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Q194872: XGEN: How EBCDIC to ASCII Translation Takes Place

Article: Q194872
Product(s): Microsoft Exchange
Version(s): WinNT:5.0,5.5
Operating System(s): 
Keyword(s): 
Last Modified: 16-MAY-1999

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The information in this article applies to:

- Microsoft Exchange Server, versions 5.0, 5.5 
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SUMMARY
=======

The connector gateways that communicate with mainframe systems (such as PROFS)
must be able to translate ASCII characters to EBCDIC and back to ASCII. This
article documents how this process occurs.

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

If the host attempts to send the letter D (which is C4 in EBCDIC), it has to
find the ASCII equivalent of the letter D in special files representing the
codepages in use on either system. The connector opens the proper host to
Exchange Server file, accesses the offset of 000000C4, looks up the value in the
column (the value is 44), and translates the character to 44, which is the ASCII
representation of the letter D.

There are eight such files located in the Exchsrvr\Connect\Exchconn directory
that contain the character mappings. These files are:

  1252_256.csm Exchange -> host
  1252_500.csm Exchange -> host
  850_256.csm Exchange -> host
  850_500.csm Exchange -> host
  256_1252.csm host -> Exchange
  500_1252.csm host -> Exchange
  256_850.csm host -> Exchange
  500_850.csm host -> Exchange

Note that the files are in pairs for each direction. The file names represent the
codepages in use on either system. If a file that is for Exchange --> host is
opened in a regular hex editor (that only knows ASCII) the values in the right
column will be incorrect. This is because the editor is attempting to read them
as ASCII while they are the EBCDIC representations).

If a file is opened in a hex editor (a snippet from 256_1252.csm is given below)
the right column shows the character to be translated and the byte columns in
the middle show the resulting character with the plain-text representation on
the far right.

NOTE: The following example should be one line:

000000C0  7B 41 42 43 44 45 46 47  48 49 AD F4 F6 F2 F3 F5
{ABCDEFGHI......

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Keywords          :  
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbZNotKeyword2
Version           : WinNT:5.0,5.5
Issue type        : kbhowto

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