copy

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=50 BGCOLOR="#333366" TEXT="#080000"> <div> <B>copy</B></div> <div> </div> </td> </tr><tr> <td valign="top" width=165 BGCOLOR="#CCCC99" TEXT="#080000"> <div> <B> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="1" WIDTH="132" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 35 ><NOBR><div> <A HREF="id808.htm" TARGET="_top" TITLE="block"><U><B><IMG SRC="003151d0.gif" border=0 width="21" height="29" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id810.htm" TARGET="_top" TITLE="more"><U><B><IMG SRC="004151d0.gif" border=0 width="21" height="29" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> </NOBR></tD> <tD VALIGN=TOP WIDTH="20"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="35" ALIGN="bottom" WIDTH="20" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP><NOBR><div> <A HREF="id797.htm" TARGET="_top" TITLE="block copy more next"><U><B><IMG SRC="0c80d1d0.gif" border=0 width="13" height="29" ALT="up" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></B></U></A></div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> <IMG BORDER="0" SRC="1x1.gif" HEIGHT="29" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" WIDTH="27"></div> </NOBR></tD> </tR> </TABLE></B></div> <div> <A HREF="tanenbaum__1987__operating_systems.htm" TARGET="_top" TITLE="Operating Systems"><U><B>Tanenbaum [1987] Operating Systems</B></U></A></div> <bR> </td> <td valign="top" height=430 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="477" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="VOID" RULES="COLS" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 142 WIDTH="180"><div>      test cx,*0x0001</div> <div>      jz L5</div> <div>      rep</div> <div>      movb</div> <div>      jmp L6</div> <bR> <div> L5:     shr cx,*1</div> <div>      rep</div> <div>      movw</div> </tD> <tD VALIGN=TOP><NOBR><div> should we copy a byte or a word at a time?</div> <div> jump if even</div> <div> copy 1 byte at a time</div> <div> byte copy</div> <div> check for more bytes</div> <bR> <div> word copy</div> <div> copy 1 word at a time</div> <div> word copy</div> </NOBR></tD> </tR> </TABLE></div> <bR> <div> <IMG SRC="2a6e14b0.gif" border=0 width="481" height="331" ALT="VISIO 5 Drawing" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </td> </tr></table></body>