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STD -- Set Direction Flag

Opcode  Instruction   Clocks    Description

FD      STD           2         Set direction flag so (E)SI and/or (E)DI
                                decrement

Operation

DF := 1;

Description

STD sets the direction flag to 1, causing all subsequent string operations to decrement the index registers, (E)SI and/or (E)DI, on which they operate.

Flags Affected

DF := 1

Protected Mode Exceptions

None

Real Address Mode Exceptions

None

Virtual 8086 Mode Exceptions

None

up: Chapter 17 -- 80386 Instruction Set
prev: STC Set Carry Flag
next: STI Set Interrupt Flag