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Code Independent Message Framing Format

IP.com Disclosure Number: IPCOM000083594D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Donnan, RA: AUTHOR

Abstract

Code independent line control procedures using framing formats are known. These use the same framing code to delineate the beginning or end of the transmission. In some instances, it may be desirable to provide different beginning and ending delimiters, to thus indicate unambiguously by the code received at the start and end of a message.

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Code Independent Message Framing Format

Code independent line control procedures using framing formats are known. These use the same framing code to delineate the beginning or end of the transmission. In some instances, it may be desirable to provide different beginning and ending delimiters, to thus indicate unambiguously by the code received at the start and end of a message.

A character such as 1111110 may be utilized as a start of message (SOM) delimiter. This pattern must not occur in the body of the message and is prevented from occurring by inserting a 0 bit within the body of the message, in the event that five contiguous 1 bits are encountered across or within a character boundary. The end of message (EOM) delimiter may conveniently have a 1 bit followed by six 0 bits and a 1 bit (10000001). In order that the end of message pattern not occur in the body of the message, a 1 bit must be inserted within the data stream following the occurrence of any five contiguous 0 bits. These two patterns provide a code independent means for designating the start of message and end of message.

Using the above-described start of message and end of message codes, a multiple segment message may be transmitted as follows: SOM (Data Segment) SOM (Data Segment) EOM.

In addition, since there is a 1 bit insertion following five contiguous 0 bits and a 0 bit insertion following five contiguous 1 bits within the data stream, a transitionless period greater than five bit times wil...