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Masking Selected Interrupts from Selected Input/ Output Devices

IP.com Disclosure Number: IPCOM000087335D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Callahan, RW: AUTHOR [+2]

Abstract

A method is described for reducing unwanted interrupts from input/output (I/O) devices attached to data processor I/O channels. The masking of unwanted status is controlled on a device basis by passing an interrupt mask to the channel by means of the channel address word (CAW) at Start I/O (SIO) time.

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Masking Selected Interrupts from Selected Input/ Output Devices

A method is described for reducing unwanted interrupts from input/output (I/O) devices attached to data processor I/O channels. The masking of unwanted status is controlled on a device basis by passing an interrupt mask to the channel by means of the channel address word (CAW) at Start I/O (SIO) time.

The drawing shows a standard IBM System/37O I/O channel address word, wherein bits 4 through 7 have been modified to contain a mask for controlling interrupts. If the mask bit is a one, the particular bit corresponding to a particular status from a device is inhibited from causing an I/O interrupt to the system. If the mash bit is a zero, then the corresponding status bit is allowed to cause an interrupt.

As part of the improved channel mechanism being described herein, the I/O channel, upon receiving status from a device, will examine this interrupt mask, kept in the subchannel, to determine if an interrupt for that particular status condition should be attempted. Any unwanted status interrupt condition is saved in the subchannel until a desired status condition is received from the device.

As an example, a user who is doing printer output may state in his user options (software) that he wants device end posting and not channel end posting. The Input/Output Supervisor (IOS) software would, at start time to that device, instruct the channel, by means of the interrupt mask in the CAW, not to interrupt with channel end status. The channel would save the channel end in the subchannel, and upon receiving device end from...