Section 2
CPU
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2.2.2 Middle
Mode
The program area in middle mode is extended to 16 Mbytes as compared with that in normal
mode.
•
Address Space
A maximum address space of 16 Mbytes can be accessed in a total of the program and data
areas. For individual areas, up to 16 Mbytes of the program area and up to 64 Kbytes of the
data area can be allocated.
•
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 (in other than the JMP and
JSR instructions), it can contain any value even when the corresponding general register (Rn)
is used as an address register. If the general register Rn is referenced in the register indirect
addressing mode with pre-/post-increment or decrement and a carry or borrow occurs,
however, the value in the corresponding extended register will be affected.
•
Instruction Set
All instructions and addressing modes can be used. Only the lower 16 bits of effective
addresses (EA) are valid and the upper eight bits are sign-extended.
•
Exception Handling Vector Table and Memory Indirect Branch Addresses
In middle mode, the top area starting at H'000000 is allocated to the exception handling vector
table in 32-bit units. In each 32 bits, the upper eight bits are ignored and one branch address is
stored in the lower 24 bits. The structure of the exception handling vector table is shown in
figure 2.4.
The memory indirect (@@aa:8) and extended memory indirect (@@vec:7) addressing modes
are used in the JMP and JSR instructions. An 8-bit absolute address included in the instruction
code specifies a memory location. Execution branches to the contents of the memory location.
In middle mode, an operand is a 32-bit (longword) operand, providing a 32-bit branch address.
The upper eight bits are reserved and assumed to be H'00.
•
Stack Structure
The stack structure of PC at a subroutine branch and that of PC and CCR at an exception
handling branch are shown in figure 2.5. The PC contents are saved or restored in 24-bit units.
Содержание H8SX/1650
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Страница 142: ...Section 5 Interrupt Controller Rev 2 00 Jun 28 2007 Page 120 of 666 REJ09B0311 0200...
Страница 326: ...Section 8 I O Ports Rev 2 00 Jun 28 2007 Page 304 of 666 REJ09B0311 0200...
Страница 470: ...Section 12 Watchdog Timer WDT Rev 2 00 Jun 28 2007 Page 448 of 666 REJ09B0311 0200...
Страница 546: ...Section 13 Serial Communication Interface SCI Rev 2 00 Jun 28 2007 Page 524 of 666 REJ09B0311 0200...
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Страница 574: ...Section 16 RAM Rev 2 00 Jun 28 2007 Page 552 of 666 REJ09B0311 0200...
Страница 584: ...Section 17 Clock Pulse Generator Rev 2 00 Jun 28 2007 Page 562 of 666 REJ09B0311 0200...
Страница 638: ...Section 19 List of Registers Rev 2 00 Jun 28 2007 Page 616 of 666 REJ09B0311 0200...
Страница 668: ...Section 20 Electrical Characteristics Rev 2 00 Jun 28 2007 Page 646 of 666 REJ09B0311 0200...
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