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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- Instruction Set --><HTML><HEAD><TITLE>The 8051 Instruction Set</TITLE></HEAD><BODY BACKGROUND="spiral.gif" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#990099" ALINK="#FF0000"><TABLE WIDTH="98%"><TR><TD WIDTH=60 VALIGN=BOTTOM NOWRAP><IMG SRC="transp.gif" ALT="" WIDTH=60 HEIGHT=20></TD><TD><!-- Ab hier Seitentext: --><BIG><BR><P><STRONG><U>III.5 The 8051 Instruction Set</U></STRONG></P><P><NOBR>ASEM-51</NOBR> implements all 8051 machine instructions includinggeneric jumps and calls. The assembler implements two instructions</P><P><BLOCKQUOTE><STRONG><PRE>JMP <address>CALL <address></PRE></STRONG></BLOCKQUOTE></P><P>that do not represent a specific opcode: generic jump and call.These instructions will always evaluate to a jump or call, not necessarilythe shortest, that will reach the specified address.<BR>JMP may assemble to SJMP, AJMP or LJMP, while CALL can only evaluate toACALL or LCALL. Note that the assembler decision may not be optimal. Forcode addresses that are forward references, the assembler always generatesLJMP or LCALL respectively. However, for backward references this is apowerful tool to reduce code size without extra trouble.</P><P>With the $PHILIPS control, <NOBR>ASEM-51</NOBR> can be switched to the reducedinstruction set of the Philips 83C75x family of microcontrollers. This disablesthe LJMP, LCALL, and MOVX instructions as well as the XDATA and XSEG pseudoinstructions, and generic jumps and calls will always assemble to absoluteaddressing.</P><P>The rest of the 8051 instruction mnemonics is listed in<A HREF="append_d.htm">Appendix D</A>.Appendices <A HREF="append_i.htm">I</A> and <A HREF="append_j.htm">J</A> arecontaining tables of all 8051 instructions with their opcodes, mnemonics,arguments, lengths, affected flags and durations.The comprehensive example program DEMO.A51 provided shows all the 8051instructions in a syntactical context.</P><P>For detailed information on the Intel <NOBR>MCS-51</NOBR> architecture andinstruction set refer to the<A HREF="mcs51man.htm">MCS® 51 Microcontroller Family User's Manual</A>.(Requires full Internet access!)</P><P>All <NOBR>MCS-51</NOBR> instruction mnemonics are copyright © byIntel Corporation!</P></BIG><!-- Seitentext Ende --><P><BR><BR><CENTER><TABLE WIDTH="70%"><TR><TH><A HREF="contents.htm"><IMG SRC="home.gif" ALT="[contents]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH> <TH><A HREF="language.htm"><IMG SRC="up.gif" ALT="[up]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH> <TH><A HREF="express.htm"><IMG SRC="back.gif" ALT="[back]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH> <TH><A HREF="pseudo.htm"><IMG SRC="next.gif" ALT="[next]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH></TR></TABLE></CENTER></P></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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