Browse Prior Art Database

Computer Controlled I/O Switch

IP.com Disclosure Number: IPCOM000078092D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Lilie, MI: AUTHOR

Abstract

There is described herein a computer controlled I/O switch, which enables several computer systems to access and share files at the device level. As shown in the figure, to perform the switching functions, there is employed a combined capability of a small computer sensor based system 10 which may suitably be a computer such as the IBM System/7, and a cross-point switch 12 which may suitably be of the solid-state type. Each channel, such as channels A and B, and each control unit, such as control units #1 and #2, terminates its system standard I/O interface consisting of bus and tag cables in a small computer multifunction module having the capability of digital input, digital output and process interrupt.

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Computer Controlled I/O Switch

There is described herein a computer controlled I/O switch, which enables several computer systems to access and share files at the device level. As shown in the figure, to perform the switching functions, there is employed a combined capability of a small computer sensor based system 10 which may suitably be a computer such as the IBM System/7, and a cross-point switch 12 which may suitably be of the solid-state type. Each channel, such as channels A and B, and each control unit, such as control units #1 and #2, terminates its system standard I/O interface consisting of bus and tag cables in a small computer multifunction module having the capability of digital input, digital output and process interrupt. The I/O modules in computer 10 are legended as "channel" modules and "control unit" modules, the distinction being that an inbound signal line to a "channel" module is an outbound signal line to a "control unit" module and vice versa. In parallel with this arrangement, the same bus and tag cables are inputs to the crosspoint switch 12 designed for interface signals.

In the operation of the arrangement, computer 10 maintains a state table of each device (module) with respect to each channel which is capable of accessing it. Computer 10 also maintains a table of control units relative to channels, in order to provide additional information on connection possibilities.

A channel indicating that access is desired to a particular device presents an interrupt to computer 10. The "channel" and "control unit" modules of computer 10 receive the interface signals as digital data, and any predetermined bit structure can be decoded to provide a process interrupt. The address of the requested device is presented by the channel and read into computer 10 on digital input lines. Computer 10 examines the...