8088/8086 Instruction I

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Data Transfer <strong>Instruction</strong>sMOV Destination, Source— Move data from source to destination; e.g. MOV [DI+100H], AH— It does not modify flags For 80x86 family, directly moving data from one memory location toanother memory location is not allowedMOV [SI], [5000H] When the size of data is not clear, assembler directives are usedMOV [SI], 0 BYTE PTR WORD PTR DWORD PTRMOV BYTE PTR [SI], 12HMOV WORD PTR [SI], 12HMOV DWORD PTR [SI], 12H You can not move an immediate data to segment register by MOVMOV DS, 1234H8-6
What is a Stack ?<strong>Instruction</strong>s for Stack Operations— A stack is a collection of memory locations. It always follows the rule oflast-in-firs-out— Generally, SS and SP are used to trace where is the latest date written into stackPUSH Source— Push data (word) onto stack— It does not modify flags— For Example: PUSH AX (assume ax=1234H, SS=1000H, SP=2000Hbefore PUSH AX)1000:1FFD??1000:1FFD??1000:1FFE??SS:SP1000:1FFE341000:1FFF??1000:1FFF12SS:SP1000:2000??1000:2000??12 34Before PUSH AX, SP = 2000HAfter PUSH AX, SP = 1FFEHAX Decrementing the stack pointer during a push is a standard way of implementing stacks in hardware8-7
Page 1 and 2: ECE 424 Design of Microprocessor-Ba
Page 3 and 4: Addressing ModesAddressing Modes Im
Page 5: Flags Commonly Tested During the Ex
Page 9 and 10: Data Transfer Instructions SAHF—
Page 11 and 12: String Instructions String is a col
Page 13 and 14: REPZ String InstructionRepeat Prefi
Page 15 and 16: String Instructions MOVSB (MOVSW)
Page 17: String Instructions SCASB (SCASW)

8088/8086 Instruction I

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