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Control Unit and Terminals on a Four Wire Circuit

IP.com Disclosure Number: IPCOM000090725D
Original Publication Date: 1969-Jun-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Doss, MW: AUTHOR [+3]

Abstract

This is a data line and control unit to enable use of a pair of two-wire send or receive terminals on a four-wire circuit having one wire pair for sending and one pair for receiving. The terminals are not capable of sending and receiving simultaneously. Thus, each requires a character interval after receipt of a character on the receiving circuit to enable assembly of an appropriate response character and the transmittal of the response character on the sending circuit. During this transmittal interval, the terminal is not receptive to signals on the receiving circuit so the control unit does not transmit a starting signal for the other connected terminals. The control unit therefore idles for one character interval between each data character.

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Control Unit and Terminals on a Four Wire Circuit

This is a data line and control unit to enable use of a pair of two-wire send or receive terminals on a four-wire circuit having one wire pair for sending and one pair for receiving. The terminals are not capable of sending and receiving simultaneously. Thus, each requires a character interval after receipt of a character on the receiving circuit to enable assembly of an appropriate response character and the transmittal of the response character on the sending circuit. During this transmittal interval, the terminal is not receptive to signals on the receiving circuit so the control unit does not transmit a starting signal for the other connected terminals. The control unit therefore idles for one character interval between each data character.

As in the drawing, the control unit transmits an addressed data character for a terminal A. This character is received by both terminals A and B after a delay due to transmission time. Only the addressed terminal A accepts the character. It answers during the idle character transmission time. After the idle time, the control unit transmits a data character addressed to terminal B. The start of this character is transmitted before terminal A completes its transmission. This causes no interference since it is not received until terminal A completes its character. There is an overlap at the control unit between the character being sent to one terminal and that being received f...