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Direct Line Control in a Communications Multiplexor

IP.com Disclosure Number: IPCOM000075645D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Zvaigzne, G: AUTHOR

Abstract

In communication multiplexors, the need arises to transfer information under program control directly to a line control word associated with each multiplexed communication line. Since this line control word is not normally program accessible, the control is accomplished in the following manner.

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Direct Line Control in a Communications Multiplexor

In communication multiplexors, the need arises to transfer information under program control directly to a line control word associated with each multiplexed communication line. Since this line control word is not normally program accessible, the control is accomplished in the following manner.

During the multiplexing operation, a unit control word is fetched from main storage at the same time that the line control word for the communication line is available to common control hardware. The programmer sets a configuration of control bits in the unit control word, which are decoded as part of the normal scanning process. Since the line control word is available at the same time, control bits from the unit control word are transferred directly to the line control word under control of the bits set in the unit control word. Thus, the line characteristics are programmed under program control by this technique of transferring control information from a line control word accessible by the main memory to a line control word, that is only accessible by the common communications line control hardware. This technique is used more generally to program control the line characteristics such as character length, line type, and stop bit configuration. This eliminates the need for plug cards or hard wiring in line adapter circuitry. It is also possible to use alternate configurations of unit control word control bits to control...