Q83087: FIX: MASM Moves Segment Register w/out Generating Error

Article: Q83087
Product(s): Microsoft Macro Assembler
Version(s): 6.0,6.0a,6.0b,6.1,6.1a
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 6.0, 6.0a, 6.0b, 6.1, 6.1a 
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SYMPTOMS
========

Microsoft Macro Assembler (MASM) may move a segment register instead of
generating an error on an invalid code statement. In the following example, the
statement:

     mov bx, es[1234h]

should generate an error. However, MASM treats the statement as:

     mov bx, es

and thus does not generate the code that may be expected. The code that the user
anticipated being generated was:

     mov bx, es:[1234h]

STATUS
======

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, 6.0b,
6.1, and 6.1a. This problem was corrected in MASM for MS-DOS version 6.11.

MORE INFORMATION
================

The following program should generate two assembler errors but does not:

Sample Code
-----------

  ; Assemble options needed: none

  .MODEL small
  .386
  .STACK 4096

  .CODE
  start:
     mov bx,es[1234h]     ; This should generate an error.
     mov es[1234h],bx     ; This should generate an error.
     mov ax, 4C00h
     int 21h
  END start

Additional query words: 6.00 6.00a 6.00b 6.10 6.10a buglist6.00a buglist6.00b buglist6.10 buglist6.10a fixlist6.11

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Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600 kbMASM610 kbMASM610a kbMASM600a kbMASM600b
Version           : :6.0,6.0a,6.0b,6.1,6.1a
Solution Type     : kbfix

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