Amdahl Corporation

David H Lin

Matthew G Noel

James E Brogan

A channel time-out apparatus in a data processing system having a channel processor for controlling the allocation of a plurality of input/output channels. The channel time-out apparatus comprises a clock for generating time indications, an address generator for generating an address for each input/output channel of the plurality of input/output channels, a time-out generator for generating a time-out indicator for an input/output channel whenever that input/output channel processes an instruction, storage for storing the last time-out indicator generated by the time-out means for each input/output channel and a comparator for comparing the last time-out indicator stored in the storage for the input/output channel whose address is presently being generated by the address generator with a time indicator presently being generated by the clock for determining when a time-out event has occurred without requiring intervention by the processor.

Method and apparatus for indicating a time-out by generating a time

An apparatus and method for processing channel time-out for input/output channels in a data processing system. A counting device is provided which cycles through a count indicative, in a first part, of each of a plurality of channels in the data processing system and, in a second part, a sequence of time indications. A time indication is saved for a particular channel upon the execution of an instruction for that channel and subsequent comparisons are made of the stored time indication and the present time indication to determine if a difference in these two time indications is sufficient to constitute a time-out.

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Santa Clara, CA, United States of America

David H Lin