PC Ext: Overlay Files and How They Work

Last reviewed: October 29, 1994
Article ID: Q101750
The information in this article applies to:
  • Microsoft Mail for PC Networks, version 3.2

The External Mail program (EXTERNAL.EXE) included with version 3.2 of Microsoft Mail for PC Networks introduces overlay files to control different forms of communication. These files are loaded into extended memory and introduce the need for EXTERNAL.EXE to be stored on the local computer.

There are three overlay files, which provide the following functions:

  • The AYSNC.OVL file controls asynchronous communication.
  • The X25EICON.OVL file controls communication with the Eicon X.25 card.
  • The X25ATLAN.OVL file controls communication with the Atlantis X.25 card.

The External Mail program must load one of these overlay files because these files contain shared code for the Mailer and Dispatch processes to distribute messages on the network.

By loading this part of the process into extended memory, more postoffices can be controlled by the External Mail program, thus getting around the memory constraints of version 3.0 of the External Mail program.


Additional reference words: 3.20
KBCategory: kbenv
KBSubCategory: MailPCExt


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.

Last reviewed: October 29, 1994
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.