01-02-2013, 12:23 PM
INTERNAL MICROPROCESSOR ARCHITECTURE
[attachment=49214]
Introduction
This chapter presents the microprocessor as a programmable device by first looking at its internal programming model and then how its memory space is addressed.
The architecture of Intel microprocessors is presented, as are the ways that the family members address the memory system.
Addressing modes for this powerful family of microprocessors are described for the real, protected, and flat modes of operation.
Chapter Objectives
Describe function and purpose of each program-visible register in the 8086-Core2 microprocessors, including 64-bit extensions.
Detail the flag register and the purpose of each flag bit.
Describe how memory is accessed using real mode memory-addressing techniques.
INTERNAL MICROPROCESSOR ARCHITECTURE
Before a program is written or instruction investigated, internal configuration of the microprocessor must be known.
In a multiple core microprocessor each core contains the same programming model.
Each core runs a separate task or thread simultaneously.
The Programming Model
8086 through Core2 considered program visible.
registers are used during programming and are specified by the instructions
Other registers considered to be program invisible.
not addressable directly during applications programming
80286 and above contain program-invisible registers to control and operate protected memory.
and other features of the microprocessor
80386 through Core2 microprocessors contain full 32-bit internal architectures.
8086 through the 80286 are fully upward-compatible to the 80386 through Core2.
Figure 2–1 illustrates the programming model 8086 through Core2 microprocessor.
including the 64-bit extensions
Segment Registers
Generate memory addresses when combined with other registers in the microprocessor.
Four or six segment registers in various versions of the microprocessor.
A segment register functions differently in real mode than in protected mode.
Following is a list of each segment register, along with its function in the system.
CS (code) segment holds code (programs and procedures) used by the microprocessor.
DS (data) contains most data used by a program.
Data are accessed by an offset address or contents of other registers that hold the offset address
ES (extra) an additional data segment used by some instructions to hold destination data.
Segments and Offsets
All real mode memory addresses must consist of a segment address plus an offset address.
segment address defines the beginning address of any 64K-byte memory segment
offset address selects any location within the 64K byte memory segment
Figure 2–3 shows how the segment plus offset addressing scheme selects a memory location.
Segment and Offset Addressing Scheme Allows Relocation
Segment plus offset addressing allows DOS programs to be relocated in memory.
A relocatable program is one that can be placed into any area of memory and executed without change.
Relocatable data are data that can be placed in any area of memory and used without any change to the program.
Because memory is addressed within a segment by an offset address, the memory segment can be moved to any place in the memory system without changing any of the offset addresses.
Only the contents of the segment register must be changed to address the program in the new area of memory.
Windows programs are written assuming that the first 2G of memory are available for code and data.
[attachment=49214]
Introduction
This chapter presents the microprocessor as a programmable device by first looking at its internal programming model and then how its memory space is addressed.
The architecture of Intel microprocessors is presented, as are the ways that the family members address the memory system.
Addressing modes for this powerful family of microprocessors are described for the real, protected, and flat modes of operation.
Chapter Objectives
Describe function and purpose of each program-visible register in the 8086-Core2 microprocessors, including 64-bit extensions.
Detail the flag register and the purpose of each flag bit.
Describe how memory is accessed using real mode memory-addressing techniques.
INTERNAL MICROPROCESSOR ARCHITECTURE
Before a program is written or instruction investigated, internal configuration of the microprocessor must be known.
In a multiple core microprocessor each core contains the same programming model.
Each core runs a separate task or thread simultaneously.
The Programming Model
8086 through Core2 considered program visible.
registers are used during programming and are specified by the instructions
Other registers considered to be program invisible.
not addressable directly during applications programming
80286 and above contain program-invisible registers to control and operate protected memory.
and other features of the microprocessor
80386 through Core2 microprocessors contain full 32-bit internal architectures.
8086 through the 80286 are fully upward-compatible to the 80386 through Core2.
Figure 2–1 illustrates the programming model 8086 through Core2 microprocessor.
including the 64-bit extensions
Segment Registers
Generate memory addresses when combined with other registers in the microprocessor.
Four or six segment registers in various versions of the microprocessor.
A segment register functions differently in real mode than in protected mode.
Following is a list of each segment register, along with its function in the system.
CS (code) segment holds code (programs and procedures) used by the microprocessor.
DS (data) contains most data used by a program.
Data are accessed by an offset address or contents of other registers that hold the offset address
ES (extra) an additional data segment used by some instructions to hold destination data.
Segments and Offsets
All real mode memory addresses must consist of a segment address plus an offset address.
segment address defines the beginning address of any 64K-byte memory segment
offset address selects any location within the 64K byte memory segment
Figure 2–3 shows how the segment plus offset addressing scheme selects a memory location.
Segment and Offset Addressing Scheme Allows Relocation
Segment plus offset addressing allows DOS programs to be relocated in memory.
A relocatable program is one that can be placed into any area of memory and executed without change.
Relocatable data are data that can be placed in any area of memory and used without any change to the program.
Because memory is addressed within a segment by an offset address, the memory segment can be moved to any place in the memory system without changing any of the offset addresses.
Only the contents of the segment register must be changed to address the program in the new area of memory.
Windows programs are written assuming that the first 2G of memory are available for code and data.