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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode LTR</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="LSL.htm"> LSL Load Segment Limit</A><BR><B>next:</B><A HREF="MOV.htm"> MOV Move Data</A><P><HR><P><H1>LTR -- Load Task Register</H1><PRE>Opcode Instruction Clocks Description0F 00 /3 LTR r/m16 pm=23/27 Load EA word into task register</PRE><H2>Description</H2>LTR loads the task register from the source register or memory locationspecified by the operand. The loaded task state segment is marked busy.A task switch does not occur.<P>LTR is used only in operating system software; it is not used inapplication programs.<H2>Flags Affected</H2>None<H2>Protected Mode Exceptions</H2>#GP(0) for an illegal memory operand effective address in the CS, DS,ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment;#GP(0) if the current privilege level is not 0; #GP(selector) if the objectnamed by the source selector is not a TSS or is already busy;#NP(selector) if the TSS is marked "not present"; #PF(fault-code) fora page fault<H2>Real Address Mode Exceptions</H2>Interrupt 6; LTR is not recognized in Real Address Mode<H2>Virtual 8086 Mode Exceptions</H2>Same exceptions as in Real Address Mode<H2>Notes</H2>The operand-size attribute has no effect on this instruction.<P><HR><P><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="LSL.htm"> LSL Load Segment Limit</A><BR><B>next:</B><A HREF="MOV.htm"> MOV Move Data</A></BODY>⌨️ 快捷键说明
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