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Multipath Channel to Channel Adapter Cross Point Switch

IP.com Disclosure Number: IPCOM000048135D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Firth, SR: AUTHOR [+4]

Abstract

A multipath channel to channel adapter (CCA) is a control unit that allows interprocessor communication through I/O channels (Fig. 1). It provides the control and the data paths to allow any attaching processor to communicate with any other attaching processor. In a simple CCA, only two channels communicate and the interfacing problem is small. However, as the number of attaching channels increase, the problems of connecting pairs of channels grow larger. A simple interface is required to reduce product and maintenance costs. In addition, this interface has to be capable of a high speed data transfer. Channels that implement the data streaming feature will communicate with each other through the adapter at high data rates.

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Multipath Channel to Channel Adapter Cross Point Switch

A multipath channel to channel adapter (CCA) is a control unit that allows interprocessor communication through I/O channels (Fig. 1). It provides the control and the data paths to allow any attaching processor to communicate with any other attaching processor. In a simple CCA, only two channels communicate and the interfacing problem is small. However, as the number of attaching channels increase, the problems of connecting pairs of channels grow larger. A simple interface is required to reduce product and maintenance costs. In addition, this interface has to be capable of a high speed data transfer. Channels that implement the data streaming feature will communicate with each other through the adapter at high data rates.

Furthermore, a multipath CCA needs to be expandable to permit attachment of additional channels. Generally, the addition of features to channels and control units is a long and involved procedure. Different hardware and part numbers are required for each feature. A Multipath Channel to Channel Adapter Cross-Point Switch that solves the interconnection problems is provided. It consists of a generalized symmetric interface capable of handling a variety of channel types. The design as embodied in the multipath CCA is described below.

Each channel attaches to a port on the CCA. A port consists of the hardware necessary to handle interface sequences for that channel and a data register (IFC register). Each port is capable of a WRITE or a READ depending on the direction of data transfer. The port sending data to a channel during data transfer is designated the READ port, because the channel is executing a READ command. Conversely, the port receiving data from a channel is called the WRITE port. The designators READ and WRITE are always in reference to the attached channel.

Besides connecting to a channel, each port also connects to the port to port interface (XPS) (Fig. 2). Logically, the XPS is a cross-point switch that provides the ability for a port to communicate with any other port for data transfer. The XPS is implemented as a bidirectional bus that is shared among all ports. The bus consists of eight data lines, one parity bit and three control signals: Request, response, and stop. A port participating in data transfer gates the proper drivers and receivers in order to communicate with an...