Browse Prior Art Database

Channel To Channel Adapter for I/O Interface Switching

IP.com Disclosure Number: IPCOM000074072D
Original Publication Date: 1971-Mar-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 3 page(s) / 33K

Publishing Venue

IBM

Related People

Cormier, R: AUTHOR [+2]

Abstract

The present system implements channel-to-channel communication by making use of the I/O interface switching provisions that are required for the systems to pool I/O devices and share a data base. I/O interface switching is provided, by an addressable interface crosspoint switch whereby one or more channel-to-channel adapters are rendered switchable so that any one of them may be used on demand for establishing a channel-to-channel communication link between any two systems connected to the switch.

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Channel To Channel Adapter for I/O Interface Switching

The present system implements channel-to-channel communication by making use of the I/O interface switching provisions that are required for the systems to pool I/O devices and share a data base. I/O interface switching is provided, by an addressable interface crosspoint switch whereby one or more channel-to-channel adapters are rendered switchable so that any one of them may be used on demand for establishing a channel-to-channel communication link between any two systems connected to the switch.

The present system changes the design of a standard channel-to-channel adapter. When System A needs to send a message to System B, it connects one side of the adapter to one of the channels on A. System A then issues an I/O command (via a SIO) to the adapter in such a way that the Reserve/Release Feature in the switch makes the connection to System B (or whichever one A indicates) dynamically.

By way of example, suppose there are four different systems each having a channel connected to a crosspoint switch as indicated in the Figure. The diagonal lines at the crosspoint switch intersections indicate the static "configuration" of the switch which defines the allowable dynamic connections. One side of the adapter is connected to an interface that is configured to every channel (at least one per system). Suppose that on that same interface Channel A has Reserved Device address a, Channel B has Reserved Device address b, etc. Here a, b, c, d are unique device addresses and, in fact, all belong to the adapter. The design of the adapter is altered so that it accepts commands issued using any of the four (in this case) device addresses. Both sides of the adapter use the same four addresses except in the bits which are required to distinguish the interface.

One side of the adapter responds to any one of the device addresses a, b, c, or d and the other side to a*, b*, c*, or d* where a and a* differ only in their interface bits.

Whenever the adapter sends an attention interrupt to the channel on one side due to a co...