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Control Unit With Means for Automatically Switching the Connections of Select in and Select Out for Controlling Priority Sequence

IP.com Disclosure Number: IPCOM000046472D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Eskay, RA: AUTHOR [+3]

Abstract

A control unit of a data processing system has a semiconductor switch system that connects the selection circuit between either of two pairs of selection ports and makes a direct connection between the other pair. The apparatus is similar to the semiconductor switches that are used for bypassing the selection circuit in case the control unit is to be disconnected from the system. Maintenance personnel electronically signal the control unit to connect the selection circuits and the jumper connection between the ports in a selected configuration. Alternatively, the processor computes a priority sequence for the control units and signals each unit to make the corresponding connections to the selection ports.

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Control Unit With Means for Automatically Switching the Connections of Select in and Select Out for Controlling Priority Sequence

A control unit of a data processing system has a semiconductor switch system that connects the selection circuit between either of two pairs of selection ports and makes a direct connection between the other pair. The apparatus is similar to the semiconductor switches that are used for bypassing the selection circuit in case the control unit is to be disconnected from the system. Maintenance personnel electronically signal the control unit to connect the selection circuits and the jumper connection between the ports in a selected configuration. Alternatively, the processor computes a priority sequence for the control units and signals each unit to make the corresponding connections to the selection ports.

In some data processing systems, a group of control units for I/O devices is connected to a selection line in a physical sequence that determines the priority sequence of the units. The selection line runs from the processor through each unit and back to the processor and it is called "select in" where it enters the processor or a unit and "select out" where it leaves the processor or a unit. Each unit has two pairs of ports for select in and select out, and the selection line passes through each unit twice. Selection circuits are located between the ports of one pair, and a jumper is located between the ports of the other pair. The p...