Cpu Operating Modes - Hitachi H8S/2646 Hardware Manual

Hitachi 16-bit single-chip microcomputer h8s/2646 series

Table of Contents

 Two-bit shift instructions have been added.

 Instructions for saving and restoring multiple registers have been added.

 A test and set instruction has been added.

• Higher speed

 Basic instructions execute twice as fast.

CPU Operating Modes

The H8S/2600 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.

Note: * Not available in the H8S/2646 Series.

CPU operating modes

Note: * Not available in the H8S/2646 Series.

(1) Normal Mode (Not Available in the H8S/2646 Series)

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.

Normal mode*

Advanced mode

Figure 2-1 CPU Operating Modes

Maximum 64 kbytes, program

and data areas combined

Maximum 16-Mbytes for

program and data areas