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Q130861: IBM SNA Formats Bit Ordering is Opposite of Intel Convention

Article: Q130861
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,4.0
Operating System(s): 
Keyword(s): kbinterop kbnetwork sna4
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 4.0 
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SUMMARY
=======

In conventional Intel bit ordering, the most significant bit (MSB) is numbered 7
and the least significant bit (LSB) is numbered 0:

MSB                         LSB
7   6   5   4   3   2   1   0

In Systems Network Architecture (SNA), IBM defined the LSB and MSB to be the
opposite of the Intel convention. The MSB is numbered 0 and the LSB is numbered
7:

MSB                         LSB
 0   1   2   3   4   5   6   7

You need to consider the difference in the Intel and IBM conventions when
interpreting SNA Server traces using the IBM SNA Formats Guide (part number:
GA27-3136-10).

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

The following is a sample message in an SNA Server SNA Formats trace:

---------------------------------------------- 13:51:52.71
                     >>SEND>> EXCHANGE ID

TH: 0d0000000600

---- Data ----
                   Byte 10
                     |
                     V
326605DF FFFF0000 B0041000 00000000     <2f..............>
00010B40 00100900 00000007 00103700     <...@..........7.>
27110C08 04F0F2F0 F0F0F00F 06D4E240     <'....020000..MS@>
E2D5C140 E2C5D9E5 C5D90908 F0F0F0F0     <SNA@SERVER..0000>
F0F0F013 11031000 10F0F0F0 F0F0F0F0     <000......0000000>
F0F0F0F0 F0F00E0E F4C1D7D5 C5E34BC3     <000000..4APNETKC>
D7D6C9D5 E3C3                           <POINTC          >

Byte 10 (=0x10) above in binary is: 0001 0000. It is read from left to right.

Additional query words: prodsna

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Keywords          : kbinterop kbnetwork sna4 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210
Version           : WINDOWS:2.0,2.1,2.11,3.0,4.0

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