Cpu Operating Modes; Normal Mode - Renesas H8S Series Hardware Manual
16-bit single-chip microcomputer
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- Hardware manual (1047 pages) ,
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- Hardware manual (875 pages)
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Section 2 CPU
2.2
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. The mode is selected by the mode pins.
2.2.1
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.
• Exception Vector Table and Memory Indirect Branch Addresses
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 differs depending on the
microcontroller. 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.
• Stack Structure
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.
Note: Normal mode is not available in this LSI.
Rev. 6.00 Mar 15, 2006 page 16 of 570
REJ09B0211-0600
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