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Chapter 2 my notes

Chapter 2 my notes - Chapter 3 Real mode memory(DOS memory...

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Chapter 3: Real mode memory (DOS memory) exists at locations 00000H-0FFFFFH o This is the first 1M byte of the memory system o Exists on all versions of the microprocessor The registers of the 8086 through the Core 2 microprocessor are used during application programming and are specified by the instructions o This is known as a program visible programming model 8 bit registers: o AH, AL, BH, BL, CH, CL, DH, DL 16 bit registers: o AX, BX, CX, DX, SP, BP, DI, SI, IP, FLAGS, CS, DS, ES, SS, FS, GS o AX, BX, CX, DX each contain a pair (like AL and AH, BL and BH etc.) of 8 bit registers 32 bit registers: o EAX, EBX, ECX, EDX, ESP, EBP, EDI, ESI, EIP, and EFLAGS o EAX, EBX, ECX, EDX, EBP, EDI, ESI multipurpose registers- hold various data sizes and are used for almost any purpose as dictated by a program 64 bit registers: o RAX, RBX, RCX, RDX, RSP, RBP, RDI, RSI, RIP, RFLAGS o R8 through R15 are addressed as a byte, word, double-word, or quad-word Only the rightmost 8 bits is a byte Multipurpose Registers: o RAX, EAX, AX, AH, AL accumulator Used for instructions such as multiplication and division in which the accumulator has a special purpose In 80386 and above EAX and RAX can hold the offset address o RBX, EBX, BX, BH, BL The BX register sometimes holds the offset address of a location in the memory system o RCX, ECX, CX, CH, CL
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