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Communication Bus Repowering Circuit

IP.com Disclosure Number: IPCOM000046228D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Austruy, P: AUTHOR [+2]

Abstract

The circuit shown in the drawing is to be used in connection with a communication bus making the connection between a central control unit (CCU) and adapters, for repowering the bus.

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Communication Bus Repowering Circuit

The circuit shown in the drawing is to be used in connection with a communication bus making the connection between a central control unit (CCU) and adapters, for repowering the bus.

The communication bus is a bidirectional bus for transfering data and associated control tags between the CCU and adapters. The OUT tags indicate in which way the bus must be repowered.

For a data transfer from CCU to an adapter, the +R/-W line is negative, and data from the CCU are transferred to the adapter. The Logic Redrive Circuit generates a DIR (Disable Inbound Receiver) signal which allows the data to be sent to the Logic Redrive Circuit through NAND gate 1. The Logic Redrive Circuit performs a parity check.

For a transfer of data from the adapter to the CCU, the +R/-W line is positive, data from adapter must be repowered to the CCU by NAND gates 1 and 2. The Logic Redrive Circuit checks data parity.

A disable command is sent to the Logic Redrive Circuit, which makes inactive the DIR signal. The +R/-W line is positive, and the redrive data are sent to the CCU by NAND gate 2. The adapter bus is isolated during the time of data transfer.

Adapter isolation may be accomplished in two ways:

- Through a disable command sent to the Logic Redrive Circuit, the adapter cannot answer to a command but the Logic Redrive Circuit is able to answer, or through a jumper which inhibits the adapter and the Logic Redrive Circuit from answering any command.

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