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<!doctype HTML public "-//W3O//DTD W3 HTML 3.0//EN"><HTML><HEAD><TITLE>MASM / TASM compatibility</TITLE><META name="description" content="MASM / TASM compatibility"><META name="keywords" content="MASM, TASM, compatibility"></HEAD><BODY bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#007099" alink="#FF0000"><TABLE WIDTH=80%><TR><TD><FONT FACE="Verdana" SIZE=3><FONT SIZE=+2><B>MASM / TASM compatibility</B></FONT><BR><BR><BR>Syntax of <I>Emu8086</I> is fully compatible with all major assemblers including<I>MASM</I> and <I>TASM</I>; though some directives are unique to <I>Emu8086</I>. If required to compile using any other assembler you may need to comment outthese directives, and any other directives that start with a '<B>#</B>' sign:<PRE><FONT FACE="Fixedsys">#MAKE_COM##MAKE_EXE##MAKE_BIN##MAKE_BOOT#</FONT></PRE><BR><HR><BR><I>Emu8086</I> does not support the <B>ASSUME</B> directive, actually mostprogrammers agree that this directive justcauses some mess in your code. Manual attachment of <B>CS:</B>, <B>DS:</B>, <B>ES:</B>or <B>SS:</B> segment prefixes is preferred, and required by <I>Emu8086</I> when data isin segment other then <B>DS</B>. For example:<PRE><FONT FACE="Fixedsys">MOV AX, [BX] ; same as MOV AX, DS:[BX]MOV AX, ES:[BX]</FONT></PRE><BR><HR><BR><I>Emu8086</I> does not require to define segment when you compilea <B>COM</B> file, though <I>MASM</I> and <I>TASM</I> may require this,for example:<BR><BR><TABLE BORDER=1 CELLPADDING=10><TR><TD><PRE><FONT FACE="Fixedsys">CSEG SEGMENT ; code segment starts here.; #MAKE_COM# ; uncomment for Emu8086.ORG 100hstart: MOV AL, 5 ; some sample code... MOV BL, 2 XOR AL, BL XOR BL, AL XOR AL, BL RETCSEG ENDS ; code segment ends here.END start ; stop compiler, and set entry point.</FONT></PRE></TD></TR></TABLE><BR><BR>Entry point for <B>COM</B> file should always be at <B>0100h</B> (first instruction after<B>ORG 100h</B> directive), though in <I>MASM</I> and <I>TASM</I> you may need to manuallyset an entry point using <B>END</B> directive.<I>Emu8086</I> works just fine, with or without it.<BR><BR>In order to test the above code, save it into <B>test.asm</B> file (or any other) and run thesecommands from command prompt:<BR><BR>For MASM 6.0:<PRE><FONT FACE="Fixedsys"> MASM test.asm LINK test.obj, test.com,,, /TINY</FONT></PRE>For TASM 4.1:<PRE><FONT FACE="Fixedsys"> TASM test.asm TLINK test.obj /t</FONT></PRE>We should get <B>test.com</B> file (11 bytes), right click it and select <B><NOBR>Send To</NOBR></B> and <B>emu8086</B>.You can see that the disassembled code doesn't contain any directives and it is identicalto code that <I>Emu8086</I> produces even without all those tricky directives.<BR><BR><HR><BR>A template used by <I>Emu8086</I> to create <B>EXE</B> files is fully compatiblewith <I>MASM</I> and <I>TASM</I>, just comment out <B>#MAKE_EXE#</B> directiveto avoid <B>Unknown character</B> error at line <B>11</B>.<BR><BR><B>EXE</B> files produced by <I>MASM</I> are identical to those produced by <I>emu8086</I>. <I>TASM</I> does not calculate the checksum, and has slightly different EXE file structure, but itproduces quite the same machine code.<BR><BR><B>Note: </B> there are several ways to encode the same machine instructions for the 8086 CPU,so generated machine code may vary when compiled on different compilers.<BR><BR><HR><BR><I>Emu8086</I> assembler supports shorter versions of <B>BYTE PTR</B> and <B>WORD PTR</B>,these are: <B>B.</B> and <B>W.</B><BR><BR>For <I>MASM</I> and <I>TASM</I> you have to replace <B>B.</B> and <B>W.</B> with<B>BYTE PTR</B> and <B>WORD PTR</B> accordingly.<BR><BR>For example:<PRE><FONT FACE="Fixedsys">LEA BX, var1MOV WORD PTR [BX], 1234h ; works everywhere.MOV w.[BX], 1234h ; same instruction, but works in Emu8086 only.HLTvar1 DB 0var2 DB 0</FONT></PRE><HR><BR><BR></FONT></TD></TR></TABLE><BR></BODY></HTML>?? 快捷鍵說明
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