DOCUMENT:Q92609  06-MAY-2001  [masm]
TITLE   :PRB: SEGMENT AT Does Not Initialize Data at Absolute Address
PRODUCT :Microsoft Macro Assembler
PROD/VER::5.0,5.1,5.1a,6.0,6.0a,6.0b
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Macro Assembler (MASM), versions 5.0, 5.1, 5.1a, 6.0, 6.0a, 6.0b 
-------------------------------------------------------------------------------

SYMPTOMS
========

When the SEGMENT directive is used with the AT combine type to place code or
initialized data at an absolute address, the generated executable file does not
initialize the segment at the specified absolute address. MASM versions 5.0,
5.1, and 5.1a do not generate any error or warning messages. MASM versions 6.0,
6.0a, and 6.0b generate the following warning message:

   A4014: instructions and initialized data not supported in AT

   segments

CAUSE
=====

This warning is expected and caused by the design of the Microsoft Linker.

The Microsoft Linker (LINK), distributed with Microsoft programming languages, is
designed to generate relocatable programs to run with MS-DOS, Microsoft Windows,
or OS/2. LINK does not generate code or data at absolute addresses. MASM
versions 6.0, 6.0a, and 6.0b generate a warning message because LINK does not
support SEGMENT AT in this manner.

RESOLUTION
==========

Link and locate tools that generate absolute addresses are available from
third-party vendors.

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

The SEGMENT AT directive is used to access a specified memory address, for
example, a code routine or data in the ROM BIOS. While SEGMENT AT allows an
application to create a template for memory at a fixed address, it does not
support initializing code or data at that address.

The code fragment below demonstrates the problem.

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


   ; Assembler options needed: none

   interrupt_table SEGMENT AT 0
   ORG 8*4
   irq0 DD 12345678h
   irq1 DD 9ABCDEF0h
   interrupt_table ENDS

   _text SEGMENT WORD PUBLIC 'CODE'
   ASSUME cs:_text
   start:
       mov ax, 4C00h
       int 21h
   _text ENDS

   END start

Additional query words: 5.00 5.10 5.10a 6.00 6.00a 6.00b romable code embedded systems

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM600 kbMASM500 kbMASM600a kbMASM510a kbMASM600b
Version           : :5.0,5.1,5.1a,6.0,6.0a,6.0b

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.