2010-6-2

1.1 Organization of This Manual

1.三中处理模式（保护、实、虚拟8086）

The processing mode of the 80386 also determines the features that are accessible. The 80386 has three processing modes:

   1.  Protected Mode.
   2.  Real-Address Mode.
   3.  Virtual 8086 Mode.

Protected mode is the natural 32-bit environment of the 80386 processor. In this mode all instructions and features are available.

Real-address mode (often called just "real mode") is the mode of the processor immediately after RESET. In real mode the 80386 appears to programmers as a fast 8086 with some new instructions. Most applications of the 80386 will use real mode for initialization only.

Virtual 8086 mode (also called V86 mode) is a dynamic mode in the sense that the processor can switch repeatedly and rapidly between V86 mode and protected mode. The CPU enters V86 mode from protected mode to execute an 8086 program, then leaves V86 mode and enters protected mode to continue executing a native 80386 program.

 

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2.书本目录

1.1 Organization of This Manual

Chapter 2 -- Basic Programming Model: Introduces the models of memory organization. Defines the data types. Presents the register set used by applications. Introduces the stack. Explains string operations. Defines the parts of an instruction. Explains addressing calculations. Introduces interrupts and exceptions as they may apply to applications programming.

Chapter 3 -- Application Instruction Set: Surveys the instructions commonly used for applications programming. Considers instructions in functionally related groups; for example, string instructions are considered in one section, while control-transfer instructions are considered in another. Explains the concepts behind the instructions. Details of individual instructions are deferred until Part IV, the instruction-set reference.

1.1 Organization of This Manual

Chapter 4 -- Systems Architecture: Surveys the features of the 80386 that are used by systems programmers. Introduces the remaining registers and data structures of the 80386 that were not discussed in Part I. Introduces the systems-oriented instructions in the context of the registers and data structures they support. Points to the chapter where each register, data structure, and instruction is considered in more detail.

Chapter 5 -- Memory Management: Presents details of the data structures, registers, and instructions that support virtual memory and the concepts of segmentation and paging. Explains how systems designers can choose a model of memory organization ranging from completely linear ("flat") to fully paged and segmented.

Chapter 6 -- Protection: Expands on the memory management features of the 80386 to include protection as it applies to both segments and pages. Explains the implementation of privilege rules, stack switching, pointer validation, user and supervisor modes. Protection aspects of multitasking are deferred until the following chapter.

Chapter 7 -- Multitasking: Explains how the hardware of the 80386 supports multitasking with context-switching operations and intertask protection.

Chapter 8 -- Input/Output: Reveals the I/O features of the 80386, including I/O instructions, protection as it relates to I/O, and the I/O permission map.

Chapter 9 -- Exceptions and Interrupts: Explains the basic interrupt mechanisms of the 80386. Shows how interrupts and exceptions relate to protection. Discusses all possible exceptions, listing causes and including information needed to handle and recover from the exception.

Chapter 10 -- Initialization: Defines the condition of the processor after RESET or power-up. Explains how to set up registers, flags, and data structures for either real-address mode or protected mode. Contains an example of an initialization program.

Chapter 11 -- Coprocessing and Multiprocessing: Explains the instructions and flags that support a numerics coprocessor and multiple CPUs with shared memory.

Chapter 12 -- Debugging: Tells how to use the debugging registers of the 80386.

1.1 Organization of This Manual

Chapter 13 -- Executing 80286 Protected-Mode Code: In its protected mode, the 80386 can execute complete 80286 protected-mode systems, because 80286 capabilities are a subset of 80386 capabilities.

Chapter 14 -- 80386 Real-Address Mode: Explains the real mode of the 80386 CPU. In this mode the 80386 appears as a fast real-mode 80286 or fast 8086 enhanced with additional instructions.

Chapter 15 -- Virtual 8086 Mode: The 80386 can switch rapidly between its protected mode and V86 mode, giving it the ability to multiprogram 8086 programs along with "native mode" 32-bit programs.

Chapter 16 -- Mixing 16-Bit and 32-Bit Code: Even within a program or task, the 80386 can mix 16-bit and 32-bit modules. Furthermore, any given module can utilize both 16-bit and 32-bit operands and addresses.

 

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3.供参考书籍

1.2 Related Literature

• Introduction to the 80386, order number 231252
• 80386 Hardware Reference Manual, order number 231732
• 80386 System Software Writer's Guide, order number 231499
• 80386 High Performance 32-bit Microprocessor with Integrated Memory Management (Data Sheet), order number 231630