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.
8-72
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