value in the corresponding

extended register (En) will be affected.

Instruction Set: All instructions and addressing modes can be used. Only the lower 16 bits of

effective addresses (EA) are valid.

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