Browse Prior Art Database

Prevention of Retransmission of Display in Multiaccess Display Network

IP.com Disclosure Number: IPCOM000088094D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Trewin, JH: AUTHOR

Abstract

In the environment of a network of display stations linked by a shared cable, as described in the IBM Technical Disclosure Bulletin, Vol. 18, No. 2, July 1975 pp. 513-514, (in which interleaved station address information and display data is passed over the cable, from a common control node to plural display stations at certain times, and data/ request information is passed back over the cable from the stations to the control node at other times), it is necessary to prevent signals from returning to their sources. A circuit providing appropriate isolation is shown above.

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Prevention of Retransmission of Display in Multiaccess Display Network

In the environment of a network of display stations linked by a shared cable, as described in the IBM Technical Disclosure Bulletin, Vol. 18, No. 2, July 1975 pp. 513-514, (in which interleaved station address information and display data is passed over the cable, from a common control node to plural display stations at certain times, and data/ request information is passed back over the cable from the stations to the control node at other times), it is necessary to prevent signals from returning to their sources. A circuit providing appropriate isolation is shown above.

Incoming display data (from the control unit) is channeled via a selected driver circuit (D1, D2,...DN) and line (L1, L2...LN) to a respective display station designated by the address information (interleaved with the data). Address detection circuit 3 selects the driver circuit and passes the data, slightly delayed by delay stage 5, to the selected circuit. The undelayed data is inverted by circuit 7 and stretched by circuit 8 to provide REFLECTION BLOCKING pulses 9 to NOR-circuit 11.

Data from the display stations (at other discrete times) passes to the control node via respective lines (L1, L2...LN), receiver/repeater circuit stages (R1, R2...RN) and respective inputs of NOR-circuit 11. At such times the REFLECTION BLOCKlNG Input enables 12. Thus the signals from the display stations pass freely to the control node via NOR...