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Data Transfer between Intelligent Terminal Controller Systems and a General Purpose Computer Channel

IP.com Disclosure Number: IPCOM000087132D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Opdahl, R: AUTHOR [+3]

Abstract

Additional functions can be provided across a general-purpose computer channel, without changing the channel architecture, by treating the existing I/O interface comprising channel commands status and sense information as a set of primitives and defining linear combination of those primitives to indicate the new functions.

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Data Transfer between Intelligent Terminal Controller Systems and a General Purpose Computer Channel

Additional functions can be provided across a general-purpose computer channel, without changing the channel architecture, by treating the existing I/O interface comprising channel commands status and sense information as a set of primitives and defining linear combination of those primitives to indicate the new functions.

Using the traditional channel architecture, a control unit sent data to the computer by raising an asynchronous interrupt with attention status, which was acted upon by the I/O supervisor (IOS) of the computer operating system to schedule a channel program, which in turn could only read a predetermined number of bytes of data. In those cases where the control unit had more data, additional asynchronous interrupts are necessary and the entire process of scheduling IOS and a channel program must be repeated.

By defining a synchronous attention status function, which is presented with channel end, device end and unit exception, the IOS can act upon the attention status while it is already in control servicing the previous data transfer end interrupt to iteratively reschedule the same read channel command word program, without the need for a separate attention interrupt and attendant overhead at the host computer and at the intelligent controller occasioned by asynchronous attention status.

The synchronous attention status defined above can also be...