User's Manual

THE 80286 INSTRUCTION SET
L TR-Load Task Register
Opcode Instruction Clocks
Description
OF 00 /3
LTR ew 17,mem=19 Load EA word into Task Register
FLAGS MODIFIED
None
FLAGS UNDEFINED
None
OPERATION
The Task Register is loaded from the source register or memory location given by the operand. The
loaded TSS
is marked busy .. A task switch operation does not occ.ur.
LTR appears.only in operating systems software. It is not used in applications programs.
PROTECTED MODE EXCEPTIONS
#GP for an illegal memory operand effective address in the CS, DS, or ES segments; #SS for an illegal
address in the SS segment.
.
#GP(O) if the current privilege level is not O. #GP (selector) if the object named by the source selector
is not a TSS or is already busy. #NP (selector) if the TSS is marked not present.
REAL ADDRESS MODE EXCEPTIONS
Interrupt 6; L TR is not recognized in Real Address mode.
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