Q75178: FIX: ASSUME Using SEG on Communal Far Data Item

Article: Q75178
Product(s): Microsoft Macro Assembler
Version(s): MS-DOS:5.10,5.10a,6.0
Operating System(s): 
Keyword(s): 
Last Modified: 04-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 5.10, 5.10a, 6.0 
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SYMPTOMS
========

When the ASSUME directive uses the SEG operator on a communal far data item in
the Microsoft Macro Assembler (MASM) versions 5.1, 5.1a, and 6.0, it may
generate an error incorrectly. The statement "cmp dog, 0" in the sample code
below incorrectly generates the following message when assembled with MASM 5.1
or 5.1a:

  A2068: Cannot address with segment register

MASM 6.0 incorrectly generates the following message:

  A2074: cannot access label through segment registers

RESOLUTION
==========

The following workarounds may be used to eliminate the error messages:

1. Use the segment name instead of the SEG operator on a label, such as "ASSUME
  ds:FAR_DATA" instead of "ASSUME ds:SEG dog".

2. Specify the segment register along with the label, such as "cmp ds:dog, 0"
  instead of "cmp dog, 0".

3. With MASM 6.0, specify that the communal data is far, such as "COMM FAR
  dog:BYTE instead of "COMM dog:BYTE".

STATUS
======

Microsoft has confirmed this to be a problem in MASM versions 5.1, 5.1a, and
6.0. This problem was corrected in MASM version 6.0a.

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

The following sample code can be used to demonstrate the problem.

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

  ; Assemble options needed: none

  .MODEL large, C

  .FARDATA
  COMM dog:BYTE

  .CODE
  cat PROC
      ASSUME ds:SEG dog
      mov ax, SEG dog
      mov ds, ax
      cmp dog, 0
      ret
  cat ENDP
  END

Additional query words: 5.10 5.10a 6.00 buglist5.10 buglist5.10a buglist6.00 fixlist6.00a

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Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600
Version           : MS-DOS:5.10,5.10a,6.0
Solution Type     : kbfix

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