User's Manual

THE 80286 INSTRUCTION SET
MOVS/MOVSB/MOVSW-Move Data from String
to String
Opcode Instruction
A4
MOVS mb,mb
A5 MOVS mW,mw
A4
MOVS8
A5
MOVSW
FLAGS MODIFIED
None
FLAGS UNDEFINED
None
OPERATION
Clocks
5
5
5
5
Description
Move byte [SI] to ES:[OI]
Move word [SI] to ES:[OI]
Move byte OS:[SI] to ES:[OI]
Move word OS:[SI] to ES:[OI]
MOYS copies the byte or word at [Sl]to the byte or word at ES:[DI). The destination operand must
be addressable from the ESregister;
no segment override is possible. A segment override may be used
for the source operand.
After the data movement
is made, both SI and DI are automatically advanced. If the direction flag is
o (CLD was executed), the registers increment; if the direction flag is 1 (STD was executed), the
registers decrement. The. registers increment or decrement by 1 if a byte
was moved; by 2 if a word
was moved.
MOYS can be preceded by the REP prefix for block movement of CX bytes or words. Refer to the
REP instruction for details of this operation.
PROTECTED MODE EXCEPTIONS
#GP(O) if the destination is in a non-writable segment. #GP(O) for an illegal memory operand effective
address in the
CS, DS, or ES segments; #SS(O) for an illegal address in the SS segment.
REAL ADDRESS MODE EXCEPTIONS
Interrupt 13 for a word operand at offset OFFFFH.
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