8088/8086 Instruction I

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String <strong>Instruction</strong>s CMPSB (CMPSW)— Compare bytes (words) at memory locations DS:SI and ES:DI;update SI and DI according to DF and the width of the data being compared— It modifies flags—Example:Assume: ES = 02A8HDI = 2000HDS = 0510HSI = 0000HCLDMOV CX, 9REPZ CMPSBWhat’s the values of CX afterThe execution?DS : SI0510:00000510:00010510:00020510:00030510:00040510:00050510:000653484F50504552Source StringSHOPPERES : DI02A8:200002A8:200102A8:200202A8:200302A8:200402A8:200502A8:200653484F5050494ESHOPPDestination StringIN8-16
String <strong>Instruction</strong>s SCASB (SCASW)— Move byte (word) in AL (AX) and at memory location ES:DI;update DI according to DF and the width of the data being compared— It modifies flags LODSB (LODSW)— Load byte (word) at memory location DS:SI to AL (AX);update SI according to DF and the width of the data being transferred— It does not modify flags STOSB (STOSW)— Store byte (word) at in AL (AX) to memory location ES:DI;update DI according to DF and the width of the data being transferred— It does not modify flags8-17
Page 1 and 2: ECE 424 Design of Microprocessor-Ba
Page 3 and 4: Addressing ModesAddressing Modes Im
Page 5 and 6: Flags Commonly Tested During the Ex
Page 7 and 8: What is a Stack ?Instructions for S
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: String Instructions MOVSB (MOVSW)

8088/8086 Instruction I

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