r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 75

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

2.2
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. The mode is selected by the mode pins.
2.2.1
The exception vector table and stack have the same structure as in the H8/300 CPU.
Note: Normal mode is not available in this LSI.
• Address Space
• Extended Registers (En)
• Instruction Set
• Exception Vector Table and Memory Indirect Branch Addresses
• Stack Structure
The H8S/2600 CPU provides linear access to a maximum 64-Kbyte address space.
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.
All instructions and addressing modes can be used. Only the lower 16 bits of effective
addresses (EA) are valid.
In normal mode the top area starting at H'0000 is allocated to the exception vector table. One
branch address is stored per 16 bits. The exception vector table in normal mode is shown in
figure 2.1. For details of the exception vector table, see section 4, Exception Handling.
The memory indirect addressing mode (@@aa:8) employed in the JMP and JSR instructions
uses an 8-bit absolute address included in the instruction code to specify a memory operand
that contains a branch address. In normal mode the operand is a 16-bit word operand,
providing a 16-bit branch address. Branch addresses can be stored in the top area from H'0000
to H'00FF. Note that this area is also used for the exception vector table.
When the program counter (PC) is pushed onto the stack in a subroutine call, and the PC,
condition-code register (CCR), and extended control register (EXR) are pushed onto the stack
in exception handling, they are stored as shown in figure 2.2. EXR is not pushed onto the stack
in interrupt control mode 0. For details, see section 4, Exception Handling.
CPU Operating Modes
Normal Mode
Rev. 1.00 Sep. 19, 2008 Page 45 of 1342
REJ09B0467-0100
Section 2 CPU