Chap#16 Protected Mode Operation
Objectives

• The way memory
• Segmented addressing
• Virtual addressing
• Paged memory management
• Multitasking
• Memory and I/O protected
• Protected-mode interrupt operation
• Virtual-8086 mode

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16.1  Introduction

• Real-mode addressing use `Segment Registers`
• Protected-mode addressing use `Segment Selector`
• Additional protected mode registers : 
  * CR0 ~ 4 : Control Registers (P401A)
  * DR0 ~ 7 : Debug Registers (P401B)
  * GDTR : Global Descriptor Table Register
  * LDTR : Local Descriptor Table Register
  * IDTR : Interrupt Descriptor Table Register
  * TR : Task Register

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16.2  Segmentation

• Segment selector (P404)
• Segment descriptor format (P405)
• Segment descriptora types (P406A)
• System segment descriptor types (P406B)
• Segment translation (P407)
• Rings of protection (P408)

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16.3  Paging

• Virtual (linear) to physical mapping (P409)
• Translating page addresses (P410)
• Actual virtual to physical address translation (P411)
• Format of : (a) page directory entry and (b) page table entry (P412)

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16.4  Protection

• Protecting Segmented Accesses (P413)
• Structure of a call gate (p414)
• Page table entry protection bits (P415)

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16.5  Multitasking

• Running multiple tasks simutaneously (P416)
• TSS Descriptors (P416B)
• 32-bit TSS structure (P417)
• TSS descriptor (P418A)
• Task register format (P418B)
• Format of a task gate (P419A)
• Task Switching (P419B)
• Logical to physical address mapping in multiple tasks (P420)

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16.6  Exceptions and Interrupts

• Using the IDTR to access the IDT (P421)
• Read & display contents of IDTR (READIDTR.ASM )
• IDT descriptors (P423)
• Protected mode interupts and exceptions (P424)
• Interrupt/exception classifications (P425)
• Generating a double fault (P426)
• Page fault error code (P427)

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16.7  Input/Output

• Sample I/O permission bit map (P428)

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16.8  Virtual-8086 Mode

• Concept of a virtual machine (P429)
• Entering and leaving virtual-8086 mode (P431)

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16.9  A Protected Mode Application

• View selected protected-mode information. (PVIEW.ASM )

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 16.10  Troubleshooting Techniques

• Summary ( page 616 )
• Study  Questions ( # )

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