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STACK MEMORY-ADDRESSING MODES The stack plays an important role in all microprocessors. It holds data temporarily and stores the return addresses used by procedures. The stack memory is an LIFO (last-in, first-out) memory, which describes the way that data are stored and removed from the stack. Data are placed onto the stack with a PUSH […]
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PROGRAM MEMORY-ADDRESSING MODES Program memory-addressing modes, used with the JMP (jump) and CALL instructions, consist of three distinct forms: direct, relative, and indirect. This section introduces these three address- ing forms, using the JMP instruction to illustrate their operation. Direct Program Memory Addressing Direct program memory addressing is what many early microprocessors used for all […]
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Addressing Modes INTRODUCTION Efficient software development for the microprocessor requires a complete familiarity with the addressing modes employed by each instruction. In this chapter, the MOV (move data) instruction is used to describe the data-addressing modes. The MOV instruction transfers bytes or words of data between two registers or between registers and memory in the […]
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QUESTIONS AND PROBLEMS 1. What are program-visible registers? 2. The 80286 addresses registers that are 8 and bits wide. 3. The extended registers are addressable by which microprocessors? 4. The extended BX register is addressed as . 5. Which register holds a count for some instructions? 6. What is the purpose of the IP/EIP register? […]
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SUMMARY 1. The programming model of the 8086 through 80286 contains 8- and 16-bit registers. The programming model of the 80386 and above contains 8-, 16-, and 32-bit extended registers as well as two additional 16-bit segment registers: FS and GS. 2. The 8-bit registers are AH, AL, BH, BL, CH, CL, DH, and DL. […]
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FLAT MODE MEMORY The memory system in a Pentium-based computer (Pentium 4 or Core2) that uses the 64-bit extensions uses a flat mode memory system. A flat mode memory system is one in which there is no segmentation. The address of the first byte in the memory is at 00 0000 0000H and the last […]
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MEMORY PAGING The memory paging mechanism located within the 80386 and above allows any physical memory location to be assigned to any linear address. The linear address is defined as the address generated by a program. The physical address is the actual memory location accessed by a program. With the memory paging unit, the linear […]
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INTRODUCTION TO PROTECTED MODE MEMORY ADDRESSING Protected mode memory addressing (80286 and above) allows access to data and programs located above the first 1M byte of memory, as well as within the first 1M byte of memory. Protected mode is where Windows operates. Addressing this extended section of the memory system requires a change to […]
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REAL MODE MEMORY ADDRESSING The 80286 and above operate in either the real or protected mode. Only the 8086 and 8088 operate exclusively in the real mode. In the 64-bit operation mode of the Pentium 4 and Core2, there is no real mode operation. This section of the text details the operation of the microprocessor […]
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The Microprocessor and Its Architecture 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 the family of Intel microprocessors is presented simultaneously, as are the ways that the family members address the memory system. The […]
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