Browse Prior Art Database

Transparency Feature for Start/Stop Communication

IP.com Disclosure Number: IPCOM000077573D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Cedarholm, JP: AUTHOR [+4]

Abstract

This description is directed to start/stop data transmission systems, wherein certain character codes are used at the receiving station for control purposes. Described is a technique that permits text containing these codes (which are not intended as control) to be transmitted through control portions of the system without causing undesirable effects, and without modifying existing communication control hardware.

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This is the abbreviated version, containing approximately 71% of the total text.

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Transparency Feature for Start/Stop Communication

This description is directed to start/stop data transmission systems, wherein certain character codes are used at the receiving station for control purposes. Described is a technique that permits text containing these codes (which are not intended as control) to be transmitted through control portions of the system without causing undesirable effects, and without modifying existing communication control hardware.

This technique permits text containing any bit patterns to be communicated among any arbitrary number of stations, operating under one of a number of different start/stop line control disciplines. A specific example of importance, is the transmission of ciphertext between a terminal and a central processing unit (CPU) through a transmission control unit. In this particular case, if the code character is accidentally contained in the ciphertext, it would be detected by the receiver and the transmission could be prematurely terminated or modified.

The general technique proposed is to examine all character codes developed at the transmitter, detect each troublesome character, change its code to an acceptable code, and interpolate a specially selected acceptable character (a flag) directly ahead of it in the character transmission sequence. At the receiver, all incoming characters are scanned and each flag character is detected. This flag is deleted from the text and the character immediately following it is...